Assessing and evaluating the health impact of environmental exposures

Abstract

Never in our Western-European history we have been as healthy as we are now. Until the 20th century the (physical) environment was the source of 70-80 percent of disease burden, nowadays, environmental factors probably contribute less than 5%, while life-style is responsible for the bulk of the current avoidable disease burden (around 25% of total). The impact of environmental exposures no longer predominantly involves clear mortality risks or loss of life expectancy, but comprises aspects of the quality of life in a broad sense as well: aggravation of pre-existing disease symptoms, social-psychological endpoints, such as severe annoyance, sleep disturbance, and unfavourable health perceptions and stress in relation to a poor quality of the local environment. We investigated an important instrument of collective health protection: risk assessment and management. We established that in principle any decent government should apply rights-based decision rules in environmental risk policy, guaranteeing every citizen an equal right to a certain level of protection or health care. However, we have also seen that purely right-based policies may go beyond the bounds of efficiency or affordability. To deal with risk as a 'social construct', as well as with equity versus efficiency trade-offs, we tentatively propose a typology of risk problems with matching procedures of increasing comprehensiveness, comprising 1) 'business as usual', traditional, quantitative analysis and management, 2) appropriate and proportional use of 'scarce resources', 3) a way out when 'calculations are simply not the issue', or 4) wisdom, when 'ignorance' is recognised in time. Procedures involve decision rules, goals, solutions, strategies (discourse) and instruments. To analyse environmental health impact in a more comparative manner, aggregating the divergent health effects associated with different types of environmental exposures, we explored the application of DALYs as some sort of 'public health currency'. The DALY is an aggregate indicator of disease burden (health loss). It integrates three important dimensions of public health, viz. life expectancy, quality of life, and number of people affected. Time is the unit of measurement: 'healthy life years' are either lost by premature death, or by loss of quality of life, measured as discounted life-years within a population. Using data from the Dutch National Environmental Outlook we estimated that the long-term effects of particulate air pollution appear to account for the greater part of the total environment related health loss in the Netherlands. Furthermore, the indoor environment appeared to be an important source of disease burden (radon, dampness, environmental tobacco smoke). Provisional calculations of monetarised health loss due to environmental exposures indicate ample opportunities for cost efficient investments in environmental quality from the perspective of public health. We applied GDP per capita, WTP-estimates, and disease group specific costs of illness to roughly approach the monetary value of environment related mortality and morbidity, respectively. The credibility as well as the transparency of this type of analyses should be improved by means of systematic peer review and involvement of stakeholders in the definition of the framework for CEA and CBA.