Forensic Gas Analysis?

[Akimbo]

This thread got me wondering why analysis of breathing gas from a diving accident isn't routinely sent to a lab for a full spectrum gas chromatograph analysis.

http://www.scubaboard.com/forums/accidents-and-incidents/500144-article-death-ginnie-springs.html

I didn't want to hijack the thread so started this one in a more appropriate forum. Apparently, the convention in some/many jurisdictions is to send dive gear to a local expert like a dive shop or instructor to evaluate.

You don't have to be a pathologist to know that there are lots of gasses beyond CO and O2 that a nefarious person could contaminate a diver's breathing gas with. Some of these gasses can be in very small amounts and dissipate in the body/corpse quickly. I suppose that applies to firefighters as well, though hard to target an individual.

I'm not a gas chromatograph tech but they are pretty common in labs and it wasn't that expensive when I have had calibration gasses certified by the suppliers. In that case we only asked for the gasses we ordered so but, perhaps mistakenly, I thought that the analysis covered the full spectrum of gasses.

Am I missing something or is there a better testing methodology?

 

[Duke Dive Medicine]

If there's no suspicion of foul play, would there be a reason to do this?

Best regards,
DDM

 

[Akimbo]

If there's no suspicion of foul play, would there be a reason to do this?...

Aside from air embolism or getting run over by a boat, how often is the death of a recreational diver conclusively explained (definitely a question and not a statement)? Granted, panic induced self-destruction is the likely cause but how can a pathologist tell the difference? Most of the "news reports" I read conclude that COD was drowning sometimes followed by guesses about contributing circumstances.

Is a full spectrum test of the gasses all that expensive? Any idea what Duke would charge?

 

[abnfrog]

the reason this was brought up was a friend of the deceased trying to mitigate his stupidity and arrogance ..............gas is analyzed (at least herein ontario ) if the death is not very obvious ...............his was

 

[Lorenzoid]

. . .
You don’t have to be a pathologist to know that there are lots of gasses beyond CO and O2 that a nefarious person could contaminate a diver’s breathing gas with. Some of these gasses can be in very small amounts and dissipate in the body/corpse quickly. I suppose that applies to firefighters as well, though hard to target an individual.

I hope I'm not inadvertently responding as though this question were in the other thread, but what is the likelihood of a nefarious person doing that? Has it EVER occurred? It sounds like a farfetched plot from a TV detective show. If the authorities on the scene weigh a first scenario that sounds very plausible, involving a diver convulsing because he breathed from a tank marked "O2" that was subsequently found to contain 98% O2, and a second scenario in which a nefarious person intentionally introduced a contaminant into a scuba tank, they might make a judgment that the first scenario is far more likely than the second scenario, and accordingly, that there is no reason to suspect a crime.

Why should sending a sample to a lab be the "routine" procedure if the scenario of someone intentionally contaminating gas is very very remote and another, far more likely scenario, is immediately evident? I suppose an analysis might be useful to someone if a civil lawsuit occurs, but that's not something for the police to be concerned with.

More generally: What DDM said.

 

[Doppler]

I can ball-park equipment cost for you.

A company I consult for supplies stand-alone gas analysis equipment to milpro customers... the unit is portable, tests for a variety of contaminates, trace gases, et al, and retails for around $12,000 US... so it is not inexpensive.

However, that level of analysis/control is fast becoming required/norm in that community.

 

[Duke Dive Medicine]

Aside from air embolism or getting run over by a boat, how often is the death of a recreational diver conclusively explained (definitely a question and not a statement)? Granted, panic induced self-destruction is the likely cause but how can a pathologist tell the difference? Most of the “news reports” I read conclude that COD was drowning sometimes followed by guesses about contributing circumstances.

Is a full spectrum test of the gasses all that expensive? Any idea what Duke would charge?

I don't know offhand what the price is but I'd think a cost-benefit analysis would be prudent. Granted most causes of death are listed as drowning because it's difficult to determine a more specific cause, but unless there is a high degree of suspicion that there is an unusual toxic gas in the diver's breathing gas supply, such testing would probably not be indicated.

Best regards,
DDM

 

[TSandM]

I remember reading a piece about a diving incident (I can't remember if it was a fatality) where benzene was felt to have played a role. I suppose there are incidents where traces of volatiles might be responsible for erratic diver behavior or even unconsciousness, but to test every tank for such after an obvious problem is identified, would seem to be not to be money or time well-spent.

 

[Akimbo]

I can ball-park equipment cost for you.

A company I consult for supplies stand-alone gas analysis equipment to milpro customers... the unit is portable, tests for a variety of contaminates, trace gases, et al, and retails for around $12,000 US... so it is not inexpensive...

As lab equipment goes, that is near chump change today, but it doesn't sound like a one-pass full spectrum analysis. What I don't really understand is do gas chromatographs report on all gasses in a sample or do they have to specifically look for them one-by-one?

We had a gas chromatograph onboard the sat system I was on in the Navy but all I ever saw were textural dot-matrix thermograph printouts. I have no idea what the medics who operated them had to go through to get them or if it looked for every gas. "Full spectrum" may well be an ASSumption on my part now that I think about it.

I am also a little fuzzy on the differences between gas chromatographs and mass spectrometers. Can a mass spec do the same job with gas mixtures?

I hope I'm not inadvertently responding as though this question were in the other thread, but what is the likelihood of a nefarious person doing that? Has it EVER occurred? ....

How would anyone know if nobody is looking? I'm not into conspiracies or suggesting that every OOA or witnessed event justifies the lab work. But it is surprising to me that what I "thought" was a fairly reasonable expense isn't standard procedure for deaths with undetermined root causes. There are also the chain of custody issues in criminal and civil cases. Maybe I'm way off on the costs though.

 

[Lorenzoid]

. . .
How would anyone know if nobody is looking?

I agree we cannot know for sure that it has never happened. But it seems to me there are so few scuba divers in the general population, and likely so few would-be murderers who have enough knowledge, motive and opportunity to taint a diver's gas, that it's pretty likely it has never happened.

I’m not into conspiracies or suggesting that every OOA or witnessed event justifies the lab work. But it is surprising to me that what I “thought” was a fairly reasonable expense isn’t standard procedure for deaths with undetermined root causes. There are also the chain of custody issues in criminal and civil cases. Maybe I’m way off on the costs though.

After thinking through the comments in these threads, I suppose I would not object to it becoming "standard procedure" for local law enforcement to treat a dead diver's gas as though it were "evidence" at a crime scene. But I'm biased because I'm a diver, not just a taxpayer. I can only imagine that non-diver taxpayers might object to the cost. There have probably been many deaths (not involving diving) where the family or some other interested party--maybe people who have something in common with the victim--would have liked the authorities to have gathered evidence, with all that entails, such as chain of custody, in case they later file some kind of civil lawsuit. But it's presently not the practice of law enforcement to do that unless there is some reason to initially suspect a crime.