Determinants of plasma DDT and DDE concentrations among South African Women exposed to indoor residual spraying for malaria control

摘要

Background/Aims: Determinants of internal exposure to DDT and DDE among people who live in homes sprayed with DDT for malaria control have been little-studied. Methods: This analysis includes 383 women aged 20-30 years enrolled in the South African Study of Women and Babies from 2010-2011 from 8 villages in Limpopo, of which indoor residual spraying (IRS) occurred in half. Information related to sociodemographics, reproduction, diet, housing, water, and items related to IRS (i.e. covering household items before IRS) were obtained as well as anthropometry and blood samples. Statistical Analysis: Analyses were conducted separately for women in unsprayed villages (N=176), women in IRS villages in households with a high likelihood of DDT use (N=107), and women in IRS villages in households with a low likelihood of DDT use (N=100). Plasma levels of DDT and DDE were natural log-transformed and multivariable models were fit, using forward stepwise selection. Lipid levels were forced into each model. Results: Median levels of DDT and DDE (μg/L) were: 0.9 (IQR:0.3-2.6) and 4.9(IQR:1.5-11.0). In unsprayed villages, women with water piped to the yard had 74% lower DDT levels and 60% lower DDE levels than women using a public tap. In IRS villages, in households with low likelihood of DDT use, no factor accounted for a majority of the variance in the DDT model and parity was the only determinant in the DDE model; parous women had lower DDE levels. In IRS villages, in households with a high likelihood of DDT use, owning livestock accounted for 95% higher DDT levels and 87% higher DDE levels. Discussion: The identification of primary determinants of DDT and DDE may inform targets for interventions aimed at decreasing exposure. In unsprayed villages, clean water may be such a target. Among households where DDT is likely to be used for IRS, raising livestock appears to be an important determinant of internal exposure.