Brominated flame retardants in Canadian chicken egg yolks

Chicken eggs categorised as conventional, omega-3 enriched, free range and organic were collected at grading stations in three regions of Canada between 2005 and 2006. Free run eggs, which were only available for collection from two regions, were also sampled during this time frame. Egg yolks from each of these egg types (n = 162) were analysed to determine brominated flame retardant levels, specifically polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCD). PBDEs were detected in 100% of the 162 samples tested, while HBCD was observed in 85% of the egg yolks. Total PBDE concentrations in egg yolks ranged from 0.018 to 20.9 ng g(-1) lipid (median 3.03 ng g(-1) lipid), with PBDE 209 identified as being the major contributor to Sigma PBDE concentrations. In addition to PBDE 209, PBDE 99, 47, 100, 183 and 153 were important contributors to Sigma PBDE concentrations. Total HBCD concentrations ranged from below the limit of detection to a maximum concentration of 71.9 ng g(-1) lipid (median = 0.053 ng g(-1) lipid). The alpha-isomer was the dominant contributor to Sigma HBCD levels in Canadian egg yolks and was the most frequently detected HBCD isomer. Sigma PBDE levels exhibited large differences in variability between combinations of region and type. Sigma HBCD concentrations were not significantly different among regions, although differences were observed between the different types of egg yolks analysed in the present study.