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Assessing Plausibility of Tentative Chemical Identifications from Suspect Screening Analyses via Chemical Function
Citation:
Phillips, K., A. McEachran, K. Isaacs, J. Sobus, A. Williams, AND J. Wambaugh. Assessing Plausibility of Tentative Chemical Identifications from Suspect Screening Analyses via Chemical Function. 2017 ISES Annual Meeting, Research Triangle Park, North Carolina, October 15 - 19, 2017.
Impact/Purpose:
Chemical functional use (i.e., the end role of a chemical in a product) is used to filter out unlikely structural matches as part of SSA to aid in SSA/NTA chemical confirmation prioritization.
Description:
Suspect screening (SSA) and non-targeted analysis (NTA) have become increasingly useful methods for identifying chemicals in indoor environments, which is where many chemical exposures occur. However, the tentative chemical identifications from these analyses must be confirmed. Traditionally, pure chemical standards might be used for confirmation, but this testing is infeasible for the hundreds to thousands of chemicals indicated by these techniques due to both time constraints and availability of standards. Instead, a sometimes laborious process of matching molecular features to a chemical structure may be employed. Here chemical functional use (i.e., the end role of a chemical in a product) is used to filter out unlikely structural matches as part of SSA. In some cases, manufacturers report the functional use of a chemical in its products, but more often than not, chemicals of toxicological interest have little-to-no use information. To fill in these data gaps, quantitative-structure use relationship (QSUR) models have been applied to chemicals with no known use. These models use the structure and physicochemical properties of a chemical to provide a probability for that chemical serving a functional role. As a case study, in a recent SSA of 100 consumer products with 1639 identified chemicals, 1451 of those were not included in data sources listing chemicals associated with consumer products. Such a low number of hits from these data sources is not surprising as many of these sources would not contain information on chemicals used as fragrances, nor of chemicals contained in household articles. However, by examining functional uses, it was found that 696 of the tentatively identified chemicals had at least one reported functional use or had a valid QSUR prediction indicating that these chemicals could serve a functional role in a product and, therefore, should be considered for future confirmation.
