Controlling Environmental Causes of Cancer

Abstract

Controlling the environmental causes of cancer requires a coordinated effort for the identification of exposed populations, particularly in low-income countries, and for effective primary prevention policies. Examples of common environmental carcinogens are aflatoxins, heavy metals, PCBs and dioxins. However, reducing exposure to chemicals identified as human carcinogens (through epidemiological studies) is not enough. Given the limitations of epidemiology, we also need to rely upon animal experiments. The total burden of cancers due to environmental exposures (pollutants, i.e. excluding personal behaviours such as tobacco smoking and infectious agents) is currently unknown. Estimates vary widely, from 3 % to 19 %. Such variation is due both to the use of different criteria in defining the environment and to different interpretations of the results of the literature. However, in spite of these uncertainties, millions of cancers could be prevented by cleaning the general environment, particularly in low-income countries. Also, prevention is characterized by the fact that people benefiting from prevention may be more than those to whom we address interventions. For example, because of herd immunity people who are not vaccinated derive benefit, and similar cumulative advantages can be achieved with reduction of exposure to environmental carcinogens.