It’s been well-understood for over 40 years, if not longer, that the chemical ethylene oxide can cause cancer. Used as disinfectant for medical equipment and a key ingredient in a host of plastic products including PET bottles and polyurethane foam, ethylene oxide is also common in the petrochemical industry. It’s regulated as a known carcinogen, and just this year, the Environmental Protection Agency finalized rules that could cut emissions by 80%.
Despite all of this, there has never been a good sense of how much ethylene oxide contaminates the air around facilities that use it — many of which are clustered in the River Parishes in southeastern Louisiana, known more notoriously as Cancer Alley.
“It’s really hard to measure ethylene oxide,” says Peter DeCarlo, a researcher at John Hopkins University. For a long time, the only way to try was to take samples of air in metal canisters and then bring them to be analyzed in a lab, which may have been fine if it weren’t for the fact that some canisters would seemingly at random develop much higher concentrations of the chemical than was reasonable to expect.
New technology has made it possible to test the air in realtime, and last year DeCarlo and his colleagues criss-crossed the river parishes with the monitors to test ethylene oxide levels in situ — and found that they were wildly higher than concentrations modeled by regulators like the EPA. Their findings were recently published by the journal “Environmental Science & Technology.”
“Some drives we were out driving and hit a parts per billion plume, which is a thousand times higher than parts per trillion,” DeCarlo says — and according to the EPA, a lifetime exposure to 11 parts per trillion presents a cancer risk. Those plumes can persist for long distances too, the researcher found, with some measuring seven miles in length.
A powerful mutagen, ethylene oxide attacks DNA cells, which is what makes it so effective at its other common industrial uses — like sterilizing medical equipment. But it’s indiscriminate: while it can kill viruses and bacteria, it can just as readily hurt human cells. It’s been linked with a variety of cancers, including leukemia, myeloma, lymphoma, and breast cancer, and other health problems. The study estimates (using the EPA’s own standards) that ethylene oxide represents 68% of the overall health risk, both cancer and non-cancer, in the River Parishes.
Because much tighter rules have already been established by the EPA, there’s already a potential solution to the ethylene oxide problem. But the sky-high concentrations in the River Parishes, where the population is disproportionately Black and poor, shows once again how overburdened such communities often are when it comes to pollution. And while the focus is often on so-called fence-line communities, where the plant that’s emitting the chemical is right next door, the persistence of high ethylene oxide concentrations are a reminder that out of sight is not out of mind.
As DeCarlo puts it, “concentrations are always going to be highest closer to the plant, but just because you can’t see the facility doesn’t mean that you aren’t impacted by the facility.”
The question now is how effective the new regulations will be at reducing overall emissions. “From a scientific standpoint,” DeCarlo says, “I’m excited to come back to the River Parishes in two or three years after these rules have been in effect and see what has changed.”
