Lead exposure in a population of Mexican children

The effects of low lead exposure were investigated in 98 children (7-12 years old) living and studying within a 1 km radius of a lead smelter (exposed population) located in Torreon, Coahuila, Mexico, and compared with 30 children living and studying 4.5 km from the same smelter (control population), Both populations had similar socioeconomic conditions. The exposed population showed higher blood lead (PbB) and free erythrocyte protoporphyrin (FEP) concentrations (17.3 +/- 5.6 mu g dl(-1) and 53.9 +/- 46.1 mu g dl(-1), respectively) than controls (PbB, 6.4 +/- 3.1 mu g dl(-1) and FEP, 13.9 +/- 7.3 mu g dl(-1)). PbB concentrations were inversely correlated to distance from the smelter (r(2) = 0.494). However, in the exposed population, wind direction also had a significant effect on the PbB and urinary lead (PbU) concentrations, The exposed population was divided according to PbB into a high level lead group (PbB > 15 mu g dl(-1)), which also showed high FEP concentrations and a low lead group (PbB < 15 mu g dl(-1)). Clinically, the high lead group showed a greater incidence of general symptoms (colic, headache, paresthesia, myalgia and dizziness), impairment of some neuromuscular functions (neuromuscular conduction velocity and motor coordination) and a decrease of intelligence quotient (IQ), which was not related with sex or socioeconomic status, These results are an evidence of morbidity in children with high PbB concentrations.