Naked Science Forum
General Science => General Science => Topic started by: thedoc on 31/07/2012 16:30:02
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Liz Pompo Majoko asked the Naked Scientists:
Hi Chris,
I need to know why is the faeces (stool) smell so intolerable?
Pinky in Bryanston, Gauteng
What do you think?
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Certainly all feces aren't created the same.
Human feces tend to be more repulsive to humans than most other species, although rat and mouse feces can be most distasteful.
One of the modes of disease transmission is "fecal-oral". A dislike for human feces would be a method to control fecal-oral disease transmission.
In other species, cows tend to dislike their own cowpies more than horseapples... and the same... horses dislike the horseapples, but not the cowpies.
Dogs, of course, seem to be attracted to all scents. [:-\]
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Natural selection (https://en.wikipedia.org/wiki/Natural_selection) for it : those repulsed by the smell are going to keep away from it and the fatal diseases it can transmit, and consequently are more likely to survive than those who don't mind the stink, all other factors being equal, and pass on the I'm-sensitive-to-the-smell-of-crap gene.
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Liz Pompo Majoko asked the Naked Scientists:
Hi Chris,
I need to know why is the faeces (stool) smell so intolerable?
Pinky in Bryanston, Gauteng
What do you think?
Human feces smells of hydrogen sulfide gas. Hydrogen sulfide gas, is a powerful poison, and acid, that can cause immediate and permanent, or fatal lung damage, when in its pure form. The body on a cellular level recognizes the danger and tries to alert you.
Hydrogen sulfide gas, is not as bad as phosgene gas, but pretty close when it is heavily concentrated. Organic vapor cartridges are effective against high concentrations of hydrogen sulfide gas, for short periods of time. It is a powerful acid that instantly burns the throat, and trachea when concentrated. It can cause the body to convulse as the lungs and airways are being destroyed, just like phosgene gas.
Many people and chemists overlook simple common acids, like carbonic acid, as being able to destroy flesh and cause almost immediate death, when a human is exposed to it in volume, and in high concentrations.
Next time you open a bottle of soda, gently fan a little of the escaping gas to your nose. You might be surprised just how potent an acid it is. That acid is responsible for the lungs being stimulated into breathing. Carbonic acid is created in your lungs and has to be removed. The body recognizes this gas, and starts the lungs moving. Years ago doctors used to use carbonic acid (Soda water gas) along with oxygen, to stimulate a person that had suffocated by gas asphyxiation or electrocution into breathing on his own again.
Sincerely,
William McCormick
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If there were enough H2S in crap to kill people, it would.
More importantly, it would do so before it got out of the body.
The only way that carbon dioxide will destroy flesh exposed to it is if it is present as dry ice and freezes the tissue.
The body deal perfectly well with stronger acids- like citric.
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You might want to check out carbonic acid, and the effects it has on wetted flesh, it is a powerful acid to those surfaces. It is the substance that triggers the breathing in the lungs.
Even regular skin on the face, once wetted by and exposed to carbonic acid will blister, over time. If you have ever spent to much time in the water, and had your skin start to shrivel up, at that point carbonic acid is dangerous to skin on the face, and body.
The body on a cellular level detects both these substances, and tries to get you to avoid them. Just like your body would try to get you to avoid phosgene gas, or even the vapor of raw onions.
You may also note that I never mentioned a sample of feces killing anyone. I said that on a cellular level, hydrogen sulfide gas, is detected as the powerful poison and acid it is. Just like the body makes it uncomfortable to stand near onions, the body recognizes the hydrogen sulfide as a poison to the body and tries to make you uncomfortable.
I have tested, all of the above mentioned gases on myself. So I have no doubts that in volume and in high concentrations they kill nicely. I was a bit startled by hydrogen sulfide gases ability to destroy the throat, trachea and lungs, instantly upon contact. Just one breath is all it takes at high concentrations.
I was diagnosed with pleurisy after encountering gases created by feces that were allowed to build up in a sealed area, above the tanks containing feces. Check it out, it is not going anywhere.
Sincerely,
William McCormick
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You may be right that H2S may, in fact, be one of the ingredients that causes feces to be unpleasant.
Confined spaces can be bad. However, I find it unlikely that our ancestors were often exposed to confined spaces in which there was a lethal buildup of toxic gases. That is, unless they had a poop area in caves, or perhaps were storing rotting food supplies in caves. Would outhouses have been invented long enough ago to trap dangerous gases to a point where it became a genetic component of our psyche?
Dangers of the consumption of rotting food would have been another related issue.
Of course, as ancient humans learned to control fire, the would have quickly also learned some of the dangers of combustion, and combustion gases, along with confined spaces.
Getting a little dog poop on one's shoe can seem repulsive, but is hardly a danger for the gasses it is emitting. Likewise, if you are the second person to use the bathroom, the dose of toxic gases is hardly dangerous. Oddly, most people hardly notice their own smells while defecating.
Your body actually has special enzymes to catalyse the production of carbonic acid as part of the dissolving carbon dioxide in the blood, and getting it to the lungs where it can be exhaled. But, you're right, atmospheric carbon dioxide is about 0.04%. However, humans will start noting toxic effects if the level is raised to over a couple of percent.
I still think that a large part of the unpleasant sensation of feces odor would have been the danger of diseases.
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You may be right that H2S may, in fact, be one of the ingredients that causes feces to be unpleasant.
Getting a little dog poop on one's shoe can seem repulsive, but is hardly a danger for the gasses it is emitting. Likewise, if you are the second person to use the bathroom, the dose of toxic gases is hardly dangerous. Oddly, most people hardly notice their own smells while defecating.
I still think that a large part of the unpleasant sensation of feces odor would have been the danger of diseases.
I totally agree that the odor of a little poop on your running shoes will not kill you, or even make you physically ill. I never implied that.
My thoughts are more of onions, I love the smell of onions, but when I get that first whiff before I know what they are, I draw away, as if they are dangerous or irritating. Until I realize the smell is just onions. My body actually automatically starts me away from the onions.
A number of times I have opened a container in the fridge, pealed back the foil or opened the lid, and just took a whiff. Sometimes I come across raw onions, it makes me draw back, until I realize what it is.
Hydrogen sulfide gas is very similar at low concentrations. It has a certain irritating effect, because it is an acid. Concentrated it even surprised me, as to just how powerful an acid it is.
I think the fear of disease is something that is in the mind/spirit, and may be subject to the individuals beliefs rather then an actual physical effect. But I am still of the belief that there is a certain signal sent by the body, as a warning. I am much more aware of the signal, now that I have been hurt by it.
Sincerely,
William McCormick
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For a start, lets stop talking nonsense about the acidity of CO2. It's a rather weak acid.
A saturated solution of CO2 at normal atmospheric pressure would be rather less acidic than apple juice.
Hydrogen sulphide is an even weaker acid than CO2.
"Even regular skin on the face, once wetted by and exposed to carbonic acid will blister, over time."
In warm or rainy weather my face is often wet and exposed to CO2 and it's not blistered.
Of course, the surface of my lungs is always wet and exposed to CO2 and they don't blister either.
"Just like your body would try to get you to avoid phosgene gas, or even the vapor of raw onions. "
The smell of phosgene isn't that strong- certainly not strong enough to act as a suitable warning.
Saying that it is may put people in danger because the think they will be safe.
Please don't do that again.
"I have tested, all of the above mentioned gases on myself. So I have no doubts that in volume and in high concentrations they kill nicely."
If that's true the you are a dead idiot.
" I was a bit startled by hydrogen sulfide gases ability to destroy the throat, trachea and lungs, instantly upon contact. Just one breath is all it takes at high concentrations. "
That's simply not what H2S does.
It messes up the body chemistry by interaction with metal ions like the iron in blood and the copper in some enzymes.
It is very toxic, more so than cyanide, but it isn't corrosive.
"I was diagnosed with pleurisy after encountering gases created by feces that were allowed to build up in a sealed area, above the tanks containing feces."
That's perfectly possible, but the point I made was that the stuff as it comes out of the gut doesn't have much H2S in it. If it did then that H2S would have killed you before you got to the bathroom.
The bacteria that fermented the stuff in the tank made a lot more H2S than was originally present. They are a lot less bothered by the toxicity so they can produce lethal (to us) quantities of the stuff.
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Phosgene gas, causes you to want to break dance, uncontrollably, with even a partial breath taken in.
As a kid my father and I used to rebuild air compressors. At that time 111, tri chlorothane was the de- greaser of choice. Before I was allowed to use it, my father took one drop, placed it on the vice in our garage. He then waved a torch over that one drop, and fanned the fumes towards me. I instantly lost control of my lungs. It is so potent that you cannot breath it in.
111, tri chlorothane exposed to flame or even elemental heat creates phosgene gas. It will kill with one full breath taken in. Even Perchloroethylene (Perc) dry cleaning fluid will create phosgene gas. Not nearly at the concentrations of 111 tri chlorothane, but still in a closed in area very dangerous. Guys in gas stations have picked up the can of perchloroethylene carburetor de greaser / cleaner, and shot it into the car while it was running. Black water like fumes come out of the tail pipe. Those fumes are not something you want to breath in. I tested them.
Sincerely,
William McCormick
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When you know what you are dealing with, you do not take in a full breath.
About twenty years ago I did a favor for someone, something I never do. I said I would repair a hole in his aluminum gas tank, by TIG welding it for him. You have to drain out all the gas, and then use a de greaser to remove any residual material on the wall of the tank. Or the tank will explode when you weld on it.
I used 111, tri chlorothane to rinse out the tank. Unfortunately I also had a small thermostatically controlled space heater in the area. It turned on, and before I could come up with a solution, I took in a partial breath of the phosgene gas. It only took three seconds to make the gas. I instantly cramped up, I had trouble walking, and just before I got to the exit, all I could see was yellow, a pale yellow green color. The next thing I knew I was standing outside.
Sincerely,
William McCormick
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Will you please stop talking nonsense.
It's hard to express just how stupid this statement is. "Phosgene gas, causes you to want to break dance, uncontrollably,"
For a start "Phosgene is an insidious poison as the odor may not be noticed and symptoms may be slow to appear.[17] The odor detection threshold for phosgene is 0.4 ppm, which is four times the Threshold Limit Value. " from
http://en.wikipedia.org/wiki/Phosgene
For a finish, the action of a flame (or an engine) on TCE also generates HCl which would explain the lung irritation you experienced.
So, you are talking about the wrong chemical and, as a result of that, you are spouting dangerous gibberish.
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Hydrochloric acid may also make phosgene gas when burned. Anything that contains chlorine may make phosgene gas. Many chemicals we use have substances added to inhibit phosgene gas being produced. It is the chlorine in 111, tri-chlorothane that makes the phosgene gas, when you apply a flame to it.
I work with muriatic acid, it can cause lung damage and it can cause you to draw back, however it is nothing like phosgene gas. Two totally different, levels of pain.
Phosgene is immediate, there is no mistaking it. There is no other gas like it. Most poisn gases pale to it, in speed and efficiency.
I believe what you are missing is that when you heat with flame, a substance that creates phosgene gas, like 111, tri-chlorothane. That the amount of gas created is huge compared to the amount of substance needed to create it. So the levels in a room are extremely lethal, even though a very small amount of the substance that creates it was used.
In other words you go from nothing to completely lethal quantities in seconds.
The same is true if you mix, hydroflouric acid and hyrdorchloric acid. Five drops of each substance, mixed together fills a small room with a lethal mixture. Again I am sure of this. I was experimenting, trying to make a chemical that could resurface porcelain. I came very close to death that day. Only my previous training and experience with chemicals allows me to survive them.
I was pretty sure five drops of each chemical could not make such an amount of gas. I was totally wrong. The gas also rose to the ceiling, so at first I did not notice it. When I did notice it the room was now filled with a deadly gas.
I worked for a few years in an EPA approved disposal facility here on Long Island, handling the worst chemicals you can find, other then going to a military base or military testing lab. My friend was the president of the company. I was trained by men from all over the United States to handle any chemical. Any accident involving, chemicals. So I am pretty confident about what I am saying.
Why the hostility?
Sincerely,
William McCormick
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Will you please stop talking nonsense.
It's hard to express just how stupid this statement is. "Phosgene gas, causes you to want to break dance, uncontrollably,"
For a start "Phosgene is an insidious poison as the odor may not be noticed and symptoms may be slow to appear.[17] The odor detection threshold for phosgene is 0.4 ppm, which is four times the Threshold Limit Value. " from
http://en.wikipedia.org/wiki/Phosgene
For a finish, the action of a flame (or an engine) on TCE also generates HCl which would explain the lung irritation you experienced.
So, you are talking about the wrong chemical and, as a result of that, you are spouting dangerous gibberish.
If you create phosgene gas in quantity it is not only immediately deadly, it is in the realm of unbelievable. You just convulse uncontrollably, you have to breath but you cannot breath. Your chest hurts so badly there are not words for it.
I have experienced it now many times, mostly at lower concentrations like you get from using a torch on piping that contains residual refrigeration gases. That is kids quantity, I would not call that a good example at all. Try 111, tri-chlorothane in flame, and you will never dispute its lethality again. Even if you just catch the smallest amount of it, fanned gently to your face just a whiff of it. You will tell others about it for the rest of your life.
Sincerely,
William McCormick
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"Hydrochloric acid may also make phosgene gas when burned."
Bollocks.
No carbon source.
"Phosgene is immediate, there is no mistaking it."
Bollocks.
It's well known for the delayed action effect causing death by pulmonary oedema hours or even days after exposure.
"I believe what you are missing is that when you heat with flame, a substance that creates phosgene gas, like 111, tri-chlorothane. That the amount of gas created is huge compared to the amount of substance needed to create it. "
Bollocks.
That's inconsistent with the law of conservation of mass.
"The same is true if you mix, hydroflouric acid and hyrdorchloric acid. Five drops of each substance, mixed together fills a small room with a lethal mixture. "
Bollocks
5 drops of each is only a few tenths of a gram. Of that typically 40% will be the halide rather than water.
A small room contains something like 10 cubic metres.
So you would get about 100mg in 10 m3 if it all evaporated at once (it won't).
That's 10 mg/m3
which is rather less than the IDHL concentration
http://www.cdc.gov/niosh/idlh/7664393.html (http://www.cdc.gov/niosh/idlh/7664393.html)
" The gas also rose to the ceiling"
HF is a bit less dense than air HCl is rather denser. The mixture is going to pretty much diffuse rather than rise.
"I have experienced it now many times, mostly at lower concentrations like you get from using a torch on piping that contains residual refrigeration gases."
You have repeatedly experiences symptoms that are consistent with HCl, but not phosgene and you have experienced them under circumstances where there would be HCl.
"So I am pretty confident about what I am saying. "
Nobody doubts you confidence, just your accuracy.
BTW, found any evidence to support your absurd assertion that the Sun is a big carbon laser yet?
"Why the hostility?"
Because the purpose of this site is to promote science and you keep cluttering it up with bollocks.
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The carbon comes from the hydrocarbon you burn the product that has chlorine in it.
Some chlorinated products like Clorox make very little
phosgene when you burn it.
Sincerely
William McCormick
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Oops, sloppy typing on my part, I should have said "Bollocks. No Carbon-chlorine bond source."
Chlorox (at least as far as I understand it) is mainly water. Have fun burning it.
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Some chlorinated products like Clorox make very little
phosgene when you burn it.
Chlorox (at least as far as I understand it) is mainly water. Have fun burning it.
The active ingredient in bleach is sodium hypochlorite (NaClO) which can be a solid, but not generally in consumer grade products.
Burning is generally considered oxidizing, and I'm not sure you could actually oxidize NaClO any further. And, as BC mentioned, you still need a carbon source if one is forming COCl2, in which case, you can't just say "burning" or "oxidizing", but should further specify the reaction.
However, since COCl2 is not a major component of feces, aren't we getting off topic a bit?
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"Hydrochloric acid may also make phosgene gas when burned."
Bollocks.
No carbon source.
"Phosgene is immediate, there is no mistaking it."
Bollocks.
It's well known for the delayed action effect causing death by pulmonary oedema hours or even days after exposure.
"I believe what you are missing is that when you heat with flame, a substance that creates phosgene gas, like 111, tri-chlorothane. That the amount of gas created is huge compared to the amount of substance needed to create it. "
Bollocks.
That's inconsistent with the law of conservation of mass.
"The same is true if you mix, hydroflouric acid and hyrdorchloric acid. Five drops of each substance, mixed together fills a small room with a lethal mixture. "
Bollocks
5 drops of each is only a few tenths of a gram. Of that typically 40% will be the halide rather than water.
A small room contains something like 10 cubic metres.
So you would get about 100mg in 10 m3 if it all evaporated at once (it won't).
That's 10 mg/m3
which is rather less than the IDHL concentration
http://www.cdc.gov/niosh/idlh/7664393.html (http://www.cdc.gov/niosh/idlh/7664393.html)
" The gas also rose to the ceiling"
HF is a bit less dense than air HCl is rather denser. The mixture is going to pretty much diffuse rather than rise.
"I have experienced it now many times, mostly at lower concentrations like you get from using a torch on piping that contains residual refrigeration gases."
You have repeatedly experiences symptoms that are consistent with HCl, but not phosgene and you have experienced them under circumstances where there would be HCl.
"So I am pretty confident about what I am saying. "
Nobody doubts you confidence, just your accuracy.
BTW, found any evidence to support your absurd assertion that the Sun is a big carbon laser yet?
"Why the hostility?"
Because the purpose of this site is to promote science and you keep cluttering it up with bollocks.
When you mix hydroflouric acid with hydochloric acid it creates heat, that is why the gases went to the ceiling. Eventually I agree they will diffuse nicely.
I use muriatic acid it is a mild substance. I use it to foam away rust from cement. I do not even use a respirator. Strong phosgene gives you one chance, that is to not take a full breath of it. And escape to fresh air. Even with a partial breath your body starts to convulse violently. You are totally not understanding the reality. Break dance is or should be the scientific description of the affect.
Sincerely,
William McCormick
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However, since COCl2 is not a major component of feces, aren't we getting off topic a bit?
I think the topic is, in some ways, very close to William's posts.
You are totally not understanding the reality. Break dance is or should be the scientific description of the affect.
Sincerely,
William McCormick
Well, it's hard to argue with logic like that.
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Guys I would suggest you give me a little credit. What we are talking about here is well known to hands on chemists and engineers that work with the stuff.
I believe if you paid my posts some attention, you would find, I had mentioned again and again flame, burning, space heaters, combustion engines, all creating rather lethal fumes with 111 trichlorothane or perchloroethylene. I gave you my experiences with the substance, to possibly save your lives. With your present joviality towards this chemical, you would die handling it.
It is by far the most effective de greaser you could ever want to use. If you breath to much in it would make you high, but you had to abuse it to get high.
Less fortunate individuals, found that 111 trichlorothance in an electrical fire, also produced deadly levels of phosgene gas. People that worked with 111 trichlorothane and heating elements were also less fortunate, apparently 111, tri chlorothane also has carbon in it. Oxidized heating element surfaces, and 111 trichlorothane were more then enough to send a whole factory to an early grave, from chronic exposure.
I was able to create moderate phosgene gas concentrations similar to those of refrigeration materials being burned with a torch, by just heating with common metals at red heat and no flame. With just heated surfaces not red hot surfaces, near 212 degrees, the smell of phosgene gas was produced. Tanks with 111 trichlorothane, that had metal sludge at the bottom, also started producing phosgene gas. Perhaps the aluminum sludge stole the chlorine, and the carbon in the 111 tri chlorothane was allowed to produce phosgene gas.
Apparently when you expose 111 trichlorothane fumes to the flame of a hydrocarbon being burned, the carbon, in the flame, is burned a second time by the chlorine in the 111 trichlorothane fumes. It could be that at higher temperatures the chlorine is a better catalyst for the carbon then the oxygen. So you get a second burn, with the chlorine as the catalyst.
I know they have overcome this with additives. One is a lemon additive, in cutting fluids, that appears to stop much of the chlorine from mating with the carbon in the flame. Very impressive to see.
They give 111 trichlorothane a one for flammability, if there is a fire, spraying it with 111 trichlorothane, instantly extinguishes it. Just don't stay around for the fumes produced. This chemical has become something of an enigma, it should never have been allowed to go into shops and factories without the proper warning. But the proper warning was too scary for our government to allow. I guess they did not want to print , on the label, instantly causes a military grade gas to be formed in the presence of flame from hydrocarbons.
Perhaps I am missing the point of your posts or the comedy. I assumed a science forum. I have told you all that I know about it, if you wish to make fun of that I cannot stop you. But the laughs will be on you if you or someone you love ever dies from it.
Sincerely,
William McCormick
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Ok this thread is closed.
William in future threads can we have less of your personal experiences with dangerous chemicals and your singular definitions of safety.