Concentrations ofpolychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls(PCBs) in human milk from Ireland: temporal trends and implications for nursing infants

Aim: The elucidation of temporal trends in human exposure to polychlorinated biphenyls (PCBs) and 17 polychlorinated dibenzo-p-dioxins and furans (PCDD Fs) since the previous Irish human milk surveys and to evaluate the impacts of legislative bans and restrictions on human exposure to these compounds. Methods: Concentrations of PCBs and 17 PCDD Fs were measured in 16 pools of human milk collected from 92 Irish primiparas participating in the Irish EPA-funded ELEVATE project between October 2016 and April 2018, using Gas-Chromatography coupled with Mass spectrometry. Results: The geometric mean upper bound concentration of 16 pooled human milk samples [PCDD Fs + dioxin-like (dl)-PCB TEQ; 4.5 ng kg-1 lipid weight] are on the lower end of those reported internationally. WHO-TEQ PCDD Fs + dl-PCB are significantly lower (P 0.005) compared to those reported in the previous Irish human milk studies in 2010 and 2002. Conclusion: Detected concentrations in this study are comparable to those reported for less industrialised countries in the last WHO UNEP global surveys for PCDD Fs. This downward temporal trend likely reflects the impact of regulatory bans and restrictions on the emissions of dioxins and PCBs. While mean upper bound WHO PCDD F PCB TEQ concentrations are lower than those estimated by EFSA to be associated with adverse health effects in children age 9, maximum upper bound concentrations do exceed EFSA reference concentrations. While the positive health benefits of breastfeeding to both mother and child significantly outweigh potential adverse health effects at reported concentrations, continued action to reduce human body burdens of dioxins and PCBs is required.