TRICHLORFON JMPR 1975
Explanation
Trichlorfon was evaluated by the Joint Meeting in 1971 (FAO/WHO,
1972).
Arising out of the list of requirements in the report of the 1971
Joint Meeting (FAO/WHO, 1972) additional information became available
on residues from supervised trials on lettuce (outdoors) and spinach
(outdoors and under glass).
A temporary ADI was estimated in 1971 and temporary tolerances
were recommended. Based on inconclusive findings in long-term studies
a temporary ADI of 0-0.01 mg/kg per day was estimated.
At the eighth Session of the Codex Committee on Pesticide
Residues (Alinorm 76/24) the delegations of the Netherlands and Israel
expressed the opinion (para. 168) that the proposed temporary
tolerance of 0.1 mg/kg for tomatoes was too low to cover residues
resulting from good agricultural practice in their countries. The
Joint Meeting was requested to re-evaluate the limit, with the help of
data to be provided. Limited data have been received from the
Netherlands.
The delegation of the Netherlands also requested (para. 169) that
the Joint Meeting should propose tolerances for pears, currants,
mushrooms, spinach, melons (under glass), cucumbers (under glass) and
bell peppers (under glass). Governments were asked to send any data in
their possession. No data on any of these crops except spinach have
however been received.
This monograph addendum includes an evaluation of the new data on
toxicology and on lettuce, spinach and tomatoes, and a re-evaluation
of data already available on cereals in the light of current use
patterns.
EVALUATION FOR ACCEPTABLE DAILY INTAKE
TOXICOLOGICAL STUDIES
Special studies on acute administration
Chicken
Groups of 6, 10, 6 broilers were given by gastric intubation, a
single administration of 40, 60 and 80 mg/kg bw trichlorfon in 1%
aqueous solution. ChE activity and blood biochemical parameters
(alkaline phosphatase, serum proteins, uric acid and electrolytes)
were examined. Plasma ChE depression reached its maximum (8.4-10.8% of
its initial value) four hours after administration and activity
recovered to 80% after seven days at all levels of administration;
decreased alkaline phosphatase activity, slight diminution in serum
proteins (total and fractions) but no noticeable change in level of
Na, K, Ca, Mg were observed. Onset of symptoms was rapid (20-30
minutes after administration) and included respiratory failure, clonic
convulsion, prostration, loss of appetite, salivation and diarrhoea.
No morphological changes were observed in organs at autopsy of dead
animals (Lazarov and Magat, 1975).
Special studies on carcinogenicity
Groups of rats and mice were administered trichlorfon at various
routes, doses and periods ranging from six weeks to the end of the
animal's life. In two studies (Gibel et al., 1971 and 1973) the
authors concluded that hepatotoxic, haematotoxic and carcinogenic
effects were observed, The following is a summary of methodology
employed in both studies.
(Weekly)
Duration Dose
Year Species Number Route of dosing (mg/kg)
1971 Rat 40 M & 40 F Oral Not specified 3 × 30 mg/kg
Rat 40 M & 40 F S.C. Not specified 2 × 30 mg/kg
Mice 10 M & 10 F Dermal 5 months 3 ×
1973 Rat 20 M & 20 F Oral Not specified 2 × 15 mg/kg
Rat 20 M & 20 F I.M. Not specified 2 × 15 mg/kg
Mice 10 M & 10 F Dermal 6 weeks 2 ×
The 1973 treatments caused hyperplasia of the blood forming
system of bone marrow and extraosseal metaplasia in the liver and
spleen. In addition, the authors diagnosed myeloproliferation and
partly extraosseal myeloid metaplasia. The authors in addition
describe extensive hepatotoxicity and carcinogenic response in both
studies.
The evaluation of these papers is difficult as doses or duration
are not specified in all cases. The hepatotoxic effects ranging from
fibrosis to cirrhosis in rats and mice are not consistent with
findings in other long-term studies in rats and dogs. Dermatological
disturbances are difficult to comprehend, especially in light of their
occurrence when dimethoate was also used in another trial.
Leukaemia-like toxic signs have not been demonstrated with dimethoate
and in general, leukaemia is difficult to produce in animal
experiments.
With reference to the carcinogenic response, the authors suggest
that benign tumours are a reflection of severe hepatotoxicity and the
mean survival time of mice was longer in the 1971 study in which
trichlorfon was administered at a higher dose for a greater period of
time. In addition there was no correlation between dose and tumour
frequency in this dermal study. The description of localization of
tumours occurring in the study gives no indication of organotrophy. In
addition, data reported in the 1971 Evaluation suggesting tumour
formation in mammary glands was not substantiated in these studies.
Basically, these two studies are contradictory in their own right of
previous studies and are in addition difficult to fully interpret. It
is difficult if not impossible to compare these studies with
previously reported long-term studies showing no carcinogenic,
hepatotoxic or haemotoxic response. In light of these difficulties and
in inconsistencies in data reported for dimethoate, little
significance is given to the above referenced studies in evaluating
the ADI.
Special studies on neurotoxicity
Groups of hens (number of birds/group not specified) were
administered trichlorfon orally or by intraperitoneal injection at
dose levels ranging from 25-100 mg/kg (acute LD50 = 75 mg/kg) and
examined for signs of delayed neurotoxicity. No ToCP-like signs of
delayed neurotoxicity were observed (Kimmerle and Loser, 1974).
Short-term studies
Rat
Morphological changes in the lung, kidney and liver were reported
following continuous inhalation exposure to trichlorfon at high
levels. Exposure to 20 mg/l and above concentrations for 90 days
resulted in bile duct hypertrophy, kidney changes, thyroid changes and
capillary enlargement of the interalveolar membrane of the lung. At 20
mg/l no effects were reported (Bonashevakaya and Tabakova, 1972).
Rats were administered trichlorfon orally at a daily dose of 8.5
mg/kg body weight in combination with carbon tetrachloride
administered three times/week for nine months (dose stated to be 0.1
mg/100 g of a 25% solution in sunflower seed oil). The combined effect
led to "more advanced and stable destructive and dystrophic changes in
the liver and enhanced the cirrhotic process". Liver metabolism was
disrupted (Rodionov and Voronina, 1973).
Subacute poisoning to rats (300 mg/kg/day) for five days resulted
in significant changes observed histologically. All changes as were
described were not specific and might appear in many cases of acute
poisoning. Biochemical lesions included cholinesterase depression and
succinate dehydrogenase and cytochrome oxidase inhibition in brain,
liver, kidney and heart (Karmelov, 1973).
Chicken
A daily dose of 5 mg/kg bw trichlorfon in 1% aqueous solution was
given by gastric intubation to a group of 5 broilers for 14 days,
after which period the dose was increased to 20 mg/kg for 14
additional days; to another group of 5 broilers, a daily dose of 10
mg/kg bw was given for 28 days. In the 5-20 mg/kg group ChE activity
after reaching a low peak at day 7, increased almost to its initial
value at day 14, after which period it decreased to 62% of its initial
value at day 28; in the 10 mg/kg group ChE activity after a slight
increase at day 7, declined gradually until day 28. Alkaline
phosphatase declined in both groups; serum proteins showed
insignificant variations and no changes were observed in electrolyte
levels; body weight gain was depressed at 20 mg as compared to 10 mg.
Clinical signs (respiratory, digestive and motor disturbances) were
more accentuated in the higher level group and more marked at day 3 to
5 of treatment (Lazarov and Magat, 1975).
Calf
Calves were fed trichlorfon for 3 months at dosage levels of
7.87, 15.9 and 41.25 ppm in the diet. No effects were noted at the low
dose level while at 15.9 ppm cholinesterase depression and generalized
histopathological signs were noted. Death occurred at the high level
(summary reviewed from abstract, no details are available) (Yasnova et
al., 1971).
COMMENTS
Trichlorfon was reviewed in 1971, at which time a temporary ADI
was estimated to be 0-0.01 mg/kg per day based on both long-term
animal studies and on extensive observations in man. There was serious
consideration given to three long-term rat studies that were basically
inconclusive with respect to the carcinogenic potential of
trichlorfon. Since that time some new work was reported again
reflecting a carcinogenic potential. A complete evaluation of the
conflicting research data was made.
The data that have come to light since the 1971 meeting do not
allow a further interpretation of the confusing observations with
respect to long-term rat studies showing a tumourigenic potential on
two studies, no such effect in a third study (in rats) and no-effect
on tumour formation in dogs. Although, as there is little indication
that the requested work on rats is to be forthcoming a current study
with mice has been reported to be in progress. In addition, some
concern was expressed of the mechanism by which trichlorfon is
transformed to dichlorvos. The potential intermediates formed in the
intramoleculan rearrangement might include carbanion or free radical
formation which may have no mutagenesis or carcinogenesis problems.
In the light of the extensive experience of use in man and with
the expectation of a new carcinogenesis study, the temporary ADI was
extended although at a lower figure.
TOXICOLOGICAL EVALUATION
Level causing no toxicological effect
Rat: 50 ppm in the diet equivalent to 2.5 mg/kg body weight.
Dog: 50 ppm in the diet equivalent to 1.25 mg/kg body weight.
ESTIMATE OF TEMPORARY ACCEPTABLE DAILY INTAKE FOR MAN
0-0.005 mg/kg body weight.
RESIDUES IN FOOD AND THEIR EVALUATION
RESIDUES FROM SUPERVISED TRIALS
See Table 1.
Each graph presents a plot of all residue values recorded in
trials in the Federal Republic of Germany, Finland and the United
States of America; a line is drawn based on the maximum values found
on the respective days after treatment, omitting one experiment on
lettuce in the United States of America showing abnormal figures.
APPRAISAL
New data from supervised trials confirmed the validity of the
recommendations for temporary tolerances made in 1971 with the
exception of that for tomatoes. Extensive data from a number of
countries reflecting trials carried out over many years provided an
adequate basis for recommendations with respect to trichlorfon
residues on lettuce and spinach as required by the 1971 Meeting. New
data on residues in tomatoes were limited, but were considered
sufficient to justify the increased temporary maximum residue limit
recommended below.
TABLE 1. Residues of trichlorfon resulting from supervised trials
Application Residue (mg/kg) intervals (days) after application
Rate kg
Crop Country Year No. a.i./ha Formulation 0 1 3/5 7 9/12 14 21 Ref.
Lettuce
(outdoors)
leaf-lettuce Finland 1972 1 1.2 wp 80% 33.5 2.6 0.61 0.21 0.03 11, 17
Finland 1972 1 1.2 wp 80% 26.4 1.3 0.23 0.26 0.02 11, 17
leaf-lettuce U.S.A. 1961 2 1.2 wp 50% 6.3 1.3 <0.1 <0.1 12
1961 2 1.2 wp 50% 3.5 1.1 <0.1 <0.1 12
1961 2 1.2 wp 50% 2.7 0.4 0.2 12
(0.8- (<0.1- (<0.1-
3.8) 0.8) 0.4)
1962 2 1.2 wp 50% 97.6 9.2 6.0 3.9 12
head-lettuce Finland 1972 1 1.2 wp 50% 22.8 1.5 0.31 0.04 0.01 13, 17
1972 1 1.2 wp 50% 31.2 1.1 0.17 0.06 <0.01 13, 17
head-lettuce Fed. Rep. 1972 1 0.75 E.C. 50% 8.1 1.8 0.54 0.41 0.20 <0.05 <0.05 14
of Germany
1972 1 0.45 E.C. 50% 5.8 1.8 0.22 0.09 <0.05 <0.05 <0.05 14
1972 1 0.45 E.C. 50% 4.8 4.3 0.27 <0.05 <0.05 <0.05 <0.05 14
1972 1 0.75 E.C. 50% 15.9 4.6 0.21 0.08 0.14 <0.05 <0.05 14
lettuce U.S.A. 1957 1 0.6 wp 50% 1.6 0.8 0.3 0.7 0.03 0.2 15
1958 1 1.2 wp 50% 0.8 0.8 0.6 <0.1 0.03 15
1959 1 0.6 wp 50% 1.8 0.3 0.1 <0.1 15
(2 days)
1959 6 1.2 wp 50% <0.1 16
7 1.2 wp 50% 0.2 16
5 1.2 wp 50% 0.5 16
TABLE 1. (Cont'd.)
Application Residue (mg/kg) intervals (days) after application
Rate kg
Crop Country Year No. a.i./ha Formulation 0 1/2 3/4 7/8 10/11 12/13 14/15 Ref.
Spinach Netherlands 1957 1 1.1 wp 50% 27.4 3.8 2.2 0.85 0.6 0.3 0.3 1
glasshouse (23.3- (2.9- (1.2- (0.4- (0.2- (0.2- (0.1-
33.3) 5.5) 3.4) 1.3) 0.9) 0.4) 0.5)
Netherlands 1957 1 1.1 wp 50% 3.0 2.0 0.55 0.4 0.2 0.1 1
(1.9- (1.2- (0.4- (0.25- (0.2- (0.06-
4.5) 3.1) 0.8) 0.5) 0.3) 0.1)
under frames Fed. Rep. 1965 1 0.75 wp 50% 4.4 2.4 1.6 2
of Germany
Fed. Rep. 1968 1 0.75 wp 50% >30 21.4 5.2 1.2 2.2 0.25 2
of Germany
TABLE 1. (Cont'd.)
Application Residue (mg/kg) intervals (days) after application
Rate kg
Crop Country Year No. a.i./ha Formulation 0 1/2 3/4 7/8 10/11 12/13 14/15 Ref.
Spinach Netherlands 1962 1 0.5 wp 50% 6.0 2.6 1.3 0.35 0.25 3
outdoors (5.7- (1.2- (0.8- (0.1- (0.2-
6.1) 2.7) 2.1) 0.6) 0.3)
Netherlands 1962 1 0.63 wp 50% 1.9 0.8 0.25 0.15 0.10 3
(1.8- (0.4- (n.d.- (0.1- (n.d.-
2.2) 1.1) 0.6) 0.2) 0.2)
Netherlands 1963 1 1.9 wp 50% 0.95 0.18 0.08 n.d. 4
(0.5- (0.05- (n.d.-
1.4) 0.3) 0.1)
Netherlands 1963 1 0.70 wp 50% 1.2 0.2 0.2 0.01 0.03 4
(0.6- (0.2- (n.d- (n.d.- (n.d.-
1.4) 0.3) 0.4) 0.03) 0.07)
Spinach Fed. Rep. 1965 1 0.75 wp 50% 2.0 1.6 0.7 0.35 5
outdoors of Germany
Fed. Rep. 1965 1 0.75 wp 50% 0.4 0.02 5
of Germany
Switzerland 1967 1 ca. 1.5 wp 80% 19.8 1.8 0.15 6
Fed. Rep. 1968 1 0.75 wp 50% 34 6.0 0.85 0.15 7
of Germany (5 days)
Fed. Rep. 1968 1 0.75 wp 50% 33 1.7 0.3 0.08 7
of Germany
TABLE 1. (Cont'd.)
Application Residue (mg/kg) intervals (days) after application
Rate kg
Crop Country Year No. a.i./ha Formulation 0 1/2 3/4 7/8 10/11 12/13 14/15 Ref.
Spinach Fed. Rep. 1968 1 0.75 wp 50% >30 13.2 5.6 1.0 1.0 0.35 7
outdoors of Germany
Canada 19 2 1.1 wp 50? 0.6 0.2 n.d. 8
Canada 19 2 1.1 wp 39 3.5 n.d. 8
U.S.A. 19 2 1.1 wp 11.2 0.3 0.3 9
U.S.A. 19 2 1.1 wp 0.9 0.4 9
U.S.A. 19 2 1.1 wp 1.8 0.2 n.d. 9
0 3
Tomato Netherlands 1973 1 1.2 wp 50% <0.03 10
glasshouse (<0.03-
0.03)
Netherlands 1973 1 1.2 wp 50% 0.10 10
(0.08-
0.13)
n.d. = not detectable.
Methods of residue analysis used to obtain the data of Table 1 and Figure. 1-4
Ref. 1, 3, 4 Non-specific method for organophosphorous compounds; spectrofotometric determination as
phosphomolybdate-quinaldine-red complex. Limit of detection about 0.01-0.03 mg/kg ("n.d." in Table 1 refers
to a limit of 0.03 mg/kg).
TABLE 1. (Cont'd.)
Ref. 2, 5, 6, 7, 8, 9 Method of analysis not quoted.
Limit of detection 0.02 mg/kg.
Ref. 10 TLC; detection by cholinesterase inhibition.
Limit of detection 0.03 mg/kg.
Ref. 11, 13 GLC P detector.
Limit of detection 0.01 mg/kg.
Ref. 14 GLC P detector.
Limit of detection 0.05 mg/kg.
Ref. 12 Method of chemagro (report 8992, January 1962).
Limit of detection 0.1 mg/kg.
Ref. 15 Method of analysis not quoted.
Limit of detection 0.1 mg/kg.
No new information has become available to indicate residue
levels in oats as requested by the 1971 Joint Meeting (FAO/WHO, 1972).
However, re-evaluation of the original data, in the light of the
current use pattern, made it clear that a maximum residue limit of 0.1
mg/kg for raw cereals including maize was more appropriate than the
separate tolerances for barley and maize, 0.1 mg/kg, and wheat, 0.2
mg/kg, previously recommended.
RECOMMENDATIONS
In addition to recommendations made in 1971, the following
temporary maximum residue limits are recommended for lettuce and
spinach. The temporary limit for residues in raw cereals replaces
recommendations previously made for barley, wheat and maize, and that
for tomatoes replaces the previously recommended temporary tolerance
of 0.1 mg/kg.
TEMPORARY MAXIMUM RESIDUE LIMITS
Pre-harvest
intervals on
Limit, which
Commodity mg/kg recommendations
are based
Raw cereals, including maize 0.1 21-30
Lettuce 0.5 Outdoors 14-21
Glasshouse 21-28
Spinach 0.5 Outdoors 14-21
Glasshouse 21-28
Tomatoes 0.2 Outdoors 14
Glasshouse 3
NATIONAL TOLERANCES AND PRE-HARVEST INTERVALS REPORTED TO
THE MEETING
Officially recommended pre-harvest or pre-slaughter intervals
reported. to the Meeting are listed in Table 2. National tolerances
reported to the Meeting are given in Table 3.
TABLE 2. Officially recommended pre-harvest and pre-slaughter intervals
Interval
Country Crop or animal days
Brazil all crops 4
Democratic fruits and vegetables, field crops 7
Rep. of
Germany cherries, strawberries 3
crops used for the production of 21
baby-foods
Federal pome fruits 10
Republic of
Germany stone fruits, beans, black radish, 14
garden beets, leafy vegetables, leek,
onions, peas, radish
sugar and fodder beets 28
France all crops 7
Hungary vegetables 14
other crops, including potatoes 10
Italy maize 10
Japan cucumbers, egg plants 3
apples, pears, cabbage, china cabbage, 7
cauliflower, Japanese radish, turnips,
pumpkins, musk melons, watermelon,
Japanese cantaloupe
grapes, potatoes, sweet potatoes, rice, 14
sugar beets, tea
Netherlands pome and stone fruits, gooseberries, red 10
and black currants, brassicas, garden
beets
Brussels sprouts, spinach 4
bell peppers, cucumbers, melons, 3 weeks.
tomatoes, other glasshouse vegetables Use not
except gherkins, leaf-celery, parsley permitted
period 1/3 - 1/11
1/11 - 1/3
TABLE 2. (Cont'd.)
Interval
Country Crop or animal days
New Zealand all crops 14
tomatoes for canning 1
Poland vegetables including root vegetables, 10
agricultural crops, pulses
fruits except raspberries and 10
strawberries
tomatoes 3
South Africa beans 5
coffee, rape seed, sweet potatoes 7
pome and stone fruit, citrus fruit, 10
cucumbers, passion fruit
maize 10
alfalfa (fresh), clover-fodder 2
U.S.A. lima beans, tobacco 3
clover 7
alfalfa, cotton 7-141
artichokes, beans (dry, snap), bean 14
vines, cowpeas, pumpkins, sugar beet
roots
barley, Brussels sprouts, cabbage, 21
cauliflower, flax, oats, peppers,
tomatoes, wheat
beets, carrots, collards, corn, lettuce, 28
sugar beet tops (used for feeding
purposes)
beef cattle, non-lactating dairy cattle 14-21
1 Depending on dosage and formulation used.
TABLE 3. National tolerances, established or considered, reported
to the Meeting
Tolerance
Country Commodity mg/kg
Argentina bananas 0.2
carrots 0
wheat, maize (kernels), coffee beans, 0.3
sugar cane
cabbage, Savoy cabbage, cauliflower, 0.75
lettuce, peanut, pecan nut, potato,
spinach, tomato
barley, rice, maize fodder, cottonseed 0.75
alfalfa (fresh), cereal fodder, clover 2
(fresh), peanut fodder, sugar beet
leaves
alfalfa fodder, clover fodder 12
Australia fruits, vegetables, dried fruits 2
Belgium fruit, vegetables except potatoes 0.5
Brazil fruit, vegetables, agricultural crops 0.5
(proposed)
meat and milk 0.001
Canada artichokes, bananas, beans, beets, Negligible
Brussels sprouts, cabbage, carrots, residue
cauliflower, collard, kale, lettuce
maize, peppers, rape seed, rutabagas,
salsify, spinach, sugar beets,
tomatoes, turnips, beef cattle
Czechoslovakia fruits, vegetables 1
Democratic pome and stone fruits, red and black 1.0
Rep. of currants, strawberries, citrus fruits,
Germany nuts
brassicas, leafy vegetables, root 1.0
vegetables, pulses, fruits of
vegetables
TABLE 3. (Cont'd.)
Tolerance
Country Commodity mg/kg
cereals, potatoes 0.02
onions 0.02
Democratic meat, fish, fat of animal and plant 0.02
Rep. of origin, eggs, milk, crops used for
Germany production of baby-food
Federal fruits and vegetables 0.5
Republic of
Germany other products of plant origin 0.1
France fruit and vegetables 0.5
Hungary fruits, vegetables, agricultural crops 1
Japan fruits, vegetables, potatoes, rice, tea 0.5
Netherlands fruits and vegetables, except potatoes 0.5
New Zealand fruits, vegetables, agricultural crops 0.1
Poland fruits and vegetables 0.5
South Africa fruits, vegetables, agricultural crops 2
U.S.A. range grass, range grass hay 240
hay of alfalfa, clover and pasture grass 90
alfalfa, clover and pasture grass 60
forage of barley, oats, and wheat 50
corn fodder and forage 30
lima bean vines, lima bean vine hay, 12
lima beans, sugar beet tops
peanut vine hay and hulls 4
bananas (of which not more than 0.2 2
parts per million will be present in
the pulp after the peel is removed)
TABLE 3. (Cont'd.)
Tolerance
Country Commodity mg/kg
staw of barley, flax, oats and wheat, 1
vines of beans and cowpeas
artichokes, barley (grain), beans 0.1
(dried), beets, Brussels sprouts,
cabbage, carrots, cauliflower, citrus
fruit, collards, corn grain (including
popcorn), fresh corn including sweet
corn (kernels plus cob with husk
removed), cottonseed, cowpeas, flaxseed,
lettuce, meat, fat and meat byproducts
of cattle, goats, horses and sheep, oats
(grain), peppers, pumpkins, safflower
seed, snap beans, sugar beets, tomatoes,
and wheat (grain)
peanuts 0.05
milk 0.01
U.S.S.R. all crops 1
fodder crops 2
REQUIRED (before June 1978)
1. Long-term carcinogenicity study.
DESIRABLE
1. Further studies on the spontaneous conversion of trichlorfon
to dichlorvos in vitro and in vivo and of the possible
intermediates involved.
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