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Ethylene Oxide - the chemical industry's defense of cancer risk

Jennifer Sass

Posted May 6, 2014

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The chemical industry is mounting a defense of its toxic product

The EPA Integrated Risk Information System (IRIS) program released its Draft hazard assessment of ethylene oxide last summer, with its updated evaluation of the cancer risks from inhaling ethylene oxide (IRIS, July 2013).  Ethylene oxide is already known to be a very toxic chemical. It is one of the 33 most hazardous air pollutants identified by EPA as posing the greatest human health risk in the largest number of urban areas.(IARC Vol 97, 2008) At room temperature, ethylene oxide is a gas. It is toxic, flammable, explosive and causes cancer.

EO World Production.jpg

Overall, the EPA IRIS program's draft chemical assessment is pretty good. If it is finalized without being weakened by industry interference, it would provide the scientific underpinning for stronger pollution restrictions, thereby reducing cancer risks.

So it is not surprising that the chemical industry is in full chemical-defense mode.

Over the last few years, as EPA was conducting its review of ethylene oxide, the chemical industry was funding research arguing that ethylene oxide isn’t harmful at the levels that people are exposed, or isn’t as harmful as EPA has calculated, or some such version of the Four Dog Defense strategy that Big Tobacco developed to defend cigarettes (see recent comments on ethylene oxide by the American Chemistry Chemical industry and others at Docket ID No. EPA-HQ-ORD-2006-0756).

Now that the EPA is preparing to convene a scientific peer review committee to review its ethylene oxide assessment, it is seeking independent experts to serve on the committee. About a half-dozen scientists with research funding or collaborations with Dow Chemical or the chemical industry trade association are short-listed to serve on the “independent”peer review committee. None of their financial and collaborative relationships with the chemical industry are identified in public biosketches see the List and Biosketches of Candidates here).

If any of these industry-collaborating individuals are selected for the committee, it seems to me that it would violate EPA’s own guidance that says these committees are supposed to be comprised of scientists without financial conflicts or the appearance of a lack of impartiality. And, it would violate the recommendations of the 2014 National Academies report on the IRIS program, that advises against having financially-conflicted experts serve on scientific panels.

So what is it that the chemical industry doesn’t want us to know about ethylene oxide?

The EPA IRIS draft assessment concludes that ethylene oxide causes cancer in people.  Ethylene oxide exposed workers have an elevated risk of breast cancer, leukemia and non-Hodgkin lymphoma (Steenland et al 2003, 2004). Ethylene oxide exposed lab rodents had similar cancers, and cellular studies confirm that ethylene oxide causes genetic (DNA) mutations and chromosomal damage that can lead to cancer (see summary of relevant cancer data here).

It is most concerning that the IRIS draft finds a strikingly high cancer risk from exposure to high but realistic levels of ethylene oxide; an excess of 1,800 cancer cases per 1 million people that breath air contaminated with 1 µg/m3 ethylene oxide (Table 1-1, page 1-6).  This is 1,800 times higher than what EPA deems an acceptable risk level for the general population. (Maximum ambient air exposure models have been measured as high as 1 µg/m3 [IARC Vol 97, 2008]). 

How are people be exposed to ethylene oxide?

People can be exposed to ethylene oxide at work, such as when sterilizing or fumigating medical and dental equipment, when manufacturing chemical products such as polyester that are made with ethylene oxide, when sterilizing food spices, when making plastic products, and when fumigating agriculture crops (See IARC Monograph here).

People can also be exposed to ethylene oxide if they are working or living near sterilizer facilities, fumigation operations, or other places where ethylene oxide is used or manufactured in large volumes. According to the EPA Toxic Release Inventory, industry reported releasing 324,000 pounds of ethylene oxide waste, mostly into the air as either fugitive (110,800 pounds) or point source (197,400 pounds) air emissions (EPA TRI, 2012).

What is ethylene oxide used for?

Ethylene oxide is a human-made industrial chemical that is a key raw ingredient in the production of many industrial chemicals including ethylene glycol, which is used to make antifreeze and polyester. Polyesters are used in many household and industrial products including fabrics for home furnishings, upholsteries, factory conveyor belts, car safety belts, plastic bottles (PET, or polyethylene terephthalate plastic), tarps, canoes, insulation for wires, wood finishes such as on guitars and pianos, and liquid crystal displays (LCDs). Ethylene oxide is also used to make polyethylene glycols, in perfumes, cosmetics, paint thinners, and plasticizers. (See report on world uses of EO here)

A much smaller amount of produced ethylene oxide –  less than 0.1% - is used as a pesticide, or for sterilizing equipment that cannot be heat-sterilized such as drugs, some medical equipment, packaging, foods, museum artifacts, furs, railcars and aircraft, and beehives.

The US produces about 4 million metric tonnes of ethylene oxide annually (about 9 billion pounds), making it the largest producer in the world. Total global production is about 19 million metric tonnes annually, and rising.

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Michael BerndtsonMay 6 2014 05:39 PM

From American Chemistry Council on ethylene oxide - first paragraph from the webpage:

"A marathon runner trains in a favorite track suit and takes a long drink of cool water from a lightweight unbreakable bottle. You relax in your comfortable overstuffed lounge chair to watch the big game. A mother applies a clean bandage to her child’s scraped knee. Surgeons use sterile instruments to complete a life-saving heart transplant. You jump into your car, turn the ignition key and it starts immediately, despite the winter cold."

This is why chemists and chemical engineers don't write copy. There's professionals who do that.

Rietha CraffordMay 13 2014 11:59 AM

There is no need in the world to use
EO - Ethylene oxide for sterilizing medical equipment, spices or any pest control neither is there a need to use MB - Methyl Bromide for that matter . There are 2 other products, NON toxic to the humans that works with it or in close proximity of it. I have stumbled onto these 2 products by change, but the Chemical Giants does not want to use them because it will replace ALL THE CHEMICALS in the world and that is just not profitable for the Dow Chemical's Monsanto's, Syngenta's of this world

Rietha Crafford
+27 72 934 9060

AnonymousMay 14 2014 02:42 PM

It would be prudent to note that the uses for ethylene glycol and hence PET mentioned above are very beneficial to life on this planet and contain NO EO as ethylene glycol & PET do not revert to the raw materials from which they are formed.

There are, in fact, some naturally occurring materials & activities pose a greater threat to human health than EO. Eating shrimp, insufficiently baked cashews, driving, flying, or being struck by lightning while attending an outdoor concert are considerably more dangerous for the average person than EO exposure.

EO is heavily regulated by the EPA & OSHA, not to mention the producers, with regards to exposure to humans and the environment.

I am not posting to start an online duel; however, I think that a few more facts from the other side are needed for a balanced discussion.

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