| High Concentrations of Heavy Metals in Neighborhoods Near Ore Smelters in Northern Mexico Andrea L. Benin,1 James D. Sargent,1 Madeline Dalton,1 and Sandy Roda2 1Dartmouth-Hitchcock Medical Center Department of Pediatrics, Dartmouth Medical School, Lebanon, NH 03766 USA
2Kettering Laboratory, Department of Environmental Health, University of Cincinnati, Cincinnati, OH 45221 USA Abstract
In developing countries, rapid industrialization without environmental controls has resulted in heavy metal contamination of communities. We hypothesized that residential neighborhoods located near ore industries in three northern Mexican cities would be heavily polluted with multiple contaminants (arsenic, cadmium, and lead) and that these sites would be point sources for the heavy metals. To evaluate these hypotheses, we obtained samples of roadside surface dust from residential neighborhoods within 2 m of metal smelters [Torreón (n = 19) ] and Chihuahua (n = 19) ] and a metal refinery [Monterrey (n = 23) ]. Heavy metal concentrations in dust were mapped with respect to distance from the industrial sites. Correlation between dust metal concentration and distance was estimated with least-squares regression using log-transformed data. Median dust arsenic, cadmium, and lead concentrations were 32, 10, and 277 µg/g, respectively, in Chihuahua ; 42, 2, and 467 µg/g, respectively, in Monterrey, and 113, 112, and 2,448 µg/g, respectively, in Torreón. Dust concentrations of all heavy metals were significantly higher around the active smelter in Torreón, where more than 90% of samples exceeded Superfund cleanup goals. At all sites, dust concentrations were inversely related to distance from the industrial source, implicating these industries as the likely source of the contamination. We concluded that residential neighborhoods around metal smelting and refining sites in these three cities are contaminated by heavy metals at concentrations likely to pose a health threat to people living nearby. Evaluations of human exposure near these sites should be conducted. Because multiple heavy metal pollutants may exist near smelter sites, researchers should avoid attributing toxicity to one heavy metal unless others have been measured and shown not to coexist. Key words: arsenic, cadmium, industrial pollution, lead, metal smelter, Mexico. Environ Health Perspect 107:279-284 (1999) . [Online 10 March 1999] http://ehpnet1.niehs.nih.gov/docs/1999/107p279-284benin/ abstract.html Address correspondence to J.D. Sargent, Pediatrics and Adolescent Medicine, Dartmouth-Hitchcock Medical Center, Lebanon, NH 03756 USA. This study was supported by an American Academy of Pediatrics resident research grant and a Helen's Fund grant from the Department of Pediatrics, Dartmouth-Hitchcock Medical Center. Received 31 August 1998 ; accepted 29 December 1998.
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