Sciencemadness Discussion Board

Most overrated and underrated hazardous chemicals?

Melgar - 25-8-2016 at 17:13

Basically, what chemicals have the greatest discrepancy between how dangerous they're perceived to be, and how dangerous they are?

For least dangerous, but most perceived danger, my vote goes to methanol. The only reason it's dangerous at all is because it kind of tastes and smells like ethanol, so the occasional idiot tries to get drunk on it. Or, someone will try and ferment something with a lot of cellulose in it, then distill it. They'll keep turning up the heat when liquid stops coming out, until all of a sudden a whole bunch more alcohol comes out! Yay! Except that this alcohol is a product of cellulose pyrolysis, and is known as "wood alcohol" for this reason. But as long as you don't drink methanol with the intent of getting drunk, it's probably among the safest organic solvents.

For most dangerous, but least perceived danger, I'd probably go with chlorine bleach. It's a strong oxidizer, halogenation agent, and a strong base all in one, but because it can kill germs (as well as just about anything else) some people use it on just about everything. Really, a few nonpathogenic bacteria are a lot less likely to harm you than their halogenated remains.

careysub - 25-8-2016 at 17:26

There is 1,1-difluoroethane found in "dust off" cans.

It can be ignited, and when it is it produces hydrogen fluoride gas, and carbonyl fluoride!

The risk of being burned is nothing compared to the chemical burns and poisoning that can result.

(There is also the frostbite hazard if you spray it on your skin.)

Woelen has cited TCCA as an unusually hazardous compound for its reactivity.

Velzee - 25-8-2016 at 17:35

Least dangerous I would say, sulfuric acid, chloroform, and hydrogen peroxide, with the exception for the eyes.

More dangerous, hmm. Caffeine, as it is very easy to overdose(especially with the pure powder), and die of a heart attack. Isopropyl alcohol, gave me a head ache a lot easier than I imagined. Oh, and although YouTube may show it to be a funny and fun thing to play with, Al2S3 and H2S had worse effects than I thought it would to others(more mentally, rather than physically. Areosolized eucalyptus oil can be a hazard; you can't breathe properly with it around.

Texium - 25-8-2016 at 17:44

Quote: Originally posted by Velzee  
Areosolized eucalyptus oil can be a hazard; you can't breathe properly with it around.
Amen. Once I was in a hotel sauna and someone sprayed some, and I felt like I was literally going to suffocate. Wasn't sure if it was just me, like an allergy, as everyone else seemed fine.

careysub - 25-8-2016 at 17:50

There is the amusing fact that thiodiglycol used as a solvent in ball point pen ink reacts with hydrogen chloride to make mustard gas.

But it is hard to imagine a scenario where sufficient ballpoint ink might be released to cause a problem, and I have never heard of an incident involving this.

Velzee - 25-8-2016 at 17:56

Quote: Originally posted by zts16  
Quote: Originally posted by Velzee  
Areosolized eucalyptus oil can be a hazard; you can't breathe properly with it around.
Amen. Once I was in a hotel sauna and someone sprayed some, and I felt like I was literally going to suffocate. Wasn't sure if it was just me, like an allergy, as everyone else seemed fine.


Yeah, I attempted to make anhydrous MgSO4, but it contained eucalyptus... Let's just say my parents couldn't breathe, and my dad was coughing for a while... For me, it burned my nose, and got annoying after a while.

Melgar - 25-8-2016 at 21:27

Quote: Originally posted by careysub  
There is the amusing fact that thiodiglycol used as a solvent in ball point pen ink reacts with hydrogen chloride to make mustard gas.

But it is hard to imagine a scenario where sufficient ballpoint ink might be released to cause a problem, and I have never heard of an incident involving this.

Wouldn't you need a ZnCl2 catalyst, or is there some reason that the hydroxyl groups wouldn't react like primary alcohols?

Incidentally, I thought I remembered reading that thioethers could be cleaved by strong acids, and looked up "thioether cleavage". I didn't get many results, so I went to delete the word "cleavage", but deleted the wrong word by mistake. Got some interesting and unexpected image results from that one. ;)

nezza - 26-8-2016 at 01:51

Sulphuric and nitric acid are dangerous when concentrated. Hydrochloric acid is relatively innocuous. Dilute mineral acids are again relatively innocuous and not as dangerous at a given concentration as alkalis, the exception being hydrofluoric acid which is just evil at all concentrations. NaOH and KOH are quite nasty dilute or concentrated. As for poisons the nastiest I have experienced is hydrogen selenide. Likewise hydrogen sulphide is known for its bad smell, but it is also a dangerous poison and far more poisonous than cyanide.

[Edited on 26-8-2016 by nezza]

Maker - 26-8-2016 at 02:27

Mercury, most seem to think it'll kill you in 24 hours if you touch even a drop.

Metacelsus - 26-8-2016 at 06:48

Silica gel (for chromatography columns) is surprisingly nasty if inhaled (although not as bad as asbestos). In my experience, many people forget this.

careysub - 26-8-2016 at 07:54

Quote: Originally posted by Melgar  
Quote: Originally posted by careysub  
There is the amusing fact that thiodiglycol used as a solvent in ball point pen ink reacts with hydrogen chloride to make mustard gas.

But it is hard to imagine a scenario where sufficient ballpoint ink might be released to cause a problem, and I have never heard of an incident involving this.

Wouldn't you need a ZnCl2 catalyst, or is there some reason that the hydroxyl groups wouldn't react like primary alcohols?


Apparently some glycols are reactive toward hydrochloric acid, see:
"The Reaction Between Alcohols And Aqueous Solutions Of Hydrochloric And Hydrobromic Acids. II.", James F. Norris, Robert S. Mulliken, J. Am. Chem. Soc., Volume 42, Issue 10, pp 2093–2098.

The use of hot concentrated hydrochloric with thiodiglycol to prepare Bis(2-chloroethyl) sulfide is in the literature (Sartori, "The War Gases" cites this):

"CLXX.—4-Alkyl- 1 : 4-thiazans", Hans Thacher Clarke, J. Chem. Soc., Trans., 1912,101, 1583-1590

"Ethylene Chlorohydrin And B,B-Dichloroethyl - Sulfide", M. Gomberg, J. Am. Chem. Soc., 1919, 41 (9), pp 1414–1431

The US Army Chemical Corps investigated making a theatre deployable mustard gas production and shell filling unit using this reaction to avoid having to store and ship the toxic agent.

During WWI Germany produced mustard gas by the "Meyer Process" (references for the actual method Ber 19, 3260 [1886], Ann. 240, 310 [1887]) which used HCl gas.

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[Edited on 26-8-2016 by careysub]

careysub - 26-8-2016 at 08:17

Quote: Originally posted by Metacelsus  
Silica gel (for chromatography columns) is surprisingly nasty if inhaled (although not as bad as asbestos). In my experience, many people forget this.


Silica gel is amorphous and this poses a much lower risk than natural crystalline silica dust, fortunately. Don't inhale it for sure, but it is apparently not very dangerous.

Crystalline silica dust through causes "silicosis" for sure and is nothing to sneeze at (so to speak). It is a crippling, even fatal disease:
https://en.wikipedia.org/wiki/Silicosis

Probably the most frequent source of exposure is in sand blasting.

It was the cause of the worst industrial disaster in U.S. history, the Hawks Nest Tunnel, which killed a large portion of the 3000 workers (several hundred, exact number is uncertain):
https://en.wikipedia.org/wiki/Hawks_Nest_Tunnel_disaster

This hazard also exists for gardener/farmers working with perlite.

A prominent optical engineer, who worked at Perkin-Elmer making optics for the government, and who should have known better, was killed by it:
https://en.wikipedia.org/wiki/Robert_E._Cox



[Edited on 26-8-2016 by careysub]

Cryolite. - 26-8-2016 at 12:29

Quote: Originally posted by Velzee  
Least dangerous I would say, sulfuric acid, chloroform, and hydrogen peroxide, with the exception for the eyes.


I actually sort of disagree with sulfuric acid. Sure, it doesn't really damage skin if it's concentrated but cold, but hot concentrated acid is a whole other story, and even cold acid wrecks cotton clothing like nothing else on earth. (I learned that the hard way...) It's risks are definitely overblown, but it is not a particularly safe substance by any means.

All of the best ones have already been used, but one of my picks would have to be dihydrogen monoxide. People keep insisting that it is just a fancy term for water, but we all know how nasty it really is, right? ;)

On a more serious note, formaldehyde is seen as liquid cancer, when it is a product of the metabolism of pectin and really not that dangerous with only short term exposure. On the other hand, people slather DCM all over the walls of their houses to strip paint, when it is really quite nasty, being a respiratory irritant and a carcinogen.

Metacelsus - 26-8-2016 at 13:48

Quote: Originally posted by careysub  

Silica gel is amorphous and this poses a much lower risk than natural crystalline silica dust, fortunately. Don't inhale it for sure, but it is apparently not very dangerous.


I had heard the bad stuff about silica, and thought that it also included amorphous silica. This makes me feel a bit safer (though inhaling amorphous silica still can't be very good.)

As for a chemical that has overrated hazard, ethidium bromide is a good example. People think it's horribly carcinogenic, but it's actually not: http://blogs.sciencemag.org/pipeline/archives/2016/04/18/the...
Quote:
toxicity of gel staining solutions is trivial compared to the risks of of burns from melted agarose or slipping on spilled gel buffer


[Edited on 8-26-2016 by Metacelsus]

Melgar - 26-8-2016 at 15:55

Quote: Originally posted by Cryolite.  
On a more serious note, formaldehyde is seen as liquid cancer, when it is a product of the metabolism of pectin and really not that dangerous with only short term exposure. On the other hand, people slather DCM all over the walls of their houses to strip paint, when it is really quite nasty, being a respiratory irritant and a carcinogen.

Honestly, I'd put DCM in the opposite category. Sure, it can causer cancer if you're inhaling it daily because you strip paint for a living, but that can be said about virtually any chemical. It's nothing that a healthy liver can't handle occasional exposure to. Considering that whenever I've bought paint stripper that contained DCM, half the can was covered with warning labels, I don't think its toxicity is underrated, by any means.

Probably its main danger is that it typically comes mixed with other, flammable organic solvents, and the combustion of such a mixture would produce phosgene, among other nasties.

AJKOER - 28-8-2016 at 14:05

Quote: Originally posted by nezza  
Sulphuric and nitric acid are dangerous when concentrated. Hydrochloric acid is relatively innocuous. Dilute mineral acids are again relatively innocuous and not as dangerous at a given concentration as alkalis, the exception being hydrofluoric acid which is just evil at all concentrations. NaOH and KOH are quite nasty dilute or concentrated. As for poisons the nastiest I have experienced is hydrogen selenide. Likewise hydrogen sulphide is known for its bad smell, but it is also a dangerous poison and far more poisonous than cyanide.

[Edited on 26-8-2016 by nezza]


Actually, my recollection is that H2S is a little less toxic than H2S, but certainly more sneaky. One can receive a fatal dose of H2S by both inhalation and skin absorption, and not realize it, described as cases of the walking dead. The suppression of the sense of smell and skin absorption likely contributing to fatalities.
-------------------------------------

Under rated is NCl3 as an unstable explosive. First, it is not an explosive, it is, in fact, a high explosive. Second, its sensitivity extends broadly to heat, light, shock and exposure to organics. The latter apparently includes even dust.

A better description of NCl3 is a broadly sensitive dangerous high explosive.

[Edited on 28-8-2016 by AJKOER]

careysub - 28-8-2016 at 19:05

Quote: Originally posted by AJKOER  
Likewise hydrogen sulphide is known for its bad smell, but it is also a dangerous poison and far more poisonous than cyanide.

[Edited on 26-8-2016 by nezza][/rquote]

Actually, my recollection is that H2S is a little less toxic than H2S, but certainly more sneaky. One can receive a fatal dose of H2S by both inhalation and skin absorption, and not realize it, described as cases of the walking dead. The suppression of the sense of smell and skin absorption likely contributing to fatalities.


Not sure which is which you mean.

H2S and HCN are roughly equally toxic. It varies with exposure time since cyanide has an efficient detoxification mechanism, and for H2S it is much less effective. On very short exposure cyanide is more toxic, on longer exposure it is less toxic, even indefinitely tolerable (that is about 30 ppm). The equal toxicity concentration (LC01) is probably about 100 ppm for 60 minutes

They both have about the same threshold detection level, 1 ppm, but perhaps H2S is more recognizable. The odor of H2S becomes hard to tolerate around 25 ppm (no such level exists for cyanide), and causes eye irritation and coughing from 50-100 ppm.

A special problem with H2S is that 10 minute exposure at 50-100 ppm destroys the sense of smell and thus results in the loss of ability to sense its presence through smell.

[Edited on 29-8-2016 by careysub]

Magpie - 28-8-2016 at 19:23

During my freshman chemistry class in 1961 H2S was on tap for qualitative analysis tests. I now find that hard to believe. What do freshman know, anyway? There was no training. There might have been a warning sign in the hood, however.

woelen - 31-8-2016 at 10:52

Perchloric acid is said to be extremely dangerous and capable of igniting nearly everything. This only is true for anhydrous perchloric acid. Commercially available perchloric acid at 60 to 70% concentration actually is one of the tamest strong acids. It only acts as strong acid, does not oxidize and also does not form complexes with metal ions. I even tried adding sodium sulfite or potassium sulfite to boiling hot 60% HClO4. Nothing happens when this is done. With the sulfite just some SO2 escapes, with the iodide only a faint yellow color was obtained, and I am inclined to think that this was due to presence of oxygen from air instead of oxidation by perchlorate.
Only anhydrous perchloric acid is extremely dangerous. Indeed, that acid can ignite wood, paper and many other things even at room temperature.

Most underrated to my opinion are TCCA and sodium chlorite. Both are available in the pure state, TCCA as pool chlorinator, NaClO2 as so-called MSM or as water-purifier. They are remarkably reactive and you can have spontaneous fires or even explosions with these chemicals. Even oxidizer/oxidizer combinations can lead to explosions:
- TCCA plus calcium hypochlorite mix leads to extremely violent and exothermic reaction when a few drops of water are added.
- NaNO2 and NaClO2, when mixed, explode when a little acid is added. The ClO2 formed in this reaction from the NaClO2 explodes in contact with the NOx formed from the NaNO2.

TCCA mixed with organics and NaClO2 mixed with e.g. sugar can ignite spontaneously (examples of both are described here on sciencemadness).

In terms of toxicity none of the chemicals I mention here are exceptional. Just use common sense, but moderate exposure is no real problem. Even getting 70% HClO4 on your skin is not a real issue, just quickly rinse it away with some water and nothing happens.

metalresearcher - 31-8-2016 at 11:41

What about ClF3 ?
I think that is the nastiest chemical which exists in the sense of oxidizing.

It ignites almost everything.

unionised - 31-8-2016 at 11:42

Quote: Originally posted by Cryolite.  
Quote: Originally posted by Velzee  
Least dangerous I would say, sulfuric acid, chloroform, and hydrogen peroxide, with the exception for the eyes.


I actually sort of disagree with sulfuric acid. Sure, it doesn't really damage skin if it's concentrated but cold, .


Oh yes it F***ing does!

aga - 31-8-2016 at 11:44

In my experience, NaOH is underrated.

Recently a few prills fell onto my hairy left leg, just above the knee.

It's hot here, so it will have encountered water in the form of sweat.

Later on i felt a stinging sensation so washed that area with water from the wash bottle.

The hairs had dissolved and fell away, leaving a 3cm circle of baldness, although no skin damage to speak of.

Σldritch - 1-9-2016 at 07:46

Quote: Originally posted by metalresearcher  
What about ClF3 ?
I think that is the nastiest chemical which exists in the sense of oxidizing.

It ignites almost everything.

ClF3 is overrated the real deal is ClF5
Tough i would not exactly say ClF3 is harmless...

Really tough i would say hydrochloric acid is not very dangerous compared to
sodium hydroxide.

Lotilko - 1-9-2016 at 10:59

Alfatoxin B1 seems to be underrated.

Chemetix - 26-9-2016 at 13:57

Would have to nominate Oxalic acid, it's hard to be poisoned by it, you'd generally have to ingest it, but for something that has such a low LD50 which can be bought at hardware stores I'd say it's underrated.

aga - 26-9-2016 at 14:26

The Greatest discrepancy on this board is between the people interested in amateur chemistry, and those who are not.