Challenges in Creating Evidence in Environmental Health Risk Assessments: The Example of Second-Hand Smoke

Public health interventions are directed to influence the (state of a) risk factor, either by behavioral or environmental changes. Therefore, environmental health risk assessments are highly relevant for public health decision making and policy development. The credibility of an environmental health risk assessment depends, to a large extent, on the strength of the scientific evidence on which it is based. In this article, the main challenges for assessing the impact of a potential adverse health effect from an environmental pollutant are described. Second-hand smoke (SHS) was chosen to illustrate the current state of evidence. The assessment of the impact of potential adverse health effects from environmental risk factors is dependent on several issues, such as the hypothesized health outcome, the nature of the exposure, the dose-response-relationship and the variability and susceptibility of the exposed population. The example of SHS exposure highlights the need for evidence-based public health. Several challenges in terms of study design, assessment methods, as well as data analysis and synthesis with respect to the stratification of results, and consideration of bias and confounding exist. Future research needs to take into account which methods and techniques will be used to generate evidence for population-level decisions.