‍BALTIMORE (October 6, 2025) — A study released today found that cancer risks from polluting facilities in Louisiana’s “Cancer Alley” are up to 11 times higher than previously thought. Using an air monitoring lab equipped with cutting-edge technology, researchers from Johns Hopkins University captured real-time data on 17 carcinogenic air pollutants across four parishes between Baton Rouge and New Orleans in February 2023. 

Using their measurements of air pollutants, the research team then assessed lifetime cancer risks faced by residents living in 15 census tracts in Cancer Alley. In 14 out of 15 of these census tracts, cancer risks from their measurements were higher than estimates from EPA’s Air Toxics Screening Assessment model. This EPA model is based on emissions data from local and state environmental agencies, which often rely on self-reported chemical emission estimates from industrial facilities rather than actual measurements of air pollutant levels. The striking difference between the research team’s measurements and the EPA models suggests that current regulatory risk methods significantly underestimate population cancer risks in a region heavily overburdened by toxic air pollution. 

“We clearly show that relying on models to predict concentrations of hazardous air pollutants — and therefore the cancer risks associated from exposure — is inadequate,” said lead researcher Peter DeCarlo, Professor of Environmental Health and Engineering at Johns Hopkins University, who studies air quality. “While these regulatory models do identify the chemicals of greatest concern, they underestimate the cancer risk in some communities by an order of magnitude.” 

The peer-reviewed paper documenting these measurements was published in the Proceedings of the National Academy of Sciences. This paper builds on research published in 2024 by Johns Hopkins University, which analyzed ethylene oxide levels captured from the same data. 

“Understanding the true magnitude of communities’ burden from air pollution requires consideration of how large groups of chemicals act together to make people sick,” said Keeve Nachman, Professor of Environmental Health and Engineering at Johns Hopkins University and co-author on the paper. “We found that communities living in the shadow of petrochemical and other industrial facilities in Cancer Alley face cancer risks far higher than we would ever allow anywhere in the United States.” 

The research team measured 17 carcinogenic volatile organic compounds (VOCs), including ethylene oxide, formaldehyde, chloroprene, and more. A team of researchers from Aerodyne Research and Johns Hopkins drove a prescribed route through Cancer Alley’s industrialized river corridor over 20 times to measure air pollutants at all times of day, gaining insight into how the concentrations of these pollutants change over time and by time of day.

Of the VOCs measured, ethylene oxide, chloroprene, and formaldehyde contributed to 96 percent of cancer risk. Ethylene oxide was the single most significant contributor to cancer risk estimates across the entire study region. However, in some isolated areas, formaldehyde and chloroprene were the largest contributors to cancer risk. 

“One case of cancer is heartbreaking. Entire communities living with cancer is a crisis. And when you travel through these neighborhoods, it is hard to knock on a door without meeting a family with a cancer story,” said Heather McTeer Toney, executive director of Beyond Petrochemicals and former EPA regional administrator. “These results confirm what communities in Louisiana are living every day. But state and federal political leaders are responding to this emergency with free passes for facilities to keep pumping poison into Louisiana’s air. They have even dictated who is and isn’t allowed to monitor the air we breathe.” 

Earlier this year, the Trump administration announced it would grant passes exempting petrochemical facilities and other industries from an EPA regulation called the “HON Rule.” This rule would have required the industry to measure and reduce the emissions of many of the VOCs measured in this study. If implemented, this rule was expected to reduce cancer risk by 96 percent in communities living within six miles of the polluting facilities and by 60 percent for those living within 31 miles. 

“We are proud to work with the team at Johns Hopkins University to bring data and science to the experience of fenceline communities,” added McTeer Toney. “For too long, industry has relied on gaps in the data, but with this information, now we know just how bad things are.” 

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MEDIA CONTACT: Matt Smelser, [email protected]

About Beyond Petrochemicals

Beyond Petrochemicals: People Over Pollution is a national campaign working to stop the rapid growth of petrochemical and plastic pollution in the U.S. Focused on over 120 proposed projects in Louisiana, Texas, and the Ohio River Valley, the campaign supports frontline community efforts and pushes for stronger regulations to safeguard the health of American communities.

For more information, please visit us at beyondpetrochemicals.org and follow us on Instagram, LinkedIn, Facebook, and X.