Investigation on main sources of persistent organic pollutants(POPs) in human breast milk

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In general, the level of dioxin analogues dioxin analogues, which are composed of polychlorinated dibenzo-p-dioxins(PCDDs), polycldorinated dibenzoftirans(PCDFs) and coplanar PCBs(Co-PCBs), in human breast milk is considered to be reflecting to their accumulation level in the body. In addition, it is well known that ca. 60% of their body storage is excreted to the baby through breast milk by nursing for a year. In 2001, however, we found that there was a great difference in a time alteration of daily decrease rate of PCDDs and PCDFs in breast milk from 7 nursing mothers and that their level in breast milk did not always decrease with time passing after delivery. This indicates that some part of dioxin analogues in milk might be delivered from other sources except for their storage in the body. Therefore, in this study, we investigated to, detect their main source of pollutants in human breast milk.Eight breast milk samples were daily obtained at a rate of once per every 3 hours in a pe … More riod of consecutive four days from 10 nursing mothers. In addition, three dietary samples were also daily obtained in the three time windows of morning(breakfast to until lunch time), day (lunch to until dinner) and night(dinner to until breakfast) from the same mothers. The body weight of babies were weighed at an every time of before and after of their milk intake, in order to detect their intake amount of milk. In the first day of experiment, 70ml of blood was sampled at hungry time such as at first three hours after meal, in to detect the body storage of dioxin analogues in tested mothers.Both the pollution level and composition ratio of dioxin analogues in the breast milk altered in a time course. The alteration was seen in all tested mothers. In addition, the composition ratio of PCDDs,. PCDFs and Co-PCBs in the milk differed frequently from that of the blood at a hungry time, which is considered to reflect on the actual pollution condition of their body storage. There was. observed a great discrepancy in the time alteration concerning pollution level and composition even within a day. From these results, we confirmed that the pollution of dioxin analogues in the breast milk is influenced by meal except for the body storage.Compared to the breast milk, meal samples showed a more remarkable time alteration on the pollution level and constituent of dioxin analogues. Especially, the dietary sample including fish and/or meat gave a high pollution level of dioxin analogues, showing fish to elevate particularly Co-PCB in comparison with PCDDs and PCDFs. Intake amounts of dioxin analogues by mother via dietary and by infant via breast milk were calculated on the bases of analytical data and infant's milk intake. Taking both the intake amounts into consideration, it was revealed that the dietary intake of dioxin analogues gave some degree of influence on the pollution level in the first and second nursing breast milks after the meal. The transfer rate was 10〜100%. This is the first discovery in the world. In addition, we also insist that the breast milk is not a suitable sample as an indicator for assessment of human exposure to dioxin analogues. In case of Co-PCBs as a major constituent among dioxin analogues in the dietary sample, it was confirmed that Co-PCBs with a short half biological half life and a low bio-accumulative ability could preferably transfer from dietary sample to breast milk. Less