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Suspect Screening Analysis to Identify Chemical Targets in Serum for Exposure Reconstruction
Citation:
Wetmore, B., K. Phillips, K. Favela, R. Church, J. Sobus, A. Yau, A. Rice, S. Garantziotis, AND J. Wambaugh. Suspect Screening Analysis to Identify Chemical Targets in Serum for Exposure Reconstruction. ISES-ISEE 2018 Joint Annual Meeting, Ottawa, CANADA, August 26 - 30, 2018.
Impact/Purpose:
Most human biomonitoring efforts to date have been limited to bioaccumulative chemicals with known or likely human health impacts, which has greatly limited the ability of exposure modelers to verify and refine exposure models designed to reconstruct the external exposure-to-internal dose continuum. The evolution of high resolution mass spectrometry affords the opportunity to expand the number of commercial chemicals for which such data are available. This effort represents a pilot study to assess the feasibility of using two-dimensional gas chromatographic data from human serum to characterize and identify more chemicals for use in such exposure model evaluation efforts. The findings indicate the potential of this approach, and ongoing efforts are underway and planned to review the dataset and assess the ability to generate quantitative or at least semi-quantitative estimates of chemical levels in serum for model evaluation.
Description:
Most human biomonitoring efforts to date have been limited to bioaccumulative chemicals with known or likely human health impacts. High throughput exposure models currently rely upon these data alone for evaluation. The evolution of high resolution mass spectrometry affords the opportunity to expand the number of commercial chemicals for which such data are available. Suspect screening analysis (SSA) using two-dimensional gas chromatography-time of flight/mass spectrometry (GCxGC-TOF/MS) was performed on serum samples obtained from the National Institute of Environmental Health Sciences Clinical Research Unit. Samples were stratified based on sex (male vs. female). Tentative chemical identifications (IDs) were only assumed if a compound peak was identified in two of the three replicates, and if the spectrum for that peak had a high similarity to a spectrum in the NIST14 mass spectral library. Five-hundred forty-six unique compounds were tentatively identified and assessed; 240 were detected in males, while nearly double (480) were found in females. Two hundred seven compounds were unique to females while only 28 were unique to male serum. Of these tentative IDs, 69 chemicals were also detected in a pilot SSA to characterize consumer product (CP) chemicals. Two hundred four are present in US EPA’s CPDat database, containing product composition and functional use data for modeling. Further, 5 chemicals monitored in the National Health and Nutrition Examination Survey (NHANES) were detected (e.g., naphthalene, cotinine, and 2,5-dichlorophenol) and can be used during method evaluation. Ongoing work is focused on identification confirmation and strategies to facilitate quantitative or semi-quantitative assessments. These preliminary findings provide support for the use of SSA in expanding the biomonitored chemical space for exposure reconstruction and model evaluation to inform chemical safety assessments. This abstract may not reflect U.S. EPA policy.
