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EC number: 237-438-9
CAS number: 13784-51-5
Thyroid hormone analysis
Text table 1 Mean serumTSH
concentrations (pg/mL) on Day 20 of gestation
Acetylacetone Peroxide (13784-51-5)
*** p< 0.001
Triiodothyronine (T3) and Thyroxine
Text table 2 Mean serum T3
Text table 3 Mean serum T4
The purpose of this study was to
assess the influence of Acetylacetone Peroxide (13784‑51‑5), a substance
used in industry, on embryo-fetal survival and development when
administered orally, by gavage, to Han Wistar rats during the
organogenesis and fetal growth phases of pregnancy. Three groups, each
comprising 20 females received the test item at doses of 50, 150 or
500 mg/kg/day at a volume dose of 10 mL/kg, from, from Day 6 to 19 after
mating and a similarly constituted Control group received the vehicle
(purified water) at the same dose volume. Animals were killed on Day 20
after mating for reproductive assessment and fetal examination.
adult, clinical observations, body weight, food consumption, organ
weights, thyroid hormones, macropathology and histopathology
investigations were undertaken. The
fetuses were examined macroscopically, the ano‑genital distance was
measured and all fetuses underwent a detailed internal visceral or
There were no clinical signs and no
signs associated with administration.
Overall body weight, gravid uterine
weight and gravid uterine adjusted body weight gain and food consumption
were unaffected by treatment.
There were no macroscopic findings in
the adult related to treatment.
Adult serum thyroid stimulating
hormone concentrations were high at 150 or 500 mg/kg/day and serum
thyroxine concentrations were low at 500 mg/kg/day. Serum
triiodothyronine concentrations were unaffected by treatment.
Thyroid weight was unaffected by
treatment and there was no pathological change in the thyroid gland. The
reduction in adult serum T4 levels at 500 mg/kg/day, together with the
clear increase in serum TSH levels suggests a minor perturbation of
thyroid function that did not result in any detectable microscopic
changes in the thyroid glands. The slight increase in serum TSH at
150 mg/kg/day did not attain statistical significance and occurred in
isolation with no supporting findings and is of uncertain biological
significance and relationship to treatment. In a 90 -day study no
effects on T4, T3 or TSH where observed.
Implantation, resorption, pre- and
post-implantation losses and the number of live young and the ratio of
male to female fetuses and placental weight were unaffected by treatment.
At 500 mg/kg/day, fetal weight was 89%
of Control,and there was an increased incidence of
unossified/incompletely ossified sternebrae and a decreased incidence of
ossified cervical vertebral centra: these findings were considered to
represent a retardation in fetal development associated with the
retarded fetal growth. The overall pattern of skeletal ossification is
consistent with a generalized delay. Generalized delays have a common
“fingerprint”, characterized by reduced ossification of bones that
normally exhibit rapid ossification during the last few days of
gestation, such as the phalanges, sternebrae (especially numbers 5 and
6), calvarium and the cervical, thoracic, sacral and caudal vertebral
centra (Carney and Kimmel 2007). There are no indications of a
deviations from the normal pattern of development, normal cartilage is
present. These minor skeletal variants are related to decreased fetal
body weight and of low significance and are therefore considered
Fetal ano-genital distancewas
unaffected by treatment.
Based on the results of this study, the
maternal NOAEL is 500 mg/kg/day.
In the range finding study when
compared with control, overall food consumption was low in females
receiving 500 or 1000 mg/kg/day and slightly correlated with the low
body weight gain observed in these animals. Overall
body weight gain (Days 6-20) was slightly low in females receiving 250
mg/kg/day and was low at 500 or 1000 mg/kg/day. Total
litter weight and overall fetal weight (both males and females) were low
at 250, 500 or 1000 mg/kg/day (83 and 93%, 76 and 88% or 67 and 79% of
Overall fetal weight (male and female) at
500 mg/kg/day was marginally, but statistically significantly low (89%
of Control), in the absence of any reduction in maternal body weight
gain/food consumption. Overall fetal weights at 50 or 150 mg/kg bw/day
were unaffected by treatment. The developmental NOAEL is 150 mg/kg/day.
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