A little-known form of medical pollution is costing Puerto Ricans their health

The US outsources much of its medical tool sterilization—and cancer risks—to the island territory.
Medtronic's headquarters.
The corporate headquarters of Medtronic, which has an ethylene oxide sterilizer plant in Puerto Rico. Deposit Photos

Catheters, stents, and other medical devices are instrumental in saving peoples’ lives, but the methods used to sterilize this equipment could be causing cancer in some parts of the country, most notably in Puerto Rico and the metro areas of Baltimore, Denver, and Richmond, Virginia. A colorless gas called ethylene oxide is used to decontaminate about 20 billion medical devices per year, about half of all medical equipment used annually. This process often happens within buildings that look like ordinary offices, lacking prominent exhaust pipes or billowing clouds often associated with chemical plants. 

The Environmental Protection Agency (EPA) classified ethylene oxide as a carcinogen in 2016, because it can cause lymphoid, breast, and other cancers if inhaled at low doses regularly or infrequently at particularly high levels. The chemical can also damage the brain and nervous system and irritate the eyes, skin, nose, throat and lungs. 

Puerto Rico, a US territory without voting power, has carried a disproportionate load of the country’s burden—both in terms of the number of plants and the effect on local communities. Its facilities tend to receive less legislative action than others, too.  When a sterilizer plant enters a neighborhood, the wealthier and whiter ones are more successful at getting it shut down, according to Adrian Wood, who works on community engagement at the University of Pennsylvania’s Center of Excellence in Environmental Toxicology, and the author of a 2022 research paper analyzing community and government responses to ethylene oxide emissions in the US and Puerto Rico.

Puerto Rico has seven sterilizer plants, including four of the most dangerous facilities, according to a new report from the Union of Concerned Scientists. “Only California and Texas, the two most populous states, have more sterilizers, even though Puerto Rico has roughly one-tenth the population of Texas and 1 percent of its land area,” the report states. The sterilizers are within five miles of more than 413,000 Puerto Ricans (roughly 13 percent of the population) and nearly 300 schools and childcare centers, according to the report.

Because most of Puerto Rico’s sterilizer plants are located in low-income and minority areas, many of the people who get cancer from the toxic fumes might not have access to hospitals with quality treatment. “It is incredibly tragic for people to get cancer and then find themselves being treated with the same materials that caused their cancer,” says Marvin Brown, an attorney for the nonprofit legal advocacy group Earthjustice. 

Accidents at these plants can be frightening. Two explosions at a Steri-Tech plant in Salinas, a small and low-income town in the south of the commonwealth, shook houses late last year and early this year. Residents told the Associated Press that the explosions were worrisome, and one woman said that several of her neighbors who lived nearby had died of cancer.

Then, last year, the EPA took air samples to measure the level of contamination across the island. The agency found extremely high concentrations of ethylene oxide in some areas, with one containing 121 micrograms per cubic meter of air, which is more than 400 times higher than the US national average of 0.3 micrograms. The four plants the EPA said posed the most elevated risks for cancer included Edwards Lifesciences Technology SARL in Añasco, Customed in Fajardo, Steri-Tech in Salinas, and Medtronic in Villalba.

Brown guesses that Puerto Rico might have so many sterilizer plants because of its sizable pharmaceutical industry. Eight percent of US pharmaceuticals are manufactured in Puerto Rico, according to the US Food and Drug Administration.

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Sterilizer plants throughout the country are required by the EPA to have emissions controls, which reduce the amount of ethylene oxide diffused into the air above sterilization chambers, aeration room vents, and other parts of the plant. But Brown suspects that most of the ethylene oxide emissions may be produced elsewhere. Ethylene oxide may be released in uncontrolled settings, such as when  product ‘off-gasses,’ or continues to release chemicals, after sterilization.

Under the Clean Air Act, the EPA’s commercial sterilizer regulations must be updated every 8 years. But in 2019, the deadline the agency gave itself for new regulations, the agency failed to produce them. Earthjustice is suing the EPA to issue updated regulations and force the agency to adhere to a court-ordered deadline. The EPA hosted a community meeting on January 24 to address residents’ concerns, though the agency did not respond to request for comment by the time of publication.

Meanwhile, wealthier and whiter communities have used political pressure to shut down facilities that open in their neighborhoods. Wood’s research paper, which analyzed US states and Puerto Rico, found that sterilizer plants located in rich neighborhoods received the most aggressive response from the community, who in turn pushed the government. “The state [came] in quicker and more aggressive with testing and air monitoring, and [got] the facility to shut down in these wealthier suburbs,” she says. 

In two such suburbs, outside Chicago and Atlanta, new sterilizer plants were shut down within a few years. The EPA typically reacts much more slowly, Wood says. “But things did happen in those two areas,” she says. “So why couldn’t they happen in all the other areas, too?”

Researchers are studying other methods for sterilizing equipment. Right now, the Food and Drug Administration has approved three methods for sterilization: heat, steam and ethylene oxide. The problem with heat and steam is that they might melt certain medical equipment. The International Organization for Standardization published standards for hydrogen peroxide, another option for sterilizing these devices, although it hasn’t yet been approved by the FDA. 

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“Hydrogen peroxide, for example, appears to be less toxic to workers and the environment,” Darya Minovi, author of the Union of Concerned Scientists report, said in a blog post. “But the status of the FDA’s effort is unclear, and given what we know about ethylene oxide, we hope the agency is considering phasing out its use in medical device sterilization altogether instead of permitting its continued use.”

But the trade association AdvaMed claims the gas can decontaminate tools that other, rougher techniques would destroy. Hospitals and labs rely on ethylene oxide “to sterilize devices and equipment to protect millions of patients from the real risks of infectious diseases caused by bacteria, viruses, and fungi,” the group argues on its website. “For the majority of these products, [ethylene oxide] sterilization is the most effective and efficient—and often the only viable—sterilization technology.” 

Any update to EPA’s ethylene oxide regulations—which Earthjustice is suing for—would affect the commonwealth, too. “Everybody under the Clean Air Act deserves to breathe clean and safe and healthy air,” Brown says. “No part of the country should be a sacrifice zone for the rest of the country.”