DNA DOSIMETRY IN BIOLOGICAL INDICATOR SPECIES LIVING ON PAH-CONTAMINATED SOILS AND SEDIMENTS

A large variety of environmental carcinogens are metabolically activat ed to electrophilic metabolites that can bind to nucleic acids, formin g covalent adducts. In organisms possessing active metabolic systems f or a particular carcinogen, DNA adducts generally have longer biologic al half-lives than the substrate carcinogens. Thus, measurement of spe cific DNA adduct concentrations in terrestrial and water organisms may provide a relevant biological indicator of prior exposure to environm ental carcinogens. Analysis of carcinogen load in indicator species wi th specific behavioral patterns may indicate human exposure risk to en vironmental carcinogens. Recently, sensitive assays have been develope d to measure carcinogen-DNA adducts in organisms exposed to complex mi xtures such as polycyclic aromatic hydrocarbons (PAH). At first instan ce, the nuclease P1 version of the P-32-postlabeling assay was used to examine the liver of eel (Anguilla anguilla) for the presence of arom atic DNA adducts. The fish were collected from six freshwater sites in the Amsterdam area with different levels of PAH contamination in thei r sediments. Chromatograms derived from DNA of fish from polluted site s revealed a broad diagonal zone indicating the presence of DNA adduct s containing aromatic or bulky hydrophobic moieties not present in DNA of fish from an unpolluted reference site. Significant correlations w ere found between the aromatic DNA adducts levels and the levels of PA H in sediments (P < 0.001). To examine the validity of DNA adduct dosi metry in terrestrial organisms earthworms (Lumbricus terrestris) were kept on industrially contaminated PAH soils for several weeks. Several aromatic DNA adducts could be detected in DNA from the exposed earthw orms; adduct levels were significantly increased with increasing expos ure time. These findings suggest that the amount of DNA adducts in eel and earthworm may be a suitable and sensitive indicator for the expos ure to carcinogenic PAH from contaminated sediments or soils, respecti vely, and therefore useful in human exposure risk assessment. (C) 1995 Academic Press, Inc.