Quantifying the health burden of environmental stressors

Abstract The Burden of Disease (BoD) concept has gained increasing importance for health risk assessments, driven by the World Health Organization (WHO) and the Global Burden of Disease (GBD) studies. BoD utilizes the disability-adjusted life year (DALY) to express the population health impact of a disease, injury or risk factor. This information is essential for priority-setting in health, monitoring and evaluation of preventive interventions. However, calculating DALYs, particularly DALYs attributable to risk factors, requires a range of choices with regards to input data and methodological aspects. In this presentation we will focus on comparative risk assessment (CRA), a frequently used method to calculate the attribution of DALYs to risk factors. CRA consists of determining outcomes that are associated with a certain risk factor and relative risks of the identified outcomes as a function of exposure. This information is usually derived from systematic literature review(s). Next, information on the level of exposure in a population is required, usually by age, sex, location and/or year, and usually using a range of data sources on level of exposure. Additionally, the level of exposure associated with a minimum risk is assessed. Population attributable fractions (PAFs) are then multiplied by the relevant outcome quantity for each population subgroup to calculate the number of DALYs attributable to risk factors. Finally, mediation of risk factors through other risk factors can be taken into account. Knowledge of and uniformity in methods used to perform CRAs will facilitate the coherence and usability of estimates of the health impacts of risk factors and strengthen evidence-based decision-making in health policy. In this presentation, we will introduce the CRA approach and outline a number of innovations that are being driven by the BEST-COST project, including new methods for correlated outdoor exposures and for outdoor exposures penetrating to indoor environments.