Incidence of cancer among persons living near a municipal solid waste landfill site in Montreal, Québec

Abstract

The Miron Quarry municipal solid waste landfill site in Montreal, Québec, generates copious quantities of methane and other gases, including a rich mixture of volatile organic compounds, some of which are recognized or suspected human carcinogens. The site is the third largest in North America and is located in the center of a densely populated area. Using data from the Québec Tumour Registry, we conducted Poisson regression analyses to evaluate whether cancer incidence among persons who lived near the site was higher than expected. Potential exposure to ambient air pollutants from the site was defined in terms of a set of geographic exposure zones proximal to the site. A set of reference areas distal from the site was selected to be similar to these exposure zones with respect to several key sociodemographic factors. Risk ratios (RRs) were adjusted for age and calendar year. Among men living in the exposure zone closest to the site, elevated risks were observed for cancers of the stomach (RR = 1.3, 95% confidence interval [95% CI] = 1.0-1.5); liver and intrahepatic bile ducts (RR = 1.3, 95% CI = 0.9-1.8); and trachea, bronchus, and lung (RR = 1.1, 95% CI = 1.0-1.2). Among women, rates of stomach cancer (RR = 1.2; 95% CI = 0.9-1.5) and cervix uteri cancer were elevated (RR = 1.2, 95% CI = 1.0-1.5), but breast cancer incidence was less than expected (RR = 0.9, 95% CI = 0.9-1.0). Prostate cancer was also elevated in one of the proximal exposure subzones (RR = 1.2, 95% CI = 1.0-1.4). Further studies at this and at other landfill sites are needed to confirm or refute these observations.