2017 Progress Report: Tracking Semivolatile Organic Compounds Indoors: Merging Models and Field Sampling to Access Concentrations, Emissions, and Exposures

EPA Grant Number: R835641
Title: Tracking Semivolatile Organic Compounds Indoors: Merging Models and Field Sampling to Access Concentrations, Emissions, and Exposures
Investigators: Bennett, Deborah H. , Shin, Hyeong-Moo , Young, Thomas M
Institution: University of California - Davis
EPA Project Officer: Carleton, James N
Project Period: September 1, 2014 through August 31, 2017 (Extended to August 31, 2018)
Project Period Covered by this Report: September 1, 2016 through August 31,2017
Project Amount: $900,000
RFA: New Methods in 21st Century Exposure Science (2013) RFA Text |  Recipients Lists
Research Category: Human Health , Safer Chemicals , Health

Objective:

The goals of this project are to (1) measure concentrations of a broad spectrum of target and non-target semivolatile organic compounds (SVOCs) in indoor dust to estimate emission rates and exposures, (2) refine and evaluate a multi-compartment indoor fate, transport, and exposure model, and (3) evaluate air-to-skin transdermal uptake models.

Progress Summary:

  1. Non-target dust analysis: We collected 38 dust samples from homes with young children.  A total of 133 organic chemicals were selected that were either frequently detected in dust, based on literature data or had multiple listings in the Consumer Product Chemical Profiles database (CPCPdb) of the U.S. EPA. The selected chemicals are spanning a broad range of the chemical space (polarity, volatility, speciation, functional groups), and from each different chemical class, indicator substances were selected.  The extraction method was optimized to streamline detection of LC-QTOF-MS and GC-QTOF-MS amenable compounds and the method was successfully validated using over 100 target compounds. Non-target screening by GC-QTOF-MS was done by spectral deconvolution followed by a library search. Suspect screening by LC-QTOF-MS was carried out with two accurate mass spectral libraries containing >10,000 chemicals and an All-Ions fragmentation acquisition. Finally, non-target screening was carried out by extracting molecular features, acquiring tandem MS/MS spectra for the most relevant features and performing compound identification using different in-silico fragmentation software tools. In total, 258 chemicals could be detected in 38 dust samples, 166 of them could be unambiguously confirmed and quantified by a reference standard. Advantages and drawbacks of the different approaches and analytical instruments are critically discussed. The results of this multi-step screening offers a far more complete chemical fingerprint of indoor dust and support efforts to identify indoor sources and human health impacts of these chemicals.
  2. Longitudinal Dust: We have continued collection of longitudinal dust samples from the 20 homes that replaced their couches.  Eight additional homes did not replace their coach and were not followed. 
  3. Dermal exposure study: To test the role of passive uptake in adults, we evaluated skin loading of SVOCs by collecting wipe samples from 13 adults. We collected three sequential wipe samples from foreheads--expected to provide an estimate of passive air to skin transfer. The data on total squalene, squalene oxidation products, and sapienic acid also offers insight into how deep in the skin we extract chemicals when using sequential wipes.
  4. Indoor exposure modeling: We developed a screening-level exposure assessment method which integrates exposure from all plausible exposure pathways as a result of indoor residential use of cleaning products. The results from this study are published in Indoor Air.    

Future Activities:

  1. Non-target dust analysis: A paper is currently under review on the methods.
  2. Longitudinal Dust: There are three remaining visits are to be conducted in January and April 2018.  All of the initial and 6-month visits are currently being analyzed for concentrations, with the later time points to be analyzed in a second batch once all samples have been collected.
  3. Dermal exposure study:  A paper on the results has been drafted and is in internal review.
  4. Indoor exposure modeling: An additional evaluation of exposure through dust has been completed and a paper is being drafted.


Journal Articles on this Report : 1 Displayed | Download in RIS Format

Other project views: All 7 publications 1 publications in selected types All 1 journal articles
Type Citation Project Document Sources
Journal Article Shin H-M, McKone TE, Bennett DH. Model framework for integrating multiple exposure pathways to chemicals in household cleaning products. Indoor Air 2017;27(4):829-839. R835641 (2016)
R835641 (2017)
  • Abstract from PubMed
  • Abstract: Wiley-Abstract
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  • Supplemental Keywords:

    indoor environment, measurement methods, modeling, organics

    Progress and Final Reports:

    Original Abstract
  • 2015 Progress Report
  • 2016 Progress Report