Elsevier

Environment International

Volume 88, March 2016, Pages 269-280
Environment International

Linking high resolution mass spectrometry data with exposure and toxicity forecasts to advance high-throughput environmental monitoring

https://doi.org/10.1016/j.envint.2015.12.008Get rights and content
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open access

Highlights

  • Exposure data are limited or non-existent for thousands of commercial chemicals.

  • We present a novel suspect screening method for characterizing chemicals in dust.

  • High-resolution mass spectrometry was used for chemical identification.

  • Exposure and toxicity forecasts were used for chemical prioritization.

  • This method is suitable for characterizing emerging environmental contaminants.

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.

Abbreviations

ACToR
EPA's Aggregated Computational Toxicology Resource
AHHS
American Healthy Homes Survey
AhR
aryl hydrocarbon receptor
AR
androgen receptor
CASRN
Chemical Abstract Services Registry Number
DI
deionized
DSSTox
EPA's Distributed Structure-Searchable Toxicity database
ERα
estrogen receptor alpha
GC × GC–TOF/MS
two-dimensional gas chromatography coupled with time-of-flight mass spectrometry
HPLC
high performance liquid chromatograph
HPV
high-production volume
HT
high-throughput
HTS
high-throughput screening
LC-Si
liquid-chromatography/silica
LC–TOF/MS
liquid chromatography time-of-flight mass spectrometry
HRMS
high resolution mass spectrometry
MFE
Molecular Feature Extraction
MS
mass spectrometry
MW
molecular weight
NFκB1
nuclear factor of kappa light polypeptide gene enhancer in B cells 1
NHANES
U.S. National Health and Nutrition Examination Survey
PPARγ
peroxisome proliferator-activated receptor gamma
RSD
relative standard deviation
RT
retention time
SPE
solid-phase extraction
ToxPi
Toxicological Priority Index

Keywords

Non-targeted
Suspect screening
Exposome
ExpoCast
ToxCast
Dust

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