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Effects of N‐heterocyclic polyaromatic hydrocarbons on survival, reproduction, and biochemical parameters in Daphnia magna

N‐heterocyclic polycyclic aromatic hydrocarbons (N‐PAHs) belong among newly identified classes of environmental pollutants with relatively high toxic potential. N‐PAHs have been detected in air, soil, marine environments, and freshwater sediments. The N‐PAHs are present at lower concentrations than their nonsubstituted analogues but their greater solubility would lead to greater bioavailibity and potential for toxic effects. Here we present results of acute and chronic toxicity in traditional aquatic invertebrate ecotoxicological model (Daphnia magna) along with assessment of biochemical responses. Studied biomarkers in D. magna exposed to N‐heterocyclic derivatives included glutathione levels and activities of detoxication and antioxidative enzymes glutathione S‐transferase and glutathione peroxidase. Phenanthrene and 1,10‐phenathroline were the most toxic of all tested compounds (EC50 < 6 μM after 48 h exposure) and all tested N‐PAHs suppressed reproduction of Daphnia magna. The data suggest that N‐PAHs can induce oxidative stress in D. magna. The significant decline of glutathione content was found in animals treated with acridine, 1,10‐phenanthroline, benzo(h)quinoline, phenantridine, and phenazine. Significant decrease of GPx activities relative to controls was found for all tested compounds except of phenanthrene and phenazine. Activities of GST increased after exposure to phenanthridine, phenazine, and benzo(h)quinoline, and declined in D. magna treated with phenanthrene (significant at one concentration) or anthracene (not significant). Our results confirmed significant acute as well as chronic toxicities of N‐PAHs as well as potential of biochemical parameters to be used as early warning signals of toxicity in Daphnia magna. © 2006 Wiley Periodicals, Inc. Environ Toxicol 21: 425–431, 2006.