Human Exposure To Halogenated Aromatic Compounds

从1978年到1982年，我们招募并跟踪了大约900名北卡罗来纳州的儿童。我们测量了他们母亲母乳中的多氯联苯和DDE等物质，并跟踪了哺乳过程。我们发现，妇女与更高的DDE，但不是PCB，水平断奶早，我们推测，DDE？雌激素的活性可能会产生这种效果。我们后来在墨西哥复制了早期断奶和DDE的发现。2001年，撒哈拉以南非洲的十几个国家要求豁免滴滴涕的全球禁令，以便将其用于预防疟疾。利用我们的断奶数据，以及NIEHS/NICHD关于DDE与早产之间关系的数据，我们估计，喷洒DDT导致的婴儿死亡率增加与有效控制疟疾导致的婴儿死亡率下降具有相同的数量级，并建议应记录所有婴儿死亡以及断奶时间。我们还估计了母乳喂养对美国等发达国家死亡率的影响，发现即使在美国，母乳喂养的儿童在出生后第一年的死亡率也大大降低。 多氯联苯（PCBs）是最普遍和持久的环境污染物之一，在全世界大多数人体内都能检测到。多氯联苯本身是有毒的，致畸的，并可能导致实验室动物的学习能力受损和行为异常。在儿童中，即使在低背景水平下，经胎盘暴露也可能产生轻微的精神、认知和记忆障碍。此外，还有两个大规模中毒的复杂混合物的热降解多氯联苯。两次这样的曝光发生在1968年的日本（友商）和台湾（禹城）。我们和台湾的同事一起，一直在跟踪调查禹城母亲所生的118名儿童，并在2002年报告说，即使他们在母亲暴露后6年出生，他们在16奥尔兹时仍然有认知障碍和行为障碍。我们现在有暴露后13年出生的儿童的数据，希望确定何时，如果有的话，母亲们开始生下不受影响的孩子。滴滴涕于1972年在美国被禁用，并于2001年在斯德哥尔摩公约上被提议在全球范围内禁用。然而，撒哈拉以南非洲国家要求豁免，理由是疟疾重新抬头，需要使用滴滴涕控制疟疾。尽管他们的推理假设DDT没有毒性，但我们已经证明，接触更多DDE的妇女断奶更早，我们的NIEHS/NICHD同事已经证明，接触DDT会增加早产。由于这两种影响都可能增加婴儿死亡率，我们做了一个风险分析，估计婴儿死亡率的增加可归因于滴滴涕暴露和减少可归因于滴滴涕病媒控制。由于多氯联苯和滴滴涕是致癌物质，它们在母乳中的存在造成了监管困境，因为当局不想建议反对母乳喂养，但又不想提倡食用受污染的食物。我们以前曾对存在致癌物的母乳喂养进行过风险-风险分析，但在发达国家几乎没有发现母乳喂养对死亡率的保护数据。今年，我们发现了一个合适的数据集，可以用来估计母乳喂养对美国新生儿后期死亡率的影响。 在撒哈拉以南非洲地区，由于使用滴滴涕而导致的过早断奶和早产婴儿死亡率的增加，与极其有效的疟疾控制所导致的死亡率下降的数量级相同。在美国，母乳喂养与新生儿后期死亡风险的大幅降低有关，如果所有儿童都母乳喂养，大约1200例死亡可以预防或延迟。

From 1978 to 1982, we enrolled and followed about 900 North Carolina children. We measured, among other things, PCBs and DDE in their mothers' breast milk, and followed the course of lactation. We found that women with higher DDE, but not PCB, levels weaned earlier, and we speculated that DDE?s estrogen activity might produce the effect. We later replicated the early weaning and DDE finding in Mexico. In 2001, more than a dozen countries in sub-Saharan Africa requested exemption from the world-wide ban on DDT in order to use it for malaria prevention. Using our data on weaning, as well as NIEHS/NICHD data on the relation between DDE and preterm birth, we estimated that the increase in infant mortality from spraying DDT was of the same order as the decrease from effective malaria control, and suggested that all infant deaths as well as time at weaning should be documented of DDT were to be used. We have also estimated the effect of breastfeeding on mortality in developed countries like the US, and find that even in the US breastfeed children have a substantially reduced mortality rate in the first year of life. Polychlorinated biphenyls (PCBs are among the most ubiquitous and persistent of environmental contaminants, and are detectable in most human beings worldwide. PCBs per se are toxic, teratogenic, and can cause impaired learning and behavioral abnormalities in laboratory animals. In children, transplacental exposure even at low, background levels may produce subtle psychomotor, cognitive, and memory impairment. In addition there have two mass poisonings by complex mixtures of heat-degraded PCBs. Two such exposures have occurred, one in Japan (Yusho) in 1968 and the other in Taiwan (Yucheng). With our colleagues in Taiwan, we have been following the 118 children born to Yucheng mothers, and reported in 2002 that they still had cognitive impairment and disordered behavior as 16 year olds, even if they had been born as long as 6 years after their mothers' exposure took place.We now have data on children born up to 13 years after the exposure, and hope to determine when, if ever, the mothers began to have unaffected children. DDT was banned in the US in 1972, and was proposed for a worldwide ban at the Stockholm Convention in 2001. However, countries in sub-Saharan Africa asked for exemptions, based on the resurgence in malaria and their need to use DDT for malaria control. Although their reasoning assumed no toxicity from DDT, we have shown that women with greater DDE exposure wean earlier, and our NIEHS/NICHD colleagues have shown that DDT exposure increases preterm births. Since both of these effects could increase infant mortality, we did a risk analysis to estimate the increase in infant deaths attributable to DDT exposure and the decrease attributable to DDT vector control.Because PCBs and DDT are carcinogens, their presence in breast milk creates a regulatory dilemma, in that authorities do not wish to recommend against breastfeeding but do not want to advocate the consumption of a contaminated food. We had previously done risk-risk analysis of breastfeeding in the presence of carcinogens, but found few data on the protection against mortality from breastfeeding in developed countries. This year we found a suitable data set with which to estimate the effect of breastfeeding on post-neonatal mortality in the US. The increase in infant mortality from early weaning and pre-term birth that would occur in sub-Saharan Africa from the use of DDT is of the same order of magnitude as the decrease resulting from extremely effective malaria control. In the US, breastfeeding is associated with a substantial reduction in the risk for post-neonatal mortality, and about 1200 deaths could be prevented or delayed if all children breastfed.