This week’s acrylonitrile train accident in Blount County, TN pointed out one of the key reasons that hospitals will play a key role in emergency planning activities involving chemical accidents. One of the byproducts of heating or partially burning acrylonitrile is hydrogen cyanide gas, a severe toxic inhalation chemical. Most emergency rooms are not equipped to handle hydrogen cyanide mass casualty events.
Thursday’s train accident involved a relatively small puncture of a rail tank car containing acrylonitrile. While the accident investigation is not complete, news reports indicate that it may have been axle break that caused the leak (see photo of damage to road be) and probably the sparks that ignited the leaking acrylonitrile.
Once the train was stopped and the problem identified, a 1 mile evacuation zone was declared and police began going door-to-door telling people to evacuate. As frequently happens in this sort of incident, some of those police personnel and first responders on site were exposed to smoke from the fire and began to exhibit signs of potential chemical exposure. Knowing that the chemical involved (probably from placard or manifest data and looking up the chemical in the ERG, Guide Number 130) was toxic, exposed personnel were taken to hospital emergency rooms. NOTE: The ERG does not say that hydrogen cyanide is produced; it is a generic reactive monomer page that simply states that: “Fire will produce irritating, corrosive and/or toxic gases”.
Somewhere along the line someone got ahold of the Safety Data Sheet (the globally harmonized replacement for the old MSDS) and determined that these individuals may have been exposed to hydrogen cyanide. This is a problem because, while at high-doses cyanide poisoning is nearly instantly fatal, lower doses may take 24 to 48 hours to present serious symptoms. Old school treatments include administering amyl nitrate, sodium nitrate and/or sodium thiosulfate. These treatments have their own problems. The newer preferred method us the use of the Cyanokit®, essentially 5g of hydroxocobalamin to be administered by intravenous infusion.
The problem is that the Cyanokit is relatively expensive, news articles have tossed around the number as $650 to $800 per single dose kit. Since cyanide poisoning is a relatively rare event, most emergency rooms don’t stock very many Cyanokits, especially since they have a pretty well defined shelf-life (not listed on the kit website).
In this case, when the number of potential cyanide poisoning cases exceeded the number of kits available at the local hospital, the call went out to other hospitals in the region, who sent part of their reserves to help resolve this incident.
Emergency Response Planning
Fortunately, none of the exposures were immediately life threatening (relatively small exposures) and the number of exposed personnel was relatively small (10 by some news reports). The local hospital, according to news reports, only had four of the kits on-hand. If the exposed personnel had had higher doses, there is a high probability that some would have died before the additional kits arrived on scene.
This is where emergency response planners get grey hairs really quick. For most communities cyanide poisoning is relatively rare. So, how many high-cost, short shelf-life kits do you buy? Keeping in mind that there are alternative, if less effective, treatments available. That is a hard question to answer and fingers will be pointed for being wrong in either direction.
On the other hand, if the emergency planner knew that their community had a potentially higher chance of seeing cyanide poisoning incidents, the calculus becomes a little bit different and the number of kits on hand would probably be higher. If, for example, you had a facility in your town that manufactured acrylonitrile or used substantial amounts of acrylonitrile as a raw material, you could assume that your community had a higher than normal chance of having to treat for cyanide poisoning. And it would be easier to justify stocking a higher number of Cyanokits.
What about having railcars of acrylonitrile being shipped routinely through your town. Would that change your calculations on how many Cyanokits would be kept on hand? Would it help to know that DOT 111 tank cars are authorized to transport acrylonitrile (DOT Class 3, pg I; see 49 CFR §172.101 and §173.243)? How many tank cars per month would be necessary to change your calculations?
In this incident there were 9 tank cars of acrylonitrile on the train. With the published destination being Waycross, GA I have a pretty good idea what chemical manufacturer was going to be the ultimate receiver of those tank cars. I don’t know exactly how much acrylonitrile they use, but I would expect to see one nine-car delivery at least once a week, probably two.
This is just one case where emergency planners need to know what types of hazardous materials and in what quantity and frequency they could expect to see those shipments. There are plenty of other emergency planning considerations that need to be taken into account based upon a knowledge of the hazardous materials being produced in, transported through or to the area.
Why Involve Hospitals
I specifically mentioned hospitals in the title of this post for a reason, even though I have mainly been talking about emergency response planners. The reason for this is that it is hard to expect emergency response planners to know about all of the potential medical treatments that might be necessary for the different hazardous materials that might come through a community. The emergency planner needs guidance from the local hospitals.
Additionally, hospitals need to look at their emergency protocols and ensure that they have identified treatment regimens for all of the hazardous materials that could cause a mass casualty event in their community. Like I said, cyanide poisoning is unusual. I would suspect that the tests for cyanide poisoning are not routinely done at most hospital labs, particularly the smaller community hospitals. But those tests might be a critical triage tool used to decide who gets treated with the limited number of Cyanokits and who would get treated with the less effective (on high dosage patients) older treatments.
I don’t expect every hospital to have their lab routinely trained on cyanide poisoning testing procedures, but a detailed written procedure and a periodic check to ensure that all of the necessary equipment was on hand, could allow the hospital to do triage testing in an emergency.