Mortality due to tumours of the digestive system in towns lying in the vicinity of metal production and processing installations

Background

Releases to the environment of pollutants from industrial metal production and processing installations can pose a health problem to humans, owing to the toxic substances that such emissions contain.

Objectives

To investigate whether there might be excess mortality due to tumours of the digestive system among the population residing near Spanish metal production and processing installations included in the European Pollutant Emission Register.

Methods

Ecological study designed to examine mortality due to malignant tumours of the digestive system (oral cavity and pharynx, oesophagus, stomach, pancreas, liver, gallbladder, and colon-rectum) at the municipal level, over the period 1994-2003. Population exposure to pollution was estimated on the basis of distance from town of residence to the pollution source. Using mixed Poisson regression models, we analysed: risk of dying from cancer in a 5-kilometre zone around installations by year of commencement of operations; effect of pollution discharge route (air or water) and type of industrial activity; and risk gradient within a 50-kilometre radius of such installations.

Results

Excess mortality (relative risk, 95% confidence interval) was detected in the vicinity of pre-1990 installations for colorectal cancer (1.05, 1.02-1.08 in men; 1.04, 1.00-1.07 in women) and liver cancer (1.06, 1.00-1.12 in men), with this risk being concentrated in installations that released pollution to air. On stratifying by type of industrial activity, statistically significant associations were also observed between the remaining tumours and certain metal production and processing activities. There was also a gradient effect in the proximity to a number of installations.

Conclusions

The results support the existence of an association between risk of dying due to some tumours of the digestive system and residential proximity to the Spanish metal production and processing installations studied.