Residential proximity to petroleum storage tanks and associated cancer risks: Double Kernel Density approach vs. zonal estimates

Background and aims: The relationship between exposure to petroleum products and cancer is well-established in occupational studies carried out among employees of transportation and oil-producing industries. However, question remains whether living near petroleum storage facilities may represent a cancer risk. In the present study, we examined cancer incidence rates associated with residential proximity to the Kiryat Haim industrial zone in Northern Israel, using different analytical techniques and adjusting for several potential confounders, such as road proximity, population density, smoking rates and socio-demographic attributes. Methods: Both traditional zonal approaches and more recently developed Double Kernel Density (DKD) tools were used to estimate relative risks of lung and NHL cancers attributed to residential proximity to the petroleum storage site. Results: Zonal approaches based on comparing ASRs across small census areas (SCAs) did not detect any significant association between residential proximity to the industrial zone and the two types of cancers under study (P > 0.2). In contrast, the DKD approach revealed that the relative density of both lung and NHL cancers declined in line with distances from the industrial zone, especially among the elderly (Lung: t > - 12.0; P < 0.01; NHL: t > - 9.0; P < 0.01), adjusted for proximity to main roads, population density, smoking rate, average income, and several other potential confounders. Conclusions: Living near petroleum storage sites may represent significant cancer risk which cannot always be detected by traditional zonal approaches commonly used in epidemiological studies, especially if the number of census areas available for the analysis is small.