Appendix D - Dossier (PDF) - Tera

date: 20–JUL–2005
5. Toxicity Substance ID: 71–43–2
______________________________________________________________________________
Species: mouse Sex: female
Strain: Swiss Webster
Route of administration: inhalation
Exposure period: gestation days 6–15
Frequency of treatment: daily/6 hours per day
Duration of test: The study was performed to investigate predominantly
effects on the developing hematopoietic system
consequently to prenatal benzene exposure. Thus,
duration of the test is related to the different time
points of investigations of offspring
Doses: 5, 10, 20 ppm (converts to 0.017, 0.033, 0.066 mg/l);
5–10 mice/dose
Control Group: yes, concurrent vehicle
Method: other
GLP: no data
Test substance: other TS: glass distilled benzene of chromatographic quality
Remark: Benzene chamber concentration measured by infrared analyser.
Control group consisted of five to ten females exposed to
filtered conditioned air.
Exposed pregnant mice were either sacrificed, their uteri
removed and the number of live, dead
and resorbed foetuses recorded or were allowed to proceed
through normal parturition and their offspring subjected to
further investigations.
At sacrifice on gestation day 16 two male and two female
foetuses/litter were weighed and examined for any external
gross morphological malformations and fetal livers were
removed for enumeration of haematopoietic colony forming
cells.
Offspring at 2 days of age: two male and two female
neonates/litter were selected, weighed and examined for any
external gross morphological malformations. Their livers
were removed for enumeration of hematopoietic colony forming
cells.
Offspring at 6 weeks of age: one male and one female were
selected from each litter, sacrificed and their spleens and
femurs removed for enumeration of hematopoietic colony
forming cells.
Offspring at 12 weeks of age: offspring exposed in utero to
10 ppm had been re–exposed to 10 ppm benzene at 10 weeks of
age for a total of two weeks. At the age of 12 weeks these
animals (numbers unspecified) were sacrificed and their
spleens and femurs removed for enumeration of hematopoietic
colony forming cells.
Result: It is reported from the study that for all exposure
concentrations of benzene employed, litter sizes and weights
as well as the numbers of dead, resorbed and malformed
foetuses were within the control limits.
Appendix D: Benzene SIDS Dossier
In foetuses at day 16 of gestation, changes in the numbers
of both erythroid precursor cells (i.e. colony forming
– 585/957 –