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I was a bit surprised when reading the following paragraph in the article "The Louisiana Environmental Apocalypse Road Trip":

The risk of cancer in Reserve, a community founded by freed slaves, is 800 times the national average, making the community, by one EPA metric, the most carcinogenic census tract in America—the cause is a DuPont/Denka chemical plant adjacent to the town that annually spews 250,000 pounds of the likely carcinogen chloroprene into the air.

A quick look at the safety data sheet for chloroprene confirms that it's not something I'd like to breathe, even if you ignore the potential carcinogenicity. And 250,000 pounds (113 tons) per year seems like a very high amount to me, for a substance as toxic as chloroprene.

I looked around a bit, but all other articles I saw about the subject don't actually mention this number.

Is that article accurate, and the plant did actually emit that much chloroprene?

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With the understanding that correlation does not equal causation, the EPA's study of air toxicity (search for St. John the Baptist Parish, LA) indicates that the levels of chloroprene adjacent to the plant are hundreds of times higher than the maximum "acceptable" level.

As chloroprene is only used as a precursor to neoprene, all neoprene in North America is produced by Denka, and Denka's plant in Laplace, LA is the only plant that synthesizes neoprene, it is safe to say that the plant was (and probably is) emitting a lot more chloroprene than it ought to.

From the EPA Action Plan for Laplace, specifically the Denka plant (emphasis mine):

The total permitted chloroprene emissions allowed across the various permits exceed 175 tons per year (tpy), with the majority of emissions emanating from emission units in the neoprene (85% of permitted site-wide total) and the chloroprene (14% of site-wide total) production areas. Actual site-wide emissions of chloroprene were reported as approximately 125 tpy in reporting year 2013.

So, regarding the initial question, the answer appears to be yes, at least in 2013, the plant emitted 125 tons of chloroprene.

Additional resources:

  • OHSA Chloroprene Data Sheet
  • EPA Data Sheet, Chloroprene - This is where multiple articles on the plant draw their "safe levels" of chronic chloroprene exposure from - exposure to 0.002 micrograms of chloroprene per cubic metre of air causes a 1-in-a-million increase in cancer incidence.
  • EPA measurements, St. John the Baptist Parish, May 25, 2016 - July 16, 2017 - This indicates that at most monitoring sites, values of hundreds to thousands of times the "safe" level were recorded during this period. The detection threshold of the monitoring devices, as indicated in this table, is 0.036 micrograms/cubic metre, already ten times the safe level, but indicates a sensitivity more than sufficient to detect pollution on this level

Some of the information contained in this post requires additional references. Please edit to add citations to reliable sources that support the assertions made here. Unsourced material may be disputed or deleted.

  • I can't tell how to extract from the link you do provide that the levels of chloroprene in the areas are "hundreds of times higher than the maximum "acceptable" level." – Oddthinking Aug 7 '17 at 8:37
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    @oddthinking - Search for St. John the Baptist Parish, LA, click on any one of the readings from which the area's totals are derived, click through to the second pie graph, and read the legend indicating that chloroprene is the dominant contaminant, and the scale indicating its value relative to what it ought to be. It's not simple, admittedly, but I couldn't find any way to link directly to the data. – jdunlop Aug 7 '17 at 8:59
  • @oddthinking - the reference provided by the OP - the reference sheet for the monomer - also includes the information I detailed in the answer; that it is used to create the polymer Neoprene. No other use is listed. – jdunlop Aug 7 '17 at 9:02
  • @Brythan - good point, added edit with link to EPA document stating the emissions claim explicitly. The actual article claim was 250 000 lbs (125 tons/113 tonnes). – jdunlop Aug 7 '17 at 19:47
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The correct value for chloroprene emissions at the plant is 403,580 pounds per year according to the following Denka document submitted to the EPA April 2016:

https://www.epa.gov/sites/production/files/2016-07/documents/fixdpe-ldeq-draft-protocol041316.pdf

See particularly table 3-1.

As explained in the document, there are 3 sources of chloroprene emissions at the Pontchartrain site: the HCl recovery unit, the Neoprene unit and the Chloroprene unit.

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