Study of DDT and loss of clinically-recognized pregnancies in South Africa

这项关于早孕丢失(流产和死胎)与滴滴涕暴露有关的前瞻性研究的试点现场工作已经完成。招生从2010年开始，到2012年结束。受试者来自南非林波波省的6个村庄，其中3个村庄目前正在使用滴滴涕控制疟疾。根据我们对2011年2月1日登记的妇女的经验，我们决定初始方案(第1部分)不能产生所需的怀孕次数，因此修改了方案(第2部分)并恢复登记。然后，我们确定第二部分中的方案不能成功地招募足够数量的受试者，我们决定停止实地工作，放弃进行全面研究的努力。 第一部分共调查442人，约一半的调查对象来自喷洒滴滴涕的村庄。我们将第一部分中442名受试者的血浆样本送到实验室进行DDT水平分析。滴滴涕水平低得令人惊讶，我们认为这可能部分是因为疟疾控制小组近年来已经用完了滴滴涕。我们仍在调查滴滴涕水平低的原因。 此外，我们对血浆进行了其他分析，以确定是否有受试者在肝功能测试或其他临床化学检查中有与DDT相关的异常证据。在第二部分中，我们还测量了血液中的碳氧血红蛋白浓度，以查看我们基于问卷的室内空气污染暴露评估是否对我们研究对象的未来研究有用。 在过去的一年里，我们准备了一份关于参与研究的女性接触滴滴涕的决定因素的手稿。一个主要的决定因素是在室内残留喷洒滴滴涕之前如何准备房屋。关于这一发现的修订报告已被发送到一家期刊进行评估。我们现在正在准备一项关于这些受试者中抗髓质激素浓度决定因素的研究。

The pilot field work has been completed for this prospective study of early pregnancy loss (miscarriage and stillbirth) in relation to DDT exposure. Enrollment began in 2010 and ended in 2012. Subjects were enrolled from 6 villages in Limpopo Province, South Africa, and DDT is currently in use for malaria control in 3 of them. Based on our experience with the women enrolled as of Feburary 1, 2011, we decided that the inital protocol (part 1) would not yield the required number of pregnancies, so the protocol was revised (part 2) and enrollment was resumed. We then determined that the protocol in part 2 would not succeed in enrolling a sufficient number of subjects, and we decided to halt the field work and abandon the effort to conduct the full study. 442 subjects were enrolled in part 1. About half of the enrolled subjects were from the villages sprayed with DDT. We sent the plasma specimens from the 442 subjects in part 1 to a laboratory for analysis of DDT levels. The DDT levels were surprizingly low, and we believe this may be partly because the malaria control teams had run out of DDT in recent years. We are still investigating the reasons for the low DDT levels. In addition, we had the plasma analyzed for other analytes, to determine if any subjects have evidence of DDT-related abnormalities in liver function tests or other clinical chemistries. We also measured blood carboxyhemoglobin concentrations in part 2, to see if our questionnaire-based assessment of exposure to indoor air pollution will be useful in future studies among the subjects in our study. In the past year we prepared a manuscript on determinants of exposure to DDT among women in the study. A major determinant was how the home was prepared before indoor residual spraying with DDT. A revised report about this finding has been sent to a journal for evaluation. We are now preparing a study about determinants of antimullerian hormone concentration in these subjects.