Levels of dichlorodiphenyltrichloroethane and deltamethrin in humans and environmental samples in malarious areas of Mexico.

Mexico used dichlorodiphenyltrichloroethane (DDT) to control malaria until 1999, when it was replaced with deltamethrin for mosquito control. Thus, we performed environmental and exposure assessments to DDT and deltamethrin in the states of Chiapas and Oaxaca. In Chiapas, samples were obtained at the time when DDT was being used in the malaria control program, while in Oaxaca, samples were collected 2 years after the final spraying of DDT and 2 days after deltamethrin application. Mean concentrations of DDT and Dichlorodiphenyldichloroethylene (DDE), as measured in whole blood, were 67.8 and 86.7 microg/L for children living in Chiapas and 27.1 and 60.8 microg/L for adults, respectively. As expected, DDT levels were lower 2 years after the final application in Oaxaca (20.4 and 13.2 microg/L for children and adults, respectively). Sprayers in Chiapas had the highest levels of exposure, with 165.5 and 188.4 microg/L of DDT and DDE, respectively. Women living in Chiapas and Oaxaca also had significantly higher blood levels of DDT and DDE than those women living in areas where less DDT had been used. Deltamethrin exposure was assessed only in children living in Oaxaca; 50% of the exposed group had urinary levels of 3-phenoxybenzoic acid above the limit of detection (LOD) and 6% had levels above 25 microg/L (five times the LOD), with a negative trend with age (r=-0.33). In Chiapas we found higher DDT and DDE levels in soil than in Oaxaca. In the latter location, large amounts of DDT and DDE were found in sediment samples and deltamethrin was detected in indoor soil samples. Considering the environmental data, the blood level results can be explained by soil/dust ingestion, human milk ingestion, and consumption of fish and other contaminated foods. (c) 2002 Elsevier Science (USA).