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A major story “broke” in the New York Times this weekend. It reported on a group of North Carolina workers with serious neurological injury from a widely used industrial chemical called n-propyl bromide. The article correctly emphasizes the broad nature of this occupational problem. But a word or two about the consumer market might also have been warranted.
The specific outbreak occurred in a foam upholstery operation, a particularly popular application for n-propyl bromide containing adhesives (http://www.nytimes.com/2013/03/31/us/osha-emphasizes-safety-health-risks-fester.html?emc=eta1&_r=0&pagewanted=print). The story may have received new, high-profile attention but, unfortunately, the problem with n-propyl bromide is not new. Back in 2008, the Centers for Disease Control featured two cases of neurological toxicity due to the chemical (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5748a2.htm) and they backed-up their report with other medical publications going back to 2005. In scientific publications the chemical is usually referred to as 1-bromopropane; its current trade shorthand is nPB.
New studies on the toxicant are being released regularly. Of particulate note, some present emerging experimental data implicating it as a cause of damage to nervous systems of very young animals as they grow. Public health experts assessing chemical risk are especially concerned when such effects are documented because “developmental” toxicity to the nervous system marks a profoundly hazardous phenomenon. For example, when the proposed fumigant methyl iodide (which was touted as an ozone-sparring chemical meant to to replace methyl bromide) was reviewed in California, potential effects of precisely this sort were a major factor driving concerns that even very low exposure presented an unacceptable degree of risk.
Facing court action, the application to license methyl iodide as a pesticide was withdrawn by its manufacturer, although its export is still allowed (http://www.panna.org/blog/saying-no-methyl-iodide-worldwide). Unlike pesticides, however, industrial chemicals like nPB do not require review before marketplace introduction. At least that is the case in the U.S.; the European Union is introducing precisely such pre-release review. But the nPB story is even worse than that. The Federal EPA has actually been promoting its use because, like methyl iodide, it spares the ozone, even if it might spoil the child’s central nervous system.
There is very little information out there on exposure to nPB beyond the factory door. A recent review of the chemical’s potential to cause cancer was released in draft form a few weeks ago by the National Institutes of Health (http://ntp.niehs.nih.gov/NTP/About_NTP/MonoPeerRvw/2013/March/DraftRoC1BPMonograph_508.pdf). It concludes that nPB causes cancer in animals and “is reasonably anticipated to be a human
carcinogen.” Yet the document admits to having no data on exposure to the general public. The one report they could find examining a relevant group of environmental chemical contaminants apparently added nPB as a laboratory analysis standard to all the samples tested, thus making that the one chemical whose public exposure the study could not assess.
Needless to say, when a chemical such as nPB is in broad commercial circulation, public exposure outside of salaried employment is almost inevitable. What can be had wholesale can usually be bought retail and come into the home. It took me a fairly short time on the internet to find at least one such nPB product. So if you would like to have your own home-based toxicology experiment for the whole family, go ahead and order up some Max-Kleen® Xtreme® Heavy Duty Degreaser. It contains 90% or more n-PB and, moreover, comes in a convenient pressurized spray can that should be most efficient at generating an inhalable mist. The manufacturer’s material safety data sheet that I was able to download does not mention a word about the kind of nervous system damage documented by the New York Times (http://www.all-spec.com/downloads/chemtronics/ES2284_052810m.pdf). Of course, they do end with the reminder that, “Although certain hazards are described herein, we cannot guarantee that these are the only hazards that may exist.”
nPB is the sort of chemical that should not be in circulation, not in the workplace and not elsewhere. But maybe this is a (non-registered trademark) xtreme proposition.
