Abstract
Recent research has indicated that the antimicrobial chemical triclocarban (TCC) represents a new type of endocrine disruptor, amplifying the transcriptional activity of steroid hormones and their receptors while itself exhibiting little affinity for these receptors. The effects of TCC were studied in the freshwater mudsnail Potamopyrgus antipodarum. Specimens were exposed to concentrations ranging from 0.05 to 10.5 microg/L dissolved TCC and were removed and dissected, and embryos contained within the brood pouch were counted and classified as shelled or unshelled after two and four weeks of exposure. After four weeks, environmentally relevant TCC concentrations of 1.6 to 10.5 microg/L resulted in statistically significant increases in the number of unshelled embryos, whereas 0.2, 1.6, and 10.5 microg/L exposures significantly increased numbers of shelled embryos. The lowest observed effect concentration (LOEC) was 0.2 microg/L, the no observed effect concentration (NOEC) was 0.05 microg/L; the 10% effective concentration (EC10) and the median effective concentration (EC50) for unshelled effects were 0.5 microg/L and 2.5 microg/L, respectively. Given the widespread occurrence of TCC in the environment and the effects shown at environmentally relevant concentrations, these results indicate that TCC may be causing reproductive effects in the environment. Furthermore, the present study indicates that environmental risk from a new class of endocrine-disrupting chemicals (EDCs) is both qualitatively and quantitatively similar to risk from existing classes of EDCs.