since you want to talk about volumes and concentrations, consider this:
- 7 mL of concentrated HF is enough to bind all free Ca in the body of an average adult.
- exposure of 1% of your total skin surface to concentrated HF is typically lethal, this is approximately equal to the palm of one hand. Due to the rapid transcutaneous uptake, exposure of 5% of your total skin surface to dilute HF has the potential to be lethal.
- the risk of fatality is significantly increased if exposure involves inhalation of vapors. HF vapor in air is severely irritating at 3 ppm and acutely lethal at 30 ppm (for comparison, carbon monoxide doesn't become acutely lethal until it reaches about 800 ppm).
HF fatalities appear to occur in the US on average about once or twice a year and are thus not all that rare. Below is an excerpt from a 2001 paper in the American Journal of Industrial Medicine. While many of these are probably industrial accidents and no doses are reported, it is especially troublesome that about half of these victims were relatively quickly treated with gluconate or even IV Ca, to no avail:
"For the 11 year period, OSHA investigated nine deaths in eight incidents which involved HF. Four deaths were from skin contact with concentrated HF, and five deaths involved both skin contact and inhalation of vapor. Unsafe work practices were factors in all of the deaths. Calcium chloride or gluconate was noted to have been administered to five of the nine victims. Calcium was administered 90 min after exposure to two victims, and more than 6 h after exposure to a third. We were able to establish that the regional poison control center had been contacted in regard to only one victim. For the period 1984-94, we were able to identify no additional deaths from CPSC reports, one additional death from AAPCC annual reports, and four other deaths from case reports in the medical literature."
There is no reason for people to fear HF when taking proper precautions, but they must be taught to respect it and made aware of its hazards, which should not be downplayed. The most common mistake is to think of HF merely as a strong acid, when it should be thought of as a strong poison.
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evident among some of my acquaintances than others)" - Sir Robert May
Dr. Johan Schijf
Assistant Professor, Aquatic Environmental Geochemistry
UMCES/Chesapeake Biological Laboratory
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e-mail: [log in to unmask] David Jones <[log in to unmask]>:
> What people always omit in their well intentions warnings is that you
> have to consider volumes and concentrations. I would be very disturbed
> if extreme conditions were introduced for handling solutions with
> "trace" levels of HF. In some labs we have been quite safely handling
> concentrated (30-50%) HF with reasonable safety precautions (face
> shields, HF resistant (not rubber) gloves, aprons, sleeves and boots
> etc) and appropriate dispensers for some time, but you could not expect
> people to use the same equipment when handling diluted HF stabilised
> standard solutions which would have <1% HF. The equipment will become a
> safety hazard in itself due to discomfort, lack of maintenance and a
> combination of other issues.
> People also often ignore the fact that the one HF related death which
> everybody uses as an example is a combination of all the worst factors.
> It involved a large volume of concentrated HF spread over a large area
> of the victims body with a long delay in seeking medical attention. This
> doesn't change the fact that HF is dangerous but it can be handled
> safely in a routine way without having to keep body bags on hand, once
> the proper precautions have been taken.
> I'm sure this is old hat to the geochemical community of rock chemists
> and they all have their own individual stories to keep awareness high,
> but to everybody else, travelling in a car is still more dangerous than
> doing HF digestions. Use the right equipment for the job, and learn how
> to use it correctly (ie safely).
> And of course none of the warnings, extreme or otherwise, will prevent
> those individuals who are just plain dangerous in the lab from injuring
> themselves, whether it be with a plastic spoon or a toxic chemical.
> David Jones
> ICP-MS Laboratory Supervisor
> ALS | Minerals Division
> 32 Shand St
> Stafford QLD 4053 Australia
> PHONE +61 7 32437269
> FAX +61 7 3243 7254
> P Please consider the environment before printing this email
> -----Original Message-----
> From: PLASMACHEM-L: Analytical Chem.(ICP's, DCP's, MIP's).
> [mailto:[log in to unmask]] On Behalf Of Jay Tompkins
> Sent: Friday, 16 September 2011 8:02 AM
> To: [log in to unmask]
> Subject: Re: HF & other ideas
> Some years ago I worked on a project in which we used normal phase HPLC
> with hexane as MPA and a mix of ether and hexane as MPB. We had to
> remove all olefins from the technical grade hexane using concentrated
> sulfuric acid mixed with the technical grade hexane in a sep funnel.
> For that task I wore a rubber apron which was at least calf length.
> Concentrated sulfuric acid will cause a lot of damage but I doubt it
> would lead to limb amputation followed by death. So HF sounds like
> really bad stuff and the PPE most of us in labs wear, well one would
> just as wear underwear in the lab, a lab coat would just be
> insufficient. I work in a bio-analytical lab and people washing dishes
> here wear a mask with respirator, a full length rubber apron and gloves
> that protect the whole arm so as to be protected from bio-hazards. I
> would think it would be foolhardy for anyone working with HF to wear
> anything less than this. I believe I ranted like this some time ago
> when HF was discussed.
> Jay Tompkins
> Associate Scientist
> Analytical BioChemistry Laboratories, Inc.,
> 4780 Discovery Drive,
> Columbia MO 65201
> Tel: 573-777-6012
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