title: An approach for assessing human exposures to chemical mixtures in the environment.
abstract: Humans are exposed daily to multiple chemicals, including incidental exposures to complex chemical mixtures released into the environment and to combinations of chemicals that already co-exist in the environment because of previous releases from various sources. Exposures to chemical mixtures can occur through multiple pathways and across multiple routes. In this paper, we propose an iterative approach for assessing exposures to environmental chemical mixtures; it is similar to single-chemical approaches. Our approach encompasses two elements of the Risk Assessment Paradigm: Problem Formulation and Exposure Assessment. Multiple phases of the assessment occur in each element of the paradigm. During Problem Formulation, analysts identify and characterize the source(s) of the chemical mixture, ensure that dose-response and exposure assessment measures are concordant, and develop a preliminary evaluation of the mixture's fate. During Exposure Assessment, analysts evaluate the fate of the chemicals comprising the mixture using appropriate models and measurement data, characterize the exposure scenario, and estimate human exposure to the mixture. We also describe the utility of grouping the chemicals to be analyzed based on both physical-chemical properties and an understanding of environmental fate. In the article, we also highlight the need for understanding of changes in the mixture composition in the environment due to differential transport, differential degradation, and differential partitioning to other media. The Results section describes the application of the method to various chemical mixtures, highlighting issues associated with assessing exposures to chemical mixtures in the environment.
authors.affiliation: U.S. Environmental Protection Agency, National Center for Environmental Assessment, 26 West Martin Luther King Drive, Cincinnati, OH 45268, USA. rice.glenn@epa.gov
authors.forename: Glenn
authors.initials: G
authors.lastname: Rice
authors.forename: Margaret
authors.initials: M
authors.lastname: MacDonell
authors.forename: Richard C
authors.initials: RC
authors.lastname: Hertzberg
authors.forename: Linda
authors.initials: L
authors.lastname: Teuschler
authors.forename: Kurt
authors.initials: K
authors.lastname: Picel
authors.forename: Jim
authors.initials: J
authors.lastname: Butler
authors.forename: Young-Soo
authors.initials: YS
authors.lastname: Chang
authors.forename: Heidi
authors.initials: H
authors.lastname: Hartmann
mesh_terms: D004781:Environmental Exposure / Q000009:adverse effects; D004784:Environmental Monitoring / Q000379:methods* / Q000592:standards; D004785:Environmental Pollutants / Q000032:analysis* / Q000633:toxicity*; D006801:Humans; D018570:Risk Assessment
chemical_list: D004785:Environmental Pollutants