The impact of production type and region on polychlorinated biphenyl (PCB), polychlorinated dibenzo-p-dioxin and dibenzofuran (PCDD/F) concentrations in Canadian chicken egg yolks

Abstract

Chicken eggs from five different production types (conventional, omega-3 enriched, free range, organic and free run) were collected, when available, from three regions (west, central and east) of Canada to determine persistent organic pollutant (POP) concentrations. Total polychlorinated biphenyl (PCB) concentrations (∑37 congeners) in yolks from the eggs ranged from 0.162ngg−1 lipid to 24.8ngg−1 lipid (median 1.25ngg−1 lipid) while the concentration of the sum of the 6 indicator PCBs ranged from 0.100ngg−1 lipid to 9.33ngg−1 lipid (median 0.495ngg−1 lipid). Total polychlorinated dibenzo-p-dioxin/dibenzofuran (PCDD/F) concentrations ranged from 2.37pgg−1 lipid to 382pgg−1 lipid (median 9.53pgg−1 lipid). The 2005 WHO toxic equivalency (TEQ) ranged from 0.089pg TEQPCDD/F+dioxin-like[DL]-PCBg−1 lipid to 12.8pg TEQPCDD/F+DL-PCBg−1 lipid (median 0.342pg TEQPCDD/F+DL-PCBg−1 lipid). PCB and PCDD/F concentrations were significantly different (p<0.001) in egg yolks from different regions of collection. In contrast to observations in Europe, PCB and PCDD/F concentrations in Canadian egg yolks were not impacted solely by the production type (e.g., conventional, free range, organic, etc.) used to maintain the laying chickens. Additionally, only one Canadian free range yolk from western Canada (12.8pg TEQPCDD/F+DL-PCBg−1 lipid) exceeded the European toxic equivalent concentration limits for eggs (5pg TEQPCDD/F+DL-PCBg−1 lipid). This differs from observations in Europe where free range/home produced eggs frequently have higher POP concentrations than eggs from other production types. Median PCB dietary intake estimates based on consumption of eggs were less than 10ngd−1 while median PCDD/F intakes were less than 45pgd−1.