Exposure and body burden of environmental pollution and risk of cancer in a historically contaminated areas

Sammanfattning: There are many villages where environmental contamination is substantial due to historical industrial activities. According to the European Environment Agency, there are about 2.5 million potentially contaminated sites in the European member states. In Sweden, there are about 80 000 more or less contaminated areas. About 1000 of them are classified into the highest risk category, Hazard Class 1, and should be remediated. Population exposure due to these industrially contaminated sites may contribute to adverse health effects and is a global environmental problem.The general aim of this thesis was to evaluate the occurrence of cancer in populations residing in contaminated areas in relation to indirect exposure via the long-term consumption of locally produced food, taking into account residential, occupational and lifestyle factors. Associations between reported local food consumption frequencies, biomarker concentrations and environmental and lifestyle factors were explored. The Swedish national cancer registers and questionnaire information was used to identify cancer risk groups in the study population. The questionnaire was evaluated regarding how well it reflected measured levels of biomarkers in human biological samples, and how the consumption of local food from contaminated areas contributed to the total body burden of contaminants.Despite historically high environmental levels of contaminants in the soil and sediments, current contaminant exposure in the studied population living in the contaminated areas was similar to or only moderately higher than that of the general population.No significant associations with increased cancer risk were detected in the highest tertile of metals concentrations in blood or PAH in urine.Reported long-term high consumption of certain local foods was associated with higher cadmium (vegetarian food) and lead (fish, meat) concentrations in blood and urine. Long-term high consumption of non-local food from places outside the study areas was not associated with increased concentrations of metals compared with consumers of local food. It was concluded that the questionnaire information on consumption of locally produced food describes differences in food consumption in the study population reasonably well.An increased risk of cancer was associated with smoking, family history of cancer and obesity. Residing in a contaminated area during the first five years of life was associated with an increased risk of cancer, which may indicate exposure to contaminants in early life. Also, long-term high consumption of particular local foods (fish, chicken, lamb, game meat) was associated with an increased risk of various forms of cancer, while reported high consumption of these foods from non-local sources was not associated with increased risk of cancer. The associations between habitual consumption of local food and different types of cancer may reflect a higher exposure in the past, and thus, if consumption of local food contributes to the risk of acquiring cancer, that contribution is probably lower today than previously. Furthermore, it cannot be ruled out that other contaminants in the food contribute to the increased cancer risks observed.In conclusion, the questionnaire that was developed for the present thesis can identify risk groups within populations and can be used as a tool in a health-risk assessment.