ANATOMICAL AND BEHAVIORAL EFFECTS OF DEVELOPMENTAL EXPOSURE TO DECAMETHYLCYLOPENTASILOXANE (D5) AND 2, 4, 6, 8-TETRAMETHYLCYCLOTETRASILOXANE

The siloxane family is made up of many different compounds that have purposes from cosmetics to industrial cleaners. However, there is little research on the effects of siloxanes on aquatic ecosystems within the United States (USA). Despite bans in multiple countries, these compounds are still used in products in the USA, with regulations only applying to a single chemical family typically used in industry. The presence of siloxane species in Anacostia water samples suggests these compounds are environmentally relevant. This current study aims to determine the effects of different siloxane species on early fish development. Developing zebrafish (Danio rerio) were exposed to two different concentrations (1nM, 1fM) of two different siloxanes - (1) Decamethylcyclopentasiloxane (D5), a siloxane commercially used in cosmetics, and (2) 2,4,6,8-tetramethylcyclotetrasiloxane (2468), an industrial siloxane, - and compared to control groups. After 5 days of exposure (on 7 days postfertilization), there were no anatomical, or survival differences with either compound. However, D5-treated larvae had slower startle responses and spent more time away from the center of the dish. D5-larvae did not survive more than 1 week of continued exposure. In contrast, 2468-treated larvae survived well, displaying slower startle responses at 7 days postfertilization, which reversed by 14 days. At 14 days postfertilization, 2468-treated larvae spent significant time in the center of the dish and displayed other non-stress-like behaviors. These results suggest sublethal exposure to different siloxane compounds have chemical- and duration-specific effects that can alter behavioral responses and differentially affect overall growth.