smoke billowing from factories behind river

Smoke billows from chemical plants in Baton Rouge, Louisiana, in 2013. "Cancer Alley," a concentration of petrochemical plants amid residential homes, runs along the Mississippi River from Baton Rouge to New Orleans.

(Photo: Giles Clarke/Getty Images)

'People Are Dying': Air in 'Cancer Alley' Louisiana More Toxic Than Previously Thought

Ethylene oxide, a carcinogenic gas, is nine times more prevalent than the EPA estimated, a study shows. And inside petrochemical plants, workers are likely subjected to much higher concentrations, an author said.

The presence of a dangerous chemical in the air of southeast Louisiana's "Cancer Alley," which has a substantial Black population, is far greater than the U.S. Environmental Protection Agency estimated and exceeds safe limits, a study published Tuesday found.

The levels of ethylene oxide, exposure to which can cause lung, breast, or other cancers, are nine times higher than the EPA estimated, the study, which was published in the journal Environmental Science & Technology, shows. Ethylene oxide is a gas used in plastic production and in the sterilization of medical equipment. Long-term exposure is exceptionally dangerous: The EPA regards it as unsafe, due to cancer risk, at a level above about 11 parts per trillion (ppt) in the air.

The new study found that the gas' presence averaged about 31 ppt in Cancer Alley, and was far higher in certain locations within the industrial corridor, which runs alongside the Mississippi River from Baton Rouge to New Orleans. In each of the census tracts the researchers studied, the level of the gas was higher than the EPA had estimated for that area, in most cases significantly, with a median discrepancy of about 21 ppt.

"We expected to see ethylene oxide in this area," Peter DeCarlo, an associate professor at Johns Hopkins University and an author of the study, toldThe Guardian, noting that it was "worrisome," especially for children. "But we didn't expect the levels that we saw, and they certainly were much, much higher than EPA's estimated levels."

Concentrations of ethylene oxide could be much higher "inside the fenceline" of petrochemical plants—areas which couldn't be studied—where workers are "getting much, much higher concentrations over the course of their day," DeCarlo toldGrist.

People in Cancer Alley are nearly twice as likely to get cancer as other Americans, and ethylene oxide accounts for most of the known carcinogenic risk there, roughly 68%, if EPA estimates are correct. "The fact that so much of the environmental risk in this area seems to come from a single chemical is remarkable," the study authors wrote.

DeCarlo said this is why the authors deemed it important to study the amount of ethylene oxide in the air there. However, he cautioned that ethylene oxide is far from the only problem.

"The reality is people aren't just breathing ethylene oxide, they are breathing a whole soup of chemicals," he told The Guardian. "When you start to add everything up it becomes a much more problematic picture."

The risk to human health is likely not limited to facilities that are emitting ethylene oxide, as the researchers found plumes of gas that were miles long. East Ascension High School in Gonzales, Louisiana, is about five miles from an ethylene oxide hotspot, the study notes.

In 2021, United Nations experts called for an end to environmental racism in Cancer Alley, and the organization's special rapporteur on the issue of human rights called the area a "sacrifice zone" the following year. In January, Human Rights Watch released a report on systemic injustice there.

Sharon Lavigne, the founder of Rise St. James, a community organization in St. James Parish, said the findings were a "step in the right direction" but must lead to accountability and change.

"These monitors are good, but in the meantime, people are dying," she toldGrist.

Earlier this year, the EPA announced new ethylene oxide rules that could cut Louisiana emissions of the gas by nearly 80%—"the first time that federal regulations for chemical plants have been updated in decades," Gristreported in April. Cancer Alley had been among the places that EPA Administrator Michael Regan visited on his 2021 "Journey to Justice" tour. Yet the new study may lead to calls for further action.

"The EPA's new rule was necessary but should only be the start of how we begin to make things right here," Heather McTeer Toney, who leads a Bloomberg Philanthropies campaign to end petrochemical plant expansion, told Grist. "I'm hopeful to see levels go down, but the data suggest we have a long way to go."

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