Monday, April 6, 2015

Methyl Bromide Incident

Long time readers of this blog will undoubtedly know about my campaign (some would call it periodic rants) to get DHS to list methyl bromide as a DHS chemical of interest (COI) for the CFATS program. An incident that occurred last month in the US Virgin Islands illustrates how easily it would be to use methyl bromide (or most toxic inhalation, TIH, chemicals for that matter) as a terrorist weapon. Thanks to a long term reader, Dr. David Grisenti, for pointing me at the story.

It appears that on the 18th of last month a local subsidiary of Terminix used methyl bromide to rid a luxury condominium of some sort of pest infestation; methyl bromide is very effective on just about any type of pest. Apparently, appropriate controls (there are no acceptable controls for this situation as methyl bromide has been outlawed in the United States and its possessions for this type of application) were not put into place to stop the migration of methyl bromide into at least one other villa in the immediate area. A family of four from Delaware was hospitalized for methyl bromide exposure.

According to at least one report, as of Saturday the mother had been released from the hospital, the father had regained consciousness, but the two teenage boys were still in a coma. The different responses could be due to the amount of methyl bromide each inhaled, individual body chemistry or a combination of the two.

As readers of this blog are painfully aware, the US EPA has been phasing out the use of methyl bromide since 2005 under provisions of the Montreal Protocol on Substances that Deplete the Ozone Layer. Only a very limited number of critical use exemptions (CUE) are approved every year. Their approval is based upon demonstrated facts that there are no other fumigants available to replace the use of methyl bromide for that application. Currently the CUE’s are all for agricultural applications.

One news story has provided the name of the actual product used in the fumigation of the condo; Meth-O-Gas. If that is true, it is a registered Canadian fumigant produced by Great Lakes Solutions, an authorized American manufacturer of methyl bromide fumigants. While the Canadian government also limits this product to agricultural uses, the existing registered label for the product contains very detailed instructions for how the product is to be used to fumigate enclosed structures. Because of the injuries to the Delaware family, it is fairly obvious that the use instructions were not completely followed.

The Chemtura (parent company of Great Lakes Solutions) MSDS reports that methyl bromide is a colorless odorless gas. Its boiling point is 38.5° F so it is actually stored in pressure cylinders as a liquid, but it evaporates almost as soon as it is released.  The acceptable time weighted average (TWA) exposure limit is 1 ppm. OSHA requires the use of supplied air respirators at concentrations above 3 ppm. The current OSHA PEL is 20 ppm and it is considered immediately dangerous to life or health (IDLH) at 2,000 ppm.

Someone who steals a cylinder of methyl bromide like that use in the fumigation incident in the Virgin Islands has an ideal weapon with which to attack targets in a relatively closed building. Since methyl bromide is significantly heavier than air it will settle to lower floors in a multistory building or it will be at higher concentrations near the floor in large contained open spaces such as a church. At exposure levels well below the IDLH there are no immediate signs of exposure that would cause people to leave an exposed area.

As I have mentioned numerous times DHS originally had listed methyl bromide in their initially published list of COI included in the original CFATS rule. DHS removed methyl bromide from the final approved Appendix A listing based upon the EPA assertion that methyl bromide was being phased out of use and thus did not need to be regulated under CFATS. Here about 7 and a half years later we have a family being injured in a methyl bromide incident far away from any approved, limited use of that chemical.

DHS needs to take immediate action to ensure that the security of methyl bromide production and storage facilities is regulated under the CFATS program by adding methyl bromide back to the listing of COI before any terrorist organization learns the very public lessons of this particular incident.

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