Monitoring river sediments contaminated predominantly with polyaromatic hydrocarbons by chemical and in vitro bioassay techniques

Extracts of sediment samples collected from the Morava River and its tribut aries (Czech Republic) were examined for mutagenic, dioxin-like, and estrog enic activities. Moreover, the human leukemic HL-60 cell line was tested as a potential model for the detection of effects of environmental contaminan ts on cell proliferation and differentiation processes. Analytical data ind icate that the sediments were contaminated predominantly with polycyclic ar omatic hydrocarbons (PAHs) and phthalate esters. The sums of concentrations of 16 U.S. Environmental Protection Agency priority PAHs ranged from 0.8 t o 13.2 mug/g and those of phthalates reached up to 3,000 ng/g, while only l ow levels of chlorinated hydrocarbons were found. The main goal of the pres ent study was to determine effects of PAH prevalence on in vitro bioassays, with special emphasis on dioxin-like activity. The dioxin like activity wa s tested using a reporter gene assay based on chemical-activated luciferase expression (the CALUX assay). Significant dioxin-like activity (2.6-40.1 m ug/g benzo[a]pyrene equivalents and 5.9-48.2 ng/g 2,3,7,8-tetrachlorodibenz o-p-dioxin equivalents) was detected in all samples. and the results obtain ed with various exposure times or with both crude and PAM-deprived extracts indicate that the response was probably caused almost exclusively by the p resence of high concentrations of PAHs. This corresponds with results of ch emical analyses and indicates that various exposure rimes would allow a dis crimination between dioxin-like activities of persistent compounds and easi ly metabolized aryl hydrocarbon (Ah) receptor inducers. Only sediment extra cts containing the highest concentrations of PAHs were mutagenic, as determ ined by the umu assay. Estrogenic activity was found in several samples (4. 75-22.61 pg/g estradiol equivalents) using cells stably transfected with an estrogen-responsive element linked to a luciferase promoter. Noncytotoxic doses of extracts had no effects on HL-60 cell proliferation, while two of the rested crude extracts significantly enhanced their all-trans retinoic a cid-induced differentiation. These activities were not associated with phth alate esters and/or PAHs. Our results indicate that cellular and biochemica l in vitro assays based on various specific modes of action may yield data complementary to results of mutagenicity tests and that they could be usefu l in environmental risk assessment. High levels of PAHs are apparently asso ciated with dioxin-like and mutagenic activities rather than with estrogeni c activity.