Contamination of free-range chicken eggs with dioxins and dioxin-like polychlorinated biphenyls

Dioxins and dioxin-like (DL) polychlorinated biphenyls (PCB) are persistent organic pollutants that enter the body mainly by food intake. A small margin exists between current exposure levels in the human population and the levels causing biological effects. Therefore, stringent control of concentrations of these contaminants in food and feed is needed. Eggs from free-range chicken are increasingly becoming an important part of the diet. These eggs have a higher risk of being contaminated with increased levels of dioxins and DL-PCB than barn or cage eggs. Ingestion of soil particles from environmentally contaminated areas may contribute to elevated dioxin levels in free-range chicken eggs. Available data show that current soil levels of dioxins and DL-PCB in residential and agricultural areas in Europe often appear to be too high to produce free-range eggs with dioxin levels below the current limit values in the EU. On the other hand, polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans concentrations in eggs from free-range chicken are not necessarily above the limit values. Contamination levels in soil should be kept low and should be controlled in areas with free foraging chicken although all modifying factors that influence uptake of dioxins and PCB from the environment and transfer into eggs are yet not well understood.