Abstract
BackgroundTools for estimating population exposures to environmental carcinogens are required to support evidence-based policies to reduce chronic exposures and associated cancers. Our objective was to develop indicators of population exposure to selected environmental carcinogens that can be easily updated over time, and allow comparisons and prioritization between different carcinogens and exposure pathways.MethodsWe employed a risk assessment-based approach to produce screening-level estimates of lifetime excess cancer risk for selected substances listed as known carcinogens by the International Agency for Research on Cancer. Estimates of lifetime average daily intake were calculated using population characteristics combined with concentrations (circa 2006) in outdoor air, indoor air, dust, drinking water, and food and beverages from existing monitoring databases or comprehensive literature reviews. Intake estimates were then multiplied by cancer potency factors from Health Canada, the United States Environmental Protection Agency, and the California Office of Environmental Health Hazard Assessment to estimate lifetime excess cancer risks associated with each substance and exposure pathway. Lifetime excess cancer risks in excess of 1 per million people are identified as potential priorities for further attention.ResultsBased on data representing average conditions circa 2006, a total of 18 carcinogen-exposure pathways had potential lifetime excess cancer risks greater than 1 per million, based on varying data quality. Carcinogens with moderate to high data quality and lifetime excess cancer risk greater than 1 per million included benzene, 1,3-butadiene and radon in outdoor air; benzene and radon in indoor air; and arsenic and hexavalent chromium in drinking water. Important data gaps were identified for asbestos, hexavalent chromium and diesel exhaust in outdoor and indoor air, while little data were available to assess risk for substances in dust, food and beverages.ConclusionsThe ability to track changes in potential population exposures to environmental carcinogens over time, as well as to compare between different substances and exposure pathways, is necessary to support comprehensive, evidence-based prevention policy. We used estimates of lifetime excess cancer risk as indicators that, although based on a number of simplifying assumptions, help to identify important data gaps and prioritize more detailed data collection and exposure assessment needs.
Highlights
Tools for estimating population exposures to environmental carcinogens are required to support evidence-based policies to reduce chronic exposures and associated cancers
In keeping with the population-level focus of the CARcinogen EXposure (CAREX) mandate, we developed three guiding principles for developing indicators for surveillance of exposures to environmental carcinogens in Canada: (1) indicators should be based on regularly collected and available data, supporting ongoing surveillance over time; (2) indicators should consider a range of environmental media, including outdoor air, indoor air or dust, drinking water, and food and beverages; and, (3) indicators should allow for comparisons among substances, exposure pathways, populations and geographic locations in order to support prioritization and targeted prevention efforts
Substances with lifetime excess cancer risk (LECR) above 1 per million based on data of moderate to high quality may be targeted for more detailed risk assessments, such as those using probabilistic methods to better characterize the range of potential exposures given current measured levels
Summary
Tools for estimating population exposures to environmental carcinogens are required to support evidence-based policies to reduce chronic exposures and associated cancers. The International Agency for Research on Cancer has identified one hundred and nine environmental factors that can increase cancer risk in humans, including a range of chemicals and complex mixtures, exposure circumstances (i.e., certain occupations), physical agents (i.e., solar radiation), biological agents (i.e., certain viruses) and lifestyle factors (i.e., tobacco smoking) [1,2]. For some key lifestyle risk factors (e.g. diet, physical activity and smoking) estimates of prevalence and trends over time in the general population exist in Canada, for example through national health surveys [9]. Efforts focus on using existing data only This distinguishes CAREX Canada from exposure surveillance programs that take an active individual monitoring approach, for example the National Dose Registry [11]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
