Health and the environment : assessing the impacts, addressing the uncertainties

Abstract

Environmental health problems have become increasingly complex. Climate change, increased urbanization or exposure to electromagnetic fields are highly divergent examples of issues about which no scientific consensus exists, for which no straightforward solutions are available and which are embedded in a wide societal context. It is challenging to assess the health impacts of such so-called “systemic risks”. Integrated Environmental Health Impact Assessment (IEHIA) has been proposed as a set of methods to deal with systemic risks in environmental health. IEHIA includes, amongst others, methods to take account of complexities and uncertainties, potential indirect effects, effects in the far future, and stakeholder perspectives. This thesis presents some methods that can be applied in IEHIA, illustrated with example applications. As such, it makes insights from other disciplines relevant and practicable for environmental health researchers. The methods that are being described include (1) the use of conceptual frameworks, (2) the selection and presentation of indicators, (3) dealing with uncertainties and (4) methods for expert elicitation. (1) Conceptual frameworks are –often graphical- representations of the issues that are being assessed and the relationships between the various elements in IEHIA. These frameworks may for example show the links between the driving forces of environmental problems, the exposure in the population and the subsequent health or economical effects. We distinguish different types of conceptual frameworks and illustrate their potential uses in IEHIA. (2) Indicators are used to communicate the results of IEHIA. They present the relevant outcomes of an assessment in a clear and effective way. This thesis provides guidelines for the selection and presentation of indicators. (3) Uncertainty is an important and often partly ignored element in assessments. Uncertainties can be expressed quantitative of qualitative, derive from natural variation or lack of knowledge, involve the boundaries of the assessment or a specific model parameter, etc. A typology of uncertainty is presented which can be used to characterize different types of uncertainties. It points into directions for dealing with these uncertainties and is illustrated using examples from environmental burden of disease studies. (4) Expert elicitation can be a tool to deal with uncertainties, in case no further empirical evidence can easily be derived. We describe a structured stepwise approach towards organizing a formal expert elicitation. Customization of these steps for specific applications is necessary, based on the types of uncertainties considered, the intended use of the elicited information, and the available resources. The expert elicitation procedure is applied in the context of impact assessment of ultrafine particles (UFP), the smallest fraction of air pollution. Opinions of twelve leading European scientists have been elicited about (1) the health effects considered to be causally related to exposure to UFP; (2) the potential causal mechanisms that underlie UFP-related cardiovascular effects and (3) the concentration-response functions that quantitatively describe the effect of UFP on a variety of health endpoints. Finally, all the methods outlined above are discussed in the context of the need for further development of IEHIA methods and the limitations and potential benefits of the methodology