Study of Health Effects of DDT in Mexico

最近的数据继续表明，使用杀虫剂滴滴涕可能会对人类健康产生不利影响，但基本上没有关于这一主题的发现被重复，因此这个问题仍然悬而未决。滴滴涕是否有不良影响很重要，因为约有12个国家仍在使用滴滴涕控制疟疾，而世界卫生组织目前支持使用滴滴涕的建议是基于这样的假设，即它对人类的健康基本没有不利影响。DDE是DDT的主要代谢物。 在动物身上的实验表明，DDE阻止了雄激素的作用，出生前接触DDE可能会对男性生殖产生不利影响。此外，之前的两项人类研究表明，较高的DDE暴露与较短的哺乳期有关。母乳喂养可防止婴儿死亡。因此，滴滴涕的使用可能会增加婴儿的死亡率。此外，最近的数据表明，DDT/DDE可能会导致人类流产。需要关于这些潜在不良影响的更多信息。 墨西哥在1999年之前一直使用杀虫剂DDT控制疟疾；那里热带地区的许多人血液中DDT代谢物DDE的水平都升高了。我在墨西哥的项目分为两个阶段；两个阶段都基于同一组主题。 我进行了这项研究的第一阶段：1)在墨西哥塔帕丘拉的781名男性新生儿中，检查母亲血清DDE水平与雄激素作用降低的证据之间的关系。所有第一阶段受试者都是在2002-2003年间入选的，应答率为95%。 这项研究的第二阶段于2004财年开始。这项研究跟踪了第一阶段登记的757名妇女和儿童，以确定接触DDT是否与母亲哺乳时间的缩短有关。此外，对后代进行跟踪，以检查早期接触DDT与感染和生长的关系。跟进工作已于去年完成。 过去几年的进展： 在第一阶段，发表了两篇论文。对男婴的人体测量与母亲体内的DDE水平无关；在第二篇论文中，人体测量的测量被证明是可靠的。 对于第二阶段，关于DDE和哺乳期长度的报告已提交给一家杂志，获得了好评，目前正在为该杂志进行修订。DDE水平与哺乳期长短无关。关于报告哺乳期长度的可靠性的手稿已经完成，不久将提交出版。撰写这两篇论文的博士前学生将于2007年9月作为博士后加入NIEHS，并将继续第二阶段手稿和项目的工作。

Recent data continue to indicate that use of the insecticide DDT may have adverse effects on human health, but essentially no findings on this topic have been replicated, so the question is still open. Whether DDT has adverse effects is important because DDT is still used for malaria control in about 12 countries, and current recommendations by the World Health Organization that support DDT use are based on the assumption that it has basically no adverse health consequences for humans. DDE is the major metabolite of DDT. Experiments in animals indicate that DDE blocks androgen action and that exposure before birth can have adverse effects on male reproduction. In addition, two previous human studies suggest that higher exposure to DDE is associated with a shortended duration of lactation. Breast feeding prevents infant death. Therefore, DDT use may have the effect of increasing infant death. Furthermore, recent data suggest that DDT/DDE may cause pregnancy loss in humans. Additional information about these potential adverse effect are needed. Mexico used the insecticide DDT for malaria control until 1999; many people there in tropical areas have elevated blood levels of the DDT metabolite, DDE. My project in Mexico has two phases; both are based on the same group of subjects. I conducted phase 1 of this study: 1) To examine the relation between maternal serum levels of DDE in relation to evidence of decreased androgen action in 781 newborn males in Tapachula, Mexico. All phase 1 subjects were enrolled in 2002-2003; the response rate was 95%. Phase 2 of this study began in FY 2004. This study followed 757 women and children enrolled in Phase 1, to determine if DDT exposure is related to reduced length of lactation among mothers. In addition, the offspring were followed to examine early-life DDT exposure in relation to infection and growth. Follow-up was completed last year. Last years progress: For phase 1, two papers were published. Anthropometric measures on infant males were unrelated to DDE levels in the mothers; in the second paper the anthropometric measures were shown to be reliably ascertained. For phase 2, the report on DDE and length of lactation was submitted to a journal, received favorable reviews, and is now being revised for that journal. DDE levels were not related to length of lactation. A manuscript on the reliability of reporting length of lactation has been completed and will be submitted for publication soon. The pre-doctoral student who wrote these two papers will be joining NIEHS as a postdoc in September of 2007, and will continue work on the phase 2 manuscripts and projects.