Eco-Epidemiology

Eco-epidemiology is an emergent area in the evolution of modern epidemiology, rooted in a new public health scientific paradigm that postulates an integrated approach to investigating disease and its prevention by subsuming levels of causation, life course trajectories, kinds of causes, and types of diseases. By incorporating this way of thinking about causes at multiple levels of organization and within the historical context of both societies and individuals, eco-epidemiology advances the adoption of a unified framework to the different domains of the discipline, emphasizing the ties that bind epidemiology to public health and implying a major shift in what qualifies as rational public health practice.

The emergent era of eco-epidemiology arises from the escalating recognition of constraints and prevailing [Page 296]criticisms of the current era of chronic disease epidemiology, with its dominant risk-factor paradigm. It also emerges from the growing strength of molecular epidemiology on the one side and of social epidemiology on the other side of the determinants of health model. A fundamental charge against the current paradigm of the present era is its general neglect of the social environment in which disease occurs: It conceives risk for disease as residing largely within individuals and their personal behavior. Under the singlelevel, risk-factor paradigm, questions about macrolevel social and physical environments or microlevel mediators and antecedents are difficult to frame: Inattention to context leads to a limited and precarious knowledge base for public health action. In addition, description of risk-factor/disease associations—increasingly related to small effects detection, particularly vulnerable to indeterminacy from confounding and bias—are afforded priority over the explanation of causal processes and linkages between them; hence the black box analogy.

Molecular epidemiology focuses on biological mechanisms of disease and social epidemiology on societal determinants of disease. Caught between biology and society, risk-factor epidemiology deals with the middle ground of behaviors and exposures. Ecoepidemiology, also known as multilevel epidemiology, recognizes these three levels of organization—the micro, the macro, and the individual—as equally fundamental to the purview of public health epidemiology. In other words, eco-epidemiology explicitly reminds that molecular, lifestyle, and societal explanations of disease are interconnected and reciprocally reinforcing, not mutually exclusive, competing alternatives to understand disease causation and to advance the cause of public health. More specifically, eco-epidemiology not only advocates this paradigm in the interpretation of findings from epidemiological research, but also by including into epidemiological study designs direct measures representing the disease process at each level.

Eco-epidemiology contends that fruitful theories of disease causation and pathogenesis can, in principle, be conceptualized at all levels of organization. Since detectable causes differ across levels, theories at different levels may each point to distinct understandings of disease and prevention. Eco-epidemiological study designs that incorporate individual-level exposures, group-level exposures, individual-level health outcomes, and group-level health outcomes that are explicitly defined and related to each other are notoriously complex—a reflection of a relentlessly multilevel, multicausal, multivariable world. It has been argued that this likely complexity may go against the epidemiologist's justified desire for parsimony. Conversely, in its unifying effort, it adds to the coherence of epidemiology. It also calls for a broader multidisciplinary thought collective and a greater methodological pluralism.

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