DDT compounds are used in many developing countries, including South Africa, for the control of
malaria vectors. This study investigated
biological exposures among workers in relation to job history. A cross-sectional study of 59 workers at the
Malaria Control Centre (MCC) in Tzaneen, South Africa, was performed. Tests included a job history questionnaire and the measurement of serum o'p' and p'p' isomers of
DDE,
DDT, and
DDD, corrected for serum total
lipids. Forty-seven (80%) workers donated a blood sample for the determination of serum
DDT. The mean number of years worked at the MCC (
malaria years) was 15.8+/-7.8 years and the mean serum
DDT was 94.3+/-57.1 microg/g of
lipid. There were no significant associations between short-to-medium-term serum
DDT exposure measures (
o'p'-DDE and o'p' and p'p' isomers of
DDD and
DDT) and
malaria years. The long-term exposure measure,
p'p'-DDE, was significantly associated with
malaria years (beta=3.0+/-1.2 microg/g
lipid/year; P=0.001; n=47; adjusted for age), but only 27% variance of
p'p'-DDE was explained. Blood total
DDT uncorrected for
lipid content was strongly related to corrected levels (B=0.74+/-0.48, P=0.00, R2=0.77), but uncorrected
p'p'-DDE had a weaker association (B=0.0024+/-0.0013, P=0.074; R2=0.53) with
malaria years than did corrected levels (beta=0.042+/-0.017; P=0.016; R2=0.56). The results show that serum
DDT levels for
malaria vector-control workers in South Africa with a long-term spraying history are high. Job history information on
DDT exposures must be very detailed in order to provide valid estimates of exposure.