In an article published on January 1, 2016 in the peer-reviewed journal Environmental Health Perspectives, researchers Joseph M. Braun and colleagues discuss the potential of epidemiological studies in investigating the impact of chemical mixtures on human health. First, the authors address several challenges posed by studying chemical mixtures in human populations, such as accurately measuring exposure to mixtures, avoiding false-positive and false-negative results in statistical analysis, and accounting for confounding due to correlated copollutant exposures. Further, the authors focus on three questions related to chemical mixtures that epidemiological studies could help answer: 1) What are the health effects of individual chemicals within a mixture? There is need to identify exposures that are most strongly correlated with adverse health effects. Knowing the substances that are most likely associated with an adverse effect would help guide public health efforts. 2) What are the interactions between chemicals within a mixture? Exposure to two or more chemicals can have synergistic or antagonistic effects on health outcomes. It could be examined whether the effect of simultaneous exposure to two different substances is greater than additive or subadditive compared to the effect of individual exposure to the single substances. 3) What is the health effect of cumulative chemical exposure? Assuming no synergistic effects, the summary effect of joint exposure to chemicals on human health shall be quantified. This is especially interesting when components of the mixture act via common biological pathways, exposure to individual components is below a certain threshold of concern, and aggregate exposure to mixture components exceeds this threshold. For each of the addressed questions, Braun and colleagues point out knowledge gaps and provide examples of suitable methodology.

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Braun, J.M. et al. (2016). “What can epidemiological studies tell us about the impact of chemical mixtures on human health?Environmental Health Perspectives 124:A6-A9.