A large variety of environmental carcinogens are metabolically activated to electrophilic metabolites that can bind to nucleic acids, forming covalent adducts. In organisms possessing active metabolic systems for a particular carcinogen, DNA adducts generally have longer biological half-lives than the substrate carcinogens. Thus, measurement of specific DNA adduct concentrations in terrestrial and water organisms may provide a relevant biological indicator of prior exposure to environmental carcinogens. Analysis of carcinogen load in indicator species with specific behavioral patterns may indicate human exposure risk to environmental carcinogens. Recently, sensitive assays have been developed to measure carcinogen-DNA adducts in organisms exposed to complex mixtures such as polycyclic aromatic hydrocarbons (PAH). At first instance, the nuclease P1 version of the 32P-postlabeling assay was used to examine the liver of eel (Anguilla anguilla) for the presence of aromatic DNA adducts. The fish were collected from six freshwater sites in the Amsterdam area with different levels of PAH contamination in their sediments. Chromatograms derived from DNA of fish from polluted sites revealed a broad diagonal zone indicating the presence of DNA adducts containing aromatic or bulky hydrophobic moieties not present in DNA of fish from an unpolluted reference site. Significant correlations were found between the aromatic DNA adducts levels and the levels of PAH in sediments (P < 0.001). To examine the validity of DNA adduct dosimetry 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 earthworms; adduct levels were significantly increased with increasing exposure time.(ABSTRACT TRUNCATED AT 250 WORDS)