PubMed · 10772624
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H A Feng, P Schlecht. Proficiency Analytical Testing (PAT) Program. August 1999.. https://pubmed.ncbi.nlm.nih.gov/10772624/
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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.
Industrial and urban workers may be exposed to significant levels of air pollutants resulting from the incomplete combustion of organic matter. The authors performed a meta-analysis of 13 DNA-adduct studies ((32)P-DNA postlabeling technique) on occupational cohorts exposed to air pollution. The association between levels of DNA adducts and air pollution exposure was significant both in heavily exposed industrial workers and in less severely exposed urban workers. Moreover, in an analysis using the seven studies that reported measuring levels of benzo[a]pyrene (B(a)P), a typical marker of exposure, DNA adduct levels in exposed workers (versus those in referents) were significantly correlated with air levels of B(a)P. The relation between DNA adducts and B(a)P was found to be linear at low doses and sublinear at high doses, indicating that DNA adduct formation tends to reach some kind of saturation point at higher levels of exposure to the chemical mixtures present in fumes. When the authors examined the efficiency of DNA adduct production associated with increasing air pollution exposures, the production of DNA adducts per unit of exposure was significantly decreased at higher B(a)P exposure levels. These findings suggest that linear downward extrapolations based on DNA adduct levels associated with B(a)P concentrations of > or =20 ng/m(3) might be affected by underestimation bias.
The organic solvent trichloroethylene has been used in dry cleaning, as an industrial degreasing agent and as a solvent for oils and resins; large numbers of workers have been exposed to trichloroethylene, mainly by inhalation. Trichloroethylene has been categorised as a Group 2A carcinogen (probably carcinogenic to humans) by the International Agency for Research on Cancer (World Health Organization) and a Category 2 carcinogen (to be regarded as carcinogenic to humans) by the Australian National Industrial Chemicals Notification and Assessment Scheme. The Administrative Appeals Tribunal was asked to determine the validity of classifying trichloroethylene as a Category 2 rather than a Category 3 (data inadequate for making a satisfactory assessment) carcinogen. In the AAT's determination, relevant epidemiological evidence was not taken into account because such evidence concerned tumour sites apart from the kidney (the site of tumour induction by trichloroethylene in rats). This mode of evaluation is fundamentally different from that used by the International Agency for Research on Cancer. The precedent set by the consideration of carcinogenicity data in this case could have significant implications for classification of other putative carcinogens