Reference Document for the Preliminary Assessment of Chloroprene Levels in St. John the Baptist Parish

Background and Statement of Issues

Site HistoryIn 1931, the DuPont chemical company invented Neoprene, a synthetic chemical-resistant and weather-resistant rubber best recognized for its use in wet suits and as a base resin in adhesives and coatings. DuPont’s Ponchartrain Works facility, located on the east bank of the Mississippi River in LaPlace, LA, became the leading producer of Neoprene. Neoprene is the trade name for polychloroprene, a rubber polymer formed by linking together molecules of chloroprene. in North America. The DuPont facility’s Neoprene operations were taken over by DENKA Co. Ltd. on November 1, 2015 [1].

National Air Toxics AssessmentOn December 17, 2015, the U.S. Environmental Protection Agency (EPA) 2011 National Air Toxics Assessment (NATA) was released. EPA developed NATA as a broad-scale screening tool to prioritize the evaluation of air pollutants and emission sources in locations of interest to gain a better understanding of risks. As stated by EPA, NATA “is subject to limitations in the data, modeling, and default assumptions used. As a result, the NATA should only be used to identify areas for further investigation and not to identify actual exposures and associated risks to specific individuals” [3]. Modeling estimates performed by this screening tool indicated the possibility of elevated cancer risk from chloroprene emissions from Denka/Dupont Neoprene production facility operations in LaPlace, Louisiana [1, 2]. Based on animal studies and a lack of human data, chloroprene has been classified by EPA as “likely to be carcinogenic to humans” since September 2010 [1, 4].

Preliminary Air SamplingIn response to the possibility of elevated risk modeled by NATA, EPA Region 6 and the Louisiana Department of Environmental (LDEQ) conducted preliminary ambient air sampling in March of 2016 to decide if a more extensive and comprehensive monitoring and assessment plan was needed. LDEQ collected instantaneous or “grab” samples and analyzed those samples using LDEQ’s Mobile Air Monitoring Lab (MAML). Additionally, EPA collected a small number of 8-hour and 24-hour canister samples. Both EPA’s and LDEQ’s air monitoring detected chloroprene off-site within and outside of a 1-mile radius of Denka.