Biomonitoring of a population of Portuguese workers exposed to lead.
Lead is a heavy metal that has been used for many centuries and it is still used for various industrial purposes thanks to its physical and chemical characteristics. Human exposure to lead can result in a wide range of biological effects depending upon the level and duration of exposure. Despite the fact that lead has been found capable of eliciting genotoxic responses in a wide range of tests, not all studies have been conclusive. Although several experimental studies have shown that lead may modulate immune responses, data in exposed humans are still preliminary. The purpose of our study was to evaluate the genotoxic and immunotoxic effects of lead exposure in a group of 70 male workers from two Portuguese factories. The control group comprised 38 healthy males. The exposed individuals showed significantly higher levels of lead in blood and zinc protoporphyrin, and significantly lower δ-aminolevulinic acid dehydratase activity than the controls, suggesting a relatively high lead exposure. Nevertheless, the limit of 70 μg/dl for lead in blood established by the Portuguese regulation was never reached. Results of the comet assay were not modified by the exposure, but a significant increase in the mutation frequency in the exposed workers was obtained in the T-cell receptor mutation assay. Furthermore, data obtained in the analysis of the different lymphocyte subsets showed a significant decrease in %CD8+ cells and a significant increase in the %CD4+/%CD8+ ratio in exposed individuals with regard to the controls. No clear effect was observed for vitamin D receptor genetic polymorphism on the parameters evaluated. In view of our results showing mutagenic and immunotoxic effects related to lead exposure in occupational settings, it seems that the Portuguese biological exposure limit for lead needs to be revised in order to increase the safety of exposed workers.
Toxicology Unit, Department of Psychobiology, University of A Coruña, Edificio de Servicios Centrales de Investigación, Campus Elviña, 15071-A Coruña, Spain.
Julia
J
García-Lestón
Joana
J
Roma-Torres
Maria
M
Vilares
Rui
R
Pinto
Luís M
LM
Cunha
João
J
Prista
Joao Paulo
JP
Teixeira
Olga
O
Mayan
Eduardo
E
Pásaro
Josefina
J
Méndez
Blanca
B
Laffon
D000328:Adult; D020552:Comet Assay; D006801:Humans; D007109:Immunity / Q000187:drug effects*; D007854:Lead / Q000633:toxicity*; D016131:Lymphocyte Subsets / Q000187:drug effects; D008297:Male; D009153:Mutagens / Q000633:toxicity*; D016273:Occupational Exposure / Q000009:adverse effects*; D011174:Portugal
D009153:Mutagens; D007854:Lead