Modeling Potential Benzene Exposure and Cancer Risk to Nearby Residences from Increased Road Traffic along a Truck Route in Edmonton, Alberta

摘要

Edmonton is located in central Alberta with a metropolitan population in excess of one million people. Prior to Canadian economic activity slowing down during the latter part of 2008, the City was expected to achieve an annual growth rate ≥2% over the next five years. Poor air quality is recognized by the public as having a potential to negatively affect health and well being. Although automobile-related emissions are acknowledged as the largest single source of air pollutants in urban areas, the indoor environment is recognized as a much more important source of human inhalation exposure to benzene. An assessment of potential benzene exposure and cancer risk was undertaken for residences adjacent to a truck route from increased road traffic between 1999 and 2007. Of interest was whether or not benzene emissions from road traffic would be important from a public health perspective taking into account amounts of benzene exposure humans typically receive at their residence. Vehicle counts along the truck route recorded by City of Edmonton and emission factors developed by Environment Canada’s Urban Transportation Emissions Calculator model were used to estimate benzene vehicle emissions. A Gaussian dispersion model was used to estimate benzene concentrations downwind. The method for estimating exposure requires information on attributable exposure concentrations in two residential locations (indoors and outdoors) and information on average time spent in these locations. Annual incremental risk of cancer (leukemia) for residents along the truck route ranged from 0.003 to 0.012 per 100,000 for both model years. This range is very small in relation to a measure of the actual incidence of leukemia in Alberta (10.4 per 100,000).