"Scientists have known for decades that ethylene oxide can cause cancer and more immediate harms. Its lethality is what makes the chemical so useful as a sterilizing agent for medical equipment and spices. Released into a chamber with these products, it disrupts on contact the cellular metabolism and reproductive processes of microorganisms. Chemical companies use ethylene oxide to produce other chemicals that are the building blocks of a wide range of products, including brake fluid, antifreeze, coolants, cosmetics, food additives, agrochemicals, and several kinds of plastics.

Yet in its gaseous form, even tiny amounts of ethylene oxide are extremely dangerous. Acute exposure can cause skin burns, twitching, convulsions, and coma, according to the Centers for Disease Control and Prevention. The cancers are thought to come from long-term exposure. Over a lifetime, an annual average of just .0002 micrograms per cubic meter of air — an infinitesimal amount — is associated with a one-in-a-million risk of getting cancer, according to the EPA’s 2016 calculations. That one-in-a-million standard was set by a 1990 amendment to the Clean Air Act, but since 2008, the EPA has increased the “upper limit of acceptability” to a risk level of 100 cancers in a million people: That’s 100 cancers in addition to the cancer risk without the contamination. Using that less protective number, the safety threshold for ethylene oxide is .02 micrograms per cubic meter of air.

In Lake County, all of the more than 400 ethylene oxide measurements in the air near the two plants performed by the local health department in 2019 were above the one-in-a-million risk threshold, and most were above even the less protective level. Some were way above that number. In one spot near Spaulding Elementary School in Gurnee, the amount measured in November 2019, when converted to an annual average, was more than 50 times the EPA’s weaker cancer risk level; that’s a cancer risk of more than 5,000 in a million. Around the same time, in a residential area near the Vantage plant, the amount measured was more than 88 times the safety level and more than 8,800 times the older, more rigorous EPA threshold, corresponding to a cancer risk of 8,800 in a million."