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Ethylene Oxide in Utah

Ethylene Oxide (EtO) is an air toxic pollutant of emerging concern. At typical ambient concentrations, EtO is an odorless and colorless gas that is used in the sterilization of materials, such as medical equipment and spices. EtO is also an ingredient in chemical products, such as antifreeze, textiles, plastics, detergents and adhesives. EtO inhalation can contribute to increased cancer risk, with the the Environmental Protection Agency (EPA) reassessing the carcinogenicity of EtO in 2016, and increasing its toxicity value by 60 times for children and 30 times for adults.

Summary of Ethylene Oxide (EtO) Study

DAQ was awarded funding through the EPA Community Air Toxics Ambient Monitoring grant to determine ambient EtO levels and their associated health risk near the two medical sterilization facilities in Utah, both of which are located in Salt Lake County.

The planned study had three main objectives:

  1. Determine how EtO levels change across Salt Lake County by collecting ambient silonite canisters at strategic locations near the facilities and at background sites. 16 sampling sites (11-12 near facilities and 4-5 background) were selected.
  2. Determine seasonal differences in EtO concentrations by sampling during the wintertime and summertime. Samples were collected once every three days for eight weeks in both seasons.
  3. Assess health risk from EtO exposure using a variety of HEM-3 model simulations, and by comparing modeled to measured ambient concentrations.

Summary of study findings

EtO measured near facilities was higher than EtO measured at background sites or further from the facilities. EtO concentrations were greater in the summer than in the winter. Background EtO concentrations are highly variable, and more work is needed to understand what might be impacting these background concentrations. Modeled and measured concentrations of EtO showed consistent spatial variation. Modeled lifetime cancer risk was greater close to the facilities. Ambient measurements were all well below levels that would be of concern for an immediate health risk.

The full final report is available below.

What’s next?

Both BD Medical and Sterigenics are in the process of installing controls to limit their EtO emissions. EPA is also updating EtO emissions regulations that should reduce EtO emissions from sterilization facilities. Using funding from a newly-awarded EPA grant, DAQ will continue monitoring EtO levels.


Related Project Lists

Read more about EPA’s risk analysis in Sandy Utah.

What is ethylene oxide and what are its uses?

Ethylene oxide is a gas used to sterilize equipment that cannot be sterilized by steam, such as medical and dental devices. It is also used to make chemicals for the manufacturing of everyday products, including antifreeze, textiles, plastics, detergents and adhesives.

Ethylene oxide in outdoor air can have various sources, including industrial facilities such as chemical manufacturers and sterilizers. It is also listed by the EPA as one of 187 “Hazardous Air Pollutants,” which are pollutants known or suspected to cause cancer or other serious health effects.

What is a safe level of ethylene oxide?

The Clean Air Act requires the EPA to regulate “Hazardous Air Pollutants” (HAPs), also known as air toxics. Rather than setting ambient air standards, which are limits on the amount of a pollutant that is allowed in outdoor air, HAPs emissions are capped for industrial sources directly. Conducting measurements along with a health risk assessment are the best approaches to assess if additional controls on ethylene oxide emissions are needed.

Read the EPA FAQ to learn more.


Rachel Edie
(385) 306-6502

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