A year after the company operating a controversial chemical plant in LaPlace agreed to reduce emissions of chloroprene by 85 percent following a study showing it's a "likely carcinogen," officials say the reduction plan is just a month away from completion.

Chuck Brown, secretary of the Louisiana Department of Environmental Quality, said at a recent St. John the Baptist Parish Council meeting that the Denka Performance Elastomer plant is in the final stages of installing a piece of equipment called a regenerative thermal oxidizer, which uses heat to destroy pollutants.

That's the final and most important piece of equipment in Denka's multi-step plan to dramatically reduce the amount of chloroprene released into the air, plant and state environmental officials have said.

It's also the last step before state and federal officials decide whether they should force the company to lower emissions of the chemical still further. 

"Whatever we end up doing, it will be protective of human health and the environment," Brown said, adding later that it would also have to be a limit "that is enforceable" on industry.

In a statement, Denka's plant manager, Jorge Lavastida, said the plant was spending more than $25 million on four different projects aimed at cutting emissions, and that they would result in "substantially reduced" chloroprene emission levels by the end of the year.

The plant will also discontinue production of the synthetic rubber neoprene, which is made from chloroprene, for two weeks while the final installations are done, Lavastida said.

St. John chemical plant: No further steps, for now, to reduce dangerous emissions

The plant, which was bought by Denka in 2015 but under prior ownership had been producing chloroprene at the site for more than half a century, has been controversial for years. 

At issue is a debate over chloroprene's health effects — a question local and national officials are scrambling to answer following a relatively new assessment of the chemical by the U.S. Environmental Protection Agency.

Since 2010, the EPA has asserted that a certain chloroprene level — more than 0.2 micrograms per cubic meter of air every day for a lifetimea  — puts people at increased risk of getting liver or lung cancer. 

In 2015, the agency released a study showing St. John Parish residents were more at risk than anyone else in the country for getting cancer because of the chemical,  thanks to Denka's emissions.

Two years ago, the EPA started monitoring air around the plant. The most recent data showed some areas have 100 times the amount the EPA says is dangerous. Other areas had minimal exposure.

The data will continue to be monitored until at least the end of 2018, officials said.

St. John residents sue LaPlace plant over chloroprene emissions; suit seeks class action status

Environmentalists and concerned residents say Denka is putting residents' health at risk. Thirteen residents sued the company in federal court, asking for damages and for production to be halted until emissions are under control.

Their lawyer, John Cummings, recently commissioned a study to test residents for chloroprene levels. It found that all 18 residents tested had metabolites of chloroprene in their urine, meaning they were exposed to the chemical.

"It's very important and it's very shocking," Cummings told the council.

Dr. Jimmy Guidry, the health officer for the Louisiana Department of Health, however, said that the new data coming in only continue to add to the challenge of answering "difficult and complicated questions."

"What do certain levels mean and what do levels in people’s bodies mean?" Guidry asked, adding that health officials were working on answering the questions. "There's not a whole lot of science about chloroprene."

Guidry analyzed 923 air monitoring samples, taken between May and September, and then shared them with an expert panel of health officials convened by Dr. LuAnn White, a toxicologist at Tulane University.

The experts, he said, told him the levels didn't amount to a public health emergency. However, he said that didn't mean he is unconcerned.

Denka says EPA estimates for chloroprene risk in St. John the Baptist Parish are too high; agency says science is sound

"It is a big deal. It’s a big deal because we don’t know," Guidry said, adding that he could "understand" residents' anger. "From what I know today those risks are something we have to consider. We have to minimize it. We have to mitigate it."

In the meantime, the EPA is reviewing its assessment of the chemical, at Denka’s request. Specifically, the agency will be taking a look at the limit scientists have advised as too risky for human exposure.

Brown said the EPA's decision will also help determine if officials will change chloroprene standards in the future.

Regardless, both the EPA and Brown say that the plant's reduction plan is the fastest course of action for residents to get relief from high emissions now.

"We're finally getting to what we call a payoff," Brown said. "So let's see what that payoff is."

Follow Della Hasselle on Twitter, @dellahasselle.