Supplemental Material | Chemical Contamination of Green Turtle (Chelonia mydas) Eggs in Peninsular Malaysia: Implications for Conservation and Public Health

Although the effects of POPs on the health of free ranging loggerhead sea turtles (Caretta caretta) has been well investigated (Keller et al. 2004; Keller et al. 2006a; Keller et al. 2006b), there was only one previous study on the toxicological effects of POPs on sea turtle embryonic development (Podreka et al. 1998). However, there are a number of studies on freshwater turtles that have investigated the effects of POPs on embryonic sex reversal. Based on these studies, the PNECs could be determined for p,p'-DDE, dieldrin and PCBs. The PNEC for p,p'-DDE was estimated as 543 ng g-1 , based on a study on C. mydas that found no sex reversal of developing embryos up to a concentration of 543 ng g-1 (Podreka et al. 1998). A study on red-eared slider turtles (Trachemys scripta) found no significant sex reversal when embryos were dosed with 5 µL of 2.6 µM dieldrin (Willingham and Crews 1999). Based on an estimated penetration of 30% and an average egg mass of ~ 10 g, this dose represented egg concentration of ~ 40 ng g-1 dieldrin. Therefore, after applying an uncertainty factor of 10 for inter-species differences, the PNECs for dieldrin were estimated at 4 ng g-1. The effects of PCBs on sex reversal have also been studied on T. scripta (Bergeron et al. 1994). In this study, the topical administration of 10 µg of single PCB compounds to T. scripta eggs produced no sex reversal. Based on an estimated penetration of 30% and an average egg mass of 11.4 g, these doses represented egg concentrations of ~ 260 ng g-1. Therefore, after applying an uncertainty factor of 10 for inter-species differences, the PNEC for a single PCB was 26 ng g-1 .