The Denka Performance Elastomer plant, formerly DuPont, seen here in LaPlace, La. Thursday, Dec. 22, 2016, has been tasked with reducing the emissions by 85 percent of a chemical, chloroprene, that the EPA has found to be "likely" carcinogenic.

The chemical company at the center of a controversy over air pollution in St. John the Baptist Parish is digging in against residents who are demanding it take more drastic steps to curb emissions of a likely carcinogen called chloroprene. 

Officials with Denka Performance Elastomer agreed in November to spend $17.5 million on technology aimed at sharply cutting the amount of chloroprene coming from its plant in LaPlace after a study by the U.S. Environmental Protection Agency showed residents in St. John Parish had a higher risk of cancer from airborne pollutants than any other area of the country.

The EPA study, released in 2015, traced the risk to the plant, which for nearly half a century has been using chloroprene to produce neoprene, a synthetic rubber. The chemical was only classified as being particularly dangerous in 2010, amid studies suggesting it could cause lung, liver and kidney cancers.

Since then, controversy has continued to engulf the plant, with residents urging the company to take safety measures beyond those in the agreement made last year.

But in a letter made public this month, Denka officials said they would take no further steps beyond what was already promised, at least for now. 

Jorge Lavastida, the company's plant manager, wrote to the Louisiana Department of Environmental Quality in late June, saying the company has already "devoted substantial resources" to emission control.

In a statement to The Advocate, Lavastida said, "These projects not only have been done voluntarily and proactively, but most companies would not even entertain the thought of spending this type of time and money without being ordered to do so."

Plans to retrofit the plant with emission reduction technology began in earnest eight months ago, when officials reached a voluntary consent agreement with state regulators. The plant pledged to reduce emissions of chloroprene by 85 percent before the end of 2017.

Some residents have said that goal isn’t nearly ambitious enough, pointing to air monitoring results that have been taken since last spring by researchers with the EPA.

An analysis done in March shows that in a year's time, residents had been exposed to an average of between 12 and 58 times the amount of chloroprene the EPA says puts residents at increased risk of cancer. An 85 percent reduction still would mean "unacceptable" exposure, according to activist group Concerned Citizens of St. John.

The group asked Denka to further reduce emissions, suggesting safety measures that go beyond those laid out in the November agreement. Residents also urged the plant to reduce or stop production altogether.

In his letter to the state, Lavastida said some measures the residents had proposed would be too dangerous. He said officials still were studying the feasibility of others.

State health officials and regulators say the risk posed by the plant is unclear, arguing that the long-term effects of chloroprene exposure are not well understood, especially when levels spike and dip over time.

Measurements show the air around the plant at times has contained as much as 765 times the amount considered risky by the EPA. But sometimes, the data show no chloroprene at all.

Chuck Brown, secretary of the Louisiana Department of Environmental Quality, has accused some environmentalists of "fear-mongering."

The EPA has said "more detailed assessments are needed" to "accurately characterize" health risks caused by chloroprene.

In the meantime, more than a dozen residents filed suit against Denka in June. The suit, which seeks class action status, asks the court to force the plant to stop production until chloroprene readings go down.

"We feel this is a nuisance and trespass interfering with the community's right to live and enjoy their property,” said Eberhard Garrison, one of the lawyers representing the residents.

In response to the lawsuit, Lavastida said the company had always worked within limits allowed in Louisiana.

He called the EPA's methodology in determining cancer risk “highly flawed,” pointing to discrepancies between the national agency’s recommendation and regulatory standards enforced by officials in Louisiana.

State regulations allow 857 micrograms of chloroprene per cubic meter for an eight-hour average — more than 4,000 times the amount the EPA says might cause harm to humans during long-term exposure, or about 70 years.

It remains to be seen whether regulatory standards in Louisiana will change as a result of further study, but Lavastida said the decision should be up to the LDEQ and EPA, not to residents.

The company is “strongly committed to taking all appropriate legal measures to defend itself against the claims,” he said.

Follow Della Hasselle on Twitter, @dellahasselle.