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EC number: 202-476-7
CAS number: 96-09-3
Styrene oxide is known to be a genotoxic carcinogen; therefore
testing on toxicity to reproduction has not to be performed according to
REACH-VO Annex VIII 8.7.1 column 2 and Annex IX 8.7 column 2. Moreover,
a relevant exposure to humans is excluded by handling styrene oxide
exclusively under strictly controlled conditions according to Annex XI,
From available data there was no evidence for a teratogenic effect in rats or rabbits exposed to styrene oxide up to the lethal dose.
In order to fulfil completeness requirements, studies on
reproductive toxicity need not to be conducted; however available data
should be reported. The only available study on reproductive toxicity of
styrene oxide in mammals has been published by Sikov et al. 1986.
This study is summarised in the IARC 1994 report as follows:
Only one study of the reproductive toxicity of styene-7,8-oxide in
mammals has been published (Sikov et al. 1986). Six groups of at least
31 Wistar rats were exposed by inhalation (whole body) to 100 ppm (490
mg/m3) or 300 ppm (1470 mg/m3) styene-7,8-oxide
(purity, 99%) vapour for 7 h per day either during a three-week (five
days/week) pre-gestational period, during a three-week (five days/week)
pre-gestational period and through days 1-19 of gestation, or on
gestational days 1-19 only. A control group was exposed to air during
the whole period. Fetuses were examined on day 21. There was extensive
mortality among rats that received prolonged exposure to 100 ppm;
exposure to 300 ppm was discontinued after one day because of mortality.
Maternal weight gain was reduced in all groups receiving 100 ppm.
Exposure only prior to mating had no effect on mating or fertility.
Gestational exposure decreased the number of animals pregnant at term by
increasing pre-implantation loss of embryos; fetal weights and lengths
were reduced, and the incidences of retarded ossification of the
sternebrae and occipital bones were increased.
In the same study, groups of 23-24 New Zealand white rabbits were
exposed by inhalation to 0, 15 or 50 ppm (74 or 245 mg/m3)
(measured concentrations, 14.6 and 51 ppm) styene-7,8-oxide (purity, 99
%) vapour for 7 h per day on days 1-24 of gestation. Fetuses were
examined on day 30. Maternal toxicity was observed at the highest dose
only, resulting in increased mortality (19/24 versus 1/23 in controls
and 4/24 at 15 ppm) and decreased food consumption and weight gain.
There was no effect on the proportion pregnant at term, i.e. there was
no marked pre-implantation loss, but there was an increase in
post-implantation loss, with 0.25, 0.93 and 1.5 resorptions per litter
in the control, low- and high-dose groups, respectively.
There was no effect on fetal weight, and no increase in the
incidence of malformations was observed in either rats or rabbits.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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