From the Johns Hopkins Bloomberg School of Public Health, Department of Epidemiology, Baltimore, MD.
Correspondence: Jonathan M. Samet, Professor and Chairman, Department of Epidemiology, Johns Hopkins University, Bloomberg School of Public Health, 615 N. Wolfe St., Suite W6041. Baltimore, MD 21205; E-mail: email@example.com
Decades of research using environmental epidemiology have informed environmental management and advanced public health through regulatory and other policy approaches. A brief list of some successes related to environmental pollutants includes lead, asbestos, radiation, outdoor air pollution catastrophes, and secondhand smoke. Construing “environment” more broadly, the burden of malaria and some other infectious diseases has been reduced by environmental alterations that control disease vectors such as mosquitoes. Despite these successes, many already-identified environmental problems are still not managed adequately and new ones continue to emerge, including global scale issues, particularly climate change, for which solutions have not yet been found.
This issue of Epidemiology includes 2 commentaries on unfinished business for environmental research and management. Both refer to the current context related to the global environment as determined by the 8 Millennium Development Goals consented to at the United Nations Millennium Summit in 2000. These goals represent an agreed-to blueprint for speeding progress in the world's poorest countries. The seventh goal is to “ensure environmental sustainability,” and, in its Millennium Declaration,1 the United Nations calls for “protecting our common environment.” Inherently, the seventh goal intersects with the others that address poverty and hunger, education, gender, child mortality, maternal health, HIV/AIDS, malaria and other diseases, and global partnership for development. Prüss-Üstün and Corvalán2 describe the current target of environment-attributable disease and Soskolne and colleagues,3 in an article based on the summation address at the 2005 annual conference of the International Society for Environmental Epidemiology (ISEE), propose a proactive approach for environmental epidemiologists on sustainability.
Prüss-Üstün and Corvalán, both at the World Health Organization, summarize estimates from a recently completed comprehensive assessment of the global burden of disease attributable to the environment.4 Their construct of the “environment” for this assessment merits emphasis, because they considered only factors that “could reasonably be modified” and they calculated the burden of disease with comparison to a counterfactual considered “reasonably achievable” rather than to a counterfactual based on complete elimination of exposure. This approach provides estimates more directly applicable to immediate policy decisions, although I am doubtful as to whether decision-makers will appreciate the distinction. Additionally, tobacco, alcohol, and diet were not considered and, with the further restriction to modifiable factors, this set of estimates is based on a particular and unique specification of “the environment.” Of the 102 diseases considered, the environment was estimated to play a role in 85, accounting for 24% of the global burden of disease. The largest contributors were diarrheal diseases, lower respiratory infections, neuropsychiatric conditions, and cardiovascular diseases. Prüss-Üstün and Corvalán comment on the relevance of these estimates for the full set of Millennium Development Goals; diarrheal diseases, for example, limit child health, interfere with education, and are costly.
The methodology for calculating burden of disease is now well established, and estimates of attributable burden have been published repeatedly.5 These estimates are intended to guide decision-making and to assure that finite resources are directed toward the optimum mix of disease targets. The reporting of the new estimates on the environment by Prüss-Üstün and Corvalán occurs not long after the World Health Organization quantified 26 major risks, 6 of which are environmental, in its Comparative Risk Assessment.6 That assessment found that 10% of disease burden could be attributed to the environment. Differences in methodology and in the definition of “the environment” likely account for the different quantitative findings of the 2 assessments. Given the resources needed to complete these assessments, including substantial involvement of researchers, we need to learn how their findings are being used to guide policy development and whether refinements to methodology, as made by Prüss-Üstün and Corvalán, improve their use for decision-makers.
Soskolne and colleagues3 begin with the premise that progress toward the Millennium Development Goals has slowed and that inaction on environmental sustainability will limit success in achieving the other goals. They call for a shift in the paradigm for environmental epidemiology research such that sustainability and equity become core elements and that the research better acknowledges the complexity and layers of factors determining risks from the environment. They seek capacity-building and technology transfer for developing countries and greater research on environmental health inequalities. A 7-element global agenda for environmental epidemiology is offered, and the authors call for input on this agenda by the members of the ISEE.
Together, these commentaries provide a strong case for a more forceful, evidence-based approach to environmental management for sustainability. Prüss-Üstün and Corvalán argue that the role of environmental management in improving health has been neglected, and they estimate a substantial burden of avoidable disease. Soskolne and colleagues call for a new and broadened approach in environmental epidemiology that addresses global equity and sustainability. This new approach might help to assure that the Millennium Development Goal of environmental sustainability is met. Both commentaries are likely correct in pointing to the interconnectedness of the 8 goals and to the consequences for the other goals of not ensuring environmental sustainability.
How will environmental epidemiology, through the proposed global agenda, advance progress toward environmental sustainability and equity? The answer to this question is best considered by not conflating environmental epidemiology and environmental epidemiologists, like in the commentary by Soskolne et al. Environmental epidemiology, as the study of health, disease, and the environment, is a scientific discipline. Soskolne and colleagues propose an agenda for environmental epidemiologists and their professional organizations, including the ISEE, that transcends the research domain of environmental epidemiology. Their call for a shift in focus from individual-level to higher levels of societal organization echoes other recent commentors.7,8
Will environmental epidemiologists support this agenda and are there potential funders? Soskolne and colleagues propose a broad set of activities and responsibilities for environmental epidemiologists, including many beyond the bounds of scientific research. They propose that “Epidemiologists need to be aware of the moral dimensions of their work” and indicate that “… environmental epidemiology must tackle power structures that adversely affect environmental health.” Many epidemiologists view their role as constrained to research and training and they fear that activism may discredit their research. Those epidemiologists, who may be the majority, may find this agenda to be too radical.
I am not certain if funders will step forward for this broad, new mission for environmental epidemiology. On reviewing the most recent strategic plan for the National Institute for Environmental Health Sciences, I find emphasis on disease and mechanisms and little discussion of sustainability.9 The new global health funders such as the Bill & Melinda Gates Foundation have not yet targeted the environment specifically. The ISEE might consider an initiative to persuade the Gates Foundation and other foundations as to the need for funding that targets the environment.
I join with Soskolne and colleagues in calling for comment on their ambitious agenda and urge the ISEE to consider its role in achieving greater environmental sustainability. However, I also offer this reminder to all: environmental epidemiologists can still best advance public health by obtaining research evidence that identifies opportunities for effective preventive interventions.
1. United Nations and General Assembly. United Nations Millennium Declaration.
55/2. New York: United Nations; September 8, 2000.
2. Prüss-Üstün A, Corvalán C. How much disease burden can be prevented by environmental interventions? Epidemiology
3. Soskolne CL, Butler CD, Ijsselmuiden C, et al. Toward a global agenda for research in environmental epidemiology. Epidemiology
4. Prüss-Üstün A, Corvalán C. Preventing Disease Through Healthy Environments. Towards an Estimate of the Environmental Burden of Disease.
Geneva: World Health Organization; 2006.
5. Steenland K, Armstrong B. An overview of methods for calculating the burden of disease due to specific risk factors. Epidemiology
6. Comparative Quantification of Health Risks.
Geneva: World Health Organization; 2005.
7. Rockhill B. Theorizing about causes at the individual level while estimating effects at the population level: implications for prevention. Epidemiology
8. McMichael AJ. Prisoners of the proximate: loosening the constraints on epidemiology in an age of change. Am J Epidemiol
9. National Institute of Environmental Health Sciences. New Frontiers in Environmental Sciences and Human Health. NIEHS 2006–2011 Strategic Plan
. Research Triangle Park, NC: Environmental Health Perspectives; 2006.