Toxic effects of Triclosan on the detoxification system and breeding of Daphnia magna

The toxic effects of different concentrations of Triclosan (TCS) (1–128 μg/L) on Daphnia magna ( D . magna ) were investigated by acute (48 h) and chronic (21-day) toxicity tests. The response of antioxidase system and Phase I metabolism process of D . magna exposed to TCS were investigated by measuring a series of biomarkers including glutathione S-transferase (GST), catalase (CAT), superoxide dismutase (SOD), malondialdehyde (MDA), 7-ethoxyresorufin O-deethylase (EROD), Erythromycin N -demethylase (ERND) and Aminopyrine N-demethylase (APND). The 48 h LC 50 of TCS was 330 μg/L for D. magna . In the chronic test, total number of neonates per female, body length and the intrinsic rate of natural increase ( r ) of D. magna increased at the low exposure concentrations (1–16 μg/L) and decreased at the high concentrations (64–128 μg/L), while the total number of molting per adult decreased continually. The GST and CAT activities showed no significant increase in all treatments, and SOD activities were induced after 24-h exposure and inhibited after 48-h exposure at 4–128 μg/L of concentrations. The MDA content increased after 6-h exposure but decreased after 48-h exposure at 4–128 μg/L. EROD activities initially increased after 6-h exposure, but decreased after 24 and 48-h exposure, ERND and APND activities showed a similar temporal pattern among different treatments groups. SOD, MDA and APND were sensitive to TCS, thus they are suitable as potential biomarkers for the exposure to TCS.