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EC number: 200-521-5
CAS number: 61-82-5
See 'Attached background material' for tables of results.
a teratogenicity study, test substance was daily administered by gavage
at dose levels of 0, 100, 500, or 1000 mg /kg bw/day in deionized water
to female CD®
rats on gestational days (gd) 6 to 15.
out of 38 plug-positive females per group were employed for the
teratology sacrifice portion. The remaining 14 plug-positive females per
group were employed for the postnatal sacrifice portion.
observations were taken daily and maternal body weights were taken on
all study females on GD 0, 6, 12, 15 and 18. Food consumption was also
mesured on all females for the intervals GD 0-3, 3-6, 6-9, 9-12, 12-15,
15-18 and 18-21. At scheduled teratology necropsy on gd 21, the
approriate dams were evaluated for body weight, liver and thyroid
weight, gravid uterine weight and status of implantation sites. Live
fetuses were dissected from the uterus, counted, weighed, sexed and
examinated for external abnormalities. Approximately one-half of the
live fetuses in each litter were examined for visceral malformations.
The fetuses were decapitated and the heads were examined for soft tissue
craniofacial malformations. The remaining fetuses in eac litter were
eviscerated and examined for skeletal defects and deficits.
females from the postnatal portion were allowed to litter. These dams
and their litters were weighed and examined on postnatal day 0, 4, 7, 14
and 21; food consumption was mesured for the intervals postnatal days
0-4, 4-7, 7-10 and 10-14. Each litter was culled to eight pups on
postnatal day 4 and sacrificed after all observations on postnatal day
21. At postnatal sacrifice maternal thyroids were weighed.
There were no treatment-related
maternal deaths. Slight maternal toxicity was indicated by reduced
weight gain for GD 6 -18 at 1000 mg/kg bw/day but not prior to or
subsequent to this period, and reduced food consumption for gd 12 -15,
15 -18 and gd 15 -21 at 500 and 1000 mg/kg bw/day. There were no
differences among groups for gestation or lactation maternal body
weights or for lactational weight gain or food consumption. No
treatment-related clinical signs were observed. At the gd 21 sacrifice
there were no effects of treatment on maternal body weight, gravid
uterine weight, or on absolute or relative liver weight. Maternal
thyroid weight was increased at 500 and 1000 mg/kg bw/day. Reproductive
parameters, including ovarian corpora lutea of pregnancy, total, viable
and nonviable implantations per litter and sex ratio were unaffected by
treatment. Fetal body weight per litter was reduced at 1000 mg/kg
There was no significant increase
in the incidence of malformations in any treated group relative to
controls and no differences among groups for pooled external, visceral,
skeletal or total variations. At 1000 mg/kg bw/day there were seven
variations with incidences different from that of controls, including
dark fetal thyroids and indications of reduced ossification. Enlarged
and/or dark fetal thyroids also exhibited an increased incidence at 500
and 1000 mg/kg bw/day relative to that in controls.
Postnatal observations indicated
no differences among groups for any pup parameters at any time points
evaluated, including litter sizes, sex ratio, pup weights per litter or
survival indices. Maternal thyroid weights were still increased at 500
and 1000 mg/kg bw/day at postnatal sacrifice.
Under the test condition,
administration of test material by gavage to CD® rats during
organogenesis resulted in evidence of maternal and fetotoxicity toxicity
at 500 and 1000 mg/kg bw/day. Postnatal evaluations indicated all
observed maternal and perinatal effects were transient except for
enlarged maternal thyroids. No teratogenicity was observed at any dose
Therefore, the NOAEL for maternal
and developmental toxicity is considered to be 100 mg/kg bw/day and the
classification of the substance as STOT-RE 2 (H373: May cause damage to
organs through prolonged or repeated exposure) for thyroid according to
the Regulation (EC) No. 1272/2008 (CLP) is confirmed.
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