Measuring ethylene oxide levels using mobile optical instruments in Louisiana’s southeastern corridor may help to improve cancer risk assessments, according to a recent study published by Robinson et al in Environmental Science & Technology.
Background
Louisiana’s southeastern corridor is sometimes known colloquially as “Cancer Alley,” because it has a high incidence rate of cancer linked to industrial air pollution. Most of the region’s air pollution–related health risks can be attributed to ethylene oxide, a volatile compound used to make plastics and sterilize medical equipment.
In 2016, the U.S. Environmental Protection Agency (EPA) classified ethylene oxide as carcinogenic to humans—particularly when inhaled. Although there has been significant concern over chronic ethylene oxide exposure among individuals residing between Baton Rouge and New Orleans, there are currently no published data of ambient concentrations of the carcinogen that aren’t derived from industry self-reported emissions data.
Fenceline communities are defined by the EPA as those where individuals live close enough to highly polluting facilities that they may be directly affected by the emissions of operation.
Study Methods and Results
In the study, researchers used a mobile monitoring system involving optical instruments to quickly determine ethylene oxide levels in Louisiana’s southeastern corridor and provide real-time results. They noted the equipment was mounted to a small truck and a van that drove a fixed route along a heavily industrialized portion of the corridor. The truck carried a tunable infrared laser direct absorption spectrometer, which measured ambient ethylene oxide in the surrounding air, whereas the van carried a cavity ringdown spectrometer to detect contaminant plumes—such as mixtures of ethylene oxide and other chemicals—downwind of petrochemical sites to indicate the type of facilities that emitted them.
After completing 23 laps of 130 miles with the mobile monitoring system between January and February 2023, the researchers discovered that all of their ethylene oxide measurements were higher than EPA estimates—which were gleaned from industry-reported emissions. Of note, ambient air measurements revealed that most of the region had ethylene oxide contents corresponding to risk levels above the EPA’s acceptable upper limit.
A few locations had contaminant concentrations representing potentially serious health risks for facility workers. The researchers’ second van identified chemical plumes up to 7 miles—1 mile beyond the 6-mile distance of fenceline communities—from their likely sources.
Conclusions
The researchers hope their mobile monitoring system can increase accurate measurements of hazardous air pollution in an area densely populated with ethylene oxide emitters. Their findings highlighted important issues related to current detection and reporting methods as well as associated health impacts on individuals residing near potential pollution sources.
Disclosure: The research in this study was funded by Bloomberg Philanthropies and the National Institute of Environmental Health Sciences. For full disclosures of the study authors, visit pubs.acs.org.
