July 29, 2019 / Ed Stuber and William Walsh

Sampling Tips for Ethylene Oxide

Sponsored by SGS Galson

In 2016, EPA identified ethylene oxide (EtO) as a potential carcinogen. The agency is addressing ambient EtO based on the results of the latest National Air Toxics Assessment, released on Aug. 22, 2018, which identified the chemical as a potential concern in several areas across the country. NATA is the agency’s nationwide air toxics screening tool, designed to help EPA and state, local, and tribal air agencies identify areas, pollutants, or types of sources for further examination.

EtO is a flammable, colorless gas used to make other chemicals that are used in making a range of products, including antifreeze, textiles, plastics, detergents, and adhesives. EtO is also used to sterilize equipment and plastic devices that cannot be sterilized by steam, such as medical equipment.

EPA based its classification of EtO as a human carcinogen on studies of workers that show an association between exposures to ethylene oxide and an increased risk of cancers of the white blood cells (the infection-fighting cells of the immune system). Studies also show an increased risk of breast cancer in females.

In response to public concerns, EPA performed sampling in May 2018 in a Chicago suburb adjacent to a sterilization facility and found ambient EtO levels in some cases to be significantly above what it considers to be a safe level (0.20 ppbv). At least one source estimated that the elevated ambient levels raised the local cancer risk to more than six cases per 1,000 people.

IH practitioners who wish to achieve precise EtO sampling must consider various issues. Here are our top five:

  1. Only use EPA method TO-15, “Determination of Volatile Organic Compounds (VOCs) in Air Collected in Specially-Prepared Canisters and Analyzed by Gas Chromatography/Mass Spectrometry (GC/MS),” when sampling for EtO. Although this method allows you to collect other VOCs, ask the lab to analyze for EtO only. This will allow for sampling in the SIM mode of the GC/MS, which provides the lowest possible detection limit for EtO.
  2. Ask your lab if they have the necessary accreditation for analyzing EtO via EPA TO-15. Using a lab accredited to ISO/IEC 17025, “General Requirements for the Competence of Testing and Calibration Laboratories,” ensures that quality assurance protocols are being followed and that you can be confident in your results.
  3. Ask if your lab is aware of the potential for the co-elution of trans-2-butene when analyzing for EtO. Your lab should be able to separate this potential interferent from EtO without compromising the detection limit needed.
  4. Always choose the correct evacuated canister size when sampling. Although many different size cans can be used, from 440 ccs to 6 liters, your detection limit will vary. EPA considers the safe level of EtO to be 0.20 ppbv or lower.
  5. In addition to selecting the correct can size, it is also important to sample for the appropriate time. Sampling times can vary from 15 minutes to one week. Discuss the options with your lab. Not all labs may have validated all the different can sizes for EtO.

Visit the SGS Galson website for more information about EtO sampling and limits of quantitation.

Ed Stuber and William Walsh


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