Organochlorine contaminants in eggs: the influence of contaminated nest material

Snake eggs were placed in a synthetic nest contaminated with known concentrations of six organochlorines (OCs) to evaluate whether OCs from contaminated nest material accumulate in eggs. It was hypothesized that contaminated nest material may have contributed to OC burdens in eggs observed previously. The six OCs tested included lindane, heptachlor, aldrin, dieldrin, endrin, and DDT. Eggs were removed at 0, 4, and 6 weeks and analyzed using gas chromatography with electron capture detection. Lindane was found at the highest concentration (153 ng/g at 4 weeks and 162 ng/g at 6 weeks). The next highest uptake was for endrin (25 ng/g at 4 weeks and 106 ng/g at 6 weeks). Heptachlor, aldrin, and dieldrin were also taken up into the eggs, but DDT was not detected in any of the eggs at any sampling period. The concentration of OCs increased from week 4 to week 6 for all the OCs except DDT. Structure–activity relationships were examined to determine which physicochemical properties of the OCs tested could be used as predictors of uptake into the eggs. A variety of physicochemical properties were evaluated including vapor pressure and molecular connectivity (a numerical description of topology). Octanol–water partition coefficient (Kow) was a good predictor (r2=0.63, p=0.06) of OC uptake into the eggs using this limited data set.