Industrial pollution and mortality from digestive cancers at the small area level in a Spanish industrialized province

The province of Cadiz, Spain, is a highly industrialized area with numerous registered industrial plants, which has led to major concern regarding the possible influence of these facilities on the high rate of cancer-related mortality observed. Our objective was to evaluate the association between digestive cancer mortality and proximity to industrial installations in the province of Cadiz over the period 1992-2014 and to analyse this risk according to different categories of carcinogenic substances. An ecological study at the census tract level was carried out. Mortality due to digestive cancer (involving the oral cavity, pharynx, oesophagus, stomach, liver, pancreas, gallbladder, colon and rectum) was analysed. Using the spatial Besag, York and Mollié (BYM) approach, we assessed the relative risk of dying from these cancers for people living between 500 m and 5 km from industrial installations. The models were adjusted to account for socioeconomic deprivation. We detected a significant, excess risk of dying due to cancer in the following organs (expressed as relative risk with 95% confidence intervals): colon/rectum (1.13; 1.04-1.22 at 4 km), stomach (1.13; 1.00-1.29 at 2 km), liver (1.28; 1.02-1.61 at 1 km), pancreas (1.19; 1.03-1.39 at 2 km), oral and pharyngeal (1.40; 1.08-1.82 at 1 km), oesophagus (2.05; 1.18-3.56 at 500 m) and gallbladder (2.80; 1.14-6.89 at 500 m) for men; and from colorectal (1.21; 1.00-1.46 at 1 km), stomach (1.15; 1.01-1.31 at 4 km) and liver (1.58; 1.20- 2.07 at 1 km) cancers for women. The results support the hypothesis of an association between several digestive cancers and proximity to polluting industrial plants.