Risk assessment of organohalogenated compounds in water bird eggs from South China

Organohalogen compounds, the pesticides aldrin, dieldrin, endrin, hexachlorobenzene, mirex, Σchlordanes, ΣDDTs, Σheptachlors, Σtoxaphenes, and the industrial chemicals ΣPCBs and ΣPBDEs, as well as total dioxin-like equivalents (TEQ_H4IIE-luc), were measured in eggs of two Ardeid species, the little egret (Egretta garzetta) and black-crowned night heron (Nycticorax nycticorax) from three port cities along the South China coast: Hong Kong, Xiamen, and Quanzhou. ΣDDTs was the predominant and most abundant residue, occurring at concentrations ranging from 2.7 × 10³ to 8.7 × 10⁴ ng/g lipid wt. The greatest concentrations of the studied compounds were observed in eggs collected from Hong Kong, with the exception of ΣDDTs, which occurred at the greatest concentrations in eggs from Quanzhou Bay and Xiamen Harbor. Concentrations of ΣPBDEs were greater in eggs from Quanzhou Bay and Xiamen Harbor, possibly because of rapid industrialization in these areas. Total concentrations of dioxin-like PCB toxic equivalents (TEQs), measured as the aryl hydrocarbon receptor (AhR)-mediated responses of the H4IIE-luc bioassay (TEQH_4IIE-luc), were greatest in Hong Kong samples. A risk assessment of the relatively great concentrations of ΣDDEs and dioxin-like (coplanar) PCBs in the eggs (threshold levels: 2.8 μg/g wet wt and 5 pg/g wet wt., respectively) predicted that concentrations of these compounds would be expected to affect some proportion of the Ardeid populations studied.