DOJ sues Denka, DuPont over Louisiana plant emissions


Mar. 02, 2023

On February 28, 2023, the Environmental Protection Agency and Department of Justice sued Denka Performance Elastomer LLC and DuPont Specialty Products USA LLC over chloroprene emissions at Denka’s neoprene production plant in Saint John the Baptist Parish, Louisiana.

Regulatory context

  • The Environmental Protection Agency (EPA) regulates hazardous air pollutants (HAPs) under the Clean Air Act (CAA). The EPA regulates 188 HAPs, including chloroprene. Chloroprene is a flammable liquid utilized in producing neoprene elastomers for use in many different products. It is colorless and readily evaporates at room temperature. The chemical acts as a mutagen when it encounters the body, causing mutations in cells that can lead to cancer over the course of a lifetime.
  • Chloroprene is categorized by the EPA as a “ likely carcinogen and the Agency estimates that breathing on average 0.2 micrograms of chloroprene per cubic meter (0.2 μg/m3) over a 70-year lifetime increases a person’s risk of developing cancer by 1-in-10,000. The EPA utilizes a 1-in-10,000 cancer risk as the threshold for the ceiling of an acceptable cancer risk, including using this formula for determining residual risks for chemicals emitted by industrial source categories.
  • Under Section 303 of the Clean Air Act (CAA), the EPA can sue a plant or other pollution source to stop air pollutant emissions. The Agency may bring this suit after receiving evidence that a pollution source (or combination of sources) presents an “imminent and substantial endangerment to public health or welfare, or the environment.” These effects on public welfare include injuries to “personal comfort and well-being, whether caused by transformation, conversion, or combination with other air pollutants.”
  • In January 2017, Denka agreed to reduce chloroprene emissions based on an order from the Louisiana Department of Environmental Quality. Denka installed various control devices based on this order, which overall reduced the facilities’ chloroprene emissions. However, the EPA still found chloroprene concentrations around the facility have averaged between .4 and 2.9 μg/m3 since April 2018.
  • In late 2022, the EPA and Denka Performance Elastomer LLC (Denka) entered into a consent agreement to address waste management practices as the company’s plant in Louisiana based on Denka’s failure to make appropriate hazardous waste determinations for chloroprene wastes generated at the plant. The consent agreement required the EPA to manage the chloroprene waste as hazardous waste as well as planning emission reduction measures to reduce chloroprene emissions from the waste. The EPA believed that the measures would reduce chloroprene emissions by two tons per year at the plant.


  • On February 28, 2023, the EPA and Department of Justice (DOJ) sued Denka and DuPont Specialty Products USA LLC (DuPont) over Denka’s neoprene plant in Saint John the Baptist Parish, Louisiana. DuPont sold the plant to Denka in 2014, but still owns the land below the plant and acts as Denka’s landlord. DuPont’s involvement in the case is due to Denka needing DuPont’s approval for certain construction projects it may undertake at the site and which may be required if the EPA prevails in the case.
  • The suit alleges that average concentration of airborne chloroprene near the plant have been consistently greater than the 0.2 μg/m3 threshold since 2016, when the EPA and Denka installed air monitors near the plant. The plant contains three main manufacturing processes, all of which emit chloroprene via venting, from opening tanks, as well as fugitive sources such as leaks and evaporative emissions. These include several brick-lined pits that Denka uses to treat chloroprene-containing wastes, which allow the chemicals to volatilize into the air before the chemicals can be captured for off-site disposal.
  • The EPA based much of the complaint off the EPA’s 2010 Integrated Risk Information System (IRIS) assessment for chloroprene. The IRIS Assessment determined that chloroprene was likely carcinogenic to humans and provided the .2 μg/m3 threshold that the EPA used to determine the lifetime cancer risk. In addition, the assessment also concluded that children could breathe up to an average concentration of 1.2 μg/m3 before their second birthday without exceeding the 1-in-10,000 cancer risk threshold.
  • Air quality monitoring data collected between April 2018 and January 2023 showed an average chloroprene concentration across all sampling sites of 1.46 μg/m3, much higher than the .2 μg/m3 threshold established in the IRIS report. In 2022, Denka installed different types of air monitors around the fenceline of the plant, with all but two of the air monitors registering higher chloroprene concentrations higher than the .2 μg/m3 threshold.
  • Under the CAA section 303, the EPA alleges that Denka’s chloroprene emissions are both imminent and substantial. The complaint details that the emissions are “imminent” because the air monitors around the plant are currently indicating that chloroprene concentrations are already above the cancer risk threshold. In addition, the EPA argues the emissions are “substantial” due to the surrounding population (including the number of people and age distribution of the population), the magnitude of Denka’s chloroprene emissions, and the potential consequences regarding cancer risk to the population.

Next steps

  • This case will likely be contentious as both sides appear ready and dug in for litigation. Earlier this year, Denka sued the EPA alleging that after the Agency denied a Request for Correction based off a study that Denka provided regarding the toxicity risks of chloroprene. The lawsuit, filed on January 11, 2023, argues that Denka has invested more than $35 million into the plant to reduce chloroprene emissions and has achieved an 85% reduction in chloroprene emissions since Denka took over the plant in 2014. In its denial, the EPA explained that the Request for Correction process was not a “mechanism to commit EPA to undertake scientific updates of its risk assessment products.” Denka argued that the results of its new study cast doubt upon the EPA’s .2 μg/m3 threshold, and therefore decided to file a lawsuit against the EPA to seek review of the Request for Correction.
  • With a greater focus on environmental justice and increased enforcement resources, the EPA is homing in on many polluted areas around the country for potential litigation. In a statement about the lawsuit, EPA Administrator Michael Regan stated that Denka “has not moved far enough or fast enough to reduce emissions or ensure the safety of the surrounding community. This action is not the first step we have taken to reduce risks to the people living in Saint John the Baptist Parish, and it will not be the last.”
  • Denka and DuPont must serve answers to the complaint within 21 days of service (unless it has waived that service requirement). However, this date can be extended by leave of court, and the companies will likely request at least 30 days of extension to the time to reply. After the companies respond to the complaint, either through an answer, a crossclaim, or some other type of filing, the EPA will generally have 21 days to respond to that filing. In the future, the litigators may turn to evidentiary claims or other procedural issues to prolong the litigation process, potentially making a settlement more likely.

To contact the author of this analysis, please email Walker Livingston.
To contact the editor of this analysis, please email Patricia Iscaro.

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