title: A review of models for near-field exposure pathways of chemicals in consumer products.
abstract: Exposure to chemicals in consumer products has been gaining increasing attention, with multiple studies showing that near-field exposures from products is high compared to far-field exposures. Regarding the numerous chemical-product combinations, there is a need for an overarching review of models able to quantify the multiple transfers of chemicals from products used near-field to humans. The present review therefore aims at an in-depth overview of modeling approaches for near-field chemical release and human exposure pathways associated with consumer products. It focuses on lower-tier, mechanistic models suitable for life cycle assessments (LCA), chemical alternative assessment (CAA) and high-throughput screening risk assessment (HTS). Chemicals in a product enter the near-field via a defined "compartment of entry", are transformed or transferred to adjacent compartments, and eventually end in a "human receptor compartment". We first focus on models of physical mass transfers from the product to 'near-field' compartments. For transfers of chemicals from article interior, adequate modeling of in-article diffusion and of partitioning between article surface and air/skin/food is key. Modeling volatilization and subsequent transfer to the outdoor is crucial for transfers of chemicals used in the inner space of appliances, on object surfaces or directly emitted to indoor air. For transfers from skin surface, models need to reflect the competition between dermal permeation, volatilization and fraction washed-off. We then focus on transfers from the 'near-field' to 'human' compartments, defined as respiratory tract, gastrointestinal tract and epidermis, for which good estimates of air concentrations, non-dietary ingestion parameters and skin permeation are essential, respectively. We critically characterize for each exposure pathway the ability of models to estimate near-field transfers and to best inform LCA, CAA and HTS, summarizing the main characteristics of the potentially best-suited models. This review identifies large knowledge gaps for several near-field pathways and suggests research needs and future directions.
authors.affiliation: Environmental Health Sciences & Risk Science Center, School of Public Health, University of Michigan, Ann Arbor, MI 48109-2029, United States. Electronic address: huanglei@umich.edu.
authors.forename: Lei
authors.initials: L
authors.lastname: Huang
authors.affiliation: Quantitative Sustainability Assessment Division, Department of Management Engineering, Technical University of Denmark, 2808 Kgs. Lyngby, Denmark.
authors.forename: Alexi
authors.initials: A
authors.lastname: Ernstoff
authors.affiliation: Quantitative Sustainability Assessment Division, Department of Management Engineering, Technical University of Denmark, 2808 Kgs. Lyngby, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Fantke
authors.affiliation: Oak Ridge Institute for Science and Education Research Participant, US Environmental Protection Agency, National Risk Management Research Laboratory, Cincinnati, OH 45268, United States.
authors.forename: Susan A
authors.initials: SA
authors.lastname: Csiszar
authors.affiliation: Environmental Health Sciences & Risk Science Center, School of Public Health, University of Michigan, Ann Arbor, MI 48109-2029, United States.
authors.forename: Olivier
authors.initials: O
authors.lastname: Jolliet
mesh_terms: D004781:Environmental Exposure; D006795:Household Products / Q000009:adverse effects*; D006801:Humans; D008962:Models, Theoretical; D018570:Risk Assessment; D012867:Skin; D012869:Skin Absorption; D014835:Volatilization
keywords: Consumer products; High-throughput risk screening; Human exposure models; Indoor environment; Life cycle impact assessment; Mass transfer fractions