Toxicity and metabolism of copper pyrithione and its degradation product, 2,2′-dipyridyldisulfide in a marine polychaete

Abstract

We conducted acute toxicity tests and sediment toxicity tests for copper pyrithione (CuPT) and a metal pyrithione degradation product, 2,2′-dipyridyldisulfide [(PS) 2], using a marine polychaete Perinereis nuntia. The acute toxicity tests yielded 14-d LC 50 concentrations for CuPT and (PS) 2 of 0.06 mg L −1 and 7.9 mg L −1, respectively. Sediment toxicity tests resulted in 14-d LC 50 concentrations for CuPT and (PS) 2 of 1.1 mg kg −1 dry wt. and 14 mg kg −1 dry wt., respectively. In addition to mortality, sediment avoidance behavior and decreases in animal growth rate were observed; growth rate was the most susceptible endpoint in the sediment toxicity tests of both toxicants. Thus, we propose lowest observed effect concentrations of 0.3 mg kg −1 dry wt. and 0.2 mg kg −1 dry wt. for CuPT and (PS) 2, respectively, and no observed effect concentrations of 0.1 mg kg −1 dry wt. for both CuPT and (PS) 2. The difference in the toxicity values between CuPT and (PS) 2 observed in the acute toxicity test was greater than the difference in these values in the sediment toxicity test, and we attribute this to (PS) 2 being more hydrophilic than CuPT. In addition to the toxicity tests, we analyzed conjugation activity of several polychaete enzymes to the toxicants and marked activity of palmitoyl coenzyme-A:biocides acyltransferase and UDP-glucuronosyl transferase was observed.