Chlorinated and brominated contaminants in Italian chicken eggs from different housing systems

Chicken eggs are universally consumed and produced globally using different rearing and husbandry systems. Eggs accumulate a range of contaminants through physiological and environmental mechanisms, with contamination levels being regulated in some regions such as the EU. This study used a unique method which allowed simultaneous determination of commonly occurring toxic environmental contaminants - polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs), polychlorinated biphenyls (PCBs), polybrominated diphenylethers (PBDEs), and hexabromocyclododecanes (HBCDDs) in the same sample. This methodology was used to investigate Italian eggs raised by three different chicken rearing systems – caged, barn and organic. Despite generally higher (literature) reported levels of these contaminants in organic produce, the study data showed remarkably similar contamination across the three systems. Contamination levels were generally lower (considerably below regulated levels) than literature reports, including in Italian eggs. Mean (and maximum) concentrations detected were 0.14 (0.58) pg TEQ/g fat for PCDD/Fs plus dioxin like-PCBs (DL-PCBs), 0.51 (2.0) ng/g fat for non-dioxin-like PCBs (NDL-PCBs) 1.08 (3.85) ng/g fat for ΣPBDE10, and 0.12 (0.44) ng/g fat for HBCDDs. The only significant differences were found for DL-PCBs and NDL-PCBs in caged chicken eggs compared to the other two systems. The low levels of contamination, particularly in organic eggs may result from: • high levels of control with respect to animal housing and regulation on feed production • limited accessibility to soil contamination that may arise through high and regular turnover of birds over the same areas which depletes inherent soil contaminants • predominance of samples taken from Northern Italy which generally shows relatively lower contamination levels