DINOCAP EXPLANATION Dinocap was previously evaluated by the JMPR in 1969 and 1974 and a toxicological monograph was published in 1969 (Annex 1, FAO/WHO, 1970a, 1975a). An ADI was not established during these evaluations due to the lack of the following: studies to investigate cararactogenicity, a chronic toxicity in a non-rodent species, metabolic studies, specifications, information on mechanism of action on cellular respiration, reproduction studies and data on residues. Dinocap is a fungicide-miticide consisting of 2,4- and 2,6-dinitrooctylphenyl crotonates where the octyl moiety is either 1-methylheptyl, 1-ethylheptyl or 1-propylpentyl. The previous monograph has been incorporated into this monograph. EVALUATION FOR ACCEPTABLE DAILY INTAKE BIOLOGICAL DATA Biochemical aspects Absorption, distribution and excretion A study of distribution and excretion of 14C-labelled (uniformly on the aromatic ring) dinocap was undertaken by dosing one male and one female adult albino rat (strain not reported) with approximately 62 mg/kg bw (730 microcuries/g) of test material incorporated into the diet for 7 days (Graham, 1970). Animals were fed untreated diet for 7 days after the cessation of dosing. Urine, feces, exhaled CO2, cage washes and various tissues were collected and analysed for radioactivity. A larger proportion of test material was eliminated in the urine of male rats (50.8%) than in female rats (38.4%). A total of 63.5% and 49.5% of radioactivity was found in the feces of female and male rats, respectively. Minor amounts (<.3%) were found in exhaled CO2, cage washes and tissues. A comparison of the pharmacokinetics of dinocap after oral, dermal and intravenous administration was undertaken in New Zealand White rabbits using 14C-2,4-dinitro-6-(1-methylheptyl)phenyl crotonate as the surrogate for the mixture of dinocap isomers (DiDonato & Longacre, 1985). Peak plasma levels of 0.29, 1.26 and 14.5 ppm were found up to 3 hours after oral dosing with 0.5, 3 and 25 mg/kg bw. Dermal application of 25, 100 and 220 ppm of test material (2.15, 8.31 and 18.3 mg/cm2, respectively) of test material resulted in peak plasma concentrations of 0.28, 0.47 and 1.51 ppm up to 24 hours after dosing. The elimination of radiolabel was biphasic. The alpha phase half-lives were 2.23-3.76 hrs after oral administration and 7.89 to 21.80 hrs after dermal administration. The half-lives for the beta-phase were 33.3 to 55.1 hrs after oral administration and 118 to 369 hrs after dermal administration. The area under the plasma/time concentration curve was proportional to the dose for both routes of administration and all doses, suggesting that saturation of absorption or excretion does not occur at the dose levels studies. The absorption ranged from 4 to 9% after dermal exposure and 60 to 69% after oral exposure. Biotransformation Rats A study of distribution, excretion and metabolism was undertaken by administering by gavage 12.5 and 11.7 mg/day of 14C-2,4-dinitro-6-(2-octyl)phenyl-crotonate for seven consecutive days to one male and one female Wistar rat (Honeycutt & Garstka, 1976a). Urine, feces and exhaled carbon dioxide were collected during the course of the study and tissues were collected at the sacrifice 6 hours after the final dosing. Urine and feces were analysed by thin layer chromatography to identify metabolites. Feces accounted for 58% of radioactivity in the male and 52% in the female. Gastrointestinal tissues accounted for 2.9% (male) and 3.8% (female); 2.9% (males) and 3.8% (females) of total administered radioactivity was found in other tissues with heart (0.85%) and liver (0.32%) containing the highest concentrations. Approximately 15% of the radioactivity was excreted in the urine by males and 20% by females. Over twenty different metabolites were found in urine and feces. Most of these constituted between 2-8% of total radioactivity. A separate study identified several of the major metabolites and they were primarily found to be hydrolysis products (Honeycutt & Garstka, 1976b). The pattern of metabolites of dinocap found in feces was similar to that observed in squash and cucumbers. More polar metabolites were observed in urine (Honeycutt & Garstka, 1976c). An earlier study found no detectable dinocap or phenol hydrolysis products in rat muscle, fat, liver, kidney or brain after feeding 500 ppm of technical dinocap to an unspecified number of rats for 30 days. The reported level of detection was 1 ppm (Gordon, 1956). Effects on enzymes and other biochemical parameters Chemicals of the dinitrophenol class, such as dinocap, are known inhibitors of oxidative phosphorylation. Dinocap was compared with 2,4-dintrophenol in oxygen consumption studies in rats. Six rats (4 males and 2 females) were given a single oral dose of 600 mg/kg body weight of dinocap. Measurements made at various intervals showed that a steady increase in oxygen consumption occurred in the females, which reached a maximum of 63% of the zero-time level after 24 hours. No increase in oxygen consumption occurred during 24 hours in male rats fed dinocap. A comparable study with 6 other rats (two males and four females) given a single oral dose of 40 mg/kg body weight of 2,4-dinitrophenol resulted in a maximum increase in oxygen consumption of 116% for the females and 90% for the males after three hours, followed by a gradual decrease after three hours (Larson, 1957). The compound 4-isooctyl-2,6-dinitrophenol (a constituent of technical dinocap) was found to be 7 to 25 times more potent than 2,4-dintrophenol in stimulation of respiration of rat-liver mitochondria. It was concluded that the pKa and the lipid solubility of the compounds as well as the pH of the media were the factors influencing this activity, and that there was no instrinsic structure-activity relationship relative to the size of the octyl group (Hemker, 1962). In an auxiliary study to a two-year dog study (see Weatherholtz et al. 1979, below), a NOEL for the reduction of liver mitochondrial oxidative phosphorylation was found to be 1.6 mg/kg bw/day (Hurwitch & Hill, 1979). Acute in vitro studies of the cytotoxicity of dinocap to liver and HeLa cells showed that dinocap was among the most acutely toxic insecticides to human cell cultures (Gabliks and Friedman, 1965a). Exposure to cell cultures of liver and HeLa for up to 84 days induced little resistance with inhibition of growth and morphological changes observed at levels below the I50 (Gabliks & Friedman, 1965b). An increased resistance to polio virus and diphtheria toxin was noted in these cell populations after dinocap exposure (Gabliks & Friedman, 1965c). Dinocap was reported to inhibit the release of calcium from the bones of rats (Oledzka & Pastuszynska, 1974a,b). The inhibition was less when vitamin D was supplemented in the diet. Sodium fluoride also was found to inhibit this effect of dinocap in rats (Oledzka, 1981). A skin irritation study of dinocap technical (purity not reported) in rabbits at dose levels of 0.5, 1.0, 2.9 and 3.9 cc/kg caused moderate to marked skin irritation at all dose levels (Larson, 1956a). Skin sensitization and irritation studies have been conducted in humans (see Human Observations below). Toxicological studies Acute toxicity TABLE 1. ACUTE TOXICITY STUDIES ON DINOCAP LD50 LC50 SPECIES SEX ROUTE (mg/kg bw) (mg/l) REFERENCE Rat M oral 2171 - Krzywicki F oral 1212 - 1985a M oral 1581 - 1985b M oral 1872 - 1985c M oral 2139 - 1985d M oral 1985 - 1985e M oral 1581-2321 - 1985f M oral 980 - Haag, 1950 F oral 1190 - Larson et al. 1959 M oral 635 - Shirasu, 1980a F oral 510 - Shirasu, 1980a ? oral >5000 - Swann, 1973 M oral 1180 - Mlodecki, 1975 F oral 1108 - Mlodecki, 1975 M oral 1175 - Ochynska, 1975 F oral 1493 - Ahmedkhodzhaeva et al. 1984 Mice M oral 180 - Krzywicki, 1985a F oral 150 - Krzywicki, 1985a M oral 200 - DeCrescente, 1981 M oral 86 - Shirasu, 1980b F oral 95 - Shirasu, 1980b M oral 50 - Mlodecki, 1975 F oral 265 - Ahmedkhodzhaeva et al. 1984 Rabbit M oral 2000 - Haag, 1955a M oral 3000 - Mlodecki, 1975 Dog M&F oral 100 - Larson, 1959 Rat M i.v. 23 - Haag, 1955c Rat M i.p. 388 - Toshima et al. 1976 M&F i.p. 433 - DeGroot, 1974 M i.p. 48 - Ochynska, 1975 F i.p. 57 - Ochynska, 1975 TABLE 1 (CONTD). LD50 LC50 SPECIES SEX ROUTE (mg/kg bw) (mg/l) REFERENCE M i.p. 200 - Toshima et al. 1976 F i.p. 178 - Toshima et al. 1976 Rat M&F s.c. >2000 - Toshima et al. 1976 Mice M s.c. 520 - Toshima et al. 1976 F s.c. 480 - Toshima et al. 1976 Rabbit M dermal >4700 - Haag, 1950 ? dermal >2000 - Swann, 1973 Rat M&F inhal. - >20.8 mg/l Kruysse & Engel, 1974 ? inhal. - <202 mg/l Swann, 1973 Short-term studies Rats Groups containing 10 weanling rats of each sex were fed diets containing 0, 10, 50, 250, 1000 and 2500 ppm of technical dinocap (purity not reported) for six months. Growth and survival were reduced at the 2500 ppm level and growth rate was reduced at 1000 ppm at weeks 1 and 2 only in males. Enlarged spleens occurred in the males receiving 2500 ppm. Hematological and microscopic examinations revealed no changes attributable to treatment. The NOAEL was 250 ppm (Larson et al. 1959). A summary report of a 90-day study in rats discussed the oral toxicity of dinocap technical (purity not reported) at dose levels of 0, .55, 5.5, 55.5 mg/kg bw/day administered by daily gavage 6 days per week (Mlodecki et al. 1976). The control group consisted of 15 males and 15 females; the two other dose levels consisted of 30 males and 30 females per dose level. Decreased body weight gain was observed at the high dose level; and increases of GOT, GPT and AP and "distinct focal, and degenerative necrotic changes of the stomach, liver and kidneys" at both dose levels. Individual animal data was not presented. A published report of a 32-day study in Wistar rats was available (Ochynska & Ochynska, 1984). A total of 14 male and 14 female rats were given increasing doses of dinocap (purity not specified) to reach a dose level of 443 mg/kg bw/day in females and 513 mg/kg bw/day in males. The cumulative lethal dose (the dose estimated to result in 50% mortality over the course of the study) was found to be 344 and 356 mg/kg bw/day for males and females, respectively. Rabbits A summary report was available for a 90-day study in male rabbits (strain not specified). Ten animals served as controls, 10 received 150 mg/kg bw/day by gavage and 10 received 30 mg/kg bw/day. The low dose level was reported to be without toxicologic effect (Szadowska et al. 1977). Dogs Groups, each containing three mongrel dogs of unspecified sex and age, were fed diets containing 10, 50, 100, 250 or 1000 ppm of technical dinocap (purity not specified) for one year. One dog in the 250 ppm group died within six weeks, another was sacrificed after marked weight loss and the third was transferred to control diet. Decreased body weight gain was reported at dose levels of 100 ppm and greater. Histopathological changes ("acute diffuse necrosis" or "acute massive necrosis" of the liver) were reported at dose levels of 250 and 1000 ppm (Larson, 1956b). Four male and 4 female beagle dogs per dose level were fed either 0, 15, or 60 ppm of dinocap technical (78% purity) for 107 weeks (Weatherholtz et al. 1979). A fourth group was initially fed 240 ppm during the first week; due to toxicity dose levels were reduced to 0 ppm during weeks 2-3, 120 ppm during weeks 4-30, 240 ppm during weeks 31-32 and 180 ppm during weeks 33-61. The high dose level animals were sacrificed after 62 weeks. A variety of toxicological effects were observed in the high dose group including weight loss, ataxia, gross and microscopic myocardial changes, and retinal atrophy. Discoloration and decreased reflectiveness of the tapetum lucidum and reduced vascularity of the retina and optic disk were also observed at the high dose level. Ocular changes similar to those observed in high dose animals were observed in 7 of 8 mid dose dogs. No other treatment-related effects were observed in mid or low dose animals. The NOAEL was 15 ppm, equivalent to 0.4 mg/kg bw/day. Long-term/carcinogenicity studies Mice Dinocap was among the 120 pesticides that were screened for carcinogenicity in hybrid mice (Innes et al. 1969). Maximum tolerated doses (1 mg/kg bw/day) were administered to 18 male and 18 female C57BL/6 x C3H/Anf mice and to 18 male and 18 female C57BL/6 x AKR mice for 18 months by gavage starting at day 7 after birth and continuing by dietary incorporation after day 21. Survival after 18 months ranged from 13-15 animals/sex/strain. No significant increase in any tumour type at any site examined was observed compared to control animals. Total number of tumour-bearing animals did not exceed 5 in any group. The most common tumour type was reticulum cell sarcoma type A which occurred in 3 male and 2 females of the B6C3F1 hybrid strain. Rats Groups containing 10 weanling rats of each sex were fed diets containing 0, 10, 50, 250 and 1000 ppm of technical dinocap for two years. There was decreased weight gain during the first year only in the male rats fed 1000 ppm, but the effect on body weight during the second year was not reported. No other effect of treatment, either gross or histopathological was noted at any of the dose levels studied (Larson et al. 1956c). A summary report was available which reported effects observed after the long-term dietary administration of dinocap (purity not specified) to Wistar rats (Mlodecki et al. 1956c). After two years' exposure, animals were fed control diet for 12 weeks prior to final sacrifice. Thirty males per group received doses of either 0, 0.15, 1.42 or 13.89 mg/kg bw/day. Females received doses of 0, 0.9, 0.92 or 8.87 mg/kg bw/day. Decreased body weight gain was reported for both the mid and high dose animals. No effects of dinocap on mortality, behaviour, clinical chemistry, hematology or gross or microscopic pathology were reported. No clear reversal of the decreased body weight gain in mid and high dose animals was apparent. A more recent chronic rat feeding study was conducted in SPF Wistar rats (Maita et al. 1980). Test material (77.5% purity) was incorporated into the diet and fed at dose levels of 0, 20, 200 and 2000 ppm for 30 months. Eighty animals of each sex were started on test at each dose level and 8 animals/sex/dose level were sacrificed after 13, 26 and 52 weeks. Body weight was recorded weekly; behaviour, food and water consumption were recorded daily. Urinalysis, clinical chemistry and hematology were examined prior to the sacrifice of the satellite groups. Gross examinations were conducted for all animals sacrificed or dying during the course of the study and weights of major organs recorded. The following tissues were examined histologically: lungs, pancreas, salivary glands, stomach, duodenum, jejunum, ileum, caecum, urinary bladder, seminal vesicles, prostrate, uterus, sternum, bone marrow of the femur, sciatic nerve and grossly observable lesions. A significantly reduced mortality was observed in both sexes primarily at the high dose. This was apparent from week 56 in females and week 89 in males. Group mean body weight gains were also reduced in both sexes at the high dose level from initiation of the study to termination. Yellowing of the urine and fur was observed at the high dose level. Both males and females at that dose level showed decreased hematocrit, hemoglobin and RBC counts during the first year of the study; no significant effects on these parameters were observed at final sacrifice. Decreased fat deposition was noted in the 2000 ppm dose groups. Other differences in both neoplastic and non-neoplastic observations (including cataract incidence) in the high dose groups could be attributed to the increased survival of animals at this dose level and older average age at sacrifice. The NOAEL in this study is 200 ppm (equal to 6.41 mg/kg bw/day for males and 8.05 mg/kg bw/day for females). Reproduction studies Rats A summary report of a preliminary study of the effects of dinocap (purity unspecified) on reproduction was available (Fraczek, 1979). Ten rats of each sex (age not specified) were reported to receive 0.5% of the LD50 for 12 weeks. Animals were mated and reproductive parameters examined. The authors reported decreased survival and lactation indices in dinocap-treated offspring. Decreased parental body weight gain was also noted in treated animals. A three generation reproduction study with a teratology phase was reported in rats (Mulligan, 1976). Dinocap technical (82% active ingredient) was incorporated into the diet of 10 male and 20 female Sprague-Dawley rats at dose levels of 0, 1, 20 and 200 ppm. Parental animals of each generation were fed either control or treated diets for at least 9 weeks prior to mating. The P1 parental animals were mated once, the two following generations were mated twice. The first litter of each mating was used as the subsequent parental generation and the second litter was sacrificed on day 19 of gestation and examined for developmental toxicity. Litters were culled to equal numbers at weaning. Ophthalmoscopic examinations were conducted on all animals prior to mating. Histopathological examinations were not conducted for parental or filial animals. Two males and one female were paired for 21 days for each mating. Males were allowed to cohabit with different females after each week. Vaginal smears were conducted daily to ascertain mating. Body weights were recorded on days 0, 7, 14 and 19 of gestation. Two-thirds of the second litters of second generation and one-third of the second litter of the third generation was stained and examined for skeletal anomalies. The remaining fetuses were viscerally examined using the technique of Wilson. Findings which appeared to be due to compound administration were not observed in the parental or filial animals. Body weights, behaviour, reproduction indices and the incidences of developmental anomalies were similar in control and treated groups for all generations. The NOAEL was therefore 200 ppm, equivalent to 6.4 mg/kg bw/day. Special studies on genotoxicity TABLE 2. RESULTS OF GENOTOXICITY ASSAYS OF DINOCAP TEST SYSTEM TEST OBJECT RESULTS REFERENCE Ames test Salmonella Negative Lohse, 1982b typhimurium TA1538, TA98, TA100 Ames test S. typhimurium Positive Shirasu, 1979, 1982 TA1538, TA98 Ames test S. typhimurium Positive Moriya et al. 1983 TA100, TA1535, TA1537, TA1538 Ames test S. typhimurium Positive Melly et al. 1981 TA1538 Ames test S. typhimurium Negative Melly, 1982a TA1538 Ames test S. typhimurium Negative Lohse, 1982b TA1538 Ames test S. typhimurium Negative Byers, 1982 TA1538 Ames test S. typhimurium Positive Higganbotham et al. TA1538 1984 TABLE 2 (CONTD). TEST SYSTEM TEST OBJECT RESULTS REFERENCE Ames test S. typhimurium Negative Higganbotham, 1985 TA1538 Reverse E. coli Negative Shirasu, 1979, 1982 mutation WP2 hcr Reverse Saccharomyces Positive Guerzoni, 1976 assay cervisiae Mouse lymphoma L5178Y Negative Cifone, 1981 cells Micronucleus Mouse bone Negative Sasaki et al. 1982 marrow Cytogenetic Mouse Negative Pilinskaya et al. 1980 DNA damage B. subtilis Negative Shirasu, 1979 Unscheduled Hepatocytes Negative Muller & Byers, 1985 DNA synthesis from Fischer 344 adult males Special studies on teratogenicity Mice Dose levels of 0, 6, 12 and 25 mg/kg bw/day (84% purity) were administered by oral gavage to CD-1 mice (resulting in 22, 7, 28 and 15 litters) on days 7 to 16 of gestation (Gray et al. 1986, 1988). Maternal toxicity was not observed at any dose level. Increased incidences of pup mortality and decreased fetal weights were observed at the mid and high dose levels. Postnatal torticollis consistent with malformations of the inner ear (missing otoliths) was found in pups of the 12 (6%) and 25 (24%) mg/kg bw/day by 30 days of age. Swimming ability was adversely affected in each of the pups with complete agenesis of the otoconia. The NOAEL for embryo/fetotoxicity was 6 mg/kg bw/day. In another mouse teratology study, CD-1 mice were dosed at levels of 5, 10, 20, 40, 80 and 120 mg/kg bw/day (84% purity) on days 7-16 of gestation, day 1 being the day of identification of the vaginal plug or of semen in the vagina (Rogers et al. 1986). All fetuses died at the highest dose level. Decreased maternal body weight gain and increased maternal mortality was observed at 80 mg/kg bw/day. Fetal body weight and gravid uterine weights were decreased at all dose levels. An increased incidence of cleft palate was observed at dose levels of 20 mg/kg bw/day and greater. The NOAEL for embryo/fetotoxicity was therefore 10 mg/kg bw/day. Rats No effects on perinatal development were observed after dosing Sprague-Dawley rats with dinocap (84%) and 100 mg/kg bw/day by gavage on days 2-20 of gestation (Gray et al. 1986). Reduced maternal weight gain was observed at this dose level. A second study reported that Sprague-Dawley rats were dosed at 0, 100, 150 and 200 mg/kg bw/day on gestation days 7-20 (Rogers et al. 1988). Fifteen sperm positive rats were dosed in the control group and 18 in each group were dosed with dinocap. Fetal weight and maternal weight gain were both reduced at the two highest dose levels. No increase in malformations was observed. The NOAEL was 100 mg/kg bw/day in these two rat studies. A teratology examination was conducted during the course of the 3 generation rat reproduction study (see Reproduction studies above). No teratogenic effects were observed. Hamsters Five groups of 10 mated female Syrian golden hamsters were dosed with 0, 25, 50, 100 or 200 mg/kg bw/day of dinocap technical on days 8-11 of gestation (10, 10, 9, 9 and 9 were pregnant). The females were allowed to deliver and pups were weighed and examined on days 1 and 5. Prior to parturition, 1 female each died at 100 and 200 mg/kg bw/day and total litter weight was reduced at all dose levels on days 1 and 5 (Gray et al. 1986). No other toxicity was observed. Dinocap was administered by gavage to Syrian golden hamsters at dose levels of 0, 12.5, 25, 50, 75, 100 or 200 mg/kg bw/day (Gray et al. 1988). A total of 29, 12, 11, 32, 17, 15 and 7 sperm positive pregnant animals were gavaged at each dose level. Decreased maternal weight gain was observed at dose levels of 50 mg/kg bw/day and greater. Mean fetal weights were decreased at dose levels of 25 mg/kg bw/day and greater. The authors reported that kidney dilatation and fetuses classified as hydronephrotic were increased at dose levels of 25 mg/kg bw/day and greater. The NOAEL is 12.5 mg/kg bw/day. Rabbits Two oral gavage teratology studies of dinocap were conducted which followed the same protocol but which had overlapping dose levels (Costlow & Kane, 1984a,b). Dose levels in these studies were established on the basis of a range-finding study which dosed 6 animals each at levels of 0, 10, 31.6, 100, 215, 464 and 1000 mg/kg bw/day of technical dinocap (84% active ingredient); fetotoxicity or embryotoxicity were observed at dose levels of 31.6 mg/kg and greater and maternal toxicity at doses of 100 mg/kg and greater (Costlow, 1984). In the primary studies, dinocap technical was administered by oral gavage to pregnant New Zealand White rabbits on days 7 through 19 of gestation. Eighteen animals per dose level were administered 0, 3, 12, 48 or 64 mg/kg bw/day in the first study and 0, 0.1, 0.5 or 48 mg/kg bw/day in the second study. Animals were periodically weighed and appearance and behaviour were recorded on a daily basis. All females were sacrificed on day 29 of gestation and fetuses examined for external, skeletal and visceral abnormalities. An increased incidence of hydrocephaly and neural tube defects, as well as post-implantation losses, were observed at dose levels of 3 mg/kg bw/day and greater. A NOAEL for embryo/fetotoxicity and teratogenicity was established as 0.5 mg/kg bw/day in this study. A dermal range-finding study in New Zealand White rabbits was conducted using dose levels of 0, 20, 50, 200 and 200 mg/kg bw/day of dinocap Wettable Dust and 20, 50, 100, 200 mg/kg bw/day dinocap Liquid Concentrate and 200 mg/kg bw/day dinocap technical (Costlow & Lutz, 1985a). Formulation blanks not containing dinocap was also tested. Severe skin irritation was observed at dose levels of 20 mg/kg and greater with LC formulation, 100 mg/kg and greater with the WD formulation and with 200 mg/kg of the technical material. An increased incidence of resorptions and/or abortions or reduced fetal weight was observed only at dose levels of 200 mg/kg. In the primary dermal teratology study, 18 New Zealand White rabbits per dose level were treated with either 0, 25, 50 or 100 mg/kg of dinocap technical (87.8% purity) (Costlow & Lutz, 1985b). Test material was applied to the shaved backs of the animals on days 7 though 19 of gestation. The site of application was alternated to reduce dermal irritation. Animals were observed daily, periodically weighed and sacrificed on day 29 of gestation. Dams were examined for corpora lutea, resorption sites and live and dead fetuses. All fetuses were weighed and examined for external, visceral and skeletal abnormalities. Dermal irritation was observed in all dinocap-treated animals. Frank maternal toxicity was observed only at 100 mg/kg bw/day. Slight increases in delayed ossification and skull abnormalities (accessory skull bone) were observed at the 100 mg/kg bw/day dose level. However, these increases did not reach statistical significance. A NOAEL for embryo/fetotoxicity is estimated as being approximately 100 mg/kg bw/day for this study. Special studies on cataractogenicity Summary reports of a series of 3 studies of the cataractogenicity of dinocap technical and 2,4-ditronitrophenol in Pekin ducks were available (Larson, 1958). Dosing for up to 12 weeks found that dinocap induced cataract formation at dose levels of 50 ppm and greater. A summary report of a second cataractogenicity study in Pekin ducks found no cataract induction at dose levels of up to 2500 ppm (Larson, 1965). A summary report of a third cataractogenicity study in Pekin ducks confirmed that no cataract induction occurred at dose levels of up to 2500 ppm (Larson, 1966). Cataract induction was observed in a study in New Zealand White rabbits at gavage dose levels of 27 and 81 mg/kg bw/day administered for 30 days (Mathason & O'Hara, 1981). Mortality and reduced body weight gain were also observed at those dose levels. A NOAEL was identified at 9 mg/kg bw/day. Observations in Humans A fatal poisoning with a mixture of dodine, monocrotophos and dinocap was followed by a forensic analysis of liver, brain, kidney, lung, blood and gastric contents (Gelbke & Schlicht, 1978). Dinocap could not be detected in the tissues that were analysed. A total of 20 mg of dinocap was found in gastric contents. The authors concluded that the primary cause of death was probably monocrotophos. Patch tests were performed on the forearms of 50 human subjects using dinocap formulated either as an emulsion or as a wettable powder. Exposure was for 48 hours. Moderate irritation resulted from the emulsion in 11 subjects and from the powder in three. Similar results occurred when the opposite forearms were patched 12 days later, 25 subjects reacting to the emulsion and nine to the powder. Intensified reactions resulted during succeeding days in three subjects (Larson et al. 1959). COMMENTS Dinocap was moderately well absorbed after oral administration. The elimination of dinocap was found to be biphasic in the rabbit, with plasma half-lives of about 3 and 33-55 hours after oral administration. Males excreted dinocap in approximately equal amounts in the urine and feces; females excreted slightly more in the feces. Although the metabolic pathway has not been well defined, the metabolites appear to be mainly hydrolysis products. Dinocap has a low acute toxicity in the species examined. No increase in any tumour type appeared to be associated with dinocap in a mouse oncogenicity study. However, only one dose level (1 mg/kg bw/day) and 18 animals/sex/dose level/strain were used in the study. Increased survival of treated animals was observed in a long-term feeding study in rats. Decreased fat deposition and an increased incidence of cataracts in the high-dose group were considered to be associated with increased longevity. The NOAEL was 200 ppm, equal to 6.4 mg/kg bw/day. Dinocap is a member of the dinitrophenol class of chemicals which inhibit oxidative phosphorylation. Cataract induction has been observed in ducks and rabbits. The NOAEL in rabbits, in which dinocap was administered by gavage, was 9 mg/kg bw/day. Ocular toxicity in the form of discolouration, decreased reflectiveness of the tapetum lucidum and reduced vascularity of the retin and optic disk were observed in a two-year dog study. The NOAEL was 15 ppm, equal to 0.4 mg/kg bw/day. No effects associated with dinocap were found in a combined rat reproduction (2 generations with 2 litters per generation)/ teratology study. The highest dose tested was 200 ppm, equal to 6.4 mg/kg bw/day. Teratology studies were conducted in mice, rats, hamsters and rabbits. a variety of forms of embryo/fetotoxicity and terata were observed, with the apparent order of species sensitivity being rabbits > mice > hamsters > rats. In rats, the NOAEL was 100 mg/kg bw/day, since body weights were decreased at the higher doses. In the hamster, indications of hydronephrosis were observed at dose levels of 25 mg/kg bw/day and greater; the NOAEL was 12.5 mg/kg bw/day. In the mouse, the NOAEL was 6 mg/kg bw/day, based on a variety of malformations at higher dose levels. The most sensitive species tested was the rabbit. Neural tube and skull defects were observed at a dose level of 3 mg/kg bw/day; the NOAEL was 0.5 mg/kg bw/day by the oral route. Because of concerns about teratogenic effects, a safety factor greater than 100 was applied. After reviewing all available in vitro and in vivo short-term tests, the Meeting concluded that there was no evidence of genotoxicity. TOXICOLOGICAL EVALUATION Level causing no toxicological effect Rat: 200 ppm, equal to 6.4 mg/kg bw/day Rabbit: 0.5 mg/kg bw/day (based on teratology) Dog: 15 ppm, equal to 0.4 mg/kg bw/day. Estimate of acceptable daily intake for humans 0-0.001 mg/kg bw. Studies which will provide information in the continued evaluation of the compound Observations in humans. Oncogenicity study in a second species. REFERENCES All reports indicated by (*) have been submitted to WHO by Rohm and Haas, Inc., Philadelphia, Pennsylvania, USA. *Akhmedkhodzhaeva, K.h.S., Kamilov, G.D. & Sadritdinov, F.S (1984) Toxicity and nature of the biological action of products and intermediates in the synthesis of the active agent in the fungicidal preparation. Karathane. Dokl. Akad. Nauk. UzSSr, 3: 44-45. *Byers, M.J. (1982) Karathane Technical Microbial Mutagen Test. Rohm and Haas Report No. 82R-233, October 28, 1982. *Cifone, M.A. (1981) Mutagenicity evaluation of Karathane (TD 80-343) in the mouse lymphoma forward mutation assay. Litton Bionetics Project No. 20989, Rohm and Haas Report No. 82RC-150, December 1981. *Costlow, R.D. & Kane, W.W. (1984a) Teratology study with Karathane in rabbits. Rohm and Haas Report No. 83R-22, January 16, 1984. *Costlow, R.D. & Kane, W.W. (1984b) Teratology study with Karathane in rabbits. Rohm and Haas Report No. 83R/113, March 30, 1984. Costlow, R.D., Kane, W.W. & Black, D.L. (1984c) Range-finding study with Karathane in rabbits. Rohm and Haas Report No. 83R/21, January 16, 1984. *Costlow, R.D. & Lutz, M.F. (1985a) A range-finding teratology study of Karathane fungicide in rabbits using the dermal route of administration. Rohm and Haas Report No. 84R-248, June 24, 1985. *Costlow, R.D. & Lutz, M.F. (1985b) A teratology study of Karathane Tech. fungicide in rabbits using the dermal route of administration. Rohm and Haas Report No. 85R-016, June 24, 1985. *DeCrescente, M.E. (1984a) Definitive mouse oral LD50. Rohm and Haas Report No. 82R-199, August 26, 1982. *deGroot, A.P. (1974) Acute intraperintoneal toxicity of Karathane in rats. Central Institute for Nutrition and Food Research. Rohm and Haas Report No. 74RC-1086, August 26, 1982. *DiDonato, L.J. & Longacre, S.L. (1985) Karathane pharmacokinetic study in female rabbits. Rohm and Haas Report No. 85R-002, May 24, 1985. *Fortak, W., Mlodecki, H. & Szadowska, A. (1977) Morphological investigations of the influence of dinocap of the (dinitrophenyl group) on some of the internal organs of laboratory animals in chronic and acute poisoning. Folia. Histochem. Cytochem., 15(2): 247. *Fraczek, S. (1979) Toxicity studies on dinocap. Part V. Preliminary studies on effects on reproduction. Bromatol. Chem. Toksykol., 12(4): 351-356. *Gabliks, J. & Friedman, L. (1965a). Responses of cell cultures to insecticides. I. Acute toxicity to human cells. Proc. Soc. Exptl. Biol. Med., 120: 163-168. *Gabliks, J. & Friedman, L. (1965b). Response of cell cultures to insecticides. II. Chronic toxicity and induced resistance. Exptl. Biol. Med., 120: 168-171. *Gabliks, J. & Friedman, L. (1965c). Responses of cell cultures to insecticides. III. Altered susceptibility to Polio virus and Diptheria toxin. Proc. Soc. Exptl. Biol. Med., 120: 172-175. *Gardner, G.A. (1977) Cataractogenic study of Karathane in rabbits. Dawson Research Corporation, Orlando, Florida. Rohm and Haas Report No. 77RC-1051, March 18, 1977. *Gehring, P.J. & Buerge, J.F. (1969) The cataractogenic activity of 2,4-dinitrophenol in ducks and rabbits. Toxicol. Appl. Pharmacol., 14: 475-486. *Glebke, H.P. & Schlicht, H.J. (1978) Fatal poisoning with a plant protective containing monochrotophos, dodine and dinocap. Toxicol. Eur. Res., 1(3): 181-184. *Graham, W.H. (1970) A material balance study in rats using 14C-Karathane uniformly labelled in the aromatic ring. Rohm and Haas Research Report 23-27, B-8712, December 8, 1970 (Report No. 70R-1002). Gray, L.E., Rogers, J.M., Ostby, J.S., Kavlock, R.J., Ferrell, J.M. (1988) Perinatal dinocap exposure alters swimming behaviour in mice due to complete otolith agenesis in the inner ear. Toxicol. Appl. Pharmacol., 92: 266-273. *Guerzoni, M.E., Del Cuplo, L. & Ponti, L. (1976) Mutagenic activity of pesticides. Riv. Sci. Technol. Aliment. Nutr. Um., 6: 161-165. *Haag, H.B. (1950) Report on the acute oral and percutaneous toxicity of Karathane. Medical College of Virginia. Rohm and Haas Report No. 50RC-1007, July 27, 1950. *Haag, H.B. (1954b) Six-month study on the effect of adding Karathane to the diet of rats. Medical College of Virginia. Rohm and Haas Report No. 54RC-1009, November 22, 1954. *Haag, H.B. (1955a) Acute oral toxicity of Karathane to rabbits. Medical College of Virginia. Rohm and Haas Report No. 55RC-1006, May 31, 1955. *Haag, H.B. (1955b) Acute oral toxicity of Karathane to dogs. Medical College of Virginia. Rohm and Haas Report No. 55RC-1007, July 31, 1955. *Haag, H.B. (1955c) Acute oral toxicity of Karathane to rats. Medical College of Virginia. Rohm and Haas Report No. 55RC-1010, August 13, 1955. *Hemker, H.C. (1962) Lipid solubility as a factor influencing the activity of uncoupling phenols. Biocim. Biophys. Acta, 63: 46-54. *Higginbotham, C. & Byers, M.J. (1984a) Microbial mutagen assay: Karathane Technical. Rohm and Haas Report No. 84R-203, October 26, 1984. *Higginbotham, C. & Byers, M.J. (1984b) Karathane Technical microbial mutagen screen. Rohm and Haas Report No. 84R-243, November 29, 1984. *Higginbotham, C. & Byers, M.J. (1985) Microbial mutagenicity assay: Karathane Technical. Rohm and Haas Report No. 85R-039, April 25, 1985. *Honeycutt, R.C. & Garstka, T.A. (1976a) Rat feeding and metabolism study with 14C-2,4-dinitro-6-2(2-octyl)phenyl crotonate. Rohm and Haas Technical Report No. 3423-76-11, March 30, 1976. *Honeycutt, R.C. & Garstka, T.A. (1976b) The identification of metabolites of 2,4-dinitro-6-(2-octyl)phenyl crotonate in rat urine and feces. Rohm and Haas Technical Report No. 3423-76-29, August 17, 1976. *Honeycutt, R.C. & Garstka, T.A. (1976c) Comparative thin layer chromatography of metabolites of 2,4-dinitro-6-(2-octyl)phenyl crotonate in rat urine and feces and from cucumbers and squash. Rohm and Haas Technical Report No. 3423-76-32, September 1, 1976. *Hurwitch, J. & Hill, J.T. (1979) The effect of Karathane (Technical) on oxidative phosphorylation in canine hepatic liver mitrochondria. Final Report. Hazleton Laboratories America, Inc. Rohm and Haas Report No. 79RC-089, May 21, 1979. *Innes, J.R.M., Ulland, B.M., Valerio, M.G., Petrucelli, L., Fishbein, L., Hart, E.R. & Pallotta, A.J. (1969) Bioassay of pesticides and industrial chemicals for tumorigenicity in mice: A preliminary note. J. Nat. Cancer Inst., 42(6): 1101-1114. Technical Report: A.J. Pallotta and E. Ross Hart, Bionetics Res. Labs. Evaluation of carcinogenic, teratongenic and mutagenic activities of selected pesticides and industrial chemicals. National Cancer Institute Report No. NCI-DCCP-CG-1973-1-1, August 1968, appended. *Kruyzsse, A., Engel, C. (1974) Acute inhalation toxicity study in rats. Central Institute for Nutrition and Food Research. Rohm and Haas Report No. 74RC-1087, October, 1974. *Krzywicki, K.M. & Hazleton, G.A. (1985a) Karathane Technical: Acute oral LD50 toxicity study in male rats and mice. Rohm and Haas Report No. 85R-47, July 23, 1985. *Larson, P.S. (1956a) The effects of the continued application of Karathane Technical (30% in dimethylphthalate) to the skin of rabbits. Medical College of Virginia. Rohm and Haas Report No. 56RC-1013, October 10, 1956. *Larson, P.S. (1956b) One-year study on the effect of adding Karathane to the diet of dogs. Medical College of Virginia. Rohm and Haas Report No. 56RC-1012, June 25, 1956. *Larson, P.S. (1956c) Toxicologic studies on the effect of adding Karathane to the diet of rats for a two-year period. Medical College of Virginia. Rohm and Haas Report No. 56RC-1011, December 28, 1956. *Larson, P.S. (1957) Studies on the effect of Karathane on oxygen consumption in the rat. Rohm and Haas Report No. 57RC-1022, January 2, 1957. *Larson, P.S. (1958) Effect on cataract formation by adding Karathane and 2,4-dinitrophenol to the diet of ducks. Medical College of Virginia. Rohm and Haas Report No. 58RC-1017, February 13, 1958. *Larson, P.S., Finnegan, J.K., Smith, R.B. Jr., Haag, H.B., Hennigar, G.R., Patterson, W.M. (1959) Acute and chronic toxicity studies on 2,4-dinitro-6(1-methyl heptyl)phenyl crotonate (Karathene). Arch. Int. Pharmacodyn., 119(1-2): 31-42. *Larson, P.S. (1965) Preliminary study of the potential cataractogenic properties in ducks of Rohm and Haas compounds RH-23,003; RH-23570; RH-23051 and 2,4-dinitrophenol. Rohm and Haas Report No. 65RC-1054, Medical College of Virginia, December 16, 1965. *Larson, P.S. (1966) Toxicologic and potential cataractogenic properties in ducks of Rohm and Haas compounds RH-23,003; RH-23570; RH-23051 and 2,4-dinitrophenol. Rohm and Haas Report No. 66RC-1029, Medical College of Virginia, May 5, 1966. *Lohse, K.L. (1982a) Karathene Technical Microbial Test. Rohm and Haas Report No. 82R-96, July 29, 1982. *Lohse, K.L. & Byers, M.J. (1982b) Dinitrooctyl phenol Microbial Mutagen Test. Rohm and Haas Report No. 82R-270, December 10, 1982. *Maita, K., Tsuda, S., Saito, T. et al. (1980) Chronic toxicity study for 30 months with Karathane in rats. The Institute of Environmental Toxicology, Japan. Rohm and Haas Report No. 80RC-1004, March 12, 1980. *Mathason, H.B. & O'Hara, G.P. (1985) Karathene technical oculotoxicity study in rabbits. Rohm and Haas Report No. 81R-172, December 15, 1980. *Melly, J.G. & Scribner, H.E. (1981) Karathene Technical Microbial Mutagen Test. Rohm and Haas Report No. 81R-290, December 16, 1981. *Melly, J.G. (1982a) Karathane Technical Microbial Mutagen Test. Rohm and Haas Report No. 82R-73, August 18, 1982. *Melly, J.G. (1982b) Karathane Technical Microbial Mutagen Test. Rohm and Haas Report No. 82R-74, August 18, 1982. *Mlodecki, H., Fortak, W., Szadowska, A., Fraczek, S., Graczyk, J. & Wejman, I. (1975) Studies on the toxicity of Dinocap. Part I. Acute toxicity. Bromatol. Chem. Toksykol., 8(4): 373-386. *Mlodecki, H., Fortak, W. & Fraczek, S. (1976) Toxicity studies on Dinocap. Part II. Subacute toxicity. Bromatol. Chem. Toksykol., 9(3): 217-233. *Mlodecki, H., Fraczek, S. & Lukaszek, S. (1978) Toxicity studies on Dinocap. Part IV. Chronic toxicity in rat. Bromatol. Chem. Toksykol., 11(2): 111-127. *Moriya, M., Ohta, T., Watanabe, K., Miyazawa, T., Kato, K. & Shirasu, Y. (1983) Further mutagenicity studies on pesticides in bacterial reversion assay systems. Mutat. Res., 116(3-4): 185-216. *Morrison, R.D. & Hazleton, G.A. (1985b) Karathane Technical: Acute oral LD50 toxicity study in male rats. Rohm and Haas Report No. 85R-55, July 23, 1985. *Morrison, R.D. & Hazleton, G.A. (1985c) Karathane Technical: Acute oral LD50 toxicity study in male rats. Rohm and Haas Report No. 85R-37, June 25, 1985. *Morrison, R.D. & Hazleton, G.A. (1985d) Karathane Technical: Acute oral LD50 toxicity study in male rats. Rohm and Haas Report No. 85R-38, June 25, 1985. *Morrison, R.D. & Hazleton, G.A. (1985e) Karathane Technical: Acute oral LD50 toxicity study in male rats. Rohm and Haas Report No. 85R-54, July 23, 1985. *Morrison, R.D. & Hazleton, G.A. (1985f) Karathane Technical: Acute oral LD50 toxicity study in male rats. Rohm and Haas Report No. 85R-53, July 23, 1985. *Muller, G. & Byers, M.I. (1985) Karathene Technical. In vitro Unscheduled DNA synthesis assay. Rohm and Haas Report No. 85R-003, February 22, 1985. *Mulligan, T. (1976) Three generation reproduction study-rats. Hazleton Laboratories America, Inc. Rohm and Haas Report No. 76RC-1o64, July 1, 1976. *Ochynska, J., Bronisz, H. & Ochynska, J. (1975) Analytical and toxicological studies of dinocap. Part II. Acute toxicity of dinocap in rats. Med. Weter., 31(11): 647-677. *Ochynska, J. & Ochynska, J. (1985) Analytic and toxicologic studies on dinocap. Part III. Cumulative toxicity of dinocap. Bromotol. Chem. Toksykol., 17(1): 75-81. *Oledzka, R., Pastuszynska, J. (1981a) Role in bone metabolism of vitamin D3 and calcium as components of diets fed to rats intoxicated with dinocap. Bromotol. Chem. Toksykol., 14(3-4): 253-257. *Oledzka, R., Pastuszynska, J. (1981b) Alterations in bone metabolism in rats intoxicated with dinocap and treated with sodium fluoride in drinking water. Bromotol. Chem. Toksykol., 14(2): 141-147. *Oledzka, R. & Pawlak-Bieniek, J. (1974a) Influence of dinocap on calcium metabolism in relation to the composition of the diet. Bromotol. Chem. Toksykol., 8(2): 153-157, abstract only. *Oledzka, R. & Sikorski, S. (1974b) Intestinal transport and excretion of calcium in the course of intoxication with dinocap. Bromotol. Chem. Toksykol., 10(1): 49-55, abstract only. *Pilinskaya, A.I., Kurinnyi, T.S., L'vova, I.V. (1980) Primary evaluation of the cytogenetic activity and potential mutagenic risk of twenty-two pesticides. Tsitolgiya i Genetika, 14(6): 41-47. Rogers, J.M., Gray, L.E., Carver, B.D. & Kavlock, R.J. (1987) Developmental toxicity of dinocap in the mouse is not due to two isomers of the major active ingredients. Teratol. Carcinog. Mutagen., 7: 341-346. Rogers, J.M. (1987) Comparison of maternal and fetal toxic dose responses in mammals. Teratol. Carcinog. Mutagen., 7: 297-306. Rogers, J.M., Carver, B., Gray, L.E., Gray, J.A. & Kavlock, R.J. (1986) Teratogenic effects of the fungicide dinocap in the mouse. Teratol. Carcinog. Mutagen., 6: 375-381. Rogers, J.M., Barbee, B., Burkhead, L.M., Rishin, E.A., Kavlock, R.J. (1988) The mouse teratogen dinocap has lower A/D ratios and is not teratogen in the rat and hamster. Teratology, 6: 553-559. *Salmowa, J. Szygendowski, A. & Bielick, D. (1974) Effects of dinocap on protein and energy utilization in young rats. Bromotol. Chem. Toksykol., 7(4): 439-445, abstract only. *Sasaki, Y., Ushida, A. & Moriya, M. (1982). Karathane: Micro-nucleus test in mice. Japan Institute for Environmental Toxicology. Rohm and Haas Report No. 83RC-16, December 1982. *Shirasu, Y., Moriya, M. & Sugiyama, F. (1979) Mutagenicity study of Karathane in bacteria. Institute for Environmental Toxicology, Japan. Rohm and Haas Report No. 79RC-1004, April 2, 1979. *Shirasu, Y., Moriya, M., Kato, K., Furuhashi, A. & Kada, T. (1976) Mutagenicity screening of pesticides in the microbial system. Mutat. Res., 40: 19-30. *Shirasu, Y., Ebihara, K., Saito, T. (1980a) Karathane acute oral toxicity study in rats. Institute for Environmental Toxicology, Japan. 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See Also: Toxicological Abbreviations Dinocap (FAO/PL:1969/M/17/1) Dinocap (WHO Pesticide Residues Series 4) Dinocap (JMPR Evaluations 1998 Part II Toxicological)