Epidemiological Assessment of Hormesis in Studies with Low-Level Exposure
Titel:
Epidemiological Assessment of Hormesis in Studies with Low-Level Exposure
Auteur:
Mundt, Kenneth A. May, Susanne
Verschenen in:
Human and ecological risk assessment
Paginering:
Jaargang 7 (2001) nr. 4 pagina's 795-809
Jaar:
2001-06-01
Inhoud:
Despite its resurgence within toxicology and, specifically, risk assessment, the concept of hormesis remains peripheral to current epidemiological practice. In this paper we examine some reasons for this, focusing on applications within occupational and environmental epidemiology. Unclear in the existing literature is whether hormesis pertains to a single biological mechanism or response, or the aggregate effect of all correlates of exposure. Although J-shaped and U-shaped relationships between risk factors and disease endpoints have been identified epidemiologically, it is unclear whether such patterns reflect biological hormesis or a combination of factors resulting in a hormetic-looking relationship. Given the potential importance of assessing hormetic responses in epidemiological studies, we identify and discuss key limitations of epidemiology in validly detecting and interpreting hormesis. For example, most observational occupational and environmental studies lack the ability to determine the dose received by each individual, and therefore poor surrogates of exposure are frequently used, potentially introducing considerable systematic and random error. Further, because exposure is not randomly assigned to humans, the potential for confounding is great. Finally, using a simple simulation to assess the impact of ignoring hormesis in the analysis of epidemiological data containing mild hormesis, we demonstrate a resulting “hormetic bias,” in which relative risks at exposure levels above the hormetic region are systematically overestimated.
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