Spatio-temporal patterns of bladder cancer incidence in Utah (1973-2004) and their association with the presence of toxic release inventory sites

The time trend of bladder cancer risk fluctuated over the study period: A steady decrease was observed, followed by an abrupt increase from 1992 to 2004. Using a Bayesian space-time model, 93 census tracts were classified as having an excess relative risk and 81 a lower relative risk, sustained over the 32 years. We showed that these high relative risk areas for bladder cancer were associated with the presence of Toxic Release Inventory sites, after adjusting for the proportion of Latter-Day Saint Church members as an area level proxy for smoking habits.Our study has demonstrated that the modeling of data in time and space has additional benefits over a purely spatial analysis. In addition to highlighting the areas with high and low relative risks, this model also allows the simultaneous study of persistency of spatial patterns over time and detection of 'unusual' time trends that may warrant further investigation.Bladder cancer (ICD10 C67) accounts for approximately two-thirds of all urinary tract cancers and is the ninth most common cancer worldwide [1]. In the US, bladder cancer is the fourth most frequent tumor in men and the eighth in women [2]. US time trends for the period 1975-2004 showed an initial increase (1975-1987) followed by stable rates from 1987 to 2004 [3].Tobacco smoking and occupational exposure to aromatic amines are the two major established risk factors for bladder cancer [4-6]; age, gender and dietary habits have been shown to influence bladder cancer risk. Environmental factors have also been linked to the risk of bladder cancer [7], especially exposure to chemical components, such as volatile organic compounds (VOC), released in the air by industrial processes [8]. In the US, facilities that release chemicals must report annually their toxic release inventory (TRI) information to the US Environmental Protection Agency (EPA) and to the State in which they are located [9]. The database contains detailed information on nearly 650 chemicals and