The U.S. Environmental Protection Agency should ignore a plea to change health-related chloroprene emission guidelines made by a company already releasing concerning amounts of the chemical, according to attorneys for plaintiffs in a related lawsuit.

In a letter sent to the EPA in September, scientific experts hired by the plaintiffs' lawyers accuse the chemical company of putting "the entire United States" at risk of exposure to "dangerous" levels of chloroprene simply to advance its own "self-interested desire to maintain profitability."

The letter was a response to another letter written by Denka Performer Elastomer LLC earlier this year, accusing the EPA of using faulty science when estimating safety limits for exposure to the chemical.

The exchange marks the latest development in a controversy involving the chemical company and residents who live and work around the plant in St. John the Baptist Parish.

The latest letter was sent by the Lambert Firm, which represents 13 plaintiffs in a lawsuit filed earlier this year against Denka. 

Echoing concerns made by environmentalists, Eberhard Garrison, one of the attorneys for the plaintiffs, has alleged the company is putting residents in imminent harm by releasing "excessive" amounts of chloroprene. 

Since 2010, the EPA has said exposure to more than 0.2 micrograms of chloroprene per cubic meter of air every day for a lifetime puts people at increased risk of getting liver or lung cancers.

Air monitoring over a single year in St. John the Baptist Parish showed that the chemical plant at times exposed residents to between 12 and 58 times the amount the EPA deems overly risky.

The plaintiffs, who are seeking monetary damages, have asked a judge to shut down the plant or order it to reduce production until emissions are lowered.

But Denka claims that the EPA's calculations are fundamentally wrong and that the flawed assessment has caused the company “severe reputational damage.”

In a letter to the agency on June 26, Robert Holden, a lawyer for the company, and Jorge Lavastida, the plant's manager, complained that the EPA’s public assessment had “created unnecessary public alarm” in the parish.

They cited a study done by Ramboll Environ, a private environmental, safety and health sciences consulting firm, that said EPA’s human inhalation unit risk, called the IUR, is 156 times too high.

The Lambert Firm responded with objections of its own, including comments by three paid experts.

Among them was Dr. Karl Brooks, a former EPA official who worked as the Region 7 administrator from 2010 to 2015 and later at the agency's headquarters.

Brooks urged current EPA officials to reject "in its entirety" Denka's request to change the guidelines because it provided "no new peer-reviewed scientific information" that wasn't already considered by the agency. Unlike the agency's earlier assessment, the Ramboll Environ report has not been subject to peer review, he added.

Brooks accused Denka officials of attempting to use political connections to undermine the scientific process required by the agency and instead appeal to its newly appointed head, Scott Pruitt.

Before being appointed as EPA administrator by President Donald Trump, Pruitt, a former attorney general of Oklahoma, often criticized the EPA for overly burdensome regulations and an "activist agenda."

Brooks said Pruitt is more interested in chemical companies' bottom line than in the science behind EPA regulations.

He urged rejection of Denka's request to ensure "that political influence does not interfere with scientific decision making."

The request "opens a new front in a calculated political and economic campaign by ... affected chemical industry members to interfere with, distort and render non-transparent decisions that governing laws and EPA policies require to be purely scientific," he said.

Brooks left the EPA in February and now works at the University of Texas in Austin.

Another of the plaintiffs' experts, Dr. Marco Kaltofen, defended the EPA's use of animal testing to determine human risk from chloroprene, a practice the Environ Ramboll report questioned. Kaltofen called animal models "scientifically reliable" and "important" and said it "is not ethical or practical to deliberately perform toxicity tests on humans." 

Both Kaltofen and a third expert, Barry S. Levy, criticized Denka's analysis of Louisiana Tumor Registry data.

Denka and Dr. LuAnn White, a toxicologist at Tulane University, said data from the registry, collected by the LSU Health Sciences Center School of Public Health, showed no higher incidence of cancer in the region near the plant than elsewhere in the state.

But Kaltofen said the registry data are "not suitable" for EPA consideration because there is no attempt to discriminate among multiple cancer causes.

Levy added that because the data are parishwide, they don't show whether people who live near the Denka plant have higher rates of cancer than those who live farther away.

Lavastida, the plant manager, replied that the company has "strong concerns" about the materials submitted by the plaintiffs' attorneys and that the company questions their "merits, conclusions and comments."

The company's request for a correction, Lavastida said through representative Jim Harris, was filed to ask the EPA to apply "sound scientific principles" to the agency's 2010 assessment on the chemical chloroprene. "The independent environmental review conducted by Ramboll Environ outlines areas where these principles were not followed or applied correctly," he said. 

Lavastida said the National Academies of Sciences' National Research Council also has "found issues" with the way the EPA decision was reached.

Denka has operated the LaPlace plant since late 2015, when the company bought it from its previous operator, DuPont.

That purchase occurred a month before the EPA released its National Air Toxic Assessment, which estimates exposure for 180 air toxins nationwide. It found that residents of St. John Parish have the highest potential risk of cancer from airborne pollutants of any area in the country. It traced that risk to the LaPlace plant, putting the facility under increased scrutiny.

Since then, plant officials have announced an $18 million plan to retrofit the plant with emission-reduction technology, but critics say the efforts won't be enough because they won't lower the rates to 0.2 micrograms per cubic meter of chloroprene.

Hugh Lambert, the head of the law firm that sent the most recent letter to the EPA, said that in the meantime, his clients continue to be "adversely affected by the harmful contaminants emitted by Denka."

Follow Della Hasselle on Twitter, @dellahasselle.