hexachlorobutadiene - Davidborowski.com

HEXACHLOROBUTADIENE 31
2. HEALTH EFFECTS
from dams exposed to hexachlorobutadiene at dose levels of 20 mg/kg/day throughout gestation and
lactation; body weights were not reduced in pups from dams exposed to 2 mg/kg/day. No other signs
of fetotoxicity were evident at doses up to 20 mg/kg/day. Teratogenic effects were not observed nor
was hexachlorobutadiene embryotoxic at the doses tested (Schwetz et al. 1977).
The highest NOAEL values and all LOAEL values from each reliable study for developmental effects
in each species and duration category are recorded in Table 2-2 and plotted in Figure 2-2.
2.2.2.7 Genotoxic Effects
No studies were located regarding genotoxic effects in humans after oral exposure to
hexachlorobutadiene.
In animals, there is some evidence that hexachlorobutadiene interacts with genetic material. Male rats
administered a single gavage dose of hexachlorobutadiene (20 mg/kg/day) showed a 40% increase in
renal deoxyribonucleic acid (DNA) repair and 0.78 alkylations per million nucleotides (Stott et al.
1981). On the other hand, when hexachlorobutadiene was administered in the diet, it did not cause
chromosomal aberrations in rat bone marrow cells (Schwetz et al. 1977).
Other genotoxicity studies are discussed in Section 2.4.
2.2.2.8 Cancer
No studies were located regarding carcinogenic effects in humans after oral exposure to
hexachlorobutadiene.
Studies in rats reported renal tubular adenomas and adenocarcinomas in male and female animals at
doses of 20 mg/kg/day (Kociba et al. 1977a). Metastasis to the lungs was observed. Combined
incidences of renal tubular neoplasms in males (9/39, 23 %) and in females (6/40, 15 %) increased
(p < 0.05) over controls (males-l/90, females-0/90, 0%). The tumor incidence was not increased in
the 0.2 and 2 mg/kg/day dose groups but there were some indications of hyperplasia in animals
exposed to 2 mg/kg/day. The EPA (1990f) evaluated these data and calculated a human potency
factor of 7.8x10 -2 (mg/kg/day) -1 (q1*), representing a 95% upper confidence limit of extra lifetime