Assessing Cumulative Health Risks from Exposure to Environmental Mixtures—Three Fundamental Questions

Abstract

Differential exposure to mixtures of environmental agents, including biological, chemical, physical, and psychosocial stressors, can contribute to increased vulnerability of human populations and ecologic systems. Cumulative risk assessment is a tool for organizing and analyzing information to evaluate the probability and seriousness of harmful effects caused by either simultaneous and/or sequential exposure to multiple environmental stressors. In this article we focus on elucidating key challenges that must be addressed to determine whether and to what degree differential exposure to environmental mixtures contributes to increased vulnerability of exposed populations. In particular, the emphasis is on examining three fundamental and interrelated questions that must be addressed as part of the process to assess cumulative risk: a) Which mixtures are most important from a public health perspective? and b) What is the nature (i.e., duration, frequency, timing) and magnitude (i.e., exposure concentration and dose) of relevant cumulative exposures for the population of interest? c) What is the mechanism (e.g., toxicokinetic or toxicodynamic) and consequence (e.g., additive, less than additive, more than additive) of the mixture’s interactive effects on exposed populations? The focus is primarily on human health effects from chemical mixtures, and the goal is to reinforce the need for improved assessment of cumulative exposure and better understanding of the biological mechanisms that determine toxicologic interactions among mixture constituents.

Using exposure biomarkers in children to compare between-child and within-child variance and calculate correlations among siblings for multiple environmental chemicals

“…Although the SHIELD study clearly demonstrates that these children were exposed to a plethora of hazardous environmental chemicals spanning multiple chemical classes, current scientific knowledge and understanding are insufficient to allow us to ascertain the seriousness of related cumulative health risks (Callahan and Sexton, 2007;Sexton and Hattis, 2007). There is, nevertheless, ample reason for concern.…”

Potential Health Risks from Uranium in Home Well Water: An Investigation by the Apsaalooke (Crow) Tribal Research Group

“…Based on the following recognized criteria for prioritizing and addressing exposures to environmental chemical mixtures [82], contamination of home well water on the Crow Reservation should be addressed as a high priority public health issue:…”

Proposta conceitual de estudo para a integração e gerenciamento do uso de marcadores bioquímicos de contaminação ambiental

“…Desta forma, verifica-se que a avaliação de riscos cumulativos depende do desenvolvimento de métodos e procedimentos que relacionem os dados de exposição aos de efeito através de indicadores a fim de caracterizar os riscos a saúde ambiental com um grau aceitável de precisão (SEXTON;HATTIS, 2007). Assim, o objetivo do presente trabalho é formular uma proposta conceitual para o estudo das respostas dos indicadores bioquímicos decorrentes da exposição de organismos a misturas de agrotóxicos no ambiente.…”