Researchers find higher levels of dangerous chemical than expected in southeast Louisiana
Researchers using high-tech air monitoring equipment drove mobile labs through an industrialized stretch of southeastern Louisiana and found levels of a carcinogenic in concentrations as much as 10 times higher than previously estimated, according to an article published on Tuesday in the journal Environmental Science & Technology.
The study from researchers at Johns Hopkins University raises new health concerns for communities living among chemical plants along a stretch of the Mississippi River between Baton Rouge and New Orleans – called “cancer alley” by environmentalists.
The Environmental Protection Agency considers long-term exposure to inhaled ethylene oxide gas a cancer risk – a position challenged by the chemical industry. The state of California, which has its own environmental health agency, also lists the chemical is known to ’cause cancer and reproductive toxicity’ in men and women.
The study also heralds newer technologies that enable better and more accurate measurements of ethylene oxide and other chemicals.
“The instrumentation technology we have at our disposal is just much more sensitive and can be put on vans and moved around in ways that you don’t get with regulatory instruments,” said Pete DeCarlo, one of the study’s researchers.
Ethylene oxide is produced in large quantities and used as a main ingredient in antifreeze and polyester. It is also used to sterilize food, cosmetics and medical equipment and as a pesticide.
The report comes as the Biden administration has taken steps to reduce people’s exposure to the gas. Earlier this year, EPA announced plans to do this limit use of the chemical. And ethylene oxide also occurs in a broad order issued in April, which will require more than 200 plants across the country to reduce toxic emissions.
Traditionally, ethylene oxide measurements are made by collecting air samples and storing them in stainless steel canisters for later laboratory analysis. The problem, DeCarlo said, is that storage in the canisters appears to change the concentration of the gas.
Current regulatory figures on ethylene oxide levels are based on samples self-reported by the industry. Those numbers, he said, are “somewhere two to 10 times lower than the values we measured with our mobile laboratory in Louisiana.”
The Johns Hopkins study involved two vans that repeatedly drove the same routes over the course of a month last year. Researchers used instruments that measure gases in real time as they flow through high-intensity light. The vans used two different instruments but measured similar results, boosting the researchers’ confidence in the tests.
DeCarlo said almost all measurements were higher than 11 parts ethylene oxide per 1 trillion parts air – a level that translates to a one in 10,000 cancer risk with long-term exposure to the gas. That’s the upper limit of what the EPA considers acceptable to many toxins in the air And carcinogenic substances.
Sometimes the levels were a thousand times higher – measured in parts per billion rather than per trillion. And, notes Keeve Nachman, another Johns Hopkins researcher, ethylene oxide is just one of the pollutants emitted in the area.
“If you think about all the other chemicals that come into play and all the other concerns that we have about people living in Cancer Alley and the other life stressors that they face, they may be less resilient to ethylene oxide exposure than someone in the general population,” Nachman said. “So, if you were to say, what is the right level or what should be the acceptable risk? It should probably be lower than 1 in 10,000 people.”
Short-term exposure to the levels poses little risk to the vast majority of people, said Reed Rustin, a professor at Tulane University’s School of Public Health who was not involved in the study.
“My concern would be for individuals who are at risk and exposed throughout their lives, which is difficult to estimate but should be a concern to investigate further,” Rustin said.
The American Chemical Council has questioned what it called “a deeply flawed” method for determining the toxicity of ethylene oxide.
Tuesday’s report will probably serve as input for further developments politically and legally battles over the string of chemical plants between small, often predominantly black communities between Baton Rouge and New Orleans.
Amid such debates, improving pollutant measurements is important, DeCarlo said. He noted that there are few high-quality measurements around industrial facilities, meaning it is not well understood what residents are actually exposed to.
“We wanted to start better assessing what those dangerous concentrations of air pollutants look like for communities living in and around industrial facilities,” he said.