Lead exposure in a population of Mexican children

Abstract

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 Torreón, Coahuila, México, and compared with 30 children living and studying 4.5 km from the same smelter (control population). Both populations had similar socio- economic conditions. The exposed population showed higher blood lead (PbB) and free erythrocyte protopor phyrin (FEP) concentrations (17.3 ± 5.6 μg dl^-1 and 53.9 ± 46.1 μg μl^-1, respectively) than controls (PbB, 6.4 ± 3.1 μg dl^-1 and FEP,13.9 ± 7.3 μg di^-1). PbB concen trations 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 popula tion was divided according to PbB into a high level lead group (PbB > 15 μg dl^-1), which also showed high FEP concentrations and a low lead group (PbB < 15 μg dl^-1). Clinically, the high lead group showed a greater incidence of general symptoms (colic, headache, paresthesia, myalgia and dizziness), impairment of some neuromus cular functions (neuromuscular conduction velocity and motor coordination) and a decrease of intelligence quotient (IQ), which was not related with sex or socio- economic status. These results are an evidence of morbidity in children with high PbB concentrations.