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
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
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
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,
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
Skin sensitization and irritation studies have been conducted
in humans (see Human Observations below).
TABLE 1. ACUTE TOXICITY STUDIES ON DINOCAP
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.
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.
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).
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
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,
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).
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
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.
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
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).
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
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
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
Ames test S. typhimurium Positive Shirasu, 1979, 1982
Ames test S. typhimurium Positive Moriya et al. 1983
Ames test S. typhimurium Positive Melly et al. 1981
Ames test S. typhimurium Negative Melly, 1982a
Ames test S. typhimurium Negative Lohse, 1982b
Ames test S. typhimurium Negative Byers, 1982
Ames test S. typhimurium Positive Higganbotham et al.
TABLE 2 (CONTD).
TEST SYSTEM TEST OBJECT RESULTS REFERENCE
Ames test S. typhimurium Negative Higganbotham, 1985
Reverse E. coli Negative Shirasu, 1979, 1982
mutation WP2 hcr
Reverse Saccharomyces Positive Guerzoni, 1976
Mouse lymphoma L5178Y Negative Cifone, 1981
Micronucleus Mouse bone Negative Sasaki et al. 1982
Cytogenetic Mouse Negative Pilinskaya et al.
DNA damage B. subtilis Negative Shirasu, 1979
Unscheduled Hepatocytes Negative Muller & Byers, 1985
DNA synthesis from Fischer
Special studies on teratogenicity
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.
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.
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
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.
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
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
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
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).
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
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
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.
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
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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
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*Costlow, R.D. & Kane, W.W. (1984b) Teratology study with Karathane
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Costlow, R.D., Kane, W.W. & Black, D.L. (1984c) Range-finding study
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*DeCrescente, M.E. (1984a) Definitive mouse oral LD50. Rohm and
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*Honeycutt, R.C. & Garstka, T.A. (1976a) Rat feeding and metabolism
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Karathane and 2,4-dinitrophenol to the diet of ducks. Medical
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Hennigar, G.R., Patterson, W.M. (1959) Acute and chronic toxicity
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*Larson, P.S. (1965) Preliminary study of the potential
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*Larson, P.S. (1966) Toxicologic and potential cataractogenic
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*Lohse, K.L. (1982a) Karathene Technical Microbial Test. Rohm and
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*Lohse, K.L. & Byers, M.J. (1982b) Dinitrooctyl phenol Microbial
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