The environment poses a diverse range of health risks. Environmental burden of disease (EBD) studies try to estimate the impact of environmental stressors in terms of mortality or morbidity on a population level. Although environmental risks have been studied in Flanders, an effort to routinely quantify the environmental disease burden completely and coherently has thus far not been established. For this reason, Sciensano and Agentschap Zorg & Gezondheid are partnering up in a project to map the Environmental Burden of Disease in Flanders (EBoD-FL).
The aim of the research is to inventory the burden of disease attributable to all relevant environmental stressors according to a coherent framework. To tackle this objective, the disease burden attributable to environmental stressors is estimated using comparative risk assessment (CRA). As this method determines the attributable burden as a proportion of the total, figures for the recorded disease burden are required to obtain absolute numbers. In EBoD-FL, the EBD is quantified as disability-adjusted life years (DALYs), a summary measure that combines both mortality and morbidity.
Given the extensive list of potential stressor-health outcome pairs, a set of priorities was defined in terms of environmental stressors and health outcomes. The risk factors that will be studied first are those related to air quality, environmental noise and extreme temperature. In terms of outcomes, priority was given to all-cause mortality, respiratory diseases and cardiovascular diseases. This report outlines the CRA methodology in general, and applied to the risk factor-outcome pairs that have been given priority. The basic steps of CRA are:
- Selection of risk factors: Which risk factors are included in the study and how is exposure quantified as a metric?
- Exposure assessment: how to measure or model exposure to the risk factors in the population?
- Identification of stressor-outcome pairs: which health outcomes are caused by the risk factors?
- Quantification of the stressor-outcome relation: what is the risk of developing the outcome in function of exposure?
- Calculation of the population attributable fraction: what is the proportion of a disease burden attributed to one or multiple risk factors?
The purpose of this report is to outline the general methodology used to tackle the objective of EBoD-FL and to apply the CRA methodology to the stressors that are prioritized. Additionally, possibilities for the application of the results for evidence-based policy are explored, as well as some challenges and limitations.