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Background: To study the changes of children lead exposure in the city of Torreon during the last five years, after environmental and public health interventions, using the timeline of lead in blood concentration as the biomarker of exposure and its relation to lead in soil concentrations., Methods: This follow-up study started in 2001 and consisted of 232 children living in nine neighborhoods in Torreon. Children were tested at 0, 6, 12 and 60 months. Lead in blood concentrations, Hemoglobin, Zinc-Protoporphyrin, anthropometric measures and socioeconomic status questionnaire was supplied to the parents., Results: Median and range of lead in blood concentrations obtained at 0, 6, 12, 60 months were: 10.12 μg/dl (1.9 - 43.8), 8.75 μg/dl (1.85 - 41.45), 8.4 μg/dl (1.7 - 35.8) and 4.4 μg/dl (1.3 - 30.3), respectively. The decrease of lead in blood levels was significantly related to ages 0, 6, 12 and 60 months of the follow-up study. The timeline of B-Pb was associated with the timeline of lead in soil concentrations., Conclusions: B-Pb levels have significantly decreased in the group of children studied. This could be explained by a) environmental interventions by authorities and the smelter companies, b) normal changes in hygienic habits as children age and c) lead redistribution from blood to hard tissues.

We evaluated environmental-lead (Pb) effects on semen quality and sperm chromatin, considering Pb in seminal fluid (PbSF), spermatozoa (PbSpz), and blood (PbB) as exposure biomarkers in urban men (9.3 microg/dL PbB). Several individuals (44%) showed decreases in sperm quality; sperm concentration, motility, morphology and viability associated negatively with PbSpz, whereas semen volume associated negatively with PbSF. Multiple linear regression estimated PbSF and PbSpz thresholds for alterations in semen quality. Forty-eight percent of samples showed high values of nuclear chromatin condensation (NCD) positively associated with PbSF and zinc in spermatozoa (ZnSpz). ZnSpz values were higher than in fertile men. These results suggest that Pb may affect sperm chromatin by altering sperm Zn availability. PbB was not associated with semen quality or NCD, suggesting that Pb in semen compartments assesses better the amount of Pb in the reproductive tract; therefore, these are better biomarkers to evaluate toxicity at low Pb-exposure levels.

Industrial growth has created the potential for environmental problems in Mexico, since attention to environmental controls and urban planning has lagged behind the pace of industrialization. The aim of this cross-sectional study was to assess lead exposure in children aged 6-9 yr attending 3 primary schools and living in the vicinity of the largest smelter complex in Mexico. One of the schools is located 650 m distant from a smelter complex that includes a lead smelter (close school); the second is located 1750 m away from the complex and at the side of a heavy traffic road (intermediate school) in Torreon, Coahuila. The third school is located in Comez Palacio, Durango, 8100 m away from the smelter complex and distant from heavy vehicular traffic or industrial areas (remote school). Lead was measured in air, soil, dust, and well water. Lead in blood (PbB) was determined in 394 children attending the above mentioned schools. Determinations were performed by atomic absorption spectrometry. Diet, socioeconomic status, hygienic habits, and other variables were assessed by questionnaire. Median (range) PbB values were 7.8 microg/dl (3.54-29.61) in the remote school, 21.8 microg/dl (8.37-52.08) in the intermediate school and 27.6 microg/dl (7.37-58.53) in children attending the close school. The percentage of children with PbB > 15 microg/dl was 6.80%, 84.9%, and 92.1% respectively. In this order, the geometric means (range) of Pb concentrations in air were 2.5 microg/m3 (1.1-7.5), 5.8 microg/m3 (4.3-8.5), and 6.1 microg/m3 (1.6-14.9). The Pb concentrations in dust from playgrounds areas in the intermediate and close school settings ranged from 1,457 to 4,162.5 mg/kg. Pb concentrations in drinking water were less than 5 microg/L. Soil and dust ingestion and inhalation appear to be the main routes of exposure. Our results indicate that environmental contamination has resulted in an increased body burden of Pb, suggesting that children living in the vicinity of the smelter complex are at high risk for adverse effects of lead.