Toxicokinetics - trdoer40164

Toxicokinetics

Some benzo(a)anthracene metabolites have been shown to induce mutations,

cell transformation, and to bind to nucleic acids. The metabolites of

benzo(a)anthracene are mutagenic and tumorigenic (IARC 1983).

Nucleic acid (DNA) adducts are formed in the skin from the metabolites 3,4-

diol-1,2-epoxide and 8,9-diol-10,11-epoxide (IARC 1983). No information is

available regarding dermal or oral absorption coefficient, although

benzo(a)anthracene was reported to be readily transported across the

gastrointestinal mucosa (USEPA 1984).

Benzo(a)anthracene induced benzo(a)pyrene hydroxylase in rat placenta

(IARC 1983).

Ecological effects

The reader is requested to review the toxicity profile for PAHs for

information regarding ecological effects.

Hinga et al. (1980) examined the biogeochemistry of C-14 labeled

benzo(a)anthracene in an enclosed marine ecosystem. The experiment was

conducted for 230 days. At the end of the experiment, 29 percent of the chemical

had been respired to CO2, while the remaining extractable activity (43 percent)

was evenly divided between parent compound and intermediate metabolic

products. Total C-14 activity was removed from the water with a half-life of

about 52 hr, while the C-14 parent compound had a half-life of 24 hr. The

chemical became associated with the sediments and was mixed deeper into the

sediments by benthic animal activity. The authors made a rough calculation of

the half-life in sediments and noted stated that half-lives on the order of 1.2 to

3 years may be calculated. They further point out, however, that the occurrence

of benzo(a)anthracene at some depth in natural sediments suggests that a fraction

of the compound and perhaps some of its metabolites may persist indefinitely.

References

Bingham, E., and Falk, H. L. (1969). "Environment carcinogens, The modifying

effect of carcinogens on the threshold response," Arch. Environ. Health 19,

779-783.

Hinga, K. R., Pilson, M., Lee, R. F., Farrington, J. W., Tjessem, K. and Davis,

A. C. (1980). "Biogeochemistry of benzoanthracene in an enclosed marine

ecosystem," Envir. Sci. & Tech. 14, 1136-1143.

Integrated Risk Information System (IRIS) on-line database. (1992).

International Agency for Research on Cancer (IARC). (1973). "Certain

monographs on the evaluation of carcinogenic risk to humans." Polycyclic

aromatic hydrocarbons and heterocyclic compounds. Vol 3. World Health

Organization, Lyon, France.

D12

Appendix D Toxicological Profiles