Workshop Report: Environmental Exposures and Cancer Prevention. (Workshop Report)
Kreiger, Nancy, Ashbury, Fredrick D., Purdue, Mark P., Marrett, Loraine D., Environmental Health Perspectives
The Workshop on Environmental Exposures and Cancer was held by Cancer Care Ontario (CCO) 25-26 April 2001. An expert panel convened to achieve consensus on a list of important environmental exposures, priority environmental exposures in Ontario, and recommendations for CCO in the areas of surveillance, research, and prevention activities to address these environmental exposures. Panel members developed a working definition of environmental exposure and criteria to prioritize the identified exposures. The process followed in the workshop provided CCO with important direction for its surveillance, research, and prevention activities to address environmental exposures and cancer. It is hoped that the environmental exposures and the opportunities identified through this workshop process will guide policy makers, program personnel, and researchers interested in and struggling with the challenges associated with surveillance, research, and prevention of environmental exposures. Key words: cancer control, environment, exposure, prevention, research, risk, surveillance. Environ Health Perspect 111:105-108 (2003). [Online 9 December 2002]
doi: 10.1289/ehp.5384 available via http://dx.doi.org/
Cancer is the second leading cause of death in Ontario after cardiovascular diseases. The National Cancer Institute of Canada estimates that in Ontario 50,200 men and women will be diagnosed with, and 23,800 people will die from, cancer in 2001 (1). As the population grows and ages, and as techniques to detect cancer in its early stages are more systematically applied and improved, the number of people diagnosed with cancer will continue to rise. It has been estimated that, if current trends continue, the number of new cancer cases will increase by 40% by the year 2010 (2). Unless mortality rates for cancer decline as significantly as they have for cardiovascular diseases, cancer will likely become the leading cause of death in Ontario within a few decades.
Given the challenges that exist in treating cancer effectively (3), prevention strategies represent an essential part of cancer control. Effective prevention initiatives can decrease cancer incidence and mortality by [greater than or equal to] 50% (4). The potential benefits of prevention initiatives are underscored by the knowledge that most cancers are caused by "environmental" (i.e., nongenetic) factors. The majority of such cancers are attributed to behavioral and lifestyle factors, viral agents, occupational exposures, and dietary factors. The proportion of cancers attributable to agents found in our physical environment (e.g., environmental pollutants, ionizing and nonionizing radiation) has been estimated to be relatively small, < 5% of all cancers (5).
This comparatively low estimate of attributable risk should be interpreted with caution, however, in light of the methodologic problems of epidemiologic studies in assessing the impact of environmental exposures and cancer risk--most notably problems in exposure measurement and identification of adequate control populations (6). The attributable risk of some environmental exposures will also be greater among some segments of the population, including those with gene polymorphisms that may leave them more susceptible to exposure effects. Moreover, the health risks of environmental contaminants are not limited to cancer risk.
Despite their seemingly low impact on the overall burden of cancer, environmental contaminants and ionizing and nonionizing radiation are a source of great concern to the general public. In a 1992 survey by Health Canada (7), > 90% of respondents believed that the air, water, and land were more contaminated than ever before, and > 75% responded that strict environmental regulation should continue. Survey respondents indicated a high level of concern over chemical products, pollution, nuclear waste, and ozone depletion and an unwillingness to accept some health risks to aid the economy. …