BD said the leak occurred Sept. 15-23 and totaled 54.5 pounds. The company said air monitoring systems inside the plant detected the presence of ethylene oxide, but employees did not discover the source — a valve that had not been properly closed — until Sept. 23.
A state Environmental Protection Division spokesman said the agency is investigating the matter.
The operations of sterilizers that use ethylene oxide, or EtO, have come under greater scrutiny since a federal Environmental Protection Agency report released last year warned of the risk for potential health concerns from long-term exposure to the gas.
The report, known as the National Air Toxics Assessment, only came to light through media reports in July. It warned of potentially higher cancer risk in census tracts near the BD plant and a Sterigenics sterilization facility in Cobb County.
Subsequent emissions modeling completed in June by Georgia EPD found that the areas of potential concern were less acute than the EPA’s initial assessment and confined to the immediate vicinity of the plants.
In response, Sterigenics and BD have each committed to millions of dollars in new emissions controls.
On Thursday, BD released results of testing it said shows the Covington plant emits a fraction of the EtO gas calculated in the state and federal reports.
The tests, conducted last month by ECSI of California and observed by Georgia EPD, found that BD’s emissions controls destroy 99.999% of EtO that passes through its stack, according to company officials.
That level of efficiency would mean that BD annually emits about 3.5 pounds, a news release said, or about 97% less EtO through its controls than previously detected in stack tests from 2012.
“The results of the latest stack test confirm that we operate our facility in a safe and responsible way, with newer, more sophisticated technology confirming that our stack emissions are extremely low,” Ellen Kondracki, a BD vice president said in a news release.
But Jason McCarthy, who leads the Stop EtO East Georgia chapter, said the company’s assurances aren’t enough because emissions data is self-reported to the state by the company.
“What we need is independent testing and we need continuous testing,” McCarthy said.
The city of Covington is conducting air testing through the end of October, and the state EPD is conducting long-term sampling of the air.
The NATA report last year that flagged neighborhoods near BD was based on emissions self-reported by a predecessor company in 2014. But BD said that self-reported data didn’t accurately reflect tests in 2012 that showed its pollution controls were more effective at eliminating EtO.
The September stack test results, if applied to prior state and federal modeling, BD said, “would have shown significantly lower emissions.”
BD said it will install $8 million in new controls to capture “fugitive” emissions at its plants in Covington and Madison. Fugitive emissions of EtO are those that escape the packaging of sterilized products and aren’t captured by pollution controls.
BD said the new controls, which are being designed, would be presented to the state EPD for approval through a new permit application.