IPCS INCHEM Home


    ANNEX 5

    A PROCEDURE FOR THE SAFETY EVALUATION OF FLAVOURING SUBSTANCES

    I.C. Munro, Ph.D., FRCPath
    CanTox, Inc.
    Mississauga, Ontario
    Canada

         This paper was considered at the forty-fourth meeting of the
    Joint FAO/WHO Expert Committee on Food Additives. The conclusions of
    the Committee relating to its consideration of the paper are provided
    in the report, which has been published in the WHO Technical Report
    Series. This paper was not endorsed by the Committee, and the opinions
    expressed therein are those of the author. Comments on the approach
    outlined in the paper are invited, which should be addressed to the
    WHO Joint Secretary of JECFA, International Programme on Chemical
    Safety, 20, Avenue Appia, World Health Organization CH-1211 Geneva 27,
    Switzerland.

    ANNEX 5

    A PROCEDURE FOR THE SAFETY EVALUATION OF FLAVOURING SUBSTANCES

    Table of Contents

    1.   INTRODUCTION

    2.   CONCEPTS EMPLOYED IN THE SAFETY EVALUATION OF FLAVOURING
         SUBSTANCES
         2.1   Exposure to flavouring substances through food
         2.2   Structure-activity relationships
         2.3   Use of toxicity data

    3.   INTEGRATED METHOD FOR THE SAFETY EVALUATION OF FLAVOURING
         SUBSTANCES
         3.1   Structure-activity relationships and metabolic fate
         3.2   Integrating information on exposure and toxicity
         3.3   Evaluation criteria
         3.4   Integrating data on the consumption ratio

    4.   CONCLUSIONS

    5.   REFERENCES

    APPENDICES

    Appendix A Estimating distribution of intakes of food ingredients
               across the population

    Appendix B Substances in reference database by order of structural
               class

    1.  INTRODUCTION

         The objective of this paper is to provide a procedure that can be
    used by the Joint FAO/WHO Expert Committee on Food Additives (JECFA)
    for the safety evaluation of flavouring substances. The procedure
    extends principles and procedures recommended by IECFA in the past and
    is consistent with international concepts in safety evaluation. These
    principles have been discussed by JECFA (JECFA, 1972; 1974b; 1976a;
    1978; 1980a,b; 1982a; 1983a; 1984a; 1986; 1987a,b; 1989; 1990a; 1991a;
    1992) and have been recapitulated in a report, which outlines criteria
    for the safety evaluation of flavouring substances (WHO, 1987).

         This paper takes this previous background into account and
    provides a scientific basis for assessing the safety of flavouring
    substances used in food by presenting a procedure for evaluating this
    large group of compounds in a consistent, timely, and appropriate
    manner.

    2.  CONCEPTS EMPLOYED IN THE SAFETY EVALUATION OF FLAVOURING
        SUBSTANCES

         Criteria for the safety evaluation of flavouring substances have
    been put forward by several national and international authorities.
    Included among these are JECFA, a special Task Group convened by the
    World Health Organization (WHO, 1987), the Committee of Experts on
    Flavoring Substances of the Council of Europe (CE), the Commission of
    the European Communities' Scientific Committee for Food (SCF, 1991),
    the British Industrial Biological Research Association (BIBRA), and
    the Flavor and Extract Manufacturers' Association of the United States
    Expert Panel (FEXPAN).

         In 1987, WHO published a health criteria document entitled
     Principles of the Safety Evaluation of Food Additives and
    Contaminants in Food, which contains a discussion of principles
    related to the safety evaluation of flavouring substances. This report
    recapitulated principles previously stated by JECFA on numerous
    occasions (JECFA, 1968; 1972; 1974b; 1976a; 1978; 1980a,b; 1982a;
    1983a; 1984a; 1986; 1987a,b; 1989; 1990a; 1991a; 1992). Early on, it
    was recognized by JECFA that the safety evaluation of flavouring
    substances warranted special consideration in light of use patterns
    and typically low levels of human exposure (JECFA, 1972). This view
    also has been recognized by the (SCF) and has been recorded in their
    document entitled  Guidelines for the Evaluation of Flavorings for Use
    in Foodstuffs. 1. Chemically, Defined Flavoring Substances
    (SCF, 1991).

         In addition, several organizations including JECFA (WHO, 1987),
    FEXPAN (Woods & Doull, 1991), SCF (1991), and the Council of Europe
    (CE, 1974, 1981, 1992) have noted that knowledge of structure-activity
    relationships and metabolism plays a key role along with exposure in
    the safety evaluation of flavouring substances. In this regard, JECFA
    (WHO, 1987) has used structure-activity relationships in evaluating
    groups of structurally related flavouring substances in a homologous
    series where toxicology studies exist on only one or a few members of
    the series. Structure-activity relationships can provide a useful
    means of assessing substances that lack toxicity data based on
    structurally related substances that have adequate toxicity data.

    2.1  Exposure to flavouring substances through food

         Flavouring substances are used in processed foods and beverages
    to impart desirable organoleptic qualities and to provide the specific
    flavour profile traditionally associated with certain food products.
    Unlike many substances which are added to food to achieve a
    technological purpose, the use of flavouring substances is generally
    self-limiting and governed by the flavour intensity required to
    provide the necessary organoleptic appeal. Thus, flavouring substances
    are used generally in low concentrations resulting in human exposures
    that are very low.

         Estimates of the intake of flavouring substances by the
    population typically have involved the acquisition of data on poundage
    used in foods. Between 1970 and 1987, the U.S. National Academy of
    Sciences/National Research Council (NAS/NRC) conducted, under contract
    with the Food and Drug Administration (FDA), a series of poundage
    surveys of substances intentionally added to food (NAS, 1978, 1979,
    1984, 1989). These surveys obtained information, both from ingredient
    manufacturers and from food processors, on the poundage of each
    substance committed to the food supply and on the usual and maximum
    levels at which each substance was added to foods in each of a number
    of broad food categories.

         Estimates of flavouring substance intake in the U.S. have been
    performed in two ways. One is to assume that the total poundage
    reported in food annually is completely consumed by the total
    population. Numerous checks using data from independent sources, such
    as imports, show that, in general, the reported poundage in the survey
    accounted for only 60% of the total used. Much more detailed and
    elaborate analyses (see Appendix A) led to the conclusion that it was
    conservative but reasonable to assume that each flavouring substance
    is consumed by only 10% of the population. A second method of
    calculating intake is to combine data on the level of use in specific
    food groups with data on food consumption to calculate the intake of
    each flavouring substance. Both methods tend to overestimate human
    intakes of flavouring substances because they deal with disappearance,
    that is the amount presumed to be used in food, and take no account of
    losses and waste during food manufacture, storage, preparation and
    consumption.

         Estimating intake of flavouring substances based on level of use
    data, coupled with data on the consumption of foods, typically leads
    to substantial overestimates of intake. This is because intake data
    for food commodities are stratified into broad categories of food
    products (e.g., baked products). Thus, cardamom, ordinarily used only
    in certain types of coffee cakes, would be assumed to be present in
    all breads, rolls, cakes and pastries In extreme cases, this may lead
    to overestimates of intake which are exaggerated several hundred-fold.

         Through a series of detailed studies conducted between 1970 and
    1987 (see Appendix A) it has become clear that, while there is at
    present no perfect way to estimate intake of flavouring substances,
    poundage used provides a reasonable basis for calculating intakes. The
    intake data reported in this paper rely on annual poundage used in
    food and the estimates of intake reflect the assumptions that: i) the
    available survey data accounted for only 60% of production; and ii)
    the total amount produced is consumed by 10% of the population. Table
    1 presents the intake data for 1323 chemically defined flavouring
    substances permitted for use in the U.S. calculated in this fashion.

    As can be seen from Table 1, most flavouring substances are consumed
    in amounts of less than 1 mg/person/day. The data are taken from the
    most recent U.S. NAS/NRC survey (NAS, 1989) of poundage used in food.
    For reasons previously stated, it can be assumed that these intake
    estimates are overestimated.

         Another important factor to consider in the evaluation of human
    exposure to flavouring substances is the extent to which flavouring
    substances intentionally added to foods also occur naturally in the
    food supply. The natural presence of flavouring substances in food is
    of course not necessarily indicative of safety. For many flavouring
    substances that occur naturally in foods, such natural occurrence,
    rather than intentionally added use, is the principal component of
    human exposure. The comparison of natural occurrence to intentional
    addition has been expressed as the consumption ratio (CR) (Stofberg &
    Kirschman, 1985). A CR of greater than one indicates food predominance
    (i.e. the flavouring substance is consumed at a higher level from
    foods than as an added substance). A CR greater than 10 indicates an
    almost insignificant contribution (-10%) of the flavouring substance
    as a food additive to the total intake (Stofberg & Grundschober,
    1987). Stofberg and Grundschober (1987) calculated that out of 499
    flavouring substances, 415 (83%) were food predominant (i.e. CR > 1)
    and 309 (62%) made an insignificant contribution to the food supply
    (i.e. CR > 10). As can be seen from this analysis, the use of natural
    occurrence as part of the safety evaluation provides an important
    perspective on the impact of intentional addition of flavouring
    substances to foods.

         If a flavouring substance is one of the few that for any reason,
    including high intake, is of relatively high safety concern, then a
    high consumption ratio likely enhances that concern because it
    indicates a much larger and uncontrolled exposure from natural
    occurrence than from intentional addition. If, on the other hand, a
    flavouring substance is one of the vast majority that have few, if
    any, safety issues and consequently low inherent concern, then a high
    consumption ratio reduces any concern still further because it
    indicates that intentionally added use is trivial. Stated in another
    way, if the added use of a flavouring substance amounts to less than
    10% of its natural occurrence, this would indicate a minimal safety
    concern about added use. If added use is < 1% of natural use (i.e. CR
    > 100) then the added use can at most be of trivial safety concern.

    2.2  Structure-activity relationships

         Toxicity is dependent on the chemical structure of a substance,
    its pharmacokinetics, and its metabolic reaction pathways. Available
    metabolic pathways are usually dose-dependent and, to a large extent,
    govern the magnitude of the toxic effect. Therefore, chemical
    structure, pharmacokinetics, metabolic fate and dose are key
    determinants of toxicity and play a critical role in safety evaluation
    of flavouring ingredients.

    Table 1.  Number of flavouring substancesa within various intake
              categories
                                                                        

    Intake categoryb                                     Cumulative
    (g/day)                   No. of flavours           frequency
                                                         (% of total)
                                                                        

    < 0.01                     349                       26
    0.01-0.1                   93                        33
    0.1-1                      274                       54
    1-10                       224                       71
    10-100                     204                       86
    100-1000                   111                       95
    1000-10 000                45                        98
    10 000-100 000             16                        99
    100 000+                   7                         100

    TOTAL                      1323
                                                                        

    a    Chemically defined flavouring substances permitted for use in the
         U.S. excluding botanicals.

    b    Intake data calculated assuming: survey poundage reflects 60% of
         actual usage, 10% of population exposed, U.S. population in 1987
         was 240 million. Formula: Intake (g/person/day) = [(annual
         flavour usage in g)0.6](24106 persons  365 days). Poundage
         data from 1987 NAS/NRC survey data.

         Refinements to the initial concepts of structure-activity came as
    a result of increasing knowledge and confidence in predicting
    structure-activity relationships for flavouring substances. This
    formed the basis of a paper by Cramer  et al. (1978) which, through
    the use of a "decision tree" approach, permitted the classification of
    flavouring substances into "classes of concern" based on structure and
    other considerations, similar in many respects to, but predating
    the "Concern Level" concept outlined by the U.S. Food and Drug
    Administration in its "Redbook" (FDA, 1982, 1993).

         The concept of establishing concern levels also has been
    investigated further by BIBRA to evaluate its applicability to food
    chemicals more generally (Phillips  et al., 1987). This group
    evaluated and established concern levels for several food additives,
    plastic monomers, as well as flavouring substances. Although they
    reported that, in their opinion, the Cramer  et al. (1978) decision
    tree misclassified a few substances, the decision tree was likely to
    be a more realistic approach for predicting toxicity than any other

    reported quantitative structure-activity relationship (QSAR)
    technique. Thus, there is general consensus, based on the work of
    Cramer  et al. (1978), the subsequent work by BIBRA (Phillips
     et al., 1987), and the fact that the FDA (1982; 1993) uses
    structure-activity relationships in defining Concern Levels for food
    substances, that structure-activity has a solid basis in science when
    applied to substances of simple and closely related structures
    encountered at low exposures, a number of which are of known low
    toxicity and safe metabolic disposition. This is particularly the case
    for all but a very few flavouring substances. As will be discussed
    later in this paper, structure-activity relationships play an
    important role in the evaluation of flavouring substances.

    2.3  Use of toxicity data

         Traditional safety evaluation procedures are only partially
    applicable to flavouring substances. Traditional approaches to the
    safety assessment of food additives typically involve the evaluation
    of considerable toxicological data, usually in an amount sufficient
    to establish a no-observed-effect-level (NOEL), permitting the
    establishment of an acceptable daily intake (ADI). Approximately half
    of the flavouring substances currently in use are naturally occurring
    simple acids, aldehydes, alcohols and esters. With few exceptions,
    these are rapidly metabolized to innocuous end products, the safety of
    which is well established or can be assumed from metabolic and
    toxicity data on the substance in question or on structurally related
    substances. Moreover, the acquisition of extensive toxicity data is
    unnecessary for the majority of flavouring substances because
    structure-activity relationships can be used as a means of assessing
    substances in a homologous series, in which only a few substances have
    toxicology data, to determine safety in use. This concept has been
    used by JECFA in the evaluation of structurally related flavouring
    substances, including the allyl esters, amyl acetate and isoamyl
    butyrate, benzyl compounds, citral compounds, alpha- and -ionones,
    and nonanal and octanal (JECFA, 1967: 1968; 1980a; 1984a,b; 1990a,b;
    1991a,b; 1993a,b). In addition, as previously indicated in Table 1,
    95% of flavouring substances are consumed at exposure levels less than
    1 mg/person/day and in keeping with the safety evaluation procedure
    outlined in this paper, only limited toxicological data are required
    in such circumstances.

         When exposure is extremely low and there are organoleptic
    limitations on use levels, a primary consideration is whether there is
    a need to establish a numerical ADI for flavouring substances. There
    are several reasons why it is not appropriate or necessary to
    establish ADIs in the case of the majority of flavouring substances.
    ADIs are based on toxicological data and the establishment of a NOEL,
    an approach that differs from the concept that a safety evaluation
    can be performed in many instances on the basis of exposure and

    structure-activity relationships. Moreover, the organoleptic and
    gustatory properties of flavouring substances typically limit their
    use and, consequently, exposure to them. In addition, because a
    majority of flavouring substances occur in nature, there is a long
    history of human experience in flavouring substance consumption from
    traditional foods. Nearly fifty percent of flavouring substances given
    full ADIs by IECFA have consumption ratios greater than 1, indicating
    their predominant natural occurrence in food (Stofberg & Grundschober,
    1987). The above factors have been noted by WHO (1987) as important in
    the evaluation of flavouring substances. It is also evident that very
    large safety margins exist for flavouring substances, as evidenced by
    the fact that the margin between the NOEL and the per capita intake of
    flavouring substances ranges from more than 50 to more than 1 000 000
    times for the flavouring substances given full ADIs by JECFA (Table 2).

    Table 2.  Safety margins between NOELs and per capita daily
              exposure for various flavouring substances given full ADIs
              by JECFAa
                                                                        

    Safety Margin                         Number of Flavours
                                                                        

    <100                                  1
    100 - 1000                            4
    1000 - 10 000                         13
    10 000 - 100 000                      9
    100 000 +                             7
                                                                        

    TOTAL                                 34
                                                                        

    a    JECFA, 1967; 1968; 1970; 1971; 1972; 1974a,b; 1976a.b; 1978;
         1980a,b,c; 1981a,b; 1982a,b; 1983a,b; 1984a,b; 1986; 1987a,b;
         1989; 1990a,b; 1991a,b; 1992; 1993a.b,c.

         The factors discussed above lend support to the argument that it
    is unnecessary to establish ADIs for the majority of flavouring
    substances. Not establishing a numerical ADI for the great majority of
    flavouring substances is also consistent with the concept that
    presumed or known metabolism can be used as a basis for safety
    evaluation.

    3.  INTEGRATED METHOD FOR THE SAFETY EVALUATION OF FLAVOURING
        SUBSTANCES

         In a continuing effort to improve the basis for the safety
    evaluation of flavouring substances, this paper presents a procedure
    which integrates information on exposure, structure-activity
    relationships, metabolic fate and toxicity. It presents a safety
    evaluation procedure which allows a determination of the safety of
    flavouring substances under conditions of intended use. The key
    elements of the safety evaluation procedure are discussed below.

    3.1  Structure-activity relationships and metabolic fate

         Without exception, flavouring substances are volatile organic
    chemicals. The vast majority of flavourings ingredients have simple,
    well characterized structures with a single functional group and low
    molecular weight (< 300). More than 700 of the 1323 chemically
    defined flavouring substances used in food in the U.S. are simple
    aliphatic acyclic and alicyclic alcohols, aldehydes, ketones,
    carboxylic acids, and related esters, lactones, ketals, and acetals.
    Other structural categories include aromatic (e.g., cinnamaldehydes
    and amhranilates), heteroaromatic (e.g., pyrazines and pyrroles) and
    heterocyclic (e.g., furanones and thiofurans) substances with
    characteristic organoleptic properties (e.g., furanones providing a
    strawberry note). For most flavouring substances, the structural
    differences are small. Incremental changes in carbon chain length and
    the position of a functional group or hydrocarbon chain typically
    describe the structural variation in groups of related flavouring
    substances. These systematic changes in structure provide the basis
    for understanding the effect of structure on the chemical and
    biological properties of a substance.

         Toxicity is dependent on the chemical structure and metabolism of
    a substance. The "decision tree" procedure (Cramer  et al., 1978)
    relies primarily on chemical structure and estimates of total human
    intake to assess toxic hazard and to establish priorities for
    appropriate testing. The procedure utilizes recognized pathways of
    metabolic deactivation and activation, data on toxicity, and the
    presence of the substance as a component of traditional foods and as
    an endogenous metabolite. Substances are classified according to three
    categories:

    Class I   -      Substances of simple chemical structure and efficient
                     modes of metabolism which would suggest a low order
                     of oral toxicity (e.g., butyl alcohol or isoamyl
                     butyrate).

    Class II  -      Contains structures that are intermediate. They
                     possess structures that are less innocuous than
                     substances in Class I, but do not contain structural
                     features suggestive of toxicity like those substances
                     in Class III. Members of Class II may contain
                     reactive functional groups (e.g., furfuryl alcohol,
                     methyl 2-octynoate, and allyl propionate).

    Class III -      Substances of a chemical structure that permit no
                     strong initial presumption of safety, or may even
                     suggest significant toxicity (e.g., 2-phenyl-
                     3-carbethoxy furan and benzoin).

         The decision tree is a tool for classifying flavour ingredients
    according to levels of concern. The majority of flavouring substances
    fall into Class I because they are simple alcohols, aldehydes,
    ketones, acids or their corresponding esters, acetals and ketals that
    occur naturally in food and, in many cases, are endogenous substances.
    They are rapidly metabolized to innocuous products (e.g., carbon
    dioxide, hippuric acid, and acetic acid) by well recognized reactions
    catalyzed by cellular enzymes that exhibit high specificity and high
    catalytic efficiency (e.g., alcohol dehydrogenase and isovaleryl
    coenzyme A dehydrogenase). Substances that do not undergo detoxication
    via these highly efficient pathways (e.g., fatty acid pathway and
    citric acid cycle) are metabolized by reactions catalyzed by enzymes
    of low specificity and relatively low efficiency (e.g., cytochrome
    P-450 and glutathione transferase). For some groups of substances
    (e.g., branched-chain carboxylic acids, allyl esters, and linear
    aliphatic acyclic ketones), metabolic thresholds for intoxication have
    been identified (Krasavage  et al., 1980; Deisinger  et al., 1994;
    Jaeschke  et al., 1987). The dose range, over which a well-defined
    change in metabolic pathway occurs, generally correlates with the dose
    range over which a transition occurs from a no-observed-adverse-effect
    level to an adverse-effect level. For such groups of substances the
    dose range at which this transition occurs is orders of magnitude
    greater than the level of exposure from use as flavour ingredients.

         Most substances in Class II belong to either of two categories;
    one includes substances with functional groups which are similar to,
    but somewhat more reactive than functional groups in Class I
    (e.g., allyl and alkyne); the other includes substances with more
    complex structures than substances in Class I, but that are common
    components of food. This category includes heterocyclic substances
    (e.g., 4-methylthiazole) and terpene ketones (e.g., carvone).

         The majority of the flavouring substances within Class III
    include heterocyclic and heteroaromatic substances and cyclic ethers.
    Many of the heterocyclic and heteroaromatic substances have sidechains
    with reactive functional groups. In a few cases, metabolism may
    destroy the heteroaromaticity of the ring system (e.g., furan).
    Although metabolism studies have been performed for Class III
    flavouring substances with elevated levels of exposure, the metabolic
    fate of many substances in this structural class cannot be confidently
    predicted. Review of the group of substances in each of the structural
    classes indicates that as structural complexity increases (Class I -
    III), the number of flavouring substances and the levels of exposure
    decrease significantly (Table 3). In all structural classes,
    one-quarter or more of the flavouring substances are consumed at
    levels below 0.01 g/day or 0.2 g/kg bw/day.

    Table 3.  Number of flavouring substancesa divided by structural class
              within various intake categories
                                                                        

    Intake Categoryb              No. of Flavours (% of Total)          
    (g/day)
                          Class I           Class II           Class III
                                                                        

    <0.01                 212 (24)          68 (28)            69 (34)
    0.01-0.1              55 (6)            20 (8)             18 (9)
    0.1-1                 169 (19)          48 (20)            57 (28)
    1-10                  145 (17)          45 (19)            34 (17)
    10-100                147 (17)          39 (16)            18 (9)
    100-1000              95 (11)           12 (5)             4 (2)
    1000-10 000           34 (4)            9 (4)              2 (1)
    10 000-100 000        16 (2)            0                  0
    100 000+              5 (0.6)           2 (0.8)            0

    TOTAL                 878               243                202
                                                                        

    a    Chemically defined flavouring substances permitted for use in the
         U.S. excluding botanicals.

    b    Intake data calculated assuming: survey poundage reflects 60% of
         actual usage, 10% of population exposed, U.S. population in 1987
         was 240 million. Formula: Intake (g/person/day) = [(annual
         flavour usage in g)0.6](24106persons  365 days). Poundage
         data from 1987 NAS/NRC survey data.

    3.2  Integrating information on exposure and toxicity

         One of the key elements of the safety evaluation procedure is
    based on the premise that intake levels can be specified for
    flavouring substances that would not present a safety concern. This
    paper presents a procedure which provides the scientific underpinnings
    for defining toxicologically inconsequential exposures for flavouring
    substances and expressing these as human exposure thresholds. The
    concept of specifying human exposure thresholds relies on principles
    that permit specifying the daily intake of a substance which can be
    considered, for practical purposes, as presenting no toxicological
    risks (and thus of no health or safety risk to consumers) even in the
    absence of specific toxicological data on the substance (Federal
    Register, 1993; Munro, 1990; Rulis, 1986; Frawley, 1967). The
    concept relies on knowledge of the range of toxicological risks for
    structurally related substances and on knowledge regarding the
    toxicological potency of relevant classes of chemicals for which good
    toxicity data exist. The principles underpinning the establishment of
    human exposure thresholds have been embodied in a recent United States
    government Federal Register (1993)1 notice emanating from the FDA,
    which provides the scientific basis for the conclusion that an
    exposure level to indirect food additives can be specified, below
    which no risk to public health would likely accrue. This exposure
    level has, in turn, been used by FDA to establish a proposed
    "threshold of regulation" for indirect food additives which precludes
    the need for toxicological evaluation of substances migrating into
    food from food-contact articles provided the amount that migrates does
    not lead to a dietary level in excess of 500 ppt (equivalent to
    1.5 g/person/day assuming a daily food intake of 3000 g). The FDA has
    noted that such a level would result in negligible risk to consumers
    even if the substance was shown later to be a carcinogen. This concept
    is in keeping with the well-established principle that resources
    should be directed to the safety evaluation of substances having high
    exposure and therefore greater potential for adverse effects and not
    toward substances with trivial exposure. The concept is particularly
    applicable to substances of low toxicity and with known or predictable
    metabolic fate. The scientific basis for the establishment of human
    exposure thresholds and the proposed FDA regulation are discussed
    below.

         Frawley (1967) initially suggested the concept of establishing
    human exposure thresholds. He showed, on the basis of studies
    conducted on several well-tested substances, including food additives,
    industrial and consumer chemicals, and pesticides that a generic
    "no-effect" level could be established that could preclude the need
    for toxicity studies and safety evaluation for a majority of
    substances intended for use as food packaging materials. Frawley
    constructed a reference database of non-tumorigenic endpoints using

    220 two-year rodent studies. He presented the NOELs for all 220
    compounds. Frawley (1967) reported that if he excluded heavy metals
    and pesticides from the analysis, there was no compound in the
    remaining database (except for acrylamide) which showed evidence of
    chronic toxicity at dietary concentrations of less than 100 ppm.
    Application of a typical 100-fold safety factor to the 100 ppm
    generalized NOEL would mean that humans could safely consume any of
    the materials provided the dietary concentration did not exceed 1 ppm.
    Frawley (1967), noting that his database was incomplete, proposed
    adding an additional safety factor of 10 which would translate to a
    toxicologically insignificant human exposure level of 0.1 ppm in the
    diet. Assuming an individual consumes 1500 grams of food per day, an
    exposure of 150 g/person/day (approximately 2.5 g/kg/day) or less to
    a chemical of unknown toxicity would be considered toxicologically
    insignificant. According to Frawley, such exposures could be
    considered of no safety concern.

         More recently, Rulis (1986) conducted a similar analysis of the
    FDA's Priority-Based Assessment of Food Additives (PAFA) database
    containing 159 compounds with subchronic or chronic toxicity data. He
    came to the same conclusion as Frawley (1967). Essentially there is no
    risk of toxicity in rodents exposed to certain food additives at
    dietary levels of less than 1 mg/kg bw/day or in human terms,
    approximately 1 to 10 g/kg bw/day depending on the safety factor
    applied. Even twenty years apart, using different databases, the
    toxicologically inconsequential levels proposed by Frawley (1967) and
    Rulis (1986) were nearly identical.

         Munro (1990) used a database of approximately 350 substances
    compiled by Gold  et al. (1984, 1989) to develop a human exposure
    threshold value to be applied to substances for which no presumption
    of safety can be made because of a complete lack of data on metabolism
    and potential toxicity. Munro (1990) proposed a threshold of
    regulation of up to 1000 ppt for indirect additives which would
    translate to a daily intake of 1.5 to 3.0 g/person/day depending upon
    assumptions regarding food intake. The acceptable exposure of
    1.5 g/day is equivalent to that considered by FDA (Federal Register,
    1993)1 to present no regulatory concern for a food packaging
    material even if later it was determined to be a carcinogen.

              

    1    FDA has proposed a dietary concentration of 500 ppt as the
         threshold of regulation for substances used in food-contact
         articles. Assuming that an individual consumes 1500 g of solid
         food and 1500 g of liquid food per day, this threshold would
         equate to a toxicologically inconsequential level of 1.5 g/day
         (Federal Register, 1993).

         The work conducted by the FDA (Federal Register, 1993), Frawley
    (1967), Rulis (1986) and Munro (1990) is expanded upon in this paper
    through the compilation of a large database of reference substances
    (Appendix B) from which a distribution of NOELs could be derived for
    chemicals of various structural types. The reference database
    describes the relationships between exposure, structure and toxicity
    for a wide variety of chemicals of divergent structure and it can be
    used as a reference point from which to judge the safety of flavouring
    substances.

         In compiling the database, strict criteria were applied in the
    selection of data sets. The objective of the exercise was to identify
    as many high quality toxicological studies as possible representing a
    variety of toxic endpoints and chemical structures. To accomplish
    this, the study types included those typically conducted in
    toxicology, such as subchronic, chronic, reproductive and teratology
    studies. Short term and acute studies were not included since these
    were considered not to be relevant for establishing chronic NOELs. The
    database consisted mainly of studies in rodents and rabbits. Very few
    studies in dogs and other species were found that met the established
    criteria. An evaluation of randomly selected dog and primate studies
    indicated that many had too few animals per group to derive a
    statistically valid NOEL. Moreover, for many dog studies, a common
    endpoint was reduced body weight and/or food consumption which was
    due, in many cases, either to palatability problems with the diet or
    vomiting. In addition, most studies in dogs and other non-rodent
    species were simply too short in duration to be classified as chronic
    studies. Only oral studies were included in the database. A further
    criterion for inclusion in the database was that a study had to have a
    demonstrated lowest-observed-effect level (LOEL) as well as a NOEL,
    thus ensuring that the study was rigorous enough to detect toxic
    effects. In some instances NOELs were included for studies not
    demonstrating a LOEL, and these were substances such as major food
    ingredients that were without toxicity at the highest dose tested in
    well-conducted studies. It should be noted that the inclusion of such
    substances in the database would not bias the database in favour of
    higher NOELs since the true NOEL for such substances probably would
    exceed the NOEL established from the available studies.

         In order to group NOELs for substances with only subchronic
    studies with those with chronic studies to derive the cumulative
    distribution of NOELs, subchronic NOELs were divided by a factor of
    three to approximate the most likely NOEL that would be derived from a
    chronic study. This conversion factor is based on research defining
    the relationship between subchronic and chronic NOELs. Weil and
    McCollister (1963) compared 3 month NOELs with 2 year NOELS for 33
    different substances (including pharmaceuticals, pesticides, and food
    additives) fed to rats. They found that for most of the compounds
    (30), the ratio of the NOELs between subchronic and chronic studies

    was 5 or less and more than half of the compounds had a ratio equal to
    2 or less. More recently, it has been discovered through further
    analysis of more chemical substances, that a more accurate adjustment
    factor for extrapolating NOELs derived from subchronic studies to
    lifetime was between 2 and 3 (Dourson, personal communication;
    Lewis  et al., 1990; Beck  et al., 1993).

         In compiling the database, emphasis was placed on retrieving data
    from certain databases known to contain well-validated toxicological
    endpoints for a series of well-defined chemical structures. An
    exhaustive search was made of compounds evaluated by JECFA. Other
    sources included the U.S. Environmental Protection Agency's (EPA)
    Integrated Risk Information System (IRIS) on-line database, the
    National Toxicology Program (NTP) studies, the Developmental and
    Reproductive Toxicity (DART) on-line database from EPA and the U.S.
    National Institute of Environmental Health Sciences and the published
    literature in general. The data entered into the database included the
    name of the chemical, Chemical Abstracts Service Registry Numbers (CAS
    No.), structural classification as assessed using the Cramer  et al.
    (1978) decision tree and the FDA "Redbook", species, sex, route of
    administration, dose levels tested, study type, duration, endpoints
    reported, LOEL, NOEL and references. In an effort to be conservative
    in the construction of the reference database, NOELs selected by the
    author(s) of each study were used even though in some cases authors
    tended to over-interpret their data. In some instances, it was found
    that the stated NOEL may have been based on a misjudgment of an
    adverse effect by the author (e.g., physiological versus toxicological
    effects) or on artifactual effects (e.g., fetal toxicity as a result
    of maternal toxicity). An example of this is isopropyl alcohol, which
    has been reported to produce teratogenic effects at very low doses
    (0.018 mg/kg) in one study; however, its structure, known metabolism
    and other toxicological data provide no evidence for concluding
    teratogenicity. Even though scientifically, some of these
    author-derived NOELs were not thoroughly substantiated, they were
    included in the reference database, thereby increasing the degree of
    its conservative nature. NOELs selected by EPA for the IRIS database
    were entered without further review. In all, the database consists of
    612 substances representing a range of industrial chemicals,
    pharmaceuticals, food substances and environmental and consumer
    chemicals likely to be encountered in commerce. Since the database was
    developed as a reference database for the evaluation of flavouring
    substances, all of which are organic chemicals, no organometallic or
    inorganic compounds were included in the database. For many of the
    substances, more than one NOEL was identified from the literature
    resulting from the fact that some substances were tested in more than
    one species and sex and/or demonstrated a range of endpoints suitable
    for establishing a NOEL. This led, in some cases, to multiple NOELs
    for individual substances. In all, the database contains 2944 entries.

         In order to correlate chemical structure with toxicity, the
    substances in the database were classified into three groups
    corresponding to the three structural classes outlined in the
    Cramer  et al. (1978) decision tree. For each substance, the most
    conservative NOEL was selected from the reference database based on
    the most sensitive species, sex and endpoint. The cumulative
    distribution of the NOELs within each class is shown in Figure 1,
    along with the lognormal distributions fitted to these data. These
    results clearly delineate the effects of structural class on toxicity,
    with the median (50th percentile) NOEL decreasing from Class I through
    III. Similar differences among structural classes exist in the range
    between the 5th and 95th percentile.

         The human exposure threshold for each of the structural classes
    was calculated from the 5th percentile NOEL. The 5th percentile NOEL
    was chosen because this value would provide 95% confidence that any
    other substance of unknown toxicity but of the same structural class
    as those comprising the reference database would not have a NOEL less
    than the 5th percentile for that particular structural class within
    the reference database.

         The 5th percentile NOELs for each structural class are shown in
    Table 4. In converting the 5th percentile NOELs to human exposure
    thresholds (Table 4) for the various structural classes, a 100-fold
    safety factor was used since such a factor would inherently be applied
    in establishing safe intake levels for the substances comprising the
    database. The use of such a factor provides a substantive margin of
    safety since the human exposure thresholds are based on a large
    database of approximately 612 compounds with good supporting
    toxicological data. Furthermore, 5th percentile NOELs were used to
    calculate the thresholds, providing a more conservative figure than
    the arithmetic mean. Moreover, the estimated daily intakes of
    flavouring substances to which the human exposure threshold are
    compared are greatly overestimated as they represent the "eaters only"
    (10%) population. Thus, it is believed that a 100-fold safety factor
    provides a wide margin of safety in relating the results of the
    analysis of the reference database to flavouring substance exposure.

         It is evident from Table 4 that there are substantial differences
    in the 5th percentile NOELs for the various structural classes,
    indicating an obvious effect of structure on toxic potency.

         It is enlightening to compare the human exposure thresholds with
    present intakes of chemically defined flavouring substances in the
    U.S. As shown in Table 5, it is clear that for nearly all (93 to
    97%) flavouring substances used in the U.S., intakes are below the
    human exposure threshold for their respective structural class.
    Because most flavouring substances possess simple structures and their
    metabolism is known or reasonably predictable, it can be concluded
    that it is highly improbable that they would present a toxicological

    FIGURE 1

    risk at exposure levels below the human exposure threshold for their
    respective structural class. However, even if information on
    structural class, metabolic fate and existing toxicity studies were
    not available, 743/1323 (56%) of flavouring substances used in the
    U.S. are consumed in amounts less than the 1.5 g/person/day standard
    proposed by the FDA (Federal Register, 1993) and Munro (1990). This
    indicates that for approximately half of the existing list of 1323
    chemically defined flavouring substances permitted for use in the
    U.S., exposure can be considered to be trivial.

    Table 4.  Fifth percentile NOELs and human exposure thresholds for
              Cramer et al. (1978) structural classes in the reference
              database
                                                                        

                        5th Percentile NOELs,    Human Exposure
                        (g/kg bw/day)           Threshold,(g/day)a,b
                                                                        

    I         137       2993                     1800
    II        28        906                      540
    III       447       147                      88
                                                                        

    a    The human exposure threshold was calculated by multiplying the
         5th percentile NOEL by 60 (assuming an individual weighs 60 kg)
         and dividing by a safety factor of 100, as discussed in the text.
    b    Numbers rounded to two (2) significant figures.

    Table 5.  Flavouring substances within each Cramer et al. (1978)
              structural class consumed in amounts below human exposure
              thresholds
                                                                        

                                         No. of        No. of Flavours
                       Human Exposure    Flavours      Under Human
    Structural Class   Threshold         Within        Exposure
                       (g/day)          Structural    Threshold (%)
                                         Classa
                                                                        

    I                  1,800             878           835 (95)
    II                 540               243           227 (93)
    III                88                202           195 (97)
                                                                        

    a    Adapted from the FEMA flavouring substance database of flavouring
         substances permitted for use in the U.S.

    3.3  Evaluation criteria

         The evaluation criteria proposed for application to flavouring
    substances in this paper involve the integration of information on
    exposure, structure-activity relationships, metabolism and, as
    required, toxicity data. It should be noted that the safety evaluation
    criteria outlined below are not intended to be applied to any
    flavouring substances with unresolved toxicity problems or to
    substances that are presumed or known carcinogens. Such substances
    warrant special consideration and must be evaluated using more
    traditional methods of safety evaluation. While toxicity data exist on
    numerous flavouring substances and can be used as the basis for
    evaluation, there are many flavouring substances that lack toxicity
    data. The evaluation criteria are intended to provide a means of
    evaluating such substances. The criteria incorporate, where the data
    permit, the concept that metabolic fate can be predicted on the basis
    of presumed structure-activity relationships. The criteria also rely,
    in part, on the NOEL reference database which provides a human
    exposure threshold for each of the three structural classes of
    flavouring substances, as shown in Table 4. The evaluation criteria
    also incorporate, where available, toxicity data on flavouring
    substances and closely related structural analogues as a basis for
    safety evaluation. One of the criteria (number 5 below) incorporates
    the concept of a minimum human exposure threshold based on the
    1.5 g/person/ day standard proposed by the FDA (Federal Register,
    1993) and Munro (1990). This standard can be applied to those
    flavouring substances for which metabolic fate is unknown and cannot
    be confidently predicted and for which there are no toxicity data on
    the flavouring substance or on a structurally related material from
    which to conclude any inference of safety in use.

         Flavouring substances that meet one of the five numbered criteria
    outlined below can be declared safe for their intended use without
    further evaluation:

    1.   a)   The flavouring substance has a simple structure and will be
              metabolized and excreted through known detoxication pathways
              to innocuous end-products; and

         b)   the conditions of intended use do not result in an exposure
              greater than the human exposure threshold for the relevant
              structural class, indicating a low probability of potential
              for adverse effects.

    2.   a)   The conditions of intended use result in an exposure that
              exceeds the human exposure threshold for the relevant
              structural class; however

         b)   the flavouring substance has a simple structure and will be
              metabolized and excreted through known detoxication pathways
              to innocuous end-products and it or its metabolites are
              endogenous human metabolites with no known biochemical
              regulating function.

    3.   a)   The flavouring substance has a simple structure and will be
              metabolized and excreted through known detoxication pathways
              to innocuous end-products; and

         b)   the conditions of intended use result in an exposure that
              exceeds the human exposure threshold for the relevant
              structural class; however

         c)   toxicity data exist on the flavouring substance which
              provide assurance of safety under conditions of intended
              use, or there are toxicity data on one or more close
              structural relatives which provide a NOEL high enough to
              accommodate any perceived difference2 in toxicity between
              the flavouring substance and the structurally related
              substance having toxicity data.

    4.   a)   The metabolic fate of the flavouring substance cannot be
              confidently predicted on the basis of structure; however

         b)   the conditions of intended use result in an exposure below
              the human exposure threshold for the relevant structural
              class indicating a low probability of potential for adverse
              effects; and

         c)   there are toxicity data on the substance, or on one or more
              structurally related substances with a NOEL at least 10
              times greater than the 5th percentile NOEL for the relevant
              structural class.

    5.   a)   The metabolic fate of the flavouring substance cannot be
              confidently predicted on the basis of structure; however

         b)   the conditions of intended use result in an exposure below
              the human exposure threshold of 1.5 g/day2, providing
              assurance that the substance will be safe under conditions
              of intended use.

         [NOTE: This criterion accommodates flavouring substances for
         which there are limited data on structure-activity and toxicity,
         but they would not be considered to present a safety concern
         below the human exposure threshold of 1.5 g/day (Federal
         Register, 1993)].

         The evaluation criteria listed above identify substances which
    are considered safe under conditions of intended use or those that may
    require additional data and further evaluation. Figure 2 presents the
    same criteria in the form of an evaluation sequence. The sequence
    contains a number of questions on structure, metabolism, exposure data
    and toxicity and provides an integrated mechanism to evaluate the
    safety of a flavour ingredient. Although the procedure incorporates
    relevant toxicity data on a substance or related substances where
    available, it does not require them. The procedure identifies those
    substances for which additional safety data may be required in order
    to perform an adequate safety evaluation.

         The effective application of this safety evaluation procedure
    depends on a substantial knowledge of toxicology, chemistry,
    metabolism, and exposure to flavouring substances. It can be applied
    most effectively when groups of structurally related flavouring
    substances are evaluated together. In a group evaluation, conclusions
    reached on the safety of individual substances are supported by
    similar conclusions for structurally related substances. For example,
    the results of the evaluation for butyl butyrate should be consistent
    with results for other esters formed from aliphatic acyclic linear
    saturated alcohols and acids having similar levels of exposure. These
    similar substances will pass through the same branch of the safety
    evaluation procedure because they fall into the same structural class,
    possess similar metabolic fate, and exhibit similar patterns of
    exposure from use as flavour ingredients and as components of food.

              

    2     In most instances, groups of structurally related materials have
          toxicology data on at least one member of the group, usually the
          flavoring substance with the highest poundage. In most cases a
          large margin of safety ( i.e., 100- to 1000-fold) exists
          between the NOEL and the calculated exposure to the substance
          having toxicological data. Such margins of safety would be
          expected to accommodate any perceived difference between the
          toxicity of a flavouring substance having no toxicological data
          and its close structural relative for which a NOEL has been
          established.

         In the first step of the safety evaluation procedure (Figure 2)
    the user must assign a decision tree structure class (Cramer  et al.,
    1978) to the substance. Following assignment of structure class, a
    question on metabolic fate appears. This question identifies those
    substances which are anticipated to be efficiently metabolized
    to innocuous products (e.g., 1-butanol) versus those which are
    transformed to more toxic metabolites (e.g., estragole) or have
    limited information on which to predict confidently the metabolic fate
    (e.g., 2-phenyl-3-carbethoxy furan).

         Once a substance has been sorted according to structure class
    and knowledge of metabolic fate, the next question compares the
    substance's daily per capita intake ("eaters only") from use as a
    flavour ingredient to the human exposure threshold (Table 4) for the
    same structure class.

         If the substance is metabolized to innocuous products (Step
    No. 2) and has an intake less than the human exposure threshold for
    the structure class (Step No. 3), the substance is considered safe
    (e.g., 1-octanol). If the intake is greater than the human exposure
    threshold (Step No. 3) and the substance or its metabolites are
    endogenous (Step No. 4), the substance is also considered safe, even
    though the intake is greater than the human exposure threshold (e.g.,
    butyric acid). If the substance is not endogenous, then the substance
    or related substances must have a NOEL (Step No. 5) significantly
    greater than the intake of the substance in order to be considered
    safe (e.g., citral). If no such data exist or the NOEL is not
    significantly greater than the intake for the substance, then
    additional data are required in order to complete the safety
    evaluation.

         If metabolic fate cannot be confidently predicted and the intake
    (Step No. 2) is greater than the human exposure threshold (Step
    No. 3), additional data on metabolic fate or toxicity on the substance
    or structurally related substances are required to complete the safety
    evaluation (e.g., dihydro-coumarin). If the intake is less than the
    human exposure threshold, the substance or structurally related
    substances must have a NOEL significantly greater than the NOEL for
    the structure class (Step No. 6) in order for the substance to be
    considered safe (e.g., 2-ethyl-4-hydroxy-3(2H)-furanone). If an
    adequate toxicity study is not available and the substance has an
    intake less than 1.5 g/day (Step No. 7), the substance is considered
    safe (e.g., 3-acetyl-2,5-dimethylthiophene). Otherwise additional data
    are required in order to complete the safety evaluation (e.g.,
    2-ethylfuran).

    FIGURE 2

         The principal objective of the safety evaluation procedure is to
    identify two groups of flavourings substances: i) those substances
    whose structure, metabolism, and relevant toxicity data clearly
    indicate that the substance would be expected not to be a safety
    concern under current conditions of intended use; and ii) those
    substances which may require additional data in order to perform an
    adequate safety evaluation.

    3.4  Integrating data on the consumption ratio

         As pointed out by WHO (1987) and SCF (1991), natural occurrence
    is no guarantee of safety, but it is important to recognize that the
    safety evaluation of added use of flavouring substances needs to be
    conducted with an appreciation of the consumption ratio. Clearly, if
    added use of flavouring substances results in an exposure that exceeds
    that from natural sources, this will increase awareness of the need to
    consider carefully overall exposure in the light of existing data on
    toxicity and structure-activity relationships. On the other hand, if
    the added use is trivial with a consumption ratio of 10 to 100, that
    is, it increases total exposure by only 1 to 10%, then this fact needs
    to be taken into consideration when applying the criteria outlined
    above.

         The substances of primary concern are those which, in Figure 2,
    receive a "No" answer to Step No. 5, or a "Yes" answer to Step No. 7,
    indicating a possible need for additional data and evaluation beyond
    that included in the evaluation procedure outlined in this paper. In
    such an evaluation, as stated immediately above, the extent of natural
    occurrence should be given appropriate weight.

         Of much less concern with respect to consumption ratio are those
    substances that drop out of further consideration as a result of "No"
    answers to Step Nos. 3 or 7, or "Yes" answers to Step Nos. 4 or 6. The
    derivation of the thresholds, the estimation of intakes (see Appendix
    A), and the special factors applicable to the use of flavours
    (volatility, self-limiting use, etc.) build in multiple conservative
    assumptions more than adequate to cover additional exposure from
    natural occurrence to substances that in any case are of low inherent
    concern.

         The advances in analytical chemistry in the past 50 years provide
    virtual assurance that no flavouring substances of extensive natural
    occurrence remain unknown. Those of potential value yet to be
    discovered (e.g., as yet unknown components of roast beef, coffee, or
    chocolate flavour) are being sought at the ppb and ppt level. This
    does not suggest exposures above any of the thresholds discussed in
    this paper.

    4.  CONCLUSIONS

         It is neither possible nor necessary to conduct toxicological
    studies on all individual flavouring substances used in food. The vast
    majority of flavouring substances are members of groups of substances
    with common metabolic pathways, and typically, individual members of
    such a group display a similar toxicity profile. This is not
    surprising in light of the close structural similarity of the various
    flavouring substances comprising a chemical group. As demonstrated in
    this paper, exposure to flavouring substances is usually low and, in
    the majority of cases, below the human exposure threshold values
    presented in this paper. This knowledge, coupled with knowledge
    regarding structure-activity relationships, metabolic disposition, and
    toxicology data, permits the establishment of the proposed paradigm
    for safety assessment which provides a solid foundation to assure the
    safety of flavouring substances under conditions of intended use.

    5.  REFERENCES

    BECK, B.D., CONOLLY, R.B., DOURSON, M.L., GUTH, D., HATTIS, D.,
    KIMMEL, C. & LEWIS, C. (1993). Symposium overview. Improvements in
    quantitative noncancer risk assessment.  Fund Appl Toxicol.,
    20: 1-14.

    COUNCIL OF EUROPE (1974).  Natural Flavouring Substances, Their
     Sources, And Added Artificial Flavouring Substances. Council of
    Europe, Strasbourg, France.

    COUNCIL OF EUROPE ( 1981 ).  Flavouring Substances And Natural Sources
     Of Flavourings, Third Edition. Council of Europe, Strasbourg, France.

    COUNCIL OF EUROPE (1992).  Flavouring Substances and Natural Sources
     of Flavourings. Volume I. Chemically-Defined Flavouring Substances,
    Fourth Edition. Council of Europe, Maissoneuve, France.

    CRAMER, G.M., FORD, R.A. & HALL, R.L. (1978). Estimation of toxic
    hazard-A decision tree approach.  Food Cosmet Toxicol., 16: 255-276.

    DEISINGER, P.J., BOATMAN, R.J. & GUEST, D. (1994). Metabolism of
    2-ethylhexanol administered orally and dermally to the female Fischer
    344 rat.  Xenobiotica, 24: 429-440.

    FOOD AND DRUG ADMINISTRATION (1982). Toxicological Principles for the
    Safety Assessment of Direct Food Additives and Color Additives Used in
    Food. Redbook. U.S. Food and Drug Administration, Bureau of Foods,
    Washington, DC.

    FOOD AND DRUG ADMINISTRATION (1993). Toxicological Principles for the
    Safety Assessment of Direct Food Additives and Color Additives Used in
    Food. Redbook II (Draft). U.S. Food and Drug Administration, Center
    for Food Safety and Applied Nutrition, Washington, DC.

    FEDERAL REGISTER (1993). Food additives; threshold of regulation for
    substances used in food-contact articles. 58(195): 52719-52729.

    FRAWLEY, J.P. (1967). Scientific evidence and common sense as a basis
    for food-packaging regulations.  Food Cosmet Toxicol., 5: 293-308.

    GOLD, L.S., SAWYER, C.B., MAGAW, R., BACKMAN, G.M., DE VECIANA, M.,
    LEVINSON, R., HOOPER, N.K., HAVENDER, W.R., BERNSTEIN, L., PETO, R.,
    PIKE, M. & AMES, B.M. (1984). A carcinogenic potency database of the
    standardized results of animal bioassays.  Environ Health Perspect.,
    58: 9-319.

    GOLD, L.S., SLONE, T.H. & BERNSTEIN, L. (1989). Summary of
    carcinogenic potency and positivity for 492 rodent carcinogens in the
    carcinogenic potency database.  Environ. Health Perspect., 79: 259-272.

    JAESCHKE, H., KLEINWAECHTER, C. & WENDEL, A. (1987). The role of
    acrolein in allyl alcohol-induced lipid peroxidation and liver cell
    damage in mice.  Biochem. Pharmacol., 36: 51-57.

    JECFA (1967). Toxicological Evaluation of Some Flavouring Substances
    and Non-Nutritive Sweetening Agents. Eleventh Meeting of the Joint
    FAO/WHO Expert Committee on Food Additives.

    JECFA (1968). Specifications for the Identity and Purity of Food
    Additives and their Toxicological Evaluation: Some Flavouring
    Substances and Non-nutritive Sweetening Agents. Eleventh Report of the
    Joint FAO/WHO Expert Committee on Food Additives, FAO Nutrition
    Meetings Report Series No. 44, WHO Technical Report Series No. 383.

    JECFA (1970). Toxicological Evaluation of Some Extraction Solvents and
    Certain Other Substances. Fourteenth Meeting of the Joint FAO/WHO
    Expert Committee on Food Additives.

    JECFA (1971). Evaluation of Food Additives. Fourteenth Report of the
    Joint FAO/WHO Expert Committee on Food Additives, WHO Technical Report
    Series No. 462.

    JECFA (1972). Evaluation of Food Additives. Some Enzymes, Modified
    Starches, and Certain Other Substances: Toxicological Evaluations and
    Specifications and a Review of the Technological Efficacy of Some
    Antioxidants. Fifteenth Report of the Joint FAO/WHO Expert Committee
    on Food Additives, WHO Technical Report Series No. 488.

    JECFA (1974a). Toxicological Evaluation of Certain Food Additives
    Including Anticaking Agents, Antimicrobials, Antioxidants, Emulsifiers
    and Thickening Agents. Seventeenth Meeting of Joint FAO/WHO Expert
    Committee on Food Additives, WHO Food Additive Series No. 5.

    JECFA (1974b). Toxicological Evaluation of Certain Food Additives with
    a Review of General Principles and of Specifications. Seventeenth
    Report of the Joint FAO/WHO Expert Committee on Food Additives, WHO
    Technical Report Series No. 539.

    JECFA (1976a). Evaluation of Certain Food Additives. Twentieth Report
    of the Joint FAO/WHO Expert Committee on Food Additives, FAO Nutrition
    Meetings Report Series No. 1, WHO Technical Report Series No. 599.

    JECFA (1976b). Toxicological Evaluation of Certain Food Additives.
    Twentieth Meeting of the Joint FAO/WHO Expert Committee on Food
    Additives, WHO Food Additive Series No. 10.

    JECFA (1978). Evaluation of Certain Food Additives and Contaminants.
    Twenty-second Report of the Joint FAO/WHO Expert Committee on Food
    Additives, WHO Technical Report Series No. 631.

    JECFA (1980a). Evaluation of Certain Food Additives. Twenty-third
    Report of the Joint FAO/WHO Expert Committee on Food Additives. World
    Health Organization, Geneva. WHO Technical Report Series No. 648.

    JECFA (1980b). Evaluation of Certain Food Additives. Twenty-fourth
    Report of the Joint FAO/WHO Expert Committee on Food Additives. World
    Health Organization, Geneva. WHO Technical Report Series No. 653.

    JECFA (1980c). Toxicological Evaluation of Certain Food Additives.
    Twenty-third Meeting of the Joint FAO/WHO Expert Committee on Food
    Additives, WHO Food Additive Series No. 14.

    JECFA (1981a). Evaluation of Certain Food Additives. Twenty-fifth
    Report of the Joint FAO/WHO Expert Committee on Food Additives,
    Technical Report Series No. 669.

    JECFA (1981b). Toxicological Evaluation of Certain Food Additives.
    Twenty-fifth Meeting of the Joint FAO/WHO Expert Committee on Food
    Additives, WHO Food Additive Series No. 16.

    JECFA (1982a). Evaluation of Certain Food Additives and Contaminants.
    Twenty-sixth Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization, Geneva. WHO Technical Report
    Series No. 683.

    JECFA (1982b). Toxicological Evaluation of Certain Food Additives.
    Twenty-sixth Meeting of the Joint FAO/WHO Expert Committee on Food
    Additives, WHO Food Additive Series No. 17.

    JECFA (1983a). Evaluation of Certain Food Additives and Contaminants.
    Twenty-seventh Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization, Geneva. WHO Technical Report
    Series No. 696.

    JECFA (1983b). Toxicological Evaluation of Certain Food Additives and
    Contaminants. Twenty-seventh Meeting of the Joint FAO/WHO Expert
    Committee on Food Additives, WHO Food Additive Series No. 18.

    JECFA (1984a). Evaluation of Certain Food Additives and Contaminants.
    Twenty-eighth Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization, Geneva. WHO Technical Report
    Series No. 710

    JECFA (1984b). Toxicological Evaluation of Certain Food Additives and
    Contaminants. Twenty-eighth Meeting of the Joint FAO/WHO Expert
    Committee on Food Additives, WHO Food Additive Series No. 19.

    JECFA (1986). Evaluation of Certain Food Additives and Contaminants.
    Twenty-ninth Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization, Geneva. WHO Technical Report
    Series No. 733.

    JECFA (1987a). Evaluation of Certain Food Additives and Contaminants.
    Thirtieth Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization. Geneva. WHO Technical Report
    Series No. 751.

    JECFA (1987b). Evaluation of Certain Food Additives and Contaminants.
    Thirty-first Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization, Geneva. WHO Technical Report
    Series No. 759.

    JECFA (1989). Evaluation of Certain Food Additives and Contaminants.
    Thirty-third Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization, Geneva. WHO Technical Report
    Series No. 776.

    JECFA (1990a). Evaluation of Certain Food Additives and Contaminants.
    Thirty-fifth Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization, Geneva. WHO Technical Report
    Series No. 789.

    JECFA (1990b). Toxicological Evaluation of Certain Food Additives and
    Contaminants. Thirty-fifth Meeting of the Joint FAO/WHO Expert
    Committee on Food Additives, WHO Food Additive Series No. 26.

    JECFA (1991a). Evaluation of Certain Food Additives and Contaminants.
    Thirty-seventh Report of the Joint FAO/WHO Expert Committee on Food
    Additives. World Health Organization, Geneva. WHO Technical Report
    Series No. 806.

    JECFA (1991b). Toxicological Evaluation of Certain Food Additives and
    Contaminants. Thirty-seventh Meeting of the Joint FAO/WHO Expert
    Committee on Food Additives, WHO Food Additive Series No. 28.

    JECFA (1992). Evaluation of Certain Food Additives and Naturally
    Occurring Contaminants. Thirty-ninth Report of the Joint FAO/WHO
    Expert Committee on Food Additives. World Health Organization, Geneva.
    WHO Technical Report Series No. 828.

    JECFA (1993a). Evaluation of Certain Food Additives and Contaminants.
    Forty-first Report of the Joint FAO/WHO Expert Committee on Food
    Additives, Technical Report Series No. 837.

    JECFA (1993b). Toxicological Evaluation of Certain Food Additives and
    Contaminants. Forty-first Meeting of the Joint FAO/WHO Expert
    Committee on Food Additives, WHO Food Additive Series No. 32.

    JECFA (1993c). Toxicological Evaluation of Certain Food Additives and
    Naturally Occurring Toxicants. Thirty-Ninth Meeting of the Joint
    FAO/WHO Expert Committee on Food Additives, WHO Food Additive Series
    No. 30.

    KRASAVAGE, W.J., O'DONOGHUE, J.L., DIVINCENZO, G.D. & TERHAAR, C.J.
    (1980). The relative neurotoxicity of methyl-n-butyl ketone, n-hexane
    and their metabolites.  Toxicol. Appl. Pharmacol., 52: 433-441.

    LEWIS, S.C., LYNCH, J.R. & NIKIFOROV, A.I. (1990). A new approach to
    deriving community exposure guidelines from "no-observed-adverse-
    effect levels".  Regul. Toxicol. Pharmacol., 11: 314-330.

    MUNRO, I.C. (1990). Safety assessment procedures for indirect food
    additives: An overview.  Regul. Toxicol. Pharmacol., 12: 001-0011.

    NAS (1978). Resurvey of the Annual Poundage of Food Chemicals
    Generally Recognized as Safe, National Technical Information Service
    (NTIS) PB288-081.

    NAS (1979). Comprehensive Survey of Industry on the Use of Food
    Additives, National Technical Information Service (NTIS) PB80-113418.

    NAS (1984). Poundage Update of Food Chemicals, National Technical
    Information Service (NTIS) PB84-162148.

    NAS (1989). 1987 Poundage and Technical Effects Update of Substances
    Added to Food. National Research Council, Washington, DC. Prepared
    for: Food and Drug Administration, Washington, D.C. NTIS Report
    No. PB91-127266.

    PHILLIPS, J.C., PURCHASE, R., WATTS, P. & GANGOLLI, S.D. (1987). An
    evaluation of the decision tree approach for assessing priorities for
    safety testing of food additives.  Food Addit. Contam., 4(2): 109-123.

    RULIS, A.M. (1986).  De Minimis and the Threshold of Regulation.
     In: Felix, C.W. (Ed.)  Food Protection Technology. Lewis Publishers
    Inc., Chelsea, MI. pp. 29-37.

    SCF (1991). Guidelines for the Evaluation of Flavourings for Use in
    Foodstuffs: I. Chemically Defined Flavouring Substances. Commission of
    the European Communities, Scientific Committee for Food, Brussels,
    Belgium.

    STOFBERG, J. & KIRSCHMAN, J. (1985). The consumption ratio of
    flavouring materials: A mechanism for setting priorities for safety
    evaluation.  Food Chem. Toxicol., 23: 857-860.

    STOFBERG, J. & GRUNDSCHOBER, F. (1987). Consumption ratio and food
    predominance of flavouring materials.  Perfumer Flavourist,
    12: 27-68.

    WEIL, C.S. & McCOLLISTER, D.D. 1963. Safety evaluation of chemicals.
    Relationship between short- and long-term feeding studies in designing
    an effective toxicity test.  Agr. Food Chem., 11(6): 486-491.

    WHO (1987).  Principles For The Safety Assessment Of Food Additives
     And Contaminants In Food. WHO Environmental Health Criteria. World
    Health Organization (WHO), International Program on Chemical Safety in
    Cooperation with the Joint FAO (Food & Agriculture Organization of the
    United Nations), WHO Expert Committee on Food Additives (JECFA),
    Geneva, Switzerland, Environmental Health Criteria 70.

    WOODS, L.A. & DOULL, J. (1991). GRAS evaluation of flavouring
    substances by the Expert Panel of FEMA.  Regul. Toxicol. Pharmacol.,
    14: 48-58.

    ANNEX 5, Appendix A

    ESTIMATING DISTRIBUTION OF INTAKES OF FOOD INGREDIENTS ACROSS
    THE POPULATION

         In response to the Food Additives Amendment of 1958 to the U.S.
    Food, Drug and Cosmetic Act, the Flavor and Extract Manufacturers'
    Association (FEMA) in 1960 conducted a comprehensive survey of all
    flavoring materials then thought or claimed to be in use. Information
    included: identity; poundage used annually in food; year of first use;
    levels (in ppm) used in major food categories; toxicological data; and
    other information related to safety. After evaluation by a panel of
    external experts, this and subsequent information was published in a
    series of "FEMA GRAS Lists" (Hall and Oser, 1965, 1970; Oser and Hall,
    1972; Oser and Ford, 1973ab, 1974, 1975, 1977, 1978, 1979; Oser  et al.,
    1984, 1985; Burdock  et al., 1990; Smith and Ford, 1993).

         FEMA determined in 1968 that another survey was needed to monitor
    trends and to improve on the previous effort. In addition, the U.S.
    Food and Drug Administration (FDA) began to plan to review its
    Generally Recognized as Safe (GRAS) lists, and in so doing, made use
    of the prior experience of FEMA. FEMA and FDA efforts merged into the
    first comprehensive survey of ingredients used in food, conducted by
    the National Academy of Sciences/National Research Council (NAS) in
    1970 (NAS, 1973) with several subsequent surveys (NAS, 1978, 1979,
    1984, 1989).

         Emerging from the 1960 and 1970 surveys was a clear indication
    that  per capita intake of an ingredient (from annual poundage),
    although useful for comparison with other ingredients, has a
    significant limitation. As an average of intakes by those who consume
    foods containing the ingredient ("eaters") and by those who do not
    (non-eaters"), it does not represent the intake by the individuals of
    concern ( i.e., the "eaters"). This is not the case for ingredients
    commonly consumed by almost everyone ( e.g., sugar), but the
    difference between the average and "eaters" is significant for other
    ingredients consumed only by few people ( e.g. raspberry flavor).

         Because of these issues, an alternative method of calculating
    intakes was used in the first (1973) NAS report. This method involved
    the average level of use of an ingredient in a broad food category
    (e.g., baked goods) multiplied by the average daily consumption of
    that food category per person. The daily consumption for each category
    was obtained by multiplying the average portion size for the category,
    obtained from the U.S. Department of Agriculture (USDA) Food
    Consumption Survey by the average daily frequency of consumption of
    foods in that category over a 14-day survey period. The frequency of
    consumption data came from a 12,000+ member panel operated by the
    Market Research Corporation of America (MRCA; see note b to Table 1).

    Thus the average intake of an ingredient for all relevant food
    categories provided the "possible average daily intake" (PADI). These
    intakes were often highly exaggerated, as much as a hundred-fold,
    because an ingredient used in only a few foods in a food category was
    assumed to be at the average level in all foods in the category. Thus,
    for example, cardamom, used only in a few coffee cakes, was assumed to
    be used in each food in the entire category of baked goods ( i.e.,
    all breads, rolls, crackers, and pastries).

         To address this issue, another method was developed to give the
    probable distribution of intakes for the entire population without
    exaggerating intake. This required an informed estimate of the
    probability that each food eaten would contain the ingredient of
    interest. The first series of such intake estimates used calculation
    "A", as shown in Table 1, and the results are summarized in Section
    "A" of Table 2.

         In Table 2, Column 1 ("Substance") lists the substances selected
    to test and improve the more refined method. In Section A, nutmeg and
    mace were chosen, among other reasons because they are not grown
    domestically in the U.S. and import data, therefore, provide a firm
    external check on pounds used. Furthermore, more than half of all
    nutmeg is consumed in four foods: bologna, pork sausage, frankfurters,
    and doughnuts. It thus presented an opportunity to see how heavy
    consumers of those foods would skew total intake distribution. The
    flavor ingredient 4-(p-hydroxyphenyl)butan-2-one was chosen because it
    is used in, and occurs naturally, almost entirely in only one flavor,
    raspberry flavor, and is far less widely consumed than chocolate,
    vanilla, or citrus flavors. Thus, it is a good example of an uncommon
    ingredient consumed by those who particularly like the few foods in
    which it is used (Hall, 1975).

         Column 2 [" per capita (External Check)"] lists  per capita
    intake derived from import data, product manufacturer surveys, or
    tariff reports, all independent of the NAS survey to serve as an
    external check. Column 3 (" per capita [NAS(lbs)/0.6]") lists the
     per capita intake from the poundage reported in the NAS survey
    assumed to be 60% complete. Further research (see references to NRC
    surveys) showed this to be generally a valid assumption, but with
    certain qualifications. Ingredients such as sugar, corn syrup, and
    salt, could not be fully or reliably reported by bakers and other
    small food processors, whereas the flavor industry reported more
    fully, and the 60% assumption, while used, usually resulted in a
    poundage  per capita overestimate.

         For Section A, Column 4 ["50th Percentile (Total Panel)"]
    presents the total panel 50th percentile for each substance, and
    Column 4a ("50th Percentile 3 S.D. Total Panel"), the 50th percentile
    plus 3 standard deviations. Column 4b ["very high (Total Panel)"]
    shows the so-called "very high intake". This is not a realistic

    figure, because no person could consume all foods using an ingredient
    at the highest level for every food in every major category. Note
    particularly, also, the earlier discussion of the exaggeration that
    arises from assuming that an ingredient used only in a few foods is
    used in all foods in a major food category. The "very high intake"
    serves simply as a wholly unreachable and therefore unrealistic value.

         Given the remaining and inevitable uncertainties due to possible
    errors in estimations, and possible non-food uses, the agreement
    between the total panel 50th percentile (Section A, Column 4), the NRC
     per capita, (Column 3), and the  per capita from external sources
    (Column 2), is entirely satisfactory. However, calculation  "A" did
    not provide data on only those who actually consumed the substance
    ("eaters only"), and the statistical treatment was not as solidly
    based as was desirable. This led to an improved calculation,  "B", as
    shown in Table 3. Table 2, Section B, presents the results of these
    calculations.

         The substances shown in Column 1 of Section B were selected, as
    discussed in the referenced reports themselves, by the FDA or the NAS
    committee (NAS, 1976). An improved method of calculation was used, as
    described below, which provides the total sample mean (Column 4 ["Mean
    (Total Panel)"]) as a check against the  per capita data in Columns 2
    and 3.

         The external  per capita figure for calcium propionate is twice
    the total panel mean, probably due primarily to usage by many small
    bakeries not included in the survey, and also to the high wastage of
    bread. The slightly smaller discrepancy for MSG may well reflect
    several added sources of error. Even so, comparison of the total panel
    mean with the  per capita data from the NAS survey and the external
    checks shows satisfactory agreement. Food consumption surveys have
    significant and well-recognized sources of error in addition to those
    affecting the NRC surveys, and it seems unlikely that it is practical
    to expect intake estimates derived by different means to correspond
    more closely than within a factor of two.

         For Section B, Column 4 ["Mean (Total Panel)"] provides the total
    panel mean, Column 4a ["Mean (Eaters Only)"] the "eaters only" mean
    age, 2 and over and Column 4b ["S.D. (Eaters Only)"], the standard
    deviation for "eaters only".

         The procedure in calculation B does not eliminate all sources of
    error. Intake is still calculated from "disappearance figures"
    ( i.e, the levels introduced into food during processing, not the
    lower levels actually consumed). Thus, ignoring the often large losses
    due, for example, to volatilization or leaching in processing,
    preparation and storage result in exaggerated estimates of intake. In
    the other direction, heavy (frequent) eaters will often eat larger
    portion sizes, resulting in a tendency to underestimate higher
    intakes. The result overall, however, remains highly satisfactory.


        Table 1                                       Calculation "A"
                                                                                                             

    Step                   Operation                                       Result
                                                                                                             

            For each specific food (SF)a e.g. bologna,
            within a broad food category, eg., meats,
            obtain from MRCAb the

    1       total number of eatings of each SF by the total
            panel, in two weeks                            
            14 days  12,337 (persons in panel)               =    mean frequency of eating,  p/d
                                 

    2       mean portion size in gc                           =    mean consumption of SF, g/p/d

                                 

    3       probability of SF containing ingredient "I"d      =    probable mean consumption of SF
                                                                   containing I g/p/d

                                 

    4       usual use level of "I" in ppm of major food       =    50th percentile of probable intake of I
            category containing SF  1,000e                        from SF in mg/p/d

                                 

    5       90th percentile MRCA frequency of eating          =    90th percentile of probable intake of I
            50th percentile MRCA frequency of eating               from SF in mg/p/d

    6 & 7   sum 4 and 5 separately across all SFs in that     =    50th and 90th percentiles of probable 
            major food category                                    intake of I from that major food category 
                                                                                                             

    Table 1 (cont'd)                              Calculation "A" 
                                                                                                             

    Step    Operation                                              Result
                                                                                                             

    8       fit a curve, assuming normal distribution, to     =    50th percentile and standard deviation
            the points determined in 6 and 7 and calculate         (SD) for each major food category

    9       repeat steps 1 through 8 and sum across all       =    50th percentile and SD in mg/p/d 
            food categories                                        probable total intake

    10      repeat steps 4 and following, using "average      =    "very high intake"
            maximum use level" from the survey for each
            major food category
                                                                                                             

    a    Specific food (SF), in this context, denotes a narrow category of very similar foods serving
         the same dietary and market niches (e.g. all bologna, all cola drinks). The eatings of each SF
         include in one total for each SF all eatings of similar brands or home-prepared versions of the
         same SF. There were approximately 10,000 such SFs.
    b    The Market Research Corporation of America (MRCA) is a private market research company that
         surveys usage of food products and components It uses a nationally representative panel and
         records for each panel member the number of servings of each specific loud for each day of a
         two-week period. The panelists' reporting periods are distributed evenly throughout the year. The
         1973 NAS report used data from the third Menu Census (1967-1968) involving 12,871 individuals.
         The dataused in calculations "A" and "B" came from the Fourth Menu Census (1972-1973) involving
         12,337 individuals.
    c    The USDA Food Consumption Survey (USDA, 1965)
    d    Obtained from a consensus panel of experts knowledgeable about the ingredient and the food.
    e    From NAS, 1973
    

    Table 2  Distribution of MRCA 14-Day Average Daily Intakes (in mg/person/day)a of Selected Food Ingredients
                                                                                                                                              

               (1)                      (2)            (3)                (4)               (4a)              (4b)              (5)
                                                                                                                                              
                                                                                                                                "High Eaters
    Section    Substance                per capita     per capita         Mean              Mean plus         "Very High"       Only"
                                        (External      [NAS (lbs.)/0.6]   (Total Panel)     3 S.D.b           (Total Panel)     [NAS
                                        Check)                                              Total Panel                         (lbs.)/0.6]10
                                                                                                                                              

    A          Nutmeg                   23.6           10.3               15.7              51.3              71.1              103
               Nutmeg Oil               1.2            1.0                2.0               5.7               7.1               10
                                                                                                                                              

    A          Mace                     3.3            2.8                3.3               8.6               14.4              28
               Mace, Oil                NAc            0.26               0.19              0.67              0.46              2.6
               Mace, Oleoresin          NA             0.070              0.13              0.39              0.41              0.70
                                                                                                                                              

    A          4-p-Hydroxyphenyl        0.048          0.086              0.041             0.16              0.37              0.86
               Butan-2-one
                                                                                                                                              

    Table 2 (cont'd).
                                                                                                                                              

               (1)                      (2)            (3)                (4)               (4a)              (4b)              (5)
                                                                                                                                              
                                                                                                                                "High Eaters
    Section    Substance                per capita     per capita         Mean              Mean plus         "Very High"       Only"
                                        (External      [NAS (lbs.)/0.6]   (Total Panel)     3 S.D.b           (Total Panel)     [NAS
                                        Check)                                              Total Panel                         (lbs.)/0.6]10
                                                                                                                                              

                                                                          Mean              Mean              S.D.
                                                                          (Total Panel)     (Eaters Only)     (Eaters Only)
                                                                                                                                              

    B          Calcium Propionate       92             33                 44.8              45.1              20.7              330
               Sodium Propionate        NA             16                 33,2              33.3              14.7              160
                                                                                                                                              

    B          Carob Bean Gum           NA             26                 35.6              36.1              35.0              260
               Chondrus Extract         19.3           13                 10.6              11.1              18.5              130
                                                                                                                                              

    B          Mono- and diglycerides   NA             727                884               885               467               7,270
               Monosodium Glutamate     186            194                98.8              99.0              88.5              1,940

               (MSG)
                                                                                                                                              

    a    See text for explanation of columns.
    b    S.D. = Standard Deviation.
            Table 3                                 Calculation "B"
                                                                                              

    1    From the MRCA survey, obtain the total
         number of eatings of each SF, by each panel
         member, each day over the 14 - day period

                              

    2    USDA mean portion size, for that person's       =     quantity of SF in g for that
         age group and the relevant major food                 person, that day
         category

                              

    3    weighted mean of usual use level of I in        =     quantity of I in mg/d, that
         ppm  1,000                                           person, that day, if all of
                                                               the SF contained I

                              

    4    probability that particular SF contains I       =     expected intake of I for
                                                               that person for that day,
                                                               mg/d

    5    Repeat steps 1 through 4 for that person for    =     expected intake of I for
         each of the 14 days                                   that person for 14 days,
                                                               mg

    6                        14                         =     average daily intake over
                                                               14 days for that person,
                                                               g/p/d

    7    tabulate all intakes and compute                =     total panel mean intake of I
                                                               mg/p/d

    8    discard all persons with zero intake for the    =     "eaters only" mean and SD
         14 day period, tabulate all "eaters only" of          for I, mg/p/d
         I, age 2 and over, and compute
                                                                                              
             Unfortunately, this more refined approach, while successful, is
    extremely elaborate, tedious, and expensive. The MRCA panel is
    expensive to maintain and operate, and the data are correspondingly
    costly. The approach requires extensive input from a broadly-based,
    necessarily large and well-informed panel of expert technologists.
    Such an effort can only be justified in those few cases where it is
    necessary to obtain the distribution of intakes with maximum accuracy.

    Given the wide safety margins food ingredients typically enjoy, and
    the uncertainties and assumptions inherent in interpreting
    toxicological data, such effort is rarely necessary. A much more
    appropriate, but quick and easy, method of estimating intake was
    needed, so long as it was conservative, but not excessively so. This
    led Rulis and others in FDA (Rulis  et al., 1984; Rulis, 1987) to
    test and adopt the assumption that, except for an unusually narrow
    margin of safety or specific concern, the  per capita "eaters only"
    intake could safely and conservatively be assumed - even for heavy
    eaters - simply by multiplying the best available estimate of  per
    capita intake by ten (Column 5 ["High Eaters Only"]). Comparison of
    Column 5 with Column 4b, for Section B, makes clear that in every case
    the: "High Eaters Only" ( per capita  10) estimate far exceeds the
    "Eaters Only mean plus 3 standard deviations", yet in no case are the
    estimates so high as to be unusable.

         With the special factors surrounding the use of flavoring
    ingredients (i.e., completeness of the surveys, typical volatility
    with consequent loss in processing, and self-limiting nature) the
    procedure in Column 5 is practical but highly conservative. It has
    been widely used in other publications (FDA, 1982, 1993; Easterday
     et al., 1993). It can be used safely in all instances except when a
    very narrow margin of safety requires maximally precise data for both
    toxicological effects and exposure.

         Recently, still more sophisticated methods for analyzing USDA
    Food Consumption Survey data have become available under license for
    those applications in which the need for relatively high precision of
    estimates justifies the cost (Helmbach, 1994). In nearly all instances
    where broadly- based ingredient disappearance data are available,
     per capita  10, in actuality, a very high "eaters only" estimate,
    remains the approach that is by far the simplest and least expensive,
    while being conservative but realistic.

    REFERENCES

    Burdock, G.A., Wagner, B.M., Smith, R.L., Munro, I.C. and Newberne,
    P.M. 1990. Recent progress in the consideration of flavoring
    ingredients under the food additives amendment. 15. GRAS substances.
    A list of flavoring ingredient substances considered generally
    recognized as safe by the Flavor & Extract Manufacturers' Association
    Expert Panel. Food Technol 44(2):78, 80, 82, 84, & 86.

    Easterday, O.D., Ford, R.A., Hall, R.L., Stofberg, J., Cadby, P. and
    Grundschober, F. 1992. A Flavor Priority Ranking System, Acceptance
    and Internationalization. In: Finley, J.W., Robinson, S.F. and
    Armstrong, D.J. (Eds.) Food Safety Assessment. American Chemical
    Society, ACS Symposium Series No. 484.

    FDA. 1982. Toxicological Principles for the Safety Assessment of
    Direct Food Additives and Color Additives Used in Food. Redbook. U.S.
    Food and Drug Administration, Bureau of Foods, Washington, DC.

    FDA. 1993. Toxicological Principles for the Safety Assessment of
    Direct Food Additives and Color Additives Used in Food. Redbook II
    (Draft). U.S. Food and Drug Administration, Center for Food Safety and
    Applied Nutrition, Washington, DC.

    Hall, R.L. and Oser, B.L. 1965. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment. III. GRAS
    substances. Food Technol 19(2):151-197.

    Hall, R.L. and Oser, B.L. 1970. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment. IV. GRAS
    substances. Food Technol 24(5):25-28, 30-32, 34.

    Hall, R.L. 1975. Unpublished data from personal communication to the
    NAS/NRC Committee on GRAS List Survey - Phase III, and to the FEMA.

    Heimbach, J.T. 1994. Personal communication re: TAS-DIET from J.T.
    Helmbach, Technical Assessment Systems, Inc., Washington, D.C.

    NAS. 1973. A comprehensive Survey on the Use of Food Chemicals
    Generally Recognized as Safe, National Technical Information Service
    (NTIS) PB-221949.

    NAS. 1976. Estimating Distribution of Daily Intakes of Certain GRAS
    Substances. National Research Council, Washington, DC. Prepared for:
    Food and Drug Administration, Washington, DC. December 1976. National
    Technical Information Service (NTIS) PB-299-381.

    NAS. 1978. Resurvey of the Annual Poundage of Food Chemicals Generally
    Recognized as Safe, National Technical Information Service (NTIS)
    PB288-081.

    NAS. 1979. Comprehensive Survey of Industry on the Use of Food
    Additives, National Technical Information Service (NTIS) PB80-113418.

    NAS. 1984. Poundage Update of Food Chemicals, National Technical
    Information Service (NTIS) PB84-162148.

    NAS. 1989. 1987 Poundage and Technical Effects Update of Substances
    Added to Food. National Research Council, Washington, DC. Prepared
    for: Food and Drug Administration, Washington, D.C. NTIS Report
    No. PB91-127266.

    Oser, B.L. and Ford, R.A. 1973a. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment 6. GRAS
    substances. Food Technol 27(1):64-67.

    Oser, B.L. and Ford, R.A. 1973b. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment 7. GRAS
    substances. Food Technol 27(11):56-57.

    Oser, B.L. and Ford, R.A. 1974. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment 8. GRAS
    substances. Food Technol 28(9):76-80.

    Oser, B.L. and Ford, R.A. 1975. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment 9. GRAS
    substances. Food Technol 29(8):70-72.

    Oser, B.L. and Ford, R.A. 1977. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment 10. GRAS
    substances. Food Technol 31(1):65-74.

    Oser, B.L. and Ford, R.A. 1978. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment 11. GRAS
    substances. Food Technol 32(2):60-70.

    Oser, B.L. and Ford, R.A. 1979. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment 12. GRAS
    substances. Food Technol 33(7):65-73.

    Oser, B.L. and Hall, R.L. 1972. Recent progress in the consideration
    of flavoring Ingredients under the Food Additives Amendment 5. GRAS
    substances. Food Technol 26(5):35-42.

    Oser, B.L. and Hall, R.L. 1977. Criteria employed by the Expert Panel
    of FEMA for the GRAS evaluation of flavoring substances. Food Cosmet
    Toxicol 15:457-466.

    Oser, B.L., Ford, R.A. and Bernard, B.K. 1984. Recent Progress in the
    consideration of flavoring ingredients under the Food Additives
    Amendment 13. GRAS substances. Food Technol 38(10):66-89.

    Oser, B.L., Well, C.S., Woods, L.A. and Bernard, B.K. 1985. Recent
    progress in the consideration of flavoring ingredients under the Food
    Additives Amendment 14. GRAS substances. Food Technol 39(11):108-117.

    Rulis, A.M., Hattan, D.G., and Morgenroth, V.H.,III. 1984. FDA's
    priority-based assessment of food additives. I. Preliminary results.
    Reg Toxicol Pharm 4:37-56.

    Rulis, A.M. 1987. Safety assurance margins for food additives
    currently in use. Reg Toxicol Pharm 7:160-168.

    Smith, R.L. and Ford, R.A. 1993. Recent progress in the consideration
    of flavoring ingredients under the Food Additives Amendment 16. GRAS
    substances. Food Technol-June 1993, pp. 104-117.

    ANNEX 5 Appendix B

    SUBSTANCES IN REFERENCE DATABASE BY ORDER OF STRUCTURAL CLASS

    Cramer  et al. (1978) Structural Class I

    1    acetic acid
    2    acetoin
    3    acetone
    4    adipic acid
    5    allura red AC
    6    aminoundecanoic acid, 11-
    7    ascorbic acid
    8    ascorbic acid, 1-
    9    benzaldehyde
    10   benzoic acid
    11   benzyl acetate
    12   benzyl alcohol
    13   bis(2-ethylhexyl)phthalate
    14   brilliant black BN
    15   butanediol, 1,3-
    16   butanol, 2-
    17   butanol, n-
    18   butyl benzyl phthalate
    19   butylated hydroxyanisole
    20   butyrolactone, gamma-
    21   calcium cyclamate
    22   calcium formate
    23   calcium stearoyl lactylate
    24   carotenoic acid, beta-apo-8'-, methyl ester
    25   cinnamaldehyde
    26   citral
    27   citranaxanthin
    28   cumene
    29   di(2-ethylhexyl)adipate
    30   dibutyl phthalate
    31   diethyl phthalate
    32   diethylene glycol
    33   diethylene glycol monoethyl ether
    34   dimethoxane
    35   dimethyl terephthalate
    36   dimethylcarbonate
    37   dimethyldicarbonate
    38   dimethylphenol, 2,4-
    39   dimethylphenol, 2,6-
    40   dimethylphenol, 3,4-
    41   dioctyl sodium sulfosuccinate
    42   disodium 5'-guanylate
    43   disodium 5'-inosinate

    44   dodecyl gallate
    45   ethanol
    46   ethyl acetate
    47   ethyl acrylate
    48   ethyl butyrate
    49   ethyl ether
    50   ethyl formate
    51   ethyl glycol monomethyl ether
    52   ethyl heptanoate
    53   ethyl nonanoate
    54   ethyl-1-hexanol, 2-
    55   ethylbenzene
    56   ethylbutyric acid, 2-
    57   ethylene glycol
    58   ethylhexanoic acid, 2-
    59   ethylphthalyl ethylglycolate
    60   eugenol
    61   FD & C blue No. 1
    62   FD & C blue no. 2
    63   formaldehyde
    64   fumaric acid
    65   geranyl acetate
    66   glutamate, monosodium
    67   glutamic acid hydrochloride
    68   glutamic acid, 1-
    69   glycerol
    70   glyceryl tribenzoate
    71   hexenal, 2- (trans)
    72   hexylresorcinol, 4-
    73   hydroquinone
    74   hydroxybenzoic acid butyl ester, p-
    75   hydroxybenzoic acid ethyl ester, p-
    76   hydroxybenzoic acid methyl ester, p-
    77   hydroxybenzoic acid propyl ester, p-
    78   hydroxybenzyl acetone, p-
    79   inosine monophosphate
    80   ionone
    81   isoamyl butyrate
    82   isoamyl salicylate
    83   isobutyl alcohol
    84   isomaltitol
    85   isopropyl alcohol
    86   isovaleric acid
    87   lactitol
    88   limonene, d-
    89   lithocholic acid
    90   malonaldehyde, sodium salt
    91   mannitol
    92   mannitol, d-
    93   menthol

    94   methanol
    95   methyl ethyl carbonate
    96   methyl methacrylate
    97   methyl salicylate
    98   methyl-1-phenylpentan-2-ol, 4-
    99   methylenebis, 2,2'-
    100  methylphenol, 3-
    101  methylphenylcarbinyl acetate
    102  myrcene, beta-
    103  nonalactone, gamma-
    104  octyl acetate
    105  octyl gallate
    106  oleylamine
    107  oxalic acid
    108  phenol
    109  phenoxyethanol
    110  phenyl-1-propanol, 2-
    111  phenylalanine
    112  potassium sorbate
    113  propyl gallate
    114  propylene glycol
    115  resorcinol
    116  retinol
    117  riboflavin
    118  sodium benzoate
    119  sodium erythorbate
    120  sodium lauryl glyceryl ether sulfonate
    121  sodium lauryl trioxyethylene sulfate
    122  sodium stearoyl lactylate
    123  sorbic acid
    124  stearyl tartrate
    125  styrene
    126  sucrose monopalmitate
    127  sucrose monostearate
    128  tartaric acid
    129  tertiary butyl hydroquinone
    130  tocopherol, alpha-
    131  tolualdehyde
    132  toluene
    133  triethylene glycol
    134  triethylene glycol monomethyl ether
    135  trimethylamine
    136  undecalactone, gamma-
    137  vanillin
    138  xylitol

    Cramer et al. (1978) Structural Class II

    1    acrylic acid
    2    allyl alcohol
    3    allyl heptanoate
    4    allyl hexanoate
    5    butylated hydroxytoluene
    6    caffeine
    7    carotene, beta-
    8    carvone
    9    carvone, d-
    10   diacetyl
    11   diallyl phthalate
    12   diketopiperazine
    13   ethyl maltol
    14   ethyl vanillin
    15   ethylhexyl phthalate, mono-2
    16   etretinate
    17   fenthion
    18   furfural
    19   isobornyl acetate
    20   isophorone
    21   maltol
    22   methyl amyl ketone
    23   methyl anthranilate
    24   piperidine
    25   piperonal
    26   propargyl alcohol
    27   pyridine
    28   thujone

    Cramer et al, (1978) Structural Class III

    1    (1-naphthyl)ethylene--diamine dihydro chloride, N-
    2    (2-chloroethyl)trimethyl-ammonium chloride
    3    (8-beta)N-cyclohexyl-6-methyl- 1 -(1 -methyl
         ethyl)ergoline-8 -carboxamide
    4    (chloroacetyl)-acetanilide, 4'-
    5    1,1'-(2,2,2-trichloroethylidene)bis(4-chloro)-benzene
    6    11-oxo-11H-pyrido(2,1-b)quinazoline-2-carboxylic acid
    7    2(2,4,5-trichlorophenoxy) propionic acid
    8    2-(2-methyl--4-chlorophenoxy)propionic acid
    9    4-(2-methyl-4-chlorophenoxy) butyric acid
    10   acenaphthene
    11   acephate
    12   acesulfame potassium
    13   acetaminophen
    14   acetoacetamide
    15   acetoacetamide-N-sulfonic acid
    16   acetochlor

    17   acetonitrile
    18   acifluorin sodium
    19   acrylamide
    20   acrylonitrile
    21   alachlor
    22   albendazole
    23   albendazole sulfoxide
    24   aldicarb
    25   aldicarb sulfone
    26   alinidine hydrobromide
    27   allyl isovalerate
    28   amaranth
    29   ameltolide
    30   ametryn
    31   amino-4-ethoxy-acetanilide, 3-
    32   amino-4-nitrophenol, 2-
    33   amino-5-nitrophenol, 2-
    34   aminophenol, p-
    35   amitraz
    36   ammonium carmine
    37   amphetamine sulfate, dl-
    38   ampicillin trihydrate
    39   anethole, trans-
    40   anilazine
    41   anisidine hydrochloride, p-
    42   anthranilic acid
    43   arochlor 1254
    44   aspartame
    45   asulam
    46   atrazine
    47   avermectin B1
    48   azaperone
    49   azinphos methyl
    50   azorubine
    51   azuletil (KT1-32)
    52   baythroid
    53   benomyl
    54   bentazon
    55   benzofuran
    56   benzoic acid, 2-[[[[N-(4-methoxy-6-methyl
         -1,2,3-triazin-2-yl)-N-methylamino]carbonyl]
         amino]sulfonyl] methyl ester
    57   benzoin
    58   benzyl violet 4B
    59   benzyl-p-chlorophenol, o-
    60   betaxolol
    61   bidrin
    62   biphenthrin
    63   biphenyl, 1,1-
    64   biphenylamine hydrochloride, 2-

    65   bis(2-chloro-1-methyl-ethyl)ether Technical Grade
    66   bis(2-chloroisopropyl)ether
    67   bisphenol A
    68   bromoacetic acid, 2-
    69   bromodichloromethane
    70   bromomethane
    71   bromoxynil
    72   bromoxynil octanoate
    73   brown FK
    74   butyl chloride, n-
    75   butylate
    76   calcium cyanamide
    77   canthaxanthin
    78   caprolactam
    79   captafol
    80   captan
    81   carazolol
    82   carbaryl
    83   carbendazim
    84   carbofuran
    85   carbon tetrachloride
    86   carbosulfan
    87   carboxin
    88   carmoisine
    89   chloramben
    90   chlordane
    91   chlorendic acid
    92   chlorimuron-ethyl
    93   chloro-p-toluidine, 3-
    94   chloroacetic acid
    95   chloroaniline hydrochloride, p-
    96   chlorobenzene
    97   chlorobenzilate
    98   chlorodibromomethane
    99   chloroform
    100  chlorofructose, 6-
    101  chloronaphthalene, beta-
    102  chlorophenol, 2-
    103  chloropropylate
    104  chlorothalonil
    105  chlorotoluene, o-
    106  chlorpheniramine maleate
    107  chlorpromazine
    108  chlorsulfuron
    109  chlorthal dimethyl
    110  chocolate brown HT
    111  C.I. Acid Orange 12
    112  C.I. Acid Orange 3
    113  C.I. Acid Red 18
    114  C.I. Disperse Blue 1

    115  C.I. acid red 14
    116  C.I. disperse yellow 3
    117  C.I. pigment red 23
    118  C.I. solvent yellow 14
    119  cimetidine
    120  clofentezine
    121  clonitralid
    122  closantel
    123  codeine
    124  coumaphos
    125  coumarin
    126  crufomate
    127  curcumin
    128  cyclodextrin, beta-
    129  cyclohexylamine
    130  cyclophosphamide
    131  cyhalothrin
    132  cypermethrin
    133  cyromazine
    134  daminozide
    135  decabromodiphenyl oxide
    136  deoxyquinine
    137  diamino-2,2'-stilbenedisulfonic acid, 4,4'-, disodium sa
    138  diaminophenol dihydrochloride, 2,4-
    139  diazinon
    140  dibenzo-p-dioxin
    141  dibromobenzene, 1,4-
    142  dicamba
    143  dichloro-2-propanol, 1,3-
    144  dichloro-p-phenylenediamine, 2,6-
    145  dichlorobenzene, 1,2-
    146  dichlorobenzene, 1,4-
    147  dichlorobenzilic acid
    148  dichlorodifluoromethane
    149  dichloroethane, 1,1-
    150  dichloroethane, 1,2-
    151  dichloroethylene, 1,1-
    152  dichloroethylene, trans- 1,2-
    153  dichloromethane
    154  dichlorophenol, 2,4-
    155  dichlorophenoxyacetic acid, 2,4-
    156  dichloropropanol, 2,3-
    157  dichloropropene, 1,3-
    158  dichlorvos
    159  dicofol
    160  dieldrin
    161  diethyldithiocarbamate
    162  diethylthiourea, N,N'-
    163  difenzoquat
    164  diflubenzuron

    165  dihydroavermectin-B1 a, 22,23-
    166  dihydroavermectin-B1 b, 22,23-
    167  dihydrocoumarin, 3,4-
    168  diiodomethyl p-tolyl sulfone
    169  dimethipin
    170  dimethoate
    171  dimethoxyaniline hydrochloride, 2,4-
    172  dimethoxybenzidine-4,4'-diisocyanate, 3,3'-
    173  dimethyl hydrogen phosphite
    174  dimethyl methylphosphonate
    175  dimethyl morpholinophosphoramidate
    176  dimethylaniline, N,N'-
    177  dinitrobenzene, m-
    178  dinitrotoluene, 2,4-
    179  dinocap
    180  dinoseb
    181  diphenamid
    182  diphenhydramine hydrochloride
    183  diphenylamine
    184  diphenylhydantoin, 5,5'-
    185  diphenylhydantoin, 5,5-
    186  diquat
    187  disulfoton
    188  dithiobiurea, 2,5-
    189  diuron
    190  dodecylguanidine acetate, n-
    191  EDTA, disodium
    192  endothall
    193  ephedrine sulfate
    194  epichlorohydrin
    195  erythromycin stearate
    196  erythrosine
    197  ethalfuralin
    198  ethephon
    199  ethion
    200  ethyl dipropylthiocarbamate, s-
    201  ethyl p-nitrophenyl phenylphosphorothioate
    202  ethylene chlorohydrin
    203  ethylene thiourea
    204  ethylmethylphenylglycidate
    205  fast green FCF
    206  febantel
    207  fenamiphos
    208  fenbendazole
    209  fenchlorphos
    210  fluometuron
    211  fluoranthene
    212  fluorene
    213  fluridone
    214  flurprimidol

    215  flutolanil
    216  fluvalinate
    217  folpet
    218  fonofos
    219  fosetyl-al
    220  glufosinate-ammonium
    221  glyphosate
    222  haloxyfop-methyl
    223  HC blue no. 1
    224  HC blue no. 2
    225  HC yellow 4
    226  heptachlor
    227  heplachlor epoxide
    228  hexabromobenzene
    229  hexachlorobenzene
    230  hexachlorobutadiene
    231  hexachlorocyclohexane, gamma-
    232  hexachlorocyclopentadiene
    233  hexachloroethane
    234  hexachlorophene
    235  hexahydro-1,3,5-trinitro-1,3,5-triazine
    236  hexamethylenetetramine
    237  hexazinone
    238  hexythiazox
    239  hydralazine
    240  hydrazobenzene
    241  hydrochlorothiazide
    242  hydroxypropyl methanethiolsulfonate, 2-
    243  hydroxyquinoline, 8-
    244  imazalil
    245  imazaquin
    246  imazethapyr
    247  iodinated glycerol
    248  ipazilide
    249  iprodione
    250  ipronidazole
    251  isopropalin
    252  isoxaben
    253  jervine
    254  lactofen
    255  lansoprazole
    256  levamisole
    257  linamarin
    258  linuron
    259  londax
    260  malaoxon
    261  malathion
    262  maleic anhydride
    263  maleic hydrazine
    264  manidipine hydrochloride

    265  melamine
    266  mepiquat chloride
    267  mercaptobenzothiazole, 2-
    268  merphos
    269  merphos oxide
    270  meso-2,3-dimercaptosuccinic acid
    271  metalaxyl
    272  methamidophos
    273  methidathion
    274  methomyl
    275  methoxychlor
    276  methoxypsoralen, 8-
    277  methyl carbamate
    278  methyl ethyl ketoxime
    279  methyl parathion
    280  methyl-4-chlorophenoxyacetic acid, 2-
    281  methyl-N-methylanthranilate
    282  methyldopa sesquthydrate, alpha-
    283  methylolacrylamide, N-
    284  metolachlor
    285  metribuzin
    286  metsulfuron methyl
    287  mexacarbate
    288  miporamicin
    289  mirex
    290  molinate
    291  monodiethanolamine salt of riboflavin-5'-phosphate
    292  monuron
    293  myclobutanil
    294  naled
    295  nalidixic acid
    296  naphthoxy acetic acid, 2-
    297  napropamide
    298  natamycin
    299  nitro-o-toluidine, 5-
    300  nitro-p-phenylenediamine, 2-
    301  nitroaniline, p-
    302  nitroanthranilic acid, 4-
    303  nitrofurantoin
    304  nitrofurazone
    305  nitroguanidine
    306  nitronaphthalene, 1-
    307  nitrosodiphenylamine, N-
    308  norflurazon
    309  ochratoxin A
    310  octabromodiphenyl ether
    311  octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine
    312  olaquindox
    313  oryzalin
    314  oxadiazon

    315  oxamyl
    316  oxfendazole
    317  oxyfluorfen
    318  oxytetracycline
    319  oxytetracycline hydrochloride
    320  oxythioquinox
    321  paclobutrazol
    322  paraquat
    323  parathion
    324  patulin
    325  pendimethalin
    326  penicillin VK
    327  pentabromodiphenyl ether
    328  pentachloroethane
    329  pentachloronitrobenzene
    330  pentachlorophenol
    331  pentaerythritol tetranitrate
    332  permethrin
    333  phenformin
    334  phenyl-2-naphthylamine, n-
    335  phenyl-3-methyl-5-pyrazolone, 1-
    336  phenylbutazone
    337  phenylenediamine, m-
    338  phenylephrine hydrochloride
    339  phosmet
    340  phosphamidon
    341  photodieldrin
    342  phthalamide
    343  phthalic anhydride
    344  picloram
    345  pilsicainide hydrochloride
    346  pirimiphos-methyl
    347  pravadoline
    348  probenecid
    349  prochloraz
    350  proflavine monohydrochloride hemihydrate
    351  promethazine hydrochloride
    352  prometon
    353  prometryn
    354  pronamide
    355  propachlor
    356  propanil
    357  propargite
    358  propazine
    359  propham
    360  propiconazole
    361  propiverine hydrochloride (P-4)
    362  propoxur
    363  propylene dichloride
    364  pydrin

    365  pyrazinamide
    366  pyrene
    367  pyrimidinone
    368  quercetin
    369  quinalphos
    370  quinine hydrochloride
    371  quinofop ethyl
    372  red 2G
    373  reserpine
    374  resmethrin
    375  thudamine 6G
    376  ronidazole
    377  rotenone
    378  saccharin
    379  sethoxydim
    380  simazine
    381  sodium 2,2-dichloropropionate
    382  sodium cyclamate
    383  sodium fluoroacetate
    384  sodium naphthionate
    385  sorbitan monolaurate
    386  sorbitan monostearate
    387  succinic anhydride
    388  sucrose acetate isobutyrate
    389  sulfadimidine
    390  sulfisuxazole
    391  sulfolene, 3-
    392  sunset yellow FCF
    393  suplatast tosilate
    394  tebuthiuron
    395  terbacil
    396  terbutryn
    397  tert-butyl-2-chlorophenol, 4-
    398  tetrachlorobenzene, 1,2,4,5-
    399  tetrachloroethane, 1,1,1,2-
    400  tetrachloroethane, 1,1,2,2-
    401  tetrachloroethylene
    402  tetrachlorophenol, 2,3,4,6-
    403  tetrachloropyridine, 2,3,5,6-
    404  tetrachlorvinphos
    405  tetracycline hydrochloride
    406  tetraethyldithiopyrophosphate
    407  tetraethylthiourea disulfide
    408  tetrahydrocannabinol, delta-9-
    409  tetrakis(hydroxymethyl)phosphonium chloride (THPC)
    410  tetrakis(hydroxymethyl)phosphonium sulphate (THPS)
    411  thiabendazole
    412  thiameturon methyl
    413  thiobencarb
    414  thiophanate-methyl

    415  thiram
    416  tocopheryl acetate, dl-alpha-
    417  toluenediamine hydrochloride, 2,6-
    418  toluenediamine sulfate, 2,5-
    419  tralomethrin
    420  trenbolone acetate
    421  trenbolone hydroxide, 17-alpha-
    422  triadimefon
    423  triallate
    424  triamterene
    425  tribromomethane
    426  trichloroacetonitrile
    427  trichlorobenzene, 1,2,4-
    428  trichloroethane, 1,1,2-
    429  trichloroethane, 1,1,1-
    430  trichloroethylene
    431  trichloroethylene, 1,1,2-
    432  trichlorogalactosucrose
    433  trichlorophenol, 2,4,5-
    434  trichlorophenoxyacetic acid, 2,4,5-
    435  tridiphane
    436  triethylene tetramine dihydrochloride
    437  trifluralin
    438  trimethylaniline, 2,4,5-
    439  trinitrotoluene, 2,4,6-
    440  tris-(2-chloroethyl) phosphate
    441  trisulfuron
    442  tylosin
    443  vinclozolin
    444  vinyl chloride
    445  zatosetron maleate
    446  zearalenone
    447  zeranol
    



















    See Also:
       Toxicological Abbreviations