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

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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.