New research reveals that the air in southeastern Louisiana’s “Cancer Alley” is likely being poisoned with a highly carcinogenic gas at levels much higher than previously thought.
Using advanced equipment that more precisely monitors for the gas, ethylene oxide, which is mainly used in plastic production, researchers found levels more than 1,000 times higher than previous measurements, and on average about 10 times higher than regulators’ models .
The levels pose a “concerning” risk to residents and workers in the region, especially children, said Pete DeCarlo, a researcher at Johns Hopkins University and senior author of the paper. Residents in the region are largely African-American and have low incomes.
“I don’t think there’s a census tract in the area that doesn’t have a higher cancer risk than we consider acceptable,” DeCarlo said. “We expected to encounter ethylene oxide in this area. But we didn’t expect the levels we saw, and they were certainly much, much higher than EPA’s estimated levels.
Ethylene oxide is linked to multiple cancers, DNA damage, lung damage and other serious health problems at low exposure levels. It is used in the production of other plastic chemicals and in a fumigation process for sterilizing surgical equipment and food cans. Although ethylene oxide is emitted from industrial plants across the country, it is most commonly used in Louisiana due to the large number of chemical facilities.
The most common route of exposure is inhalation. The EPA found a cancer risk in air samples of 11 parts per trillion, an exceptionally low level compared to many other common air pollutants, such as ozone.
“This is a very, very, very small amount,” DeCarlo said, which is why it is essential to get an accurate reading of the levels, he added.
The Environmental Protection Agency collects air samples in and around facilities that emit the gas and takes them to laboratories for measurements. But once the gas is in a sampling container, the gas changes rapidly and its actual volume becomes difficult to measure.
Researchers spent a month repeatedly driving a heavily industrialized route along the Mississippi River between New Orleans and Baton Rouge for a month in the winter of 2023, collecting air and testing it in real time as they drove past large industrial facilities and nearby residential areas.
The equipment detected plumes as long as eight miles (12 kilometers) emanating from some facilities, showing that the gas is concentrated enough at that distance to still pose a health threat. East Ascension high school in Gonzales, Louisiana, is about five miles from one of the identified ethylene oxide hotspots.
It is unclear whether the chemicals are released from smokestacks or as fugitive emissions escaping through pipes or equipment in the factories.
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The EPA established lower cancer risk levels for the chemical in 2018, DeCarlo said, noting that the industry disagrees with the agency’s assessment. It is classified as a hazardous air pollutant, so the government aims to allow no emissions, but polluters are allowed to emit some of the substance each year.
Using an EPA tool that weighs the overall hazard of a chemical in the region, researchers found that ethylene oxide made up 68% of the threat for hazardous air pollutants in “Cancer Alley.”
While the tool paints a broad picture, “it is notable that a large portion of the environmental risks in this area appear to come from a single chemical,” the authors wrote in the study.
DeCarlo said researchers focused on ethylene oxide because it is so carcinogenic and very little data exists, but he noted it is just one of numerous chemicals that people in the area are exposed to.
“The reality is that people are not just breathing in ethylene oxide, but a whole soup of chemicals,” he said. “When you put it all together, it becomes a much more problematic picture.”