Effects of triclosan on the early life stages and reproduction of medaka Oryzias latipes and induction of hepatic vitellogenin

Triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether) is widely used as antibacterial agent in various industrial products, such as textile goods, soap; shampoo, liquid toothpaste and cosmetics, and often detected in wastewater effluent. In this study, the effects of TCS on the,. early life stages and reproduction of medaka (Oryzias latipes) were investigated. The 96-h median lethal concentration value of TCS for 24-h-old larvae was 602 mug/l. The hatchability and time to hatching in fertilized eggs exposed to 313 mug/l TCS for 14 days were significantly decreased and delayed, respectively. An assessment of the effects of a TCS 21-day exposure period on the reproduction of paired medaka showed no significant differences in the number of eggs produced and fertility among the control and 20, 100 and 200 mug/l TCS treatment groups. However, concentrations of hepatic vitellogenin were increased significantly in males treated with TCS at 20 and 100 mug/l. In the F-1 generations, although the hatching of embryos in the 20 mug/l treatment showed adverse effects, there was no dose-response relationship between hatchability and TCS treatment levels. These results suggest that TCS has high toxicity on the early life stages of medaka, and that the metabolite of TCS may be a weak estrogenic compound with the potential to induce vitellogenin in male medaka but with no adverse effect on reproductive success and offspring. (C) 2003 Elsevier B.V. All rights reserved.