World Health Organization WHO/UNEP/ILO International Programme on Chemical Safety
Over the last two decades, concerns about the potential health and ecological impacts of exposure to endocrine disrupting chemicals (EDCs) have led to the establishment of new, multi-stakeholder research and testing initiatives, committees, expert groups, newsletters, databases, etc., throughout the world. In addition to generating an influx of new data, these activities have catalyzed a number of scientific controversies. Controversies range from how to spell, define, and detect "endocrine disrupters" to whether adverse effects observed in wildlife and humans are due to EDC exposures (at levels found in general populations) or other causes. Despite a lack of scientific consensus, this tidal wave of activity has significantly advanced our understanding of the scope and magnitude of risks posed by EDCs. Nevertheless, as the perceptive article by Daston et al. (2003; this issue) indicates, many genuine uncertainties remain and key questions continue to go unanswered.
The recent "Global Assessment of the State-of-the-Science of Endocrine Disruptors" (Damstra et al., 2002), published (with input from over 60 independent, international scientific experts) by the WHO/UNEP/ILO International Programme on Chemical Safety (IPCS), concluded that:
Overall the biological plausibility of possible damage to certain human functions; (particularly reproductive and developing systems) from exposure to EDCs seems strong when viewed against the background of known influences of endogenous and exogenous hormones on many of these processes. Furthermore, the evidence of adverse outcomes in wildlife and laboratory animals exposed to EDCs substantiates human concerns. The changes in human health trends in some areas for some outcomes are also sufficient to warrant concern and make this area a high research priority, but non-EDC mechanisms also need to be explored. (Damstra et al., 2002, p. 3)
In addition to its global perspective, the WHO assessment was unique in that it developed a weight-of-evidence framework utilizing objective criteria to evaluate causality between exposure to EDCs and particular health outcomes.
Why then, despite a wealth of scientific expertise and enthusiasm, and an estimated 150 million U.S. dollars devoted annually to EDC-related research and testing programs globally, is there continuing uncertainty, controversy, and lack of scientific consensus? My personal view is that in a number of cases, past EDC-related research suffered from "blurred" vision, which can lead to distorted interpretations of the data. Now is an opportune time for a vision check and a new pair of lenses. I propose that, at minimum, our refocused vision needs the following characteristics:
In summary, studies on EDCs need to focus on many components at many different levels. Multilevel, multidisciplinary approaches can lead to insights not possible from narrow viewpoints. Only through a weight-of-evidence approach will we be able to address causal associations of exposure to complex mixtures of contaminants to health outcomes (which are often subtle, and may take years to develop). The challenges facing the international research, industry, and regulatory community in assessing risks posed by EDCs are enormous and require the commitment, expertise, and resources available throughout the world.
The WHO/UNEP/ILO IPCS is committed to a continuing evaluation of scientific developments in this field, to addressing the global implications of the data, and to promoting international collaboration and coordination.
REFERENCES
Damstra, T., Barlow, S., Bergman, A., Kavlock, R., and Van der Kraak, G. (2002). Global Assessment of the State-of-the-Science of Endocrine Disruptors. WHO publication no. WHO/PCS/EDC/02.2. World Health Organization, Geneva, Switzerland.
Daston, G., Cook, J. C., and Kavlock, R. J. (2003). Uncertainties for endocrine disrupters: Our view on progress. Toxicol. Sci. 74(2), 245252.
|