DDE in Eggs of Two Crocodile Species from Belize Ted H. Wu, † Thomas R. Rainwater, † Steven G. Platt, ‡ Scott T. McMurry, † and Todd A. Anderson* ,† The Institute of Environmental and Human Health, Texas Tech University, Box 41163, Lubbock, Texas 79409, and Wildlife Conservation Society, 185th Street and Southern Boulevard, Bronx, New York 10460-1099 Organochlorine (OC) residues were recently detected in nonviable Morelet’s crocodile (Crocodylus moreletii) eggs from northern Belize. To further the assessment of contaminant exposure in Belizean crocodiles, nonviable Morelet’s crocodile eggs (n ) 11) from southern Belize and American crocodile (Crocodylus acutus) eggs (n ) 12) from the coastal zones of Belize were screened for 20 OCs. Results indicated p,p-DDE to be the most prevalent OC (96% occurrence) in eggs examined, with concentrations ranging from 5 to 372 ng/g. These concentrations are similar to those observed in crocodile eggs (10-180 ng/g) from northern Belize. A general trend toward higher DDE concentra- tions in Morelet’s crocodile eggs (mean ) 103 ppb) compared with American crocodile eggs (mean ) 31 ppb) was observed. However, this trend may be due to site-specific contamination rather than differences in interspecific susceptibility to chemical exposure. Other OCs detected in crocodile eggs included the parent compound, p,p-DDT, and its metabolite, p,p-DDD. Keywords: DDE; crocodile eggs; Belize; organochlorine residues INTRODUCTION Widespread use of organochlorine (OC) pesticides in agriculture, industry, and vector control has resulted in worldwide distribution of OCs in the environment (Snedaker et al., 1999). This is particularly true in developing countries where regulations governing the production, distribution, application, and disposal of these chemicals are either not legislated or poorly enforced (Murray, 1994). In industrialized countries, the persistence of OC pesticides in the environment has led to their discontinuation in favor of less persistent alternatives (Waliszewski et al., 1999). However, OC residues are still detected worldwide in abiotic and biotic samples, particularly in samples with high lipid content. For example, OCs have been recently detected in human adipose tissue from residents in the United States (Stellman et al., 1998), foodstuffs from Nigeria (Osibanjo and Adeyeye, 1997), snapping turtle (Chelydra serpen- tina serpentina) eggs from Canada (Bishop et al., 1998), and pelican (Pelecanus crispus and Pelecanus onocro- talus) eggs from Greece (Crivelli et al., 1999). A persistent OC that is frequently encountered in soils and biological systems is DDE [1,1-dichloro-2,2- bis(p-chlorophenyl)ethylene], a degradation product of DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethylene] (Helling et al., 1971). DDE can be formed by photo- chemical processes (Maugh, 1973) and by bacterial (Subba-Rao and Alexander, 1985) or abiotic (Boul, 1995) dehydrochlorination. Studies have shown that DDE is extremely recalcitrant to further biological degradation under aerobic or anaerobic conditions (Strompl and Thiele, 1997), resulting in its long-term contamination of the environment. For example, in New Zealand, a pasture contained substantial levels of DDE in the soil 27 years after treatment with DDT (Boul et al., 1994). OC contaminants have a tendency to bioaccumulate in the food chain at high concentrations, placing top- level predators in a position of high toxicological risk (Fossi et al., 1999). Crocodilians would be in this position because of their high trophic status and long life span. To our knowledge, OCs have been detected in 7 of the 23 species of crocodilians. A frequently occurring OC detected in crocodilian eggs is DDE (Ogden et al., 1974; Wessels et al., 1980; Phelps et al., 1986; Heinz et al., 1991; Skaare et al., 1991; Wu et al., 2000). OC exposure at these early developmental stages can have toxicologi- cal implications. Current studies indicate that certain OCs have the potential to disrupt hormones in the endocrine system necessary for reproductive develop- ment. For example, Willingham and Crews (1999) recently reported significant (40%) sex reversal in red- eared sliders (Trachemys scripta) following administra- tion of DDE to eggs incubated at male-producing temperatures. In addition, high DDE levels may have contributed to abnormally developed testes and reduced phalli in juvenile alligators from Lake Apopka, Florida, following a spill of DDT and dicofol (Guillette et al., 1994; Heinz et al., 1991). The data from Lake Apopka suggest that young crocodilians are sensitive to OC exposure. However, very little is known about the variability of chemical residues in crocodilian eggs, such as variability within a clutch, between clutches, or among different crocodile species. OC residues in crocodilian eggs are likely the result of maternal transfer from exposed females. The lipo- philic nature of OCs facilitates their mobilization from fat depots in the female into developing follicles during vitellogenesis (Ferguson, 1985). Exposure to OCs in contaminated nest material and soil may also add to chemical burdens in eggs following oviposition (Wu et * Author to whom correspondence should be addressed [fax (806) 885-4577; e-mail todd.anderson@tiehh.ttu.edu]. † The Institute of Envionmental and Human Health. ‡ Wildlife Conservation Society. 6416 J. Agric. Food Chem. 2000, 48, 6416-6420 10.1021/jf000321u CCC: $19.00 © 2000 American Chemical Society Published on Web 12/01/2000