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Laboratory Evaluation of Fugitive and Ambient Ethylene Oxide (EtO) Methods
Citation:
George, I., A. Gitipour, T. Yelverton, M. Lewandowski, E. Thoma, K. Loftis, J. Nwia, M. Sieffert, M. Berry, G. Queiroz, P. Burnette, AND C. Singer. Laboratory Evaluation of Fugitive and Ambient Ethylene Oxide (EtO) Methods. ACE BOSC Subcommittee, NA, October 12 - 14, 2021.
Impact/Purpose:
Ethylene oxide (EtO) is considered an emerging contaminant by EPA due to its recently updated cancer risk estimate and 2014 NATA results. Comprehensive EtO emission characterization and ambient measurements are needed to understand health risks of EtO exposure and develop mitigation strategies. Low-level measurement methods suitable for near-source fugitive and background categories are needed to meet these critical needs. This presentation gives a high level summary of a method intercomparison study that evaluates several emerging online, real-time EtO measurement technologies as well as offline, time integrated EtO methods under a range of controlled conditions while sampling from an atmospheric smog chamber. Preliminary findings suggest that several of the online and offline methods evaluated were capable of quantifying EtO concentrations typical of near source/fenceline monitoring and ambient conditions; however, some measurement bias issues need to be further evaluated. This research will ultimately generate information to better understand the performance of these methods and will inform future guidance on application of these methods for EtO measurements in emissions and ambient environments.
Description:
Ambient EtO levels have become an increasingly important environmental health concern because of the updated December 2016 Integrated Risk Information System (IRIS) assessment, which increased the estimated lifetime cancer unit risk resulting from EtO inhalation by a factor of 60. The updated unit risk assessment corresponds to a 100-in-a-million cancer risk concentration of 11 pptv EtO. Using this new risk estimate, the 2014 National Air Toxics Assessment (NATA, released in 2018) identified EtO as a major regional cancer risk driver with over 20 EtO-emitting facilities in the US contributing to census tract-level cancer risks of greater than 100-in-1 million. To better understand and characterize EtO emission sources, analytical instrumentations with more sensitive detection boundaries are needed to detect EtO at near source concentrations and in ambient conditions. This laboratory EtO method intercomparison study was conducted to assess the performance of multiple novel real-time optical-based online EtO technologies and offline EtO measurement methods (EPA Method TO-15A and a modified OSHA Method 1010). The EtO measurement methods sampled from an atmospheric chamber under a range of controlled conditions and EtO concentrations that are relevant to measurement of near-source fenceline environments. This presentation provides a brief overview of this method intercomparison research effort. Additional work will include determining statistical significance of the measurement biases and method accuracy compared to reference concentrations.