Dose-response and Kinetics of the Formation of DNA Adducts in the Earthworm Eisenia Fetida Andrei Exposed to B(A)P-contaminated Artificial Soil

Abstract

Earthworms, Eisenia fetida andrei (E. f. a.), were exposed to soils contaminated with increasing concentrations of benzo(a)pyrene for different periods of time to investigate: the possible metabolism pathways of B(a)P; the toxicological significance of DNA adduct formation in the worm; and the suitability of the ³²P-postlabelling method as a bioassay for chemical toxicity testing and for surveys of soil contamination.

Our results indicate that B(a)P could be metabolized via either cytochrome P-450 dependent activities or free radical oxidation. For short-term exposures, the level of DNA adducts formed was dose-dependent and could thus be considered toxicologically significant. At the highest doses, the formation of DNA adducts reached a steady state. Moreover, the ³²P-postlabelling method is particularly sensitive, as DNA adducts was significant upon exposure to just 50 μg B(a)P/kg artificial soil. In conclusion, the method used and the species, E. f. a., are potential tools in chemicals or contaminated soils genotoxicity evaluation. However, some technical improvement are needed to validate this method.

Key Words:

• Earthworm
• Eisenia fetida
• Genotoxicity
• Benzo(a)pyrene
• DNA adducts
• Polycyclic aromatic hydrocarbons