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Author: Subject: UCSD Claims Bromine Is More toxic than HF! Wha..??
The Chemistry Shack
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[*] posted on 7-8-2015 at 07:31
UCSD Claims Bromine Is More toxic than HF! Wha..??


So while researching the toxicity of HF, I came across an interesting observation. According to the following source: http://www-ehs.ucsd.edu/lab/Gas/toxic-gas-hazclassChart.html

Bromine is about 10 times more toxic than HF when measured by the IDLH and a little less than 10 times more toxic when measured by the LC50.

Of course, this generated my immediate skepticism. How can such a dangerous compound that nearly every chemist is scared of (HF) be ten times safer than a relatively common chemical that many of us have worked with, and even breathed the occasional whiff (Br2)?

My theory is that the IDLH and LC50 values only refer to immediate acute toxicity. Br2 is a much more corrosive respiratory agent, and it makes sense that it can become harmful at concentrations lower than that of HF. I'm not sure if the IDLH for HF accounts for the effects of fluoride poisoning, or if it is merely limited to immediate respiratory problems like pulmonary edema (which, again, it makes sense that Br2 can cause this at much lower concentrations than HF).

Also, this information is limited to the compounds in the gaseous phase. Dermal contact with HF solution would likely be much more toxic than dermal contact with liquid Br2 due to the effects of the fluoride ion.

Is this surprising to anyone else? Or am I confusing the significance and/or meanings of LC50 and IDLH values?

[Edited on 7-8-2015 by The Chemistry Shack]




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nuchem
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[*] posted on 7-8-2015 at 08:02


I think the rating for Bromine is higher because most lab samples of Bromine are Anhydrous, unlike HF where it is dissolved in solution. I looked at the MSDS sheets for both, and Bromine's listed as 100% by weight while HF is listed as 48%

So that might be an important factor.

Edit: I looked at multiple MSDS sheets from different suppliers. The HF MSDS varied concentration, 48% being the highest. Although, Bromine was fairly consistent, at 100% by weight.

[Edited on 7-8-2015 by nuchem]
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[*] posted on 7-8-2015 at 09:10


Quote: Originally posted by nuchem  
I think the rating for Bromine is higher because most lab samples of Bromine are Anhydrous, unlike HF where it is dissolved in solution. I looked at the MSDS sheets for both, and Bromine's listed as 100% by weight while HF is listed as 48%

So that might be an important factor.

Edit: I looked at multiple MSDS sheets from different suppliers. The HF MSDS varied concentration, 48% being the highest. Although, Bromine was fairly consistent, at 100% by weight.

[Edited on 7-8-2015 by nuchem]


Yes, although the UCSD source specifies that these values refer to the anhydrous gasses




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Brom
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[*] posted on 7-8-2015 at 19:22


I read somewhere that something like 10 square inches of concentrated hf acid solution on your skin will kill you from permeability of your skin to it. I may be wrong but that stuff scares me and I use bromine all the time with no worries other than the respect that I have for all chemicals.
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[*] posted on 7-8-2015 at 19:57


I actually got poisoned once while working with HBr-Br2. Bromine (elemental) vapors target lungs, while HF does not care about lungs. For the same reason phosgen is so dangerous - it attacks specifically lungs and kidney, regardless of administration route, you can absorb phosgen reactally and still it will attack lungs and kidney.
And in a long term toxicity bromine is just as dangerous as HF, because bromine is slowly removed from body.
I'm not scared of HF, I've got a bottle of it standing next room.
IDHL and LC50 are scalar one dimention values, they can't cover all scenarios.
nuchem, nobody supplies HF gas, but IDHL and LC50 are all about gases, so I dont understand your point.
Brom, I'm sure you need to wait some time without washing HF away from skin for it to kill you. 10 square inches is a lot, it's a full hand burned. Neoprene gloves will save you.
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