Abstract:
The insecticide DDT is still used in specific areas of South Africa for indoor residual spray (IRS) to control
malaria vectors. Local residents could be exposed to residues of DDT through various pathways including
indoor air, dust, soil, food and water. The aims of this study were to determine the levels of DDT
contamination, as a result of IRS, in representative homesteads, and to evaluate the possible routes of human
exposure. Two villages, exposed (DV) and reference (TV) were selected. Sampling was done two months
after the IRS process was completed. Twelve homesteads were selected in DV and nine in TV. Human serum,
indoor air, floor dust, outside soil, potable water, leafy vegetables, and chicken samples (muscle, fat and
liver) were collected and analyzed for both the o,p′- and p,p′-isomers of DDT, DDD and DDE. DDT was
detected in all the media analyzed indicating a combination of potential dietary and non-dietary pathways of
uptake. DV had the most samples with detectable levels of DDT and its metabolites, and with the exception
of chicken muscle samples, DV also had higher mean levels for all the components analyzed compared to TV.
Seventy-nine percent of participants from DV had serum levels of DDT (meanΣDDT 7.3 μg g−1 lipid). These
residues constituted mainly of p,p′-DDD and p,p′-DDE. ΣDDT levels were detected in all indoor air (mean
ΣDDT 3900.0 ng m−3) and floor dust (meanΣDDT 1200.0 μg m−2) samples. Levels were also detected in
outside soil (mean ΣDDT 25.0 μg kg−1) and potable water (mean ΣDDT 2.0 μg L−1). Vegetable sample
composition (meanΣDDT 43.0 μg kg−1) constituted mainly p,p′-DDT and p,p′-DDD. Chicken samples were
highly contaminated with DDT (muscle mean ΣDDT 700.0 μg kg−1, fat mean ΣDDT 240,000.0 μg kg−1,
liver mean ΣDDT 1600.0 μg kg−1). The results of the current study raise concerns regarding the potential
health effects in residents living in the immediate environment following DDT IRS.
