Survey on human contamination by brominated flame retardants and chlorinated/brominated dioxins for the health risk factor of mother and child

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In order to clear human exposure by Co-PXBs, it was investigated the Co-PXBs concentration in the breast milk (sampling day; 5 and 30 days) of Japanese multiparae and primiparae. The concentration of Co-PXBs ranged between 0.42 and 1.41 pg TEQ/g lipid, and this observation is our first finding for human exposure by Co-PXBs. With respect the average TEQ level in mother's milk, there is no difference between of multiparae and primiparae, not in the case of CO-PCBs. Interestingly, when the level of Co-PCBs at 5 and 30 days of same woman was compared, that at 5 days-breast milk samples were higher than that at 30days-samples for almost sample analyzed. However, in the case of CO-PXBs, such tendency was not always observed.Then, the abundant congeners of Co-PXBs were #126A, #126 B and #169, and it was estimated that human exposure by this Co-PXBs #126B is derived from the eating of fish. Then, it was compared the contribution ratio of four kinds of dioxin analogues for total TEQ concentration in mother's milk of Japan. Major analogues were PCDDs/DFs, Co-PCBs and Co-PXBs, and PXDDs/DFs were negligible level, showing unexpected high contribution ratio of Co-PXBs in the breast milk of multiparae. As there are theoretically more few hundreds congeners in the Co-PXBs group, and therefore it needs further detail survey of Co-PXBs contaminationFurther study is warranted to evaluate whether Co-PXBs exposures to nursing infants pose a health risk. Additional investigations of Co-PXBss in the daily foods are warranted to better understand the nature and extent of Co-PXBs contamination of Japanese food supply.