sign on stone building reading "Department of Justice"

DOJ Seeks to Compel Manufacturer in Area with High Cancer Rates to Reduce Airborne Chloroprene Emissions

The complaint was filed Tuesday in U.S. District Court for Eastern Louisiana on behalf of the EPA under the Clean Air Act.

Elizabeth Chuck and Maite Amorebieta from NBC News and Oliver Laughland in the New Orleans issue of The Guardian broke the story about the U.S. Department of Justice (DOJ) seeking to compel a chemical manufacturing plant to curb its environmental emissions in a region where the estimated cancer risk is among the highest in the U.S. The action raises the stakes in a longstanding conflict between the Louisiana plant (LA), nearby residents and the EPA. Unveiled on Tuesday, the lawsuit alleges emissions at the Pontchartrain Works facility, subsidiary of the U.S. chemical giant DuPont, which constructed the plant in LaPlace, LA, violated the Clean Air Act and “presents an imminent and substantial endangerment to public health and welfare.” 

The current Japanese company Denka Performance Elastomer (DPE) plant along with former owner DuPont, along the Mississippi River, is the only facility in the U.S. that still produces chloroprene (2-chloro-1,3-butadiene; β-chlorobutadiene), a chemical used to produce neoprene. Neoprene is a synthetic rubber found in many different commercial products such as adhesives, automotive and industrial parts (e.g., belts and hoses), wire and cable covers, caulks, flame-resistant cushioning and other applications requiring chemical, oil and/or weather resistance. The Denka facility has been on the EPA’s radar for years after a 2011 National Air Toxics Assessment (NATA) revealed “estimated higher than expected levels of chloroprene in the community of LaPlace, LA.

DuPont sold the plant to DPE in 2015, after the EPA’s decision to classify chloroprene as a likely human carcinogen in 2010. According to the complaint, DuPont remains the landowner of the Denka’s facility and acts as a landlord. DuPont may need to grant permissions in order for emissions to be reduced. Chloroprene is a colorless, mobile, flammable, volatile liquid slightly soluble in water. The vapor pressure for chloroprene is 188 mm Hg at 20 degrees Celsius, which may a relatively volatile organic solvent.

DPE said in a statement that it has reduced emissions by about 85 percent since it took over the plant in 2015. But the estimated pollution-related cancer risk in the area is still one of the highest in the country, according to the EPA. Now, the DOJ has filed a complaint to compel Denka to further reduce its hazardous emissions. The complaint, first reported by NBC News, was filed Tuesday in U.S. District Court for Eastern Louisiana on behalf of the EPA under the Clean Air Act. In the 56-page letter, the EPA said residents of neighborhoods around the Denka plant have been exposed to concentrations of chloroprene that puts them at “an estimated 100-in-1 million risk of developing chloroprene‑linked cancers over a 70‑year lifetime.” The agency found that children who attend the nearby Fifth Ward Elementary School in St. John the Baptist Parish are also exposed to this increased risk of cancer.

In its statement, Denka said it strongly disagrees with the federal government's decision to file a legal complaint and with the EPA's assessment of the health risks the plant's emissions pose to the surrounding community. In total, those changes have cost more than $35 million. But on-site inspections by the EPA in April and May 2022 found that Denka was not meeting regulatory requirements for the storage and disposal of chloroprene waste, which contributes to emissions of chloroprene from the plant. Environmental air monitoring results on September 23, 2021, showed two out of 10 air samples had detectable chloroprene in the air downwind from the plant. One positive air sample (0.78 µg/m3) was collected on September 23, 2021, by the 5th Ward Elementary School at the gate of the EPA air monitoring station. This evidence supported a positive chloroprene sample (0.85 µg/m3) that was collected back on September 23, 2001.

Metabolites indicating VOC exposures were detected in all of the nine urine samples collected from seven participants residing at the three locations sampled in 2021. The EPA noted DPE was the sole source of chloroprene in the area—it does not occur naturally (NTP 2011).

Even when Denka's facility was shut down for a month in September 2021 after Hurricane Ida, a small monitoring demonstration test by the Louisiana State University School of Public Health revealed detectable levels of chloroprene in two out of 10 air samples, according to the researchers. That 2021 test, which was not a formal study, found levels approximately four times above the EPA’s recommended maximum annual average chloroprene concentration. EPA air monitoring around the facility has consistently shown readings well in excess of the recommended lifetime exposure limit of 0.2 micrograms per cubic meter (µg/m3). 

LaPlace is in the majority-Black St. John the Baptist Parish, about 30 miles outside of New Orleans. The plant is one of many that activists argue puts undue health risks on Black communities in the area. The company added that it "remains committed to identifying and implementing additional emission reductions where possible." The Denka's facility is along a stretch of the Mississippi River that activists and residents have nicknamed "Cancer Alley" because of the unusually high cancer risk among communities there and the emissions that come from the numerous plants in the area. 

The EPA's Office of Environmental Justice and External Civil Rights in part blames state agencies; In an October 2021 letter, it wrote that the Louisiana Department of Environmental Quality and the Louisiana Department of Health's failure to pursue stronger action against DPE since it disproportionately exposed Black residents to harmful air pollutants. The EPA said it found during an investigation that state agencies failed to provide residents with information about the cancer risks associated with chloroprene levels in the area, among other problems.

In a statement, EPA Administrator Michael Regan said the DOJ's move followed his pledge to take strong action for communities living near the plant. "The company has not moved far enough or fast enough to reduce emissions or ensure the safety of the surrounding community," said Regan, who has been vocal about his commitment to environmental justice. "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."

Historical information regarding the adverse health effects of chloroprene exposure was found in the National Institute for Occupational Safety and Health (NIOSH) Criteria for Recommended Standard in 1977. Chloroprene was first synthesized in 1930 by Carothers et al. The first study of chloroprene toxicity was reported by Von Oettingen et al thereafter in 1936. In 1942, Roubal reported an investigation of the toxicologic and hygienic aspects of the Czechoslovak chloroprene rubber industry. This is believed to be the first report of human exposure. Workers involved in the washing and polymerization operations experienced the loss of hair. Other workers complained of a sensation of pressure in the chest with a rapid pulse, severe fatigue and conjunctivitis and necrosis of the corneal epithelium. Albumin was reported to be present in the urine of a small number of workers who, according to Roubal, presumably had had massive chloroprene exposure.

Nystrom described a series of medical studies carried out in Swedish chloroprene plants between 1944 and 1947. These were the first and only studies to include experimental reports of human exposure to airborne chloroprene and to report a human fatality. Experimental exposure of human subjects to chloroprene at 973 ppm led to nausea and giddiness in 15 minutes in resting subjects and in five to 10 minutes in subjects performing light work. Nystrom noted anemia in pilot plant workers who were exposed to air concentrations estimated to be approximately 459 ppm. The range of concentrations of chloroprene in the air was from 56 to greater than 334 ppm in the main chloroprene plant after the full operation was achieved.

Workers, especially those in the fractional distillation department, developed extreme fatigue and unbearable chest pains after exertion about one month after starting work. The symptoms were particularly severe by the end of the workday. Because of fatigue and severe chest pains, 90 percent of the workers often had great difficulty bicycling to their homes after work and had to rest repeatedly. Both pain and fatigue usually subsided by the following morning, returning during the next workday. Workers also noted changes in their personalities towards irritability and quick-tempered behavior. Contact dermatitis (25 to 30 percent) and reversible hair loss were also noted in some workers, especially in the polymerization area, where 90 percent of the workers showed hair loss.

According to the 1981–83 National Occupational Exposure Survey (NOES, 1997), as many as 18,000 workers in the U.S. were potentially exposed to chloroprene. National estimates of workers potentially exposed were not available from other countries. Occupational exposures to chloroprene have been measured mainly in polymer production. During 1973, at a chloroprene polymerization plant in the U.S., airborne concentrations of chloroprene were found to range from 14 to 1420 ppm (50 to 5140 mg/m3) in the make-up area, from 130 to 6,760 ppm (470 to 24 470 mg/m3) in the reactor area, from 6 to 440 ppm (22 to 1,660 mg/m3) in the monomer recovery area and from 113 to 252 ppm (409 to 912 mg/m3) in the latex area (Infante et al., 1977). Concentrations in the air inside a Russian polychloroprene rubber plant were 14.5 to 53.4 mg/m3 (Mnatsakayan et al., 1972). In a Russian chloroprene latex manufacturing facility, chloroprene concentrations varied from 1 to 8 mg/m3 (Volkova et al., 1976).

Recent data from two chloroprene polymerization plants in the U.S. with 650 to 800 exposed workers show relatively little decline in average exposure concentrations from the late 1970s through 1996. This is partly due to the fact that workers with jobs having a low potential for exposure are no longer routinely monitored, resulting in upwardly biased time-weighted average exposures. At present, however, average exposures of process operators and mechanics are typically below 5 ppm, while other workers in these facilities are exposed to concentrations below 2 ppm (DuPont Dow Elastomers, 1997). Exposure to residual chloroprene monomer in polychloroprene latex and polymer has been described. In 1977, mean airborne concentrations of chloroprene of up to 0.2 ppm (0.72 mg/m3) were reported in a roll-building area at a metal fabricating plant in the U.S. where polychloroprene was applied extensively to metal cylinders before vulcanization (Infante, 1977). Workers in a Russian shoe factory were reportedly often exposed to chloroprene concentrations of 20 to 25 mg/m3 (Buyanov and Svishchev, 1973).

Industrial chloroprene emissions to the atmosphere reported to the EPA for the Toxic Chemical Release Inventory (TRI) totaled about 838 tons in 1987, 667 tons in 1991 and 446 tons in 1995 (United States National Library of Medicine, 1997b). Chloroprene has been detected in industrial wastewater and nearby groundwater in the People’s Republic of China (Huang et al., 1996), in wastewaters from polychloroprene and dichlorobutadiene production plants in Russia (Avetisyan et al., 1981; Geodak Chloroprene has been detected as an impurity at levels of several parts per million in commercial vinyl chloride in Italy (Sassu et al., 1968) in Japan (Kurosaki et al., 1968), in acrylonitrile in the USSR (Panina & Fain, 1968). yan et al., 1981) and in waste gas from a chloroprene plant in Japan (Kawata et al., 1982). 

Looking at current occupational health exposures, federal OSHA established a maximum ceiling value of 25 parts per million (ppm) for acute exposures that should never be exceeded during work. NIOSH Recommended Exposure Limit (REL) and the American Conference of Governmental Industrial Hygienists (ACGIH) established a 1 ppm exposure guideline for an eight-hour Time-Weighted Average (TWA) for more chronic exposure. Exposure to chloroprene occurs by inhalation of the vapor. Workers may be occupationally exposed to chloroprene by both inhalation and/or dermal exposure if gloves and personal protective equipment and clothing. Skin notations have been assigned to the use of chloroprene by NIOSH and ACGIH from claims of loss of hair on exposed body parts.

Both NIOSH and ACGIH consider chloroprene exposure as a suspect lung carcinogen in humans and liver and lung cancer in animals. It also can cause upper respiratory tract and eye irritation. Reports of other chronic effects such as liver cancer, reproductive hazards that may cause damage to the developing fetus, spontaneous abortions or interference with sperm production have not been fully investigated. Residents may be exposed to environmental exposures that may occur during its manufacture, transport and chemical storage. Very little air sampling information was collected by OSHA for manufacturing facilities using or exposing workers to chloroprene. Of the total 136 air samples collected between 1984 and 2021, only four air sample results in worker exposure were reported in Texas and Ohio above non-detectable (ND) levels. All of the four air sample results were slightly below the 1 ppm NIOSH REL and ACGIH TLV, but no air samples were collected to evaluate a ceiling airborne concentration.

EPA-reported symptoms from acute (short-term) human exposure to high concentrations of chloroprene include giddiness, headache, irritability, dizziness, insomnia, fatigue, respiratory irritation, cardiac palpitations, chest pains, nausea, gastrointestinal disorders, dermatitis, temporary hair loss, conjunctivitis and corneal necrosis. Symptoms of chronic (long-term) exposure in workers were fatigue, chest pains, giddiness, irritability, dermatitis and hair loss. Chronic occupational exposure to chloroprene vapor may contribute to liver function abnormalities, disorders of the cardiovascular system and depression of the immune system. Occupational studies have found that exposure to chloroprene increases the risk of liver cancer. Studies in animals have found an increased risk of tumors in multiple organs. EPA has classified chloroprene as likely to be carcinogenic to humans.

Chloroprene has been reported to cause various physiological responses such as respiratory, eye and skin irritation, chest pains, temporary hair loss, neurological symptoms (e.g., dizziness, insomnia, headache) and fatigue in exposed workers. Effects on the cardiovascular system (rapid heartbeat, reduced blood pressure) and changes in blood cell parameters (red blood cells, hemoglobin content, white blood cells and platelets) have also been reported in occupationally exposed workers.

In animals, toxicity in multiple organ systems, including in the respiratory tract, kidney, liver, spleen and forestomach, has been reported in chronic inhalation studies. The EPA Reference Concentration (RfC) for chloroprene is 0.02 milligrams per cubic meter (mg/m3). The RfC is an estimate (with uncertainty spanning perhaps an order of magnitude) of continuous inhalation exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious noncancer effects during a lifetime. It is not a direct estimator of risk but rather a reference point to gauge the potential effects. At exposures increasingly greater than the RfC, the potential for adverse health effects increases. Lifetime exposure above the RfC does not imply that an adverse health effect would necessarily occur. The RfC for chloroprene was identified based on consideration of sensitive cellular effects observed in the nose, lung and blood of male and female rats and female mice, respectively.

EPA has high confidence in the study on which the RfC was based because it was a well-designed study using two test species (rats and mice) with 50 animals per dose group. EPA has medium-to-high confidence in the overall database because the database contains several chronic inhalation studies in three species, well-designed embryotoxicity, teratological and reproductive toxicity studies and subchronic and chronic studies observing potential neurotoxic and immunotoxic effects. A major limitation in the database is the lack of a complete two-generation reproductive toxicity study. As a result, EPA has medium-to-high confidence in the RfC. EPA has not established a Reference Dose (RfD) for chloroprene.

Regarding reproductive hazards, a study reported functional disturbances in spermatogenesis in workers exposed to chloroprene and increased spontaneous abortions in the wives of exposed workers. However, insufficient details are available in the reports to adequately evaluate the results. Reproductive effects, including a decreased number of spermatogonia, a decline in sperm motility, an increased number of dead sperm and degeneration of the testes, have been observed in male rats exposed by inhalation or dermal contact. Increased embryonic mortality and decreased fetal weight were reported in rats exposed by inhalation, although contamination may have occurred during this study. No effects on embryonic or fetal survival nor incidence of soft tissue or skeletal defects were observed in other studies of rats exposed by inhalation.

When looking at cancer risk, four occupational epidemiological studies reported statistically significant associations (two- to five-fold increased risk) between chloroprene exposure and liver/biliary passage cancer. A few epidemiological studies reported a non-statistically significant increased risk of lung cancer incidence and mortality associated with chloroprene exposure. An inhalation bioassay by the National Toxicology Program (NTP) showed clear evidence of carcinogenic activity in both rats and mice, based on increased incidences of neoplasms of the oral cavity, thyroid gland, lung, kidney, liver, skin, mammary glands and other organs. 

In 2010, EPA classified chloroprene as likely to be carcinogenic to humans based on statistically significant and dose-related information from the chronic NTP bioassay showing the early appearance of tumors, development of malignant tumors and the occurrence of multiple tumors within and across animal species; evidence of an association between liver cancer risk and occupational exposure to chloroprene; suggestive evidence of an association between lung cancer risk and occupational exposure; proposed mutagenic action of chloroprene; and structural similarities between chloroprene and the known human carcinogens, butadiene and vinyl chloride. EPA additionally concludes that the weight of evidence supports a mutagenic mode of action for chloroprene carcinogenicity. 

Chloroprene has been manufactured at the DPE site since 1969, thus it constitutes a chronic (more than five decades) exposure. Based on air monitoring data from both EPA and Denka, chloroprene continues to occur with some regularity at levels exceeding 0.2 µg/m3, even after emission control technologies were installed in February 2018. In 2021, chloroprene air concentrations were as high as 1.8 µg/m3 at a site two miles away from the facility (at Edgard Courthouse, Site #7); and as high as 20.2 µg/m3 at a site one mile from the facility (at Ochsner Hospital). When the proximity of 5th Ward Elementary School is considered (0.3 miles or 500 yards from the Denka facility), it is not unexpected that levels were detected at the school in 2021 as high as 20.7 µg/m3 by DPE (103 times higher than 0.2 µg/m3), and up to 3.34 µg/m3 by EPA (16 times higher than 0.2 µg/m3).

EPA uses mathematical models, based on human and animal studies, to estimate the probability of a person developing cancer from breathing air containing a specified concentration of a chemical. EPA calculated an inhalation unit risk estimate of 3 × 104 (µg/m3)1 for chloroprene based on tumor incidence in multiple organ systems of mice and rats. Taking into account the mode of action conclusion, EPA estimates that, if an individual were to continuously breathe air containing chloroprene at an average of 0.002 µg/m3 (2 x 10-6 mg/m3) over his /her entire lifetime, that person would theoretically have no more than a one-in-a-million increased chance of developing cancer as a direct result of breathing air containing this chemical substance. Similarly, EPA estimates that continuously breathing air containing 0.02 µg/m3 (2 x 10-5 mg/m3) would result in not greater than a one-in-a-hundred thousand increased chance of developing cancer, and air containing 0.2 µg/m3 (2 x 10-4 mg/m3) would result in not greater than a one-in-ten thousand increased chance of developing cancer. 

Photo credit: Paul Brady Photography /

About the Author

Bernard L. Fontaine, Jr. CIH, CSP, FAIHA is the Managing Partner of The Windsor Consulting Group, Inc.

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