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

一般来说，由多氯二苯并对二恶英（pcdd）、多氯二苯并tirans（pcdf）和共面多氯联苯（Co-PCBs）组成的二恶英类似物在人类母乳中的水平被认为反映了它们在体内的积累水平。此外，众所周知，大约60%的身体储存通过母乳喂养一年排泄给婴儿。然而在2001年，我们发现7位哺乳期母亲的母乳中PCDDs和PCDFs的日下降率在时间变化上存在很大差异，并且它们在母乳中的水平并不总是随着分娩后时间的推移而下降。这表明，牛奶中二恶英类似物的一部分除了储存在体内外，还可能从其他来源输送。因此，在本研究中，我们调查了人类母乳中污染物的主要来源。每天从10位哺乳期母亲中以每3小时一次的速率获得8份母乳样本，连续4天以上。此外，每天从同一位母亲的三个时间窗口(早上（早餐至午餐时间）、白天（午餐至晚餐时间）和晚上（晚餐至早餐时间）获取三份膳食样本。在婴儿吸奶前后每一次称重一次体重，以检测婴儿吸奶量。在实验的第一天，在饥饿时间（如餐后最初3小时）抽取70ml血液，检测被试母亲体内二恶英类似物的储存情况。母乳中二恶英类似物的污染水平和组成比例随时间变化而变化。这种变化在所有接受测试的母亲身上都能看到。此外，pcdd的组成比，。牛奶中的pcdf和Co-PCBs在饥饿时与血液中的pcdf和Co-PCBs经常出现差异，这被认为反映了其体内储存的实际污染状况。有。即使在一天之内，污染程度和成分的时间变化也有很大的差异。由此证实，母乳中二恶英类似物的污染除了受人体储存影响外，还受膳食的影响。与母乳相比，膳食样品中二恶英类似物的污染水平和成分的时间变化更为显著。特别是，包括鱼类和/或肉类在内的膳食样本中二恶英类似物的污染水平很高，与多氯联苯和多氯联苯相比，鱼类的污染水平尤其高。根据分析数据和婴儿的母乳摄入量，计算了母亲通过饮食和婴儿通过母乳摄入的二恶英类似物的量。综合考虑两种摄入量，发现膳食中二恶英类似物的摄入对餐后第一次和第二次母乳中的污染水平有一定程度的影响。转移率为10 ~ 100%。这是世界上第一次发现。此外，我们还坚持认为，母乳不是评估人类接触二恶英类似物的合适样本。当饮食样本中二恶英类似物的主要成分为Co-PCBs时，证实了Co-PCBs具有较短的半衰期和较低的生物积累能力，更容易从饮食样本转移到母乳中。少

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