title: Exploration of different methods for measuring DDT exposure among malaria vector-control workers in Limpopo Province, South Africa.
abstract: 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.
authors.affiliation: Occupational and Environmental Health Research Unit, School of Public Health and Family Medicine, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory, 7925 Cape Town, South Africa. aqiel@cormack.uct.ac.za
authors.forename: Mohamed A
authors.initials: MA
authors.lastname: Dalvie
authors.forename: Jonathan E
authors.initials: JE
authors.lastname: Myers
authors.forename: Mary Lou
authors.initials: ML
authors.lastname: Thompson
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Robins
authors.forename: Shaheed
authors.initials: S
authors.lastname: Omar
authors.forename: John
authors.initials: J
authors.lastname: Riebow
mesh_terms: D000818:Animals; D001774:Blood Chemical Analysis / Q000379:methods; D003430:Cross-Sectional Studies; D003634:DDT / Q000097:blood*; D004784:Environmental Monitoring / Q000379:methods*; D006801:Humans; D008288:Malaria / Q000517:prevention & control; D008297:Male; D009032:Mosquito Control; D016273:Occupational Exposure / Q000009:adverse effects*; D011237:Predictive Value of Tests; D013019:South Africa; D011795:Surveys and Questionnaires
chemical_list: D003634:DDT