Comparative toxicity of acrylic acid to marine and freshwater microalgae and the significance for environmental effects assessments

In this study, we compared the sensitivity of freshwater and marine organis ms to two structurally similar substances, acrylic acid and methacrylic, ac id. Reported acute toxicity data (L(E)C-50-values) for freshwater organisms range from 0.1 to 222 mg/l and 85 to > 130 mg/l for acrylic acid and metha crylic acid, respectively. The large variation in toxicity data for acrylic acid is due to a specific toxicity to certain species of freshwater microa lgae, with algae EC50-values being two to three orders of magnitude lower t han L(E)C-50-values reported for fish and invertebrates. To evaluate the se nsitivity of marine organisms, ecotoxicity data was generated for ten speci es of microalgae, one invertebrate species and one fish species. For methac rylic acid, we found a marine acute toxicity that ranged from 110 to > 1260 mg/l, which is comparable to reported data on freshwater organisms. In str ong contrast, the resulting L(E)C-50-values for acrylic acid ranged from 50 to > 1000 mg/l, and there was no specific sensitivity of marine algae when compared to marine invertebrates and fish. For acrylic acid, therefore, us e of the available freshwater toxicity data for an effects assessment for t he marine environment is likely to overestimate the hazard and risk from th is substance. Overall, the results of the study suggest that ecotoxicity da ta generated on freshwater species may not always be appropriate for the ef fects assessments of organic chemicals in the marine environment, thus emph asising the importance of using ecologically relevant data to assess enviro nmental risk. (C) 2001 Elsevier Science Ltd. All rights reserved.