Acute and Chronic Toxicity to Daphnia magna of Diuron and Capsaicin Used in Antifouling Paints

Diuron is a biocidal active substance commonly and typically used in antifouling paints, and capsaicin is a new-type of natural products used for antifouling paints. To evaluate acute and chronic toxicity of diuron and capsaicin on aquatic organism, Daphnia magna was selected as a model test organism. Based on the toxicity effects on fatality, time of the first reproduction, number of brood per female, body length, number of total offspring in acute and chronic test, a dose-response relationship was established and the most sensitive biological indices were proposed. The acute toxicity test showed that the 48 h-EC50 of diuron to Daphnia magna was 17.1 mg·L-1, the 48 h-EC50 of capsaicin to Daphnia magna was 12.4 mg·L-1. The chronic toxicity test showed that there were signifi-cant effects on all observed biological indices. The sensitive biological indices for diuron from strong to weak were number of total offspring > time of the first reproduction > body length > number of brood per female, and the sensitive biological indices for capsaicin from strong to weak were number of total offspring > body length > number of brood per female > time of the first reproduction. Based on the number of total offspring, the 21 d-EC10 of diuron was calculated to be 0.830 mg·L-1, the 21d-EC10 of capsaicin was 1.63 mg·L-1. Capsaicin was readily biodegradable and its EC10 of reproduction to Daphnia magna was greater than 1 mg·L-1. According to the "Rules for Classification and Labeling of Chemicals-Part 28:Hazardous to the Aquatic Environment" (GB 30000.28-2013), capsaicin can be considered to have low chronic risk for aquatic environment and an environment-friendly potential.