The exposure data landscape for manufactured chemicals

National Exposure Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, NC 27711, United States.
Science of The Total Environment (Impact Factor: 4.1). 11/2011; 414:159-66. DOI: 10.1016/j.scitotenv.2011.10.046
Source: PubMed


The U.S. Environmental Protection Agency is developing chemical screening and prioritization programs to evaluate environmental chemicals for potential risk to human health in a rapid and efficient manner. As part of these efforts, it is important to catalog available information on chemical toxicity and exposure from widely dispersed sources. The main objective of this analysis is to define important aspects of the exposure space and to catalog the available exposure information for chemicals being considered for analysis as part of the U.S. EPA ToxCast™ screening and prioritization program. Publicly available exposure data have been extracted into ACToR (Aggregated Computational Toxicology Resource), which combines information for hundreds of thousands of chemicals from >600 public sources. We use data from ACToR to assess the exposure data landscape for environmental chemicals. Of the roughly 100,000 chemicals that have at least limited toxicity information available, less than one-fifth also have exposure information - and for most of these the information is of limited utility (e.g., production volume). Readily accessible data on concentrations in exposure-related media are only available for a much smaller fraction. Among these, the largest number of chemicals is measured in water with over 1150 unique compounds, followed by 788 substances measured in soil, and 670 in air. These small numbers clearly reflect a focus of resources on those substances previously identified as possibly posing a hazard to human health. Exposure to a much broader number of chemicals will need to be measured in order to fully realize the envisioned goal of using exposure information to guide toxicity testing.

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Available from: Shad Mosher, Oct 13, 2015
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    • "These programs have invested in new tools, technologies, and studies to better characterize the breadth of human exposures, and the linkages between exposure and disease. As primary research drivers, it has been recognized that exposure data are sparse for many existing chemicals (Egeghy et al., 2012), and that knowledge-driven approaches alone are unlikely to meet the demands of this rapidly evolving field of research (Rappaport and Smith, 2010). Exposure scientists have therefore begun to advance exposome research efforts, in part, by expanding environmental monitoring through the application of " non-targeted " and " suspect screening " analyses. "
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    ABSTRACT: There is a growing need in the field of exposure science for monitoring methods that rapidly screen environmental media for suspect contaminants. Measurement and analysis platforms, based on high resolution mass spectrometry (HRMS), now exist to meet this need. Here we describe results of a study that links HRMS data with exposure predictions from the U.S. EPA's ExpoCast™ program and in vitro bioassay data from the U.S. interagency Tox21 consortium. Vacuum dust samples were collected from 56 households across the U.S. as part of the American Healthy Homes Survey (AHHS). Sample extracts were analyzed using liquid chromatography time-of-flight mass spectrometry (LC–TOF/MS) with electrospray ionization. On average, approximately 2000 molecular features were identified per sample (based on accurate mass) in negative ion mode, and 3000 in positive ion mode. Exact mass, isotope distribution, and isotope spacing were used to match molecular features with a unique listing of chemical formulas extracted from EPA's Distributed Structure-Searchable Toxicity (DSSTox) database. A total of 978 DSSTox formulas were consistent with the dust LC–TOF/molecular feature data (match score ≥ 90); these formulas mapped to 3228 possible chemicals in the database. Correct assignment of a unique chemical to a given formula required additional validation steps. Each suspect chemical was prioritized for follow-up confirmation using abundance and detection frequency results, along with exposure and bioactivity estimates from ExpoCast and Tox21, respectively. Chemicals with elevated exposure and/or toxicity potential were further examined using a mixture of 100 chemical standards. A total of 33 chemicals were confirmed present in the dust samples by formula and retention time match; nearly half of these do not appear to have been associated with house dust in the published literature. Chemical matches found in at least 10 of the 56 dust samples include Piperine, N,N-Diethyl-m-toluamide (DEET), Triclocarban, Diethyl phthalate (DEP), Propylparaben, Methylparaben, Tris(1,3-dichloro-2-propyl)phosphate (TDCPP), and Nicotine. This study demonstrates a novel suspect screening methodology to prioritize chemicals of interest for subsequent targeted analysis. The methods described here rely on strategic integration of available public resources and should be considered in future non-targeted and suspect screening assessments of environmental and biological media.
    Full-text · Article · Mar 2016 · Environment International
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    • "There are very few human health or exposure data for the majority of the > 80,000 chemicals in commerce (Egeghy et al. 2012; Judson et al. 2009). The lack of data poses challenges to those looking to mitigate the potential risks or evaluate impacts in a comprehensive manner. "
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    Preview · Article · Apr 2015 · Environmental Health Perspectives
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    • "First, operationalizing " exposure " as the control variable is difficult because of the high and poorly defined number of chemicals that fall under the umbrella of " chemical pollution " . More than 100,000 substances are in commerce (Egeghy et al., 2012), including pesticides, biocides and pharmaceuticals, industrial chemicals, building materials and substances in personal care products and cosmetics (e.g., Howard and Muir, 2010, 2011; ECHA, 2013) and very few of them have undergone adequate risk assessment for adverse effects. "
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