Evaluation of organochlorine pesticide residues in human serum from an urban and two rural populations in Portugal.

Organochlorine pesticide residues were measured in human serum from an urban and two rural populations in Portugal, in an attempt to evaluate the contamination level of Portuguese population. Serum levels of 12 residues were determined using a validated methodology that included gas chromatography-electron-capture detection. It was made an attempt to point out the differences of contamination between rural and urban populations; and among these, if it could be established a relation with sex and with age of individuals. p,p'DDE, alpha-hexachlorocyclohexane (HCH), p,p'DDD, and beta-HCH were the most frequently identified residues. p,p'DDE concentrations ranged from undetected to 390.5 microg/l in urban samples, and from undetected to 43.5 microg/l and to 171.2 microg/l in both rural samples. Maximum alpha-HCH concentration level was 114.4 microg/l in urban samples, 261.3 and 45.5 microg/l in both rural samples. Mean total DDT levels were always higher than mean total HCH levels. About p,p'DDE, in all three populations, the majority of the results above the limit of quantification were found among female sex. The analysis of different aged groups showed that younger groups continue to reveal contamination. Comparing obtained results with others from Europe, Asia and America, it was observed that Portugal is between the highest levels of contamination.