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    2-ETHYL-1-HEXANOL

    First draft prepared by
    Dr K. Ekelman, Additives Evaluation Branch
    Division of Health Effects Evaluation
    Center for Food Safety and Applied Nutrition
    Food and Drug Administration, Washington, DC, USA

    1.  EXPLANATION

         2-Ethyl-1-hexanol (EH; also known as 2-ethylhexyl alcohol and
    2-ethylhexanol) has not been reviewed previously by JECFA.

         EH is a colorless liquid with a mild floral odor (Furia and
    Bellanca, 1975) that occurs naturally in food.  EH is prepared by
    petrochemical synthesis and is used as a flavoring ingredient in food. 
    Total annual consumption of EH in the United States from its natural
    occurrence in food is reported to be 120 kg (Stofberg and
    Grundschober, 1987); total annual production for use as a flavor
    additive is estimated to be 209 kg (NRC, 1989).  Estimated intake in
    the United States from the use of EH as a flavoring ingredient is
    approximately 0.65 g/kg bw/day (FEMA, 1993).

    2.  BIOLOGICAL DATA

    2.1     Biochemical aspects

    2.1.1  Absorption, distribution, and excretion

         Two adult male CD-strain rats (300 g) were gavaged with
    radiolabeled 2-ethyl-1-14C-hexanol (14C-EH; 1 Ci; 8.8 g) in
    cottonseed oil.  Two others were given the same amount of 14C-EH and
    cottonseed oil, but also were given 0.1 ml (0.64 mmol) of unlabeled
    EH.  Following administration of the test substance, rats were housed
    in metabolism cages with  ad libitum access to feed and water;
    expired CO2, urine, and faeces were collected every hour for 28 hrs. 
    Most (99.8%) of the orally administered radioactivity was accounted
    for by radioactivity in expired CO2, urine, faeces, an ethanol wash
    of the metabolism cage at the end of the experiment, heart, brain,
    liver, kidneys, and "residual carcass."  EH was efficiently absorbed
    following oral administration and rapidly excreted in respired CO2
    (6-7%), urine (80-82%), and faeces (8-9%); elimination was essentially
    complete by 28 hrs.  The major urinary metabolite of EH in the rat was
    shown to be 2-ethylhexanoic acid through acid extraction of urine. 
    This metabolite can undergo partial -oxidation and decarboxylation to
    produce 14CO2 and 2- and 4-heptanone (in the urine).  Other urinary
    metabolites of EH were identified as 2-ethyl-5-hydroxyhexanoic acid,
    2-ethyl-5-ketohexanoic acid, and 2-ethyl-1,6-hexanedioic acid. 
    Approximately 3% of the parent compound was excreted unchanged.

         Rats and other mammals hydrolyze orally ingested DEHP
    (di-[2-ethylhexyl]phthalate, a plasticizer in food-contact materials)
    to EH and MEHP (mono-[2-ethylhexyl]phthalate) prior to absorption of
    MEHP by the intestine (Albro, 1975).

         An  in vitro dermal absorption study of EH and seven other
    compounds was conducted with full thickness rat skin and human stratum
    corneum.  The ratio of the rate of absorption of EH through rat and
    human skin (rat/human) was reported to be 5.8, indicating that rat
    skin is more permeable to EH than is human skin.  Damage to skin by
    dermal application of EH was defined as the ratio of the permeability
    constant for 3H2O after contact with EH to the permeability
    constant for 3H20 before application.  Ratios for human skin
    (1.50.4 and 3.72.1) and rat skin (31.95.1) indicated that dermal
    application of EH damages rat skin more than human skin (Barber
     et al., 1992).

         Excretion balance studies were conducted on female Fischer 344
    rats (4 animals/group) following acute oral doses of 50 or 500 mg/kg
    bw 14C-EH and repeated oral doses of 50 mg/kg bw/day 14C-EH for 14
    days; results of acute gavage doses of 500 mg/kg bw 14C-EH
    administered neat and as aqueous suspensions containing 5 mg Polyoxyl
    35 castor oil/100 ml were compared.  Dermal exposures to 14C-EH

    (1 g/kg bw applied dose) for 6 hours and i.v. exposures to 1 mg/kg bw
    14C-EH were also studied.  Acute oral doses of 50 or 500 mg/kg bw and
    repeated oral doses of 50 mg/kg bw/day showed similar excretion
    balance profiles of 14C, with some evidence of metabolic saturation
    at the high dose.  No evidence of metabolic induction was reported
    following repeated dosing.  All oral doses were rapidly eliminated
    during the first 24 hours after dosing, predominantly in the urine. 
    Approximately 5% of the dermal dose was absorbed.  A majority of the
    oral and dermal doses were eliminated as glucuronides of oxidized
    metabolites of EH, principally glucuronides of 2-ethyladipic acid,
    2-ethylhexanoic acid, 5-hydroxy-2-ethylhexanoic acid, and 6-hydroxy-2-
    ethylhexanoic acid.  Only trace amounts of unchanged EH were
    eliminated in the urine.  Bioavailability of EH orally administered
    with the gavage vehicle was slightly greater than bioavailability of
    EH administered alone (Deisinger  et al., 1992).

    2.1.2  Biotransformation

         Knaak and coworkers (1966) studied the metabolism of 8 mg 14C-EH
    in rats and 200 mg 14C-EH in rabbits following i.p. injection.  The
    major urinary metabolite in rats was 2-ethylhexanoyl glucuronide; EH
    and 2-ethyl hexanoic acid were also identified in rat urine.  In
    rabbits, the major urinary metabolite also was 2-ethylhexanoyl
    glucuronide; 2-ethyl-2,3-dihydroxyhexanoic acid and EH were also
    identified in rabbit urine (Knaak  et al., 1966).

         The metabolism, distribution and elimination of 14C-DEHP
    following oral administration to male and female B6C3F1 mice, Fischer
    344 rats, and  Cynomolgus monkeys was investigated.  Orally
    administered DEHP is rapidly hydrolyzed to the monoester (MEHP), then
    the alcohol and acid.  The GI tract had appreciable amounts of EH, and
    absorbed 14-C appeared to be primarily EH.  The alcohol was oxidized
    by -oxidation, omega-, and omega-1-oxidation generating several major
    and minor products including acids, ketones, ketoacids, hydroxy acids,
    and diacids (such as ethylhexanoic acid [EHA], ethylhexanedioic acid
    [DiEHA], and 5-hydroxyethylhexanoic acid [5-OH EHA]).  The three
    species were able to form glucuronic acid conjugates of the alcohol
    oxidation products, but no sulfites were detected.  However,
    differences between species were noted: metabolism appeared to be less
    extensive in the monkey (which excreted largely MEHP and EH as their
    glucuronides) than in rodents (which excreted largely products of
    faster oxidation, primarily EHA, 5-OH EHA, and diEHA) (Midwest
    Research Institute, 1984).

    2.1.3  Effects on enzymes and other biochemical parameters

         Gavage administration of 1 mmol/kg bw/day EH (approximately
    130 mg/kg bw/day) to five male Wistar rats for 14 days was not
    associated with liver peroxisome proliferation (Rhodes  et al.,
    1984).

         However, in another study, administration of 2% EH in the diet
    (approximately 1 000 mg/kg bw/day) to five male Fischer 344 rats for
    three weeks was reported to cause peroxisome proliferation and
    significant increases in the activities of liver catalase and
    carnitine acetyltransferase (Moody and Reddy, 1978).

         When gavage doses of 0, 100, 320, or 950 mg/kg bw/day EH were
    administered to male and female Fischer 344 rats (5/sex/group) for 21
    days, significant hepatomegaly at 950 mg/kg bw/day, significant
    increases in cyanide-insensitive palmitoyl CoA oxidation (a marker for
    peroxisome proliferation) in males (dose-related, 320 and 950 mg/kg
    bw/day) and females (950 mg/kg bw/day), and significant increases in
    lauric acid hydroxylase activity in males and females at 950 mg/kg
    bw/day were shown.  As well, electron microscopy showed only a slight
    increase in the number of peroxisomes in hepatocytes of high-dose rats
    (Hodgson, 1987).

         Groups of five male and five female Alderley Park rats and mice
    were gavaged with 0, 140, 350, 700, 1050, or 1750 mg/kg bw/day EH for
    14 days.  Rats in the high-dose group exhibited toxic effects (not
    specified) and died or were killed during the course of the study. 
    Dose-related increases in relative liver weights of rats and mice were
    observed; the increases were statistically significant in rats at 700
    and 1050 mg/kg bw/day, in male mice at 700, 1050, and 1750 mg/kg
    bw/day, and in female mice at 1750 mg/kg bw/day.  EH administration
    resulted in a nearly linear dose-related induction of peroxisomal
    -oxidation (measured as palmitoyl CoA oxidation activities) in both
    rats and mice, although the dose(s) at which this effect was
    statistically significant were not stated (Keith  et al., 1992).

         Activity of succinic dehydrogenase was increased and activity of
    lactic dehydrogenase was decreased after 12 daily dermal applications
    of 2 ml/kg bw undiluted EH to the shaved skin of the rat.  In
    addition, EH-treated rats had significantly lower body weights than
    control rats 17 days after dermal application of EH was terminated
    (Schmidt  et al. 1973).

         Microsomal P-450 content increased and glucose-6-phosphatase
    activity decreased in rat liver microsomal pellets following oral
    administration of EH to the intact animal.  Administration of EH
    increased alcohol dehydrogenase activity demonstrated histochemically
    in the centrilobular area of the liver, the number of microbodies, the
    dilatation of the smooth endoplasmic reticulum, and the number of
    microperoxisomes in the hepatocytes of rats (Lake  et al., 1975).

         Concentrations of EH ranging from 2.5-15 mM significantly
    inhibited the activities of rat liver aminopyrine N-demethylase
    (approximately 60% inhibition at 15 mM EH) and aniline hydroxylase
    (approximately 50% inhibition at 15 mM EH)  in vitro (Seth, 1982).

         Rhodes and coworkers (1984) reported that 0.1 or 0.5 mM EH did
    not induce palmitoyl CoA oxidase activity (a marker for peroxisome
    proliferation) in rat hepatocytes  in vitro (Rhodes  et al., 1984).

         The activity of carnitine acetyltransferase (a peroxisomal
    enzyme) in rat liver cells  in vitro was significantly induced
    (approximately 9X level in untreated cultures) by 1mM EH but not by
    0.2 mM EH (Gray  et al., (1982).

         In an  in vitro test system using viable plugs from periportal
    or pericentral regions of rat liver, Liang and coworkers (1991)
    demonstrated that incubation of these plugs with EH (0.1 to 3 mM)
    decreased urea synthesis in a dose-related manner (up to 80%
    inhibition at 800 M 02) and caused extensive cell damage (assessed
    by lactate dehydrogenase leakage) Liang  et al., 1991).

    2.2  Toxicological Studies

    2.2.1  Acute toxicity studies

         Results of acute toxicity studies with EH are summarized in 
    Table 1.

         Rabbits given 0, 0.2, 0.4, 0.6, 0.8, 1.6 or 3.2 x 10-5 mol/kg EH
    (0.26 to 4.16 mg/kg bw i.v.) had dose-related increases in heart rate
    and frequency of respiration.  However, when EH was administered to
    dogs (doses reported as 4.05 and 8.10 mol/kg i.v.), no compound-
    related hypotensive effects were seen.  Finally, when rabbits and rats
    were given acute iv doses of EH (doses not provided), direct toxic
    damage to the heart and smooth muscle elements of the blood vessels
    was observed (Hollenbach  et al., 1972).

    2.2.2  Short-term toxicity studies

    2.2.2.1  Mice

         Doses of 0, 100, 330, 1 000, or 1 500 mg 2-ethyl-1-hexanol/kg
    bw/day were administered by gavage for 11 days (9 administrations) to
    groups of 10 male and 10 female C3B6F1 mice.  Effects clearly related
    to administration of the test substance occurred in male and female
    mice receiving 330, 1 000, or 1 500 mg/kg bw/day.  One male mouse
    receiving 330 mg/kg bw/day for 11 days showed ataxic gait and
    piloerection following the administration of the 8th dose, but these
    symptoms were reported to have disappeared by the next day.  Two male
    and two female mice receiving 330 mg/kg bw/day were reported to have
    acanthosis in the mucous membrane of the forestomach that was usually
    associated with hyperkeratosis and was once associated with focal
    inflammatory oedema in the submucosa.

        Table 1: Summary of Acute Toxicity Studies with EH

                                                                                       

    Species        Route       LD50 (mg/kg bw)             Reference

                                                                                       

    Rat            Oral        2053 (2.46 mL/kg)           Smyth  et al., 1969

    Rat            Oral        37301                       Scala and Burtis, 1973

    Rat            Oral        3 250                       Albro, 1975

    Rat            Oral        3200 - 6400                 Treon, 1963

    Rat            Oral        3200                        NIOSH, 1976

    Rat            I.P.        650                         Treon, 1963

    Mice           I.P.        780                         Treon, 1963

    Rat            I.V.        1670                        Mashkina, 1966

    Mice           I.V.        1670                        Mashkina, 1966

    Rabbit         Dermal      1986 (2.38 mL/kg)2          Smyth  et al., 1969

    Rabbit         Dermal      >26003                      Scala and Burtis, 1973

    Guinea pig     Dermal      >8300 (>10 mL/kg)           Treon, 1963

                                      LC50

    Mice           Inhal.      >227 ppm (6 hr)4            Scala and Burtis, 1973
                                                                                       

    Table 1 (contd).

                                                                                       

    Species        Route       LD50 (mg/kg bw)             Reference

                                                                                       

    Rat            Inhal.      >227 ppm (6 hr)4            Scala and Burtis, 1973

    Guinea pig     Inhal.      >227 ppm (6 hr)4            Scala and Burtis, 1973

    Rat            Inhal.      saturated vapors (8 hr)     Smyth  et al., 1969

    Rat            Inhal.      >235 ppm                    Treon, 1963
                                                                                       

    (1)  Gastrointestinal irritation was reported in rats after oral administration of
         EH undiluted or in corn oil.
    (2)  Mild dermal irritation (3 on a scale of 0 [no irritation] to 10) was reported
         when EH was applied to the uncovered rabbit belly and moderate corneal injury
         in rabbits when undiluted EH was instilled in the eye (5 on a scale of 0 [no
         injury] to 10).
    (3)  Moderate skin irritation was reported in rabbits following dermal application
         of EH and severe eye irritation with persistent, wide-spread corneal opacity
         when 0.1 ml undiluted EH was applied to the conjunctival sac.
    (4)  Mice, rats and guinea pigs (10 each) were exposed for 6 hours to 227 ppm EH,
         then observed for 24 hours before necropsy.  No deaths occurred during exposure
         or observation.  All animals exposed to EH exhibited central nervous system
         depression and labored breathing and one guinea pig had a clonic convulsion.
         During exposure, mucous membranes of the eyes, nose, throat, and respiratory
         passages of animals exposed to EH were irritated, but animals recovered within
         one hour after exposure was terminated.  Gross necropsy revealed areas of slight
         haemorrhage in animals exposed to EH.
    
         One female mouse receiving 1 000 mg 2-ethyl-1-hexanol/kg bw/day
    showed abdominal position and loss of consciousness; the mouse died
    later the same day; microscopic examination revealed tubular
    dilatation in the renal cortex and centrilobular fatty infiltration in
    the liver of this mouse.  Also the following significant effects were
    reported to be associated with administration of 1 000 mg/kg bw/day
    for 11 days: 1) increased absolute stomach weights in males and
    females; 2) increased liver-to-bw ratio for males; 3) increased
    stomach-to-bw ratio for females; 4) foci in the forestomach of 3 males
    and 2 females; 5) hyperkeratosis and focal or multifocal acanthosis
    and inflammatory oedema in the submucosa of the forestomach of males
    and females, including focal or multifocal ulceration of the mucous
    membrane of a few males and females; and 6) hypertrophy of hepatocytes
    in one male and one female.

         Males (9/10) and females (6/10) receiving 1 500 mg 2-ethyl-1-
    hexanol/kg bw/day for 11 days had clinical signs such as ataxia and
    lethargy, some animals also had piloerection, and a few animals showed
    abdominal or lateral position and loss of consciousness; one male and
    four females died during the study.  Microscopic evaluation showed
    tubular dilatation and nephrosis in the renal cortices of males and
    females that died intercurrently, and centrilobular fatty infiltration
    in the liver of females that died intercurrently.  The following
    statistically significant effects were reported, associated with
    administration of 1 500 mg 2-ethyl-1-hexanol/kg bw/day: 1) increased
    absolute liver and stomach weights in males and females; 2) increased
    organ-to-bw ratios for stomach and liver in males and females; 3)
    increased organ-to-brain weight ratios for stomach and liver in males
    and females; 4) foci in the forestomach of 7/10 males and 5/10
    females; 5) hyperkeratosis and focal or multifocal acanthosis and
    inflammatory oedema in the submucosa of the forestomach of most males
    and females, including focal or multifocal ulceration of the mucous
    membrane in a few males and females; 6) hypertrophy of hepatocytes in
    the liver of males and females, including focal necrosis of liver
    cells in one male and one female; and 7) bilateral tubular giant cells
    in the testicular tubules of two males (BASF, 1992b).

         Doses of 0, 25, 125, 250, or 500 mg 2-ethyl-1-hexanol/kg bw/day
    were administered by gavage to groups of 10 male and 10 female B6C3F1
    mice for 3 months.  Animals in the 250 and 500 mg/kg bw/day groups
    showed toxic effects related to administration of the test compound. 
    For male mice receiving 250 mg/kg bw/day, statistically significant
    increased stomach-to-bw ratio was observed.  Statistically significant
    effects observed in animals receiving 500 mg 2-ethyl-1-hexanol/kg
    bw/day included: a) increased stomach-to-bw ratio in males and 2)
    slight focal or multifocal acanthosis in the mucosa of the forestomach
    of 2/10 males and 1/10 female (BASF, 1992b).

    2.2.2.2  Rats

         Doses of 0, 100, 330, 1 000, or 1 500 mg 2-ethyl-1-hexanol/kg
    bw/day were administered by gavage for 11 days (9 applications) to
    groups of 10 male and 10 female Fischer 344 rats.  Clear toxic effects
    occurred in the male and female rats receiving 330, 1 000, or 1 500
    mg/kg bw/day.

         Female rats receiving 330 mg/kg bw/day for 11 days had increased
    kidney-to-bw ratios, but not increased absolute kidney weights or
    kidney-to-brain weight ratios.  Microscopic findings included
    inflammatory oedema in the forestomach of one female rat and decreased
    thymus size (microscopic examination) in 1 female and 2 male rats.

         Male and female rats receiving 1 000 mg 2-ethyl-1-hexanol/kg
    bw/day had reduced feed consumption, body weight, and body weight gain
    compared to control rats.  Some rats in this dose group showed ataxia
    and apathy; a single rat showed piloerection and the genital region of
    one rat was smeared with urine.  The following statistically
    significant effects were also reported to be associated with
    administration of 1 000 mg/kg bw/day for 11 days: a) serum cholesterol
    and reticulocytes in rats of both sexes were reduced; b) absolute
    spleen weights of rats of both sexes were reduced; c) absolute liver
    weights of male and female rats were increased; d) organ-to-bw ratios
    for stomach, liver and kidneys were increased for male and female
    rats; e) brain-to-bw ratio was increased in female rats; f)
    spleen-to-bw ratios were reduced in male and female rats; g) liver-to-
    brain weight ratios were increased in male and female rats; h) spleen-
    to-brain weight ratios were decreased in male and female rats; i) foci
    were reported in the forestomachs of 2 males; j) hyperkeratosis and
    focal or multifocal acanthosis in the mucous membrane of the
    forestomach of most male and female rats, as well as epithelial
    degeneration, ulceration and subcutaneous inflammatory oedema; k)
    parenchymal involution of lymphoreticular tissue in the spleens of 5
    female rats; l) decreased thymus size in 2 males and 5 females
    (microscopic evaluation); l) lymphocyte depletion in the thymus of 5
    females and lymphocyte necrosis in the thymus of 4 females.

         Male and female rats receiving 1 500 mg 2-ethyl-1-hexanol/kg
    bw/day showed reduced feed consumption, body weight, and body weight
    gain compared to control rats.  All animals in the dose group
    demonstrated ataxia and lethargy, some animals showed abdominal or
    lateral position and appeared to be unconscious, almost all animals
    had piloerection, and a few rats had genital regions smeared with
    urine.  The following statistically significant effects were also
    reported to be associated with administration of 1 500 mg 2-ethyl-1-
    hexanol/kg bw/day: a) reduced serum cholesterol, glucose, and
    reticulocytes in male and female rats; b) increased serum alanine
    aminotransferase in male rats; c) decreased absolute spleen, brain,
    and adrenal weights and increased absolute liver and stomach weights
    in male and female rats; d) increased organ-to-body weight ratios for

    stomach, liver, kidney, and brain in male and female rats, decreased
    spleen-to-bw ratios for male and female rats, increased adrenal-to-bw
    ratio for male rats, and increased lung-to-bw ratio for female rats;
    e) increased organ-to-brain weight ratios for liver and stomach in
    rats of both sexes, decreased spleen-to-brain weight ratio for male
    and female rats, and decreased adrenal-to-brain weight ratio in female
    rats.

         Foci were reported in the forestomach of 4 male and 7 female rats
    dosed with 1 500 mg 2-ethyl-1-hexanol/kg bw/day.  Microscopic findings
    at this dose level were reported to include: a) hyperkeratosis and
    focal or multifocal acanthosis in the mucous membrane of the
    forestomach of all male and female rats, as well as epithelial
    degeneration, ulceration, and subcutaneous inflammatory oedema in some
    animals; b) slight hypertrophy of hepatocytes in the liver of 8 males
    and 8 females; c) focal hepatocellular necrosis in 1 female and 2 male
    rats; d) parenchymal involution of lymphoreticular tissue in the
    spleen of 9 male and 9 female rats; e) decreased thymus size in 10
    male and 9 female rats; and f) lymphocyte depletion in the thymus of
    9 male and 8 female rats and lymphocyte necrosis in the thymus of 1
    male and 6 female rats (BASF, 1992a).

         Doses of 0, 25, 125, 250, or 500 mg 2-ethyl-1-hexanol/kg bw/day
    were administered by gavage to groups of 10 male and 10 female Fischer
    344 rats for 3 months.  Animals in the 250 and 500 mg/kg bw/day groups
    showed toxic effects.  For animals receiving 250 mg/kg bw/day,
    statistically significant effects were reported to include: a)
    decreased serum alkaline phosphatase and glucose in male rats and
    decreased serum alanine aminotransferase in female rats; b) increased
    liver-to-bw ratios in male and female rats and increased stomach-to-bw
    ratio in female rats; and c) decreased fat deposition of the liver
    cells of male rats.

         Statistically significant effects observed in animals receiving
    500 mg 2-ethyl-1-hexanol/kg bw/day included: a) decreased body weight
    and body weight gain in male and female rats; b) decreased serum
    alanine aminotransferase, glucose, and cholesterol in male and female
    rats, increased reticulocytes in male and female rats, decreased serum
    alkaline phosphatase in male rats, and increased serum protein and
    albumin in male rats; c) increased absolute liver weights in male and
    female rats and increased absolute stomach weights in female rats;
    d) increased organ-to-body weight ratios for liver and stomach in male
    and female rats; and e) increased organ-to-brain weight ratios for
    liver and stomach in male and female rats.

         Slightly elevated single or multiple foci were observed in the
    mucosa of the forestomach of male and female rats receiving 500 mg/kg
    bw/day.  Macroscopic findings at this dose level were reported to
    include: a) focal or multifocal achanthosis in the mucosa of the
    forestomach of 1 male and 5 female rats; b) acanthosis of the whole
    mucosa, ballooning degeneration of the epithelia, and inflammatory

    oedema in the submucosa of 1 male rat; and c) decreased fat deposition
    in the liver and fewer animals with fatty infiltration of the lobular
    periphery of the liver compared to vehicle-control rats (BASF, 1992a).

         Five male Wistar-derived rats were administered 1 mmol/kg/day
    (approximately 130 mg/kg bw/day) EH dissolved in polyethylene glycol
    300 (10 ml/kg/day) by gavage for 14 days; 10 control rats were
    administered the gavage vehicle alone.  At the end of the treatment
    period, rats were killed and blood was withdrawn for analysis of
    plasma cholesterol and triglyceride levels; livers and testis were
    weighed, liver samples were taken for light and electron microscopy,
    and the remaining liver was homogenized for determination of total
    catalase and CN-insensitive palmitoyl CoA oxidation.  No major
    pathological signs of hepatotoxicity were observed, although slight
    centrilobular hypertrophy (controls: 4/10 rats; EH-treated: 2/5),
    slight/moderate glycogen vacuolization (controls: 9/10; EH-treated:
    5/5), and slight/moderate centrilobular "fat" vacuolation (controls:
    9/10; EH-treated: 1/5) were reported in control and EH-treated rats. 
    Administration of EH had no significant effect on body weight gain,
    liver-to-body-weight ratio, testis-to-body-weight ratio, number of
    peroxisomes/504 m2 liver, serum catalase activity, serum
    cholesterol, or serum triglycerides.  In addition, 0.1 mM EH had no
    effect on acyl CoA oxidase activity after 72 hrs in  in vitro culture
    with rat hepatocytes (Rhodes  et al., 1984).

         Gavage administration of 1335 mg/kg bw/day EH in corn oil to 6
    male Wistar albino rats for 7 days resulted in significantly increased
    liver-to-body-weight ratio (control: 3.50.1 g/100 g bw; EH-treated:
    4.90.1 [p<0.001]), decreased glucose-6-phosphatase activity
    (control: 242 g/min/mg microsomal protein; EH-treated: 151
    [p<0.01]), increased biphenyl 4-hydroxylase activity (control:
    1.60.1 mol/hr/g liver; EH-treated: 2.10.1 [p<0.01]), and increased
    microsomal cytochrome P-450 content (control: 0.070.003  delta-E
    450-500 nm/mg microsomal protein; EH-treated: 0.10.004 [p<0.001])
    (Lake  et al. 1975).

    2.2.3  Long-term toxicity/carcinogenicity studies

    2.2.3.1  Mice

         2-ethyl-1-hexanol (0, 50, 200, or 750 mg/kg bw/day) was
    administered by gavage to groups of 50 male and 50 female B6C3F1 mice
    five days per week for a period of 18 months.  The purity of the test
    substance was reported to be greater than 99.87%.  The gavage vehicle
    was doubly distilled water containing 5 mg Polyoxyl 35 castor oil per
    100 ml.  An additional control group of 50 male and 50 female rats was
    gavaged with double distilled water only.  All rats received 10 ml/kg
    bw test substance emulsion, vehicle or double distilled water per
    dose.

         The method of preparing test substance emulsions was changed
    after 6 months of dosing because homogeneity analyses of emulsions
    showed considerable variation, ranging from approximately 70% to 140%
    of target concentrations.  However, variability in dosing during the
    early part of the study did not significantly affect the outcome of
    the study because of the "clear biological distinction between dose
    levels during treatment."

         Mice were housed singly and feed and water were available  ad
     libitum throughout the study.  At the initiation of dosing, mice
    were 49 days old; mean body weight of males was 23 g (range 21-26 g)
    and mean body weight of females was 19 g (range 17-23 g).  At the end
    of the study, non-fasted mice were decapitated under CO2 anaesthesia.

         The general health of the test animals was checked daily, and
    test animals were examined and palpated once a week.  Mice were
    weighed weekly during the first 13 weeks, then every four weeks for
    the duration of the study.  Feed consumption was determined for a
    period of one week every four weeks during the study.  Blood samples
    were drawn from the tail vein of all surviving animals for
    haematological examination at 12 months and at the end of the study. 
    Animals that survived to the end of the study were necropsied; tissues
    and organs were subjected to gross and microscopic pathology
    examination.

         No EH-related changes were observed in mice administered 50 or
    200 mg/kg bw/day EH for 18 months.  In mice administered 750 mg/kg
    bw/day, the following effects were observed: 1) decreased body weight
    gain in males (approximately 26%) and females (24%) that was
    associated with a substantial reduction in feed consumption (males:
    decreased from about 9% to 20%; females: decreased from about 9% to
    30%); 2) increased mortality in males (vehicle controls: 4%;
    EH-treated: 30%) and females (vehicle controls: 8%; EH-treated: 30%);
    3) treatment-related haematological changes, including slightly
    increased polymorphonuclear neutrophils in males and females (males:
    controls--19.85.9% [12 mo] and 20.57.6% [18 mo]; 750 mg/kg
    bw/day--26.49.1% [12 mo] and 26.913.5% [18 mo])(females: controls--
    20.65.6% [12 mo] and 22.610.7% [18 mo]; 750 mg/kg bw/day--24.25.4
    [12 mo] and 25.19% [18 mo]) and slightly decreased lymphocytes in
    males and females (males: controls--776.9% [12 mo] and 76.67.6% [18
    mo]; 750 mg/kg bw/day--69.19% [12 mo] and 70.613.2% [18 mo]); and 4)
    treatment-related, but not statistically significant, increased focal
    hyperplasia of the epithelium of the forestomach in males (controls--
    1/50; 50 mg/kg bw/day--1/50; 200 mg/kg bw/day--1/50; 750 mg/kg
    bw/day--5/50) and females (controls--1/50; 50 mg/kg bw/day--1/50; 200
    mg/kg bw/day--0/50; 750 mg/kg bw/day--4/50).  Also, a slight increase
    in the incidence of hepatocellular carcinomas in high-dose females was
    statistically significant when compared to the incidence in vehicle
    control females but not when compared to the incidence in water-
    gavaged control females (vehicle control--0/50; 50 mg/kg bw/day--1/50;

    200 mg/kg bw/day--3/50; 750 mg/kg bw/day--5/50).  No statistically
    significant increase in tumour incidence occurred in male mice.  EH is
    not oncogenic in the mouse under the conditions of this study (BASF,
    1992b).

         In a satellite study to the carcinogenicity study in mice cited
    above as BASF, 1992b, EH was administered by gavage (vehicle:
    distilled water containing 5 mg Polyoxyl 35 castor oil per 100 ml) to
    two groups of male and female B6C3F1 mice at 750 mg/kg bw/day.  A
    control group of 10 males and 10 females was gavaged with the vehicle
    only for 13 months; a second (non-recovery) group of 10 males and 10
    females was gavaged with EH for 13 months, 5 days/week; a third
    (recovery) group of 50 males and 50 females was gavaged with EH for 13
    months, 5 days/week, then gavaged with the vehicle only for 5 months,
    5 days/week.  Mice were killed at the end of the treatment periods--13
    months for groups one and two; 18 months for group three--and
    subjected to gross pathological assessment.  The general health of the
    test animals was checked daily, and animals were examined and palpated
    once a week.  Body weights were determined once a week during the
    first 13 weeks of the study, then once every four weeks.  Feed
    consumption was determined one week in every four weeks throughout the
    study.  Microscopic examination of tissues and organs was performed
    only on mice that died during the study.

         Administration of 750 mg/kg bw/day EH to male and female mice for
    13 months caused increased mortality in males and females (males:
    control--0%, non-recovery--30%, recovery--22% during the first 13
    months; females: control--0%, non-recovery--20%, recovery--16% during
    the first 13 months).  For the non-recovery mice and recovery mice
    during treatment with EH, feed consumption was significantly decreased
    compared to control mice (at 13 months, males: control--4.70.4 g/day,
    non-recovery--3.70.5 g/day, recovery--4.40.6 g/day; females:
    control--6.01.3 g/day, non-recovery--5.61.5 g/day, recovery--5.81.0
    g/day); following the 5 month recovery period, feed consumption for
    mice in the recovery group was in the same range as feed consumption
    for control mice (males: control--4.80.9 g/day, recovery--4.90.8
    g/day; females: control--6.31.3 g/day, recovery--5.91.1 g/day).  For
    the non-recovery mice and recovery mice during treatment with EH, body
    weight gain was significantly decreased (at 13 months, males:
    control--40.92.7 g, non-recovery--36.72.8 g, recovery--38.73.2 g;
    females: control--38.75.4 g, non-recovery--33.84.4 g, recovery--
    34.94.8 g); following the 5 month recovery period, body weight gain
    of female mice that had been gavaged with EH for 13 weeks was still
    significantly decreased compared to control mice (males: control--
    42.73.5 g, recovery--42.43.6 g; females: control--41.15.6 g,
    recovery--36.95.1 g).  Some statistically significant changes in
    organ weights and masses or foci in liver and stomach were observed to
    be associated with EH administration; these were similar to changes
    noted in the results of the carcinogenicity study (BASF, 1992d).

    2.2.3.2  Rats

         2-ethyl-1-hexanol (0, 50, 100, or 150 mg/kg bw/day) was
    administered by gavage to groups of 50 male and 50 female Fischer 344
    rats five days/week for a period of 24 months.  The purity of the test
    substance was reported to be greater than 99.3%.  The gavage vehicle
    was doubly distilled water containing 5 mg Polyoxyl 35 castor oil per
    100 ml.  An additional control group of 50 male and 50 female rats was
    gavaged with double distilled water only.  All rats received 10 ml/kg
    bw/day test substance emulsion, vehicle or double distilled water per
    dose.

         The method of preparing test substance emulsions was changed
    after 6 months of dosing because homogeneity analyses of emulsions
    showed considerable variation, ranging from approximately 70% to 140%
    of target concentrations.  However, the report concluded that
    variability in dosing during the early part of the study did not
    significantly affect the outcome of the study because of the "clear
    biological distinction between dose levels during treatment."

         Rats were housed singly and food and water were available  ad
     libitum throughout the study.  At the initiation of dosing, rats
    were 42 days old; mean body weight of males was 103 g (range 86-128 g)
    and mean body weight of females was 81 g (range 64-95 g).  At the end
    of the study, non-fasted rats were decapitated under CO2 anaesthesia.

         The general health of the test animals was checked daily, and
    test animals were examined and palpated once a week.  Rats were
    weighed weekly during the first 13 weeks, then every four weeks for
    the duration of the study.  Feed consumption was determined for a
    period of one week every four weeks during the study.  Blood samples
    were drawn from a tail vein of all surviving animals for
    haematological examination at 12 and 18 months and at the end of the
    study.  At the end of the study, surviving animals were necropsied;
    tissues and organs were subjected to gross and microscopic pathology
    examination.

         No compound-related changes were associated with administration
    of 50 mg/kg bw/day for 24 months; however, body weights and body-
    weight gains of rats receiving 50, 150, or 500 mg 2-ethyl-1-hexanol/kg
    bw/day were decreased in a statistically significant dose-dependent
    manner compared to vehicle control rats.  At the end of the study,
    body weights were about 5%, 11%, and 23% below control values and body
    weight gains were about 8%, 16%, and 33% below control values,
    respectively.  Feed consumption of male and female rats receiving 500
    mg/kg bw/day showed occasional statistically significant decreases
    compared to both control groups of rats, but no dose-response
    relationship was observed.

         An EH-associated increase in mortality was observed for female
    mice of the high-dose group only (males: vehicle controls--34%, 50
    mg/kg bw/day--46%, 150 mg/kg bw/day--32%, 500 mg/kg bw/day--38%;
    females: vehicle controls--28%, 50 mg/kg bw/day--28%, 150 mg/kg
    bw/day--26%, 500 mg/kg bw/day--52%).

         For rats receiving 100 mg/kg bw/day, the study reported a)
    statistically significant reductions in body weight (males: 11%;
    females: 9%) and body weight gain (males: 16%; females: 12%) compared
    to vehicle control rats and b) slightly increased numbers of animals
    with clinical symptoms and incidences of symptoms (frequency/animals)
    such as poor general condition (100 mg/kg bw/day: males--69/15;
    vehicle control: males--62/12), labored breathing (100 mg/kg bw/day:
    males--4/1, females--30/5; vehicle control: males--2/1, females--9/3),
    piloerection (100 mg/kg bw/day: males--17/1; vehicle control: males--
    0/0), and genital regions smeared with urine (100 mg/kg bw/day:
    females--31/4; vehicle controls: females--0/0).  Feed consumption of
    male and female rats receiving 150 mg/kg bw/day showed occasional
    statistically significant decreases compared to both control groups of
    rats, but no dose-response relationship was observed.

         The following treatment-related changes were observed in rats
    dosed with 500 mg/kg bw/day 2-ethyl-1-hexanol for 24 months: a)
    statistically significant reductions in body weight gain for males
    (33%) and females (31%); b) increased incidences of male and female
    rats with clinical symptoms (frequency/animals) such as poor general
    condition (500 mg/kg bw/day: males--200/14, females--248/21; vehicle
    control: males--62/12, females--34/8), labored breathing (500 mg/kg
    bw/day: males--41/4, females--75/12; vehicle control: males--2/1,
    females--9/3), piloerection (500 mg/kg bw/day: males--67/2, females--
    21/5; vehicle control: males--0/0, females--2/1), and/or genital
    region smeared with urine (500 mg/kg bw/day: males--13/1, females--
    502/21; vehicle control: males--0/0, females--44/6); and c)
    statistically significant increased mortality in dosed females as
    reflected in the number of animals that died or were sacrificed in a
    moribund condition during the study (52%) compared with vehicle
    control females (28%).

         Male rats dosed with 500 mg/kg bw/day had slightly increased
    anisocytosis, predominantly microcytosis at 12 months, but not at 18
    nor 24 months, compared to vehicle control males.  No malignant
    tumours were detected in high-dose animals that died before scheduled
    termination and the sum of primary tumours, benign tumours and
    malignant tumours was remarkably lower in the high-dose group compared
    to both control groups of rats.  Thus, 2-ethyl-1-hexanol was not
    oncogenic in the rat under conditions of this assay (BASF, 1992a).

         In a satellite study to the BASF carcinogenicity study in rats
    cited above as BASF 1992a, EH was administered by gavage (vehicle:
    distilled water containing 5 mg Polyoxyl 35 castor oil per 100 ml) to
    two groups of male and female Fischer 344 rats at 500 mg/kg bw/day.

    A control group of 10 males and 10 females was gavaged with the
    vehicle only for 18 months; a second (non-recovery) group of 10 males
    and 10 females was gavaged with EH for 18 months, 5 days/week; a third
    (recovery) group of 50 males and 50 females was gavaged with EH for 18
    months, 5 days/week, then gavaged with the vehicle only for 6 months,
    5 days/week.  Rats were killed at the end of the treatment periods--18
    months for groups one and two; 24 months for group three--and
    subjected to gross pathological assessment.  The general health of the
    test animals was checked daily, and animals were examined and palpated
    once a week.  Body weights were determined once a week during the
    first 13 weeks of the study, then once every four weeks.  Feed
    consumption was determined one week in every four weeks throughout the
    study.  Microscopic examination of tissues and organs was performed
    only on rats that died during the study. 

         Administration of 500 mg/kg bw/day EH to male and female rats for
    18 months caused slightly increased mortality in females (control--
    20%, non-recovery--40%, recovery--34% during the first 18 months) and
    decreased feed consumption in males (maximum decrease of approximately
    12%).  For the non-recovery rats and recovery rats during treatment
    with EH, body weight gain was significantly decreased (at 18 months,
    males: control--298.719.6 g, non-recovery--215.421.3 g,
    recovery--211.222.4 g; females: control--149.919.8 g, non-
    recovery--128.721.7 g, recovery--128.518.3 g); following the 6 month
    recovery period, body weight gains of males and females that had been
    gavaged with EH for 18 weeks had partially recovered but were still
    significantly decreased compared to controls (males: control--
    266.530.7 g, recovery--216.123.0 g; females: control--177.527.0 g,
    recovery--150.621.5 g).

         The following changes were observed in rats that had been gavaged
    with 500 mg/kg bw/day EH for 18 months compared to control rats: 1) a
    greater number of animals and/or a higher incidence of clinical
    symptoms such as poor general condition, labored breathing, and
    genital region smeared with urine in males and females; 2)
    statistically significant decreases in the absolute weights of brain
    (males and females) and stomach (males); 3) statistically significant
    decreases in organ-to-body weight ratios of brain (males and females),
    liver (males and females), kidneys (males and females), stomach (males
    and females), and testes (BASF, 1992c).

    2.2.4  Reproduction studies

         The response of mixed cultures of Sertoli and germ cells prepared
    from Sprague-Dawley rat testes to model testicular toxicants was
    studied.  After incubation of the cultures with 2 x 10-4 M EH for 24
    hrs, no increase was observed in the normal rate of germ cell
    detachment from Sertoli cells into the culture medium (Gray and
    Beamand 1984).

         Effects of EH on rat testes were examined  in vivo and
     in vitro.  No testicular damage was observed in male Sprague-Dawley
    rats given oral doses of 2.7 mmol EH/kg bw/day for 5 days and
    incubation with EH (0-1 000 M for 24 or 48 hours) did not enhance
    detachment of germ cells from primary mixed cultures of rat Sertoli
    and germ cells (Sjoberg  et al., 1986).

         EH did not increase lactate and pyruvate concentrations in the
    medium of  in vitro cultures of rat Sertoli cells.  Such increases
    are considered to be sensitive indicators of altered Sertoli cells
    function associated with Sertoli-cell toxicants (Williams & Foster
    1988).

    2.2.5  Special studies on developmental toxicity and teratogenicity

    2.2.5.1  Mice

         Pregnant CD-1 mice were gavaged on gestation days 6-13 with 1525
    mg/kg bw/day EH in corn oil; control mice were gavaged with corn oil;
    dams were allowed to litter.  Administration of EH caused
    statistically significant (p<0.05) decreased maternal body weight
    gain (control: 7.02.5 g; EH: 3.93.2 g), decreased number of viable
    litters (control: 33/34; EH: 11/20), decreased liveborn per litter
    (control: 9.92.4; EH: 6.83.4), decreased percentage survival of pups
    (control: 98.28.8; EH: 73.432.2), and decreased birth weight
    (control: 1.60.1 g/pup; EH: 1.40.2 g/pup) and weight gain for pups
    (control: 0.60.1 g/pup; EH: 0.30.2 g/pup) (Hardin  et al., 1987).

    2.2.5.2  Rats

         Pregnant Wistar rats were administered undiluted di(2-ethylhexyl)
    phthalate (DEHP; 12.5 or 25 mmol/kg bw), EH (6.25 or 12.5 mmol/kg bw,
    approximately equivalent to 800 and 1600 mg/kg bw), or 2-ethylhexanoic
    acid (EA; 6.25 or 12.5 mmol/kg bw) by gavage on day 12 of gestation. 
    Control rats were not gavaged (untreated controls).  Caffeine (150
    mg/kg) was dissolved in water and injected i.p. in some pregnant rats
    of each group.  Rats were killed on day 20 of gestation; following
    Caesarean section, implantation sites were determined  in situ and
    the number of dead or resorbed fetuses was determined.  Live fetuses
    were removed and examined; internal and external soft tissue and
    skeletal malformations were recorded.  At least seven litters for each
    experimental condition were analyzed.

         Administration of each test compound resulted in statistically
    significant, dose-related increases in malformed live fetuses (DEHP:
    12.5 mmol/kg bw [7 litters]--4.54.5%, 25 mmol/kg bw [7 litters]--
    20.87.3%; EH: 6.25 mmol/kg bw [7 litters]--2.01.3%, 12.5 mmol/kg bw
    [7 litters]--22.214.7%; EA: 6.25 mmol/kg bw [7 litters]--0.80.8%;
    12.5 mmol/kg bw [10 litters]--67.810.9%) compared to controls (no
    malformed live fetuses in 7 litters).  Defects in fetuses following

    treatment with EH included hydronephrosis (7.8% of live fetuses), tail
    defects (4.9% of live fetuses), limb defects (9.7% of live fetuses),
    and other defects (1.0% of live fetuses).  For each test compound,
    caffeine was reported to potentiate (increase) the percent of
    malformed live fetuses.  However, administration of test compounds did
    not significantly affect the percentage of dead and resorbed fetuses
    compared to controls.  No maternal effects associated with the test
    compounds were reported.  These results are consistent with the
    hypothesis that the proximal teratogen for DEHP is EA, the metabolic
    product of EH (Ritter  et al., 1986 and 1987).

         The developmental toxicity of dermally applied EH was studied in
    Fischer 344 rats; results of a dose range-finding study for the
    developmental toxicity study were also included.  In the dose range-
    finding study 0, 420, 840, 1680, or 2520 mg/kg bw/day EH (undiluted)
    was applied to the clipped dorsal skin of pregnant F344 rats (8
    rats/group); a positive dermal control group (2-methoxyethanol) and a
    sham-treated (deionized water) dermal control group were included in
    the study.  In the developmental toxicity study, 0, 252, 840, or 2520
    mg/kg bw/day EH (undiluted) was applied to the clipped dorsal skin of
    pregnant F344 rats (25/group); a positive dermal control group
    (2-methoxyethanol) and a sham-treated (deionized water) dermal control
    group also were included in this study.

         Body weights were recorded on gestation days 0, 6, 9, 12, 15, and
    21; feed consumption was estimated for 3-day intervals from gestation
    days 0-21.  Skin irritation was measured before and after each 6-hr
    application period.  Surviving females were killed on gestation day
    21; uterine and liver weights (both studies) and weights of spleen,
    adrenals, kidneys, and thymus (developmental toxicity study) were
    recorded.  Corpora lutea and uterine implantation sites were counted;
    ovaries, cervices, vaginas, and abdominal and thoracic cavities were
    examined grossly.  All live and dead fetuses and resorption sites were
    noted.  Live fetuses were sexed, weighed, and examined for external,
    visceral, and skeletal malformations and variations.

         All pregnant females treated with EH survived.  Clinical findings
    for EH-treated pregnant rats were limited to body weight changes, skin
    irritation, and nasal and ocular effects.  Decreased body weight gain
    was observed in the dose range-finding study for gestation days 6-15
    at doses of 1 680 (10.17.1 g) and 2 520 mg/kg bw/day EH (10.74.8 g)
    compared to sham-treated control rats (18.96.4 g).  In the main
    study, weight gain was statistically significantly decreased for
    gestation days 6-9 at 2 520 mg/kg bw/day EH (0.12.4 g) compared to
    sham-treated controls (3.31.2 g), and was somewhat, but not
    statistically significantly, decreased at 840 mg/kg bw/day EH.  No
    significant changes in feed consumption were reported at any treatment
    level of EH in either study throughout gestation (data not given). 
    EH-related irritation effects at the treatment site were identified as
    mild, and included exfoliation, encrustation and erythema for all
    treatment groups in both studies; oedema was not observed.

         Gestational effects were observed for neither study at any dose
    of EH applied dermally.  Also, dermal administration of EH was not
    associated with external, visceral, or skeletal malformations. 
    Dermally applied EH does not produce developmental or teratogenic
    effects when administered at doses associated with demonstrable
    maternal toxicity (Tyl  et al., 1992).

         Groups of approximately 15 pregnant Sprague-Dawley rats were
    exposed for 7 hrs/day to air saturated with EH vapor (approximately
    850 mg/m3 EH) throughout gestation (Nelson  et al., 1988).  Dams
    were weighed daily during the first week of exposure, then weekly. 
    Dams were killed on gestation day 20; fetuses were removed, sexed,
    weighted and examined for external, visceral and skeletal defects.  EH
    reduced maternal feed intake but did not produce significant maternal
    toxicity (data not provided).  Inhalation of EH under conditions of
    this experiment was not associated with increased malformations
    (Nelson  et al., 1988).

    2.2.6  Special studies on genotoxicity

         The results of genotoxicity assays on EH are summarized in Table
    2.  All reports except Seed (1982) were of negative results for
     in vitro assays; results were negative for several  in vivo assays,
    including a dominant lethal assay, a chromosomal aberration assay, and
    a mutagenicity assay on rat urinary metabolites of EH.

    2.2.7  Observations in humans

         Hollenbach and coworkers (1972) reported that laboratory workers
    exposed to EH (among other substances) reported headaches, dizziness,
    fatigue and gastrointestinal disorders; also that exposed workers had
    slightly decreased blood pressure during the day.


        Table 2: Results of genotoxicity assays on EH

                                                                                                                     

    Test                     Test Subject                 EH Conc.                 Result     Reference

                                                                                                                     

    Ames test1               S. typhimurium TA98          0-1.0 L/plate           neg.       Kirby et al., 1983
                             TA100 TA1535
                             TA1537 TA1538

    Ames test1               S. typhimurium TA98          0-220 g/plate           neg.       Zeiger et al., 1985
                             TA100 TA1535 TA1537

    Ames test1               S. typhimurium TA98          0-2 000 g/plate         neg.3      Agarwal et al., 1985
                             TA100 TA1535 TA1537
                             TA1538 TA2637

    Ames test1               S. typhimurium TA98          0-1.8 l/plate           neg.       Litton Bionetics Inc., 1982a
                             TA100 TA1537 TA1535
                             TA1538

    Ames test1               S. typhimurium TA98          urine from rats          neg.       DiVincenzo et al., 1983
                             TA100 TA1535 TA1537          gavaged with 1 g/kg
                             TA1538                       bw/day EH for 15 day

    In vitro cell            BALB/3T3 cells               0-0.162 g/ml            neg.4      Litton Bionetics Inc., 1982b
    transformation
    assay1

    8-Azaguanine             S. typhimurium TA100         0-1.5 mM                 pos.5      Seed, 1982
    resistance assay2

    Mouse micronucleus       B6C3F1 mouse bone            456 mg/kg bw/day         neg.6      Litton Bionetics Inc., 1982c
    test                     marrow cells                 i.p. for 1 or 2 day
                                                                                                                     

    Table 2 (contd)

                                                                                                                     

    Test                     Test Subject                 EH Conc.                 Result     Reference

                                                                                                                     

    mouse lymphoma           L5178Y/TK+/- mouse           0.01-0.24 L/mL          neg.       Kirby et al., 1983
    assay1                   lymphoma cells

    Rec-assay                Bacillus subtilis            500 g/disk              neg.       Tomita et al., 1982

    CHO mutation assay       Chinese hamster ovary        1.5-2.8 mM               neg.       Phillips et al., 1982
                             (CHO) cells

    Unscheduled DNA          Primary rat hepatocytes      Not given                neg.       Hodgson et al., 1982
    synthesis assay

    In vivo dominant         ICR/SIM mice                 250, 500, 1 000          neg.       Rushbrook et al., 1982
    lethal assay                                          mg/kg bw/day
                                                          for 5 day

    In vivo chromosomal      F344 rat bone marrow cells   .02, .07, .21 g/kg       neg.       Putnam et al., 1983
    aberration assay                                      bw/day for 5 day
                                                                                                                     

    (1)  Both with and without metabolic activation
    (2)  Without metabolic activation
    (3)  Moderate cytotoxicity reported in most cultures
    (4)  Negative from 0-225 l/ml without metabolic activation; negative from 0-0.162 l/ml
         with rat hepatocytes for metabolic activation
    (5)  Small dose-related increase (maximum increase was approximately 3.5 times background)
         in mutation frequency accompanied by decreased survival (cytotoxicity)
    (6)  Negative with and without activation with S9 and with and without
         -glucuronidase/arylsulfatase
    

    3.  COMMENTS

         In rats, orally administered 2-ethyl-1-hexanol is absorbed and
    rapidly eliminated within 28 hours, mainly in urine and faeces.  The
    major urinary metabolite is 2-ethylhexanoic acid.  In mice, rats and
    monkeys, the compound is oxidized by -, omega-, and omega-1-oxidation
    to various metabolites, including 2-ethylhexanoic acid,
    ethylhexanedioic acid, and 5-hydroxyethylhexanoic acid.  Glucuronic
    acid conjugates are formed in all three species.

         The Committee concluded that the available data do not indicate
    that 2-ethyl-1-hexanol is genotoxic.  With a single exception, in
    which a positive result occurred in the presence of significantly
    decreased cell survival (cytotoxicity), the results of both  in vivo
    and  in vitro genotoxicity tests were negative.

         Although teratogenic effects were reported in the offspring of
    mice administered 1 500 mg 2-ethyl-1-hexanol/kg bw/day by gavage on
    days 6-13 of gestation, these effects occurred in the presence of
    severe maternal toxicity.   The body weight gain of treated females
    was approximately 40% less than that of untreated controls.  In rats,
    administration of 1600 mg/kg  bw 2-ethyl-1-hexanol by gavage (but not
    800 mg/kg bw) on day 12 of gestation was associated with a
    statistically significant increase in the number of malformed live
    fetuses (malformations included hydronephrosis, tail defects and limb
    defects).  Maternal toxicity was not reported in this study.

         The results of several short-term toxicity studies suggested that
    2-ethyl-1-hexanol administered orally to rats and mice at doses
    greater than approximately 350 mg/kg bw/day induces liver peroxisome
    proliferation and/or marker enzymes for peroxisome proliferation. 
    However, the results of carcinogenicity studies did not indicate that
    long-term oral administration of 2-ethyl-1-hexanol leads to induction
    of liver tumours in mice or rats.

         The results of long-term oral carcinogenicity studies indicated
    that 2-ethyl-1-hexanol is not carcinogenic in rats (24 months) or mice
    (18 months).  The incidence of hepatocellular carcinomas at 750 mg/kg
    bw/day in female mice was slightly higher than in historical controls,
    however this effect was considered to be incidental and unrelated to
    the administration of 2-ethyl-1-hexanol.  The increase was
    statistically significant when compared with the incidence in vehicle
    control females but not when compared with the incidence in control
    females given distilled water by gavage.  In these studies, the 750
    mg/kg bw/day dose of the compound produced a number of statistically
    significant, non-carcinogenic adverse effects, but these effects were
    not observed at 50 or 200 mg/kg bw/day in mice or at 50 mg/kg bw/day
    in rats.

    4.  EVALUATION

         On the basis of a NOEL of 50 mg/kg bw/day from the long-term
    study in rats and using a safety factor of 100, the Committee
    established an ADI of 0-0.5 mg/kg bw for 2-ethyl-1-hexanol.

    5.  REFERENCES

    AGARWAL, D.K., LAWRENCE, W.H., NUNEZ, L.J. & AUTIAN, J. (1985). 
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    See Also:
       Toxicological Abbreviations