Effect of Dichlorodiphenyltrichloroethane on Sex Determination of the Common Snapping Turtle (Chelydra serpentina serpentina)

Abstract

Recent evidence indicates that 1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and some of its metabolites alter reproductive and endocrine function in wildlife. Exposure to such endocrine-disrupting compounds during embryonic development can affect sexual differentiation. The authors tested the hypothesis that dichlorodiphenyltrichloroethane (p,p′-DDE) causes feminization of the common snapping turtle (Chelydra s. serpentina), a species with temperature-dependent sex determination, during embryonic development. Eggs from eight clutches (total eggs tested=237) were incubated at a male-producing temperature (26°C). At stage 14 of embryonic development, p,p′-DDE was applied topically at four concentrations and estrogen (estradiol-17 β) was applied as a positive control. Although application of estrogen did induce female development at this temperature, application of p,p′-DDE did not affect sex determination at the exposure levels used. Residue analysis indicated that the amount of p,p′-DDE detected in the eggs 72 h after application was considerably less than the concentrations applied. However, the amounts that penetrated the shells were comparable to levels which have been found in moderately contaminated sites in the Great Lakes. These results indicate that p,p′-DDE, at levels that exist in the environment in the Great Lakes, does not cause the feminization of snapping turtles during embryonic development.