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EC number: 203-733-6
CAS number: 110-05-4
In groups 2, 3, and 4, the mean number of
corpora lutea was considered to be not influenced by treatment with the
test item. In groups 1, 2, 3, and 4, the mean number of corpora lutea
was 13.8, 13.9, 14.6, and 14.7, respectively.
In groups 2, 3, and 4, the implantation rate
and the post implantation loss were considered to be not influenced by
treatment with the test item. In groups 1, 2, 3, and 4, the mean
implantation rate was 12.2, 13.0, 14.1, and 13.7, respectively. In
groups 1, 2, 3, and 4, the total post implantation loss was 12, 16, 12,
and 10, in 8, 9, 5, and 6 litters, respectively. These data correspond
to 9.8%, 12.3%, 8.5%, and 8.1% of implantations.
In groups 2, 3, and 4, the number of living
pups at first litter check, were considered to be not influenced by
treatment with the test item. In groups 1, 2, 3, and 4, the mean number
of living pups was 11.0, 11.4, 12.9, and 12.6, respectively. One, 1, and
2 dead pups were noted in 1, 1, and 2 litters of groups 2, 3, and 4,
In groups 2, 3, and 4, the postnatal loss
was considered to be not influenced by treatment with the test item. In
groups 1, 2, 3, and 4, the postnatal loss was 2, 1, 1, and 3 dead pups
noted in 2, 1, 1, and 3 litters, respectively. These data correspond to
1.8%, 0.9%, 0.8%, and 2.7% of dead pups during the postnatal period.
At first litter check, no test item-related
findings were noted. Female pup no. 14 in litter 46 (group 1) was noted
with a missing tail and an anal atresia. It was killed for ethical
reasons on day 1 post partum. Female pup no. 14 in litter 77 (group 4)
was noted with a missing tail. It was necropsied as scheduled.
Sex ratios were considered to be not
influenced by treatment with the test item. Sex ratios (% male/% female)
were 49 / 51, 48 / 52, 43 / 57, and 48 / 52 in groups 1, 2, 3, and 4,
respectively, at first litter check.
The mean body weight of pups up to day 4
post partum was considered to be not influenced by treatment with the
test item. Compared with the other groups’ values, slightly higher pup
body weights were noted for male and female pups in group 4 that were
considered to reflect the normal biological variability.
At scheduled necropsy, no test item-related
findings were noted.
The purpose of this study was to generate
preliminary information concerning the effects of Di-tert-butyl peroxide
on the possible health hazards likely to arise from repeated exposure
over a relatively limited period of time. In addition, information on
possible effects on male and female reproductive performance such as
gonadal function, mating behavior, conception, development of the
conceptus and parturition was provided.
Di-tert-butyl peroxide was administered once
daily orally (by gavage) at dosages of 0, 100, 300, and 1000 mg/kg/day,
to male rats for 42 days in total and to female rats throughout the
prepairing, the pairing, the gestation and the lactation periods until
day 4 post partum (last dosing).
Treatment at 1000 mg/kg was associated with
body weight effects in male animals. Food consumption was decreased in
male animals during the study. A sign of discomfort was noted in all
animals at 1000 mg/kg/day in the way that the animals moved their heads
through the bedding material after the daily administration of test
item. Some male and female animals were noted with ruffled fur.
Treatment at 1000 mg/kg/day and 300
mg/kg/day was associated with increased liver and kidney weights.
Histopathological effects were noted in liver (minimal centrilobular and
diffuse hepatocellular hypertrophy with association of a consequent
increase in diffuse follicular cell hypertrophy in thyroid glands in
males and females at 1000 mg/kg/day), kidneys (moderate diffuse tubular
degeneration/regeneration with slight multifocal single cell necrosis
and hyaline casts as well as hyaline droplets in males at 1000
mg/kg/day), and fore stomach (minimally increased incidence and severity
of diffuse hyperkeratosis in males at 1000 mg/kg/day and
females at 1000 mg/kg/day and 300
Behavioral effects were considered to be not
influenced by the treatment with the test item. No effects were noted on
reproduction data, for the parameters during the clinical laboratory
investigations, or for macroscopic findings during necropsy.
The histopathological evaluation of the
reproductive organs did not reveal any relevant changes in high-dose
animals. Especially the emphasis on stages of spermatogenesis and
histopathology of interstitial testicular cell structure did not reveal
any differences between control (group 1) and high-dose (group 4) males.
Except female no. 79 in group 4, all mated
females were pregnant. In groups 2, 3, and 4, mating performance was
considered to be not influenced by treatment with the test item. The
fertility index was 100.0, 100.0, 100.0, and 90.0% in groups 1, 2, 3,
and 4, respectively. In groups 2, 3, and 4, the pre-implantation loss,
the implantation rate, the post implantation loss, the number of living
pups at first litter check, the post natal loss, and the gestation
length, respectively, were considered to be not influenced by treatment
with the test item.
Based on these data, it can be concluded
that the parental No Observed Effect Level (NOEL) was at 100 mg/kg body
weight/day and 1000 mg/kg/day for reproductive and developmental effects.
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