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Advancements in Life Cycle Human Exposure and Toxicity Characterization
Citation:
Fantke, P., L. Aylward, J. Bare, W. Chiu, R. Dodson, R. Dwyer, A. Ernstoff, B. Howard, M. Jantunen, O. Jolliet, R. Judson, N. Kirchhubel, D. Li, A. Miller, G. Paoli, P. Price, L. Rhomberg, B. Shen, H. Shin, J. Teeguarden, D. Vallero, J. Wambaugh, Barbara A. Wetmore, R. Zaleski, AND T. McKone. Advancements in Life Cycle Human Exposure and Toxicity Characterization. ENVIRONMENTAL HEALTH PERSPECTIVES. National Institute of Environmental Health Sciences (NIEHS), Research Triangle Park, NC, 126(12):3871, (2018). https://doi.org/10.1289/EHP3871
Impact/Purpose:
The Life Cycle Initiative hosted at the United Nations Environment Programme (UNEP) has selected human toxicity impacts from exposure to chemical substances as a Life Cycle Impact Assessment (LCIA) category for global guidance development and convened the Human Toxicity Task Force. The Task Force outlined a roadmap for advancing human toxicity characterization in LCIA discussed at three workshops, addressing the main current scientific challenges and questions. Two major issues emerged, namely addressing near-field exposures and improving dose-response modeling. Human exposure to chemical substances in consumer products during and after product use (e.g. inhalation of air fresheners), exposure of bystanders (e.g. humans living near agricultural fields treated with pesticides), and occupational exposure (e.g. inhalation and dermal contact with industrial substances in working environments) are currently missing in LCIA. The Task Force recommends including missing exposure settings and pathways by coupling additional fate and exposure processes in consumer and occupational environments (near-field) with existing processes in outdoor environments (far-field) and human receptors. Environments will be coupled using a consistent, mass-balance based set of chemical mass fractions transferred between environmental compartments to quantify overall aggregate exposure. With respect to dose-response, the Task Force raised concerns about the way LCIA currently characterizes human toxicity effects, specifically using a (linear) dose-response extrapolation to zero. Several potential solutions were discussed, concluding that the current important challenge is identifying a metric for human toxicity impacts that is aligned with the spatiotemporal resolution of current LCIA methodology, yet adequately indicates health impact potential. The Task Force developed 13 recommendations for future actions on exposure and dose-response modeling in LCIA human toxicity characterization.
Description:
Background: The Life Cycle Initiative, hosted at the United Nations Environment Programme, selected human toxicity impacts from exposure to chemical substances as an impact category that requires global guidance to overcome current assessment challenges. The initiative leadership established the Human Toxicity Task Force to develop guidance on assessing human exposure and toxicity impacts. Based on input gathered at three workshops addressing the main current scientific challenges and questions, the task force built a roadmap for advancing human toxicity characterization, primarily for use in life cycle impact assessment (LCIA). Objectives: The present paper aims at reporting on the outcomes of the task force workshops along with interpretation of how these outcomes will impact the practice and reliability of toxicity characterization. The task force thereby focuses on two major issues that emerged from the workshops, namely considering near-field exposures and improving dose–response modeling. Discussion: The task force recommended approaches to improve the assessment of human exposure, including capturing missing exposure settings and human receptor pathways by coupling additional fate and exposure processes in consumer and occupational environments (near field) with existing processes in outdoor environments (far field). To quantify overall aggregate exposure, the task force suggested that environments be coupled using a consistent set of quantified chemical mass fractions transferred among environmental compartments. With respect to dose–response, the task force was concerned about the way LCIA currently characterizes human toxicity effects, and discussed several potential solutions. A specific concern is the use of a (linear) dose–response extrapolation to zero. Another concern addresses the challenge of identifying a metric for human toxicity impacts that is aligned with the spatiotemporal resolution of present LCIA methodology, yet is adequate to indicate health impact potential.
URLs/Downloads:
DOI: Advancements in Life Cycle Human Exposure and Toxicity Characterization
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