DAQ-2024-009060

The
•Of the 8 sites , 6 of the AERMOD modeled estimates were statistically different from the
As the sites increase in distance from the point source, the median EtO concentrations
decrease
•canister-based measurements
•Estimates > Measurements at sites 1,3, and 4
•Estimates < Measurements at sites 2,5, and 7
•Sites 6 and 8 were not statistically different
A Comparison of Ambient Ethylene Oxide Concentrations from
Modeling Estimates of Stack and Fugitive Emission Source to
Canister-based Measurements in Salt Lake City
Skyler Spooner, Rod Handy, Nancy Daher, Rachel Edie, Trent Henry, & Darrah Sleeth
DEPARTMENT OF FAMILY & PREVENTIVE MEDICINE
•Ethylene Oxide (EtO) is a colorless, flammable gas at room
temperature, procured by the catalytic oxidation of ethylene[1]
•EtO has alkylating properties used to sterilize medical devices
and equipment[2]
•In 2016, epidemiological studies lead the EPA to updated the
inhalation hazard unit for EtO due to more potent carcinogenic
findings
•Chronic EtO exposure is associated with an increased risk of
white blood cells related cancers, including non-Hodgkin
lymphoma, myeloma, and leukemia[3]
•The Salt Lake City geography and metrological conditions may
prevent EtO from being diluted in the ambient air after emitted
•Background environmental sources of EtO are unknow, but the
EPA proposed automobile combustion and biological metabolic
by-product as possible source emitters [4]
•A local sterilization facility was identified as point source of
ambient EtO emission in Salt Lake City
•Fugitive and stack emission information was obtained
•New, whole-air passive canisters lined with silonite collected 24-
hour samples of ambient EtO concentrations
•8 sites near the sterilization facility
•5 background sites
•Lab analyzed with the EPA’s TO-15 Method using gas
chromatography and mass spectrometry techniques
•Summer and Winter background values were computed and
added to modeled estimates using Mean-of-the-Median values
calculated from EtO concentrations measured at background
canister sites
•To investigate how the method of measuring ambient EtO using
the EPA’s dispersion modeling techniques (AERMOD)
compares to canister-based measurements
•If a discrepancy is found, a correction factor could be derived to
aid in subsequent cancer risk assessment of the nearby
community using human exposure modeling (HEM-4)
Introduction
•The American Meteorological Society –U.S. EPA
Regulatory Model (AERMOD) used dispersion modeling to
estimated EtO concentration outputs from the point sources’
stack and fugitive emissions
•Measured and estimated concentrations of ambient EtO were
compared with a Wilcoxon Signed-ranked test for paired,
non-parametric datasets
•16 one-sided tests to determine directionality
Conclusion
References
Purpose
Methods
Methods
Results
The project was funded by grants from the U.S. EPA and completed with help from the
Utah’s Division of Air Quality.
•The background EtO value was approximately 2.5x greater
for measured concentrations in summer compared to winter
•Background site 3, a residentially and industrially mixed
location, showed the greatest EtO median concentration for
both seasons
•After comparing the estimated EtO concentrations from dispersion modeling to
canister-based measurements, 5 of the closest sites, and site 7, were statistically
different.
•Because neither method indicated being more conservative than the other, a
correction factor could not be derived for future cancer risk assessment modeling
with the EPA’s human exposure modeling
•A vast seasonal difference was found between background data, which deserves
further investigation
1.Olaguer, E. P., et al. 2019. Ethylene Oxide Exposure Attribution and Emissions Quantification Based on Ambient Air Measurements near a
Sterilization Facility. International Journal of Environmental Research and Public Health, 17(1), 42.
2.Sheehan, P. J. et al. 2021. Ethylene Oxide Exposure in U.S. Populations Residing Near Sterilization and Other Industrial Facilities: Context
Based on Endogenous and Total Equivalent Concentration Exposures. International Journal of Environmental Research and Public Health,
18(2), 607.
3.EPA. 2022. Our Current Understanding of the Human Health and Environmental Risks of Ethylene Oxide. U.S. Environmental Protection
Agency. https://www.epa.gov/hazardous-air-pollutants-ethylene-oxide/our-current-understanding-human-health-and-environmental.
Retrieved Feb 7, 2023.
4.EPA. 2022. Frequent Questions about Ethylene Oxide (EtO). U.S. Environmental Protection Agency. https://www.epa.gov/hazardous-air-
pollutants-ethylene-oxide/frequent-questions-about-ethylene-oxide-eto. Retrieved Feb 7, 2023.
U nt i t l ed map
si te_geo_l oca ti on.csv
All it ems
Figure 1. Map showing where the canister-based measurements were taken across Utah's Salt Lake City. There are 8
sampling sites near the medical sterilization facility (see blown up image) and 5 background sites locations.
U nt i t l ed map
si te_geo_l ocati on.csv
All it ems
Site 1
Site 2
Site 3
Site 4
Site 5
Site 6
Site 7
Site 8
•As the sites increase in distance from the point source, the median EtO concentrations
generally decreased
•Of the 8 sites sampled around the point source, 6 of the AERMOD estimates were
statistically different from the canister-based measurements
•AERMOD estimates > canister measurements at sites 1, 3, and 4
•AERMOD estimates < canister measurements at sites 2, 5, and 7
•Sites 6 and 8 were not statistically significant in either direction
Acknowledgments
Results