Sciencemadness Discussion Board

Odor Threshold Table

smuv - 7-2-2011 at 20:54

I found a pretty comprehensive table, recording the odor threshold of various organic compounds. I thought I would share. This is useful, to determine, if smelling a chemical is adequate warning of overexposure.

www.cschi.cz/odour/files/world/Thresholds%20table.pdf (seems this was compiled by a Czech society of chemical engineering)

DJF90 - 8-2-2011 at 09:48

Thats really useful smuv! Thanks for the contribution!

karmapolice - 13-2-2011 at 22:11

very usefull ! thanks .

peach - 14-2-2011 at 05:16

Saved.

There are quite a few of these on Wiki, but only for that specific material per page.

For instance, here's the one for H2S
Quote:
# 0.00047 ppm is the recognition threshold, the concentration at which 50% of humans can detect the characteristic odor of hydrogen sulfide,[12] normally described as resembling "a rotten egg".
# Less than 10 ppm has an exposure limit of 8 hours per day.
# 10–20 ppm is the borderline concentration for eye irritation.
# 50–100 ppm leads to eye damage.
# At 100–150 ppm the olfactory nerve is paralyzed after a few inhalations, and the sense of smell disappears, often together with awareness of danger.[13][14]
# 320–530 ppm leads to pulmonary edema with the possibility of death.
# 530–1000 ppm causes strong stimulation of the central nervous system and rapid breathing, leading to loss of breathing.
# 800 ppm is the lethal concentration for 50% of humans for 5 minutes exposure (LC50).
# Concentrations over 1000 ppm cause immediate collapse with loss of breathing, even after inhalation of a single breath.


It is, of coarse, handy to know that the threshold for smelling it is far below the point at which is becomes immediately lethal.

It would great if there was a list of things that are dangerous below their detection threshold. Monoxide is an obvious one.

Jor - 14-2-2011 at 22:34

Well most common inorganic gasses can be smelt at relatively low concentrations, thus giving a fair warning. However they do not always irritate. For example, NO2 can be present in dangerous concentrations, while on may not notice any irritation. Phosgene has very poor warning properties, and can be dangerous when one hardly notices it's presence AFAIK.
HCN is obviously very dangerous, as many people can't mell it. I am not sure if I can, but I should try it sometime, as I use the salts sometimes. This weekend for example I tried to prepare K3[Cr(CN)6].
Many organics have poor warning properties. Toxic solvents like benzene and chloroform are detected far above STEL if I remember right.
Yes CO can't be smelled, but I don't consider it dangerous in a lab setting. You need very high concentrations to get you down ( far more than other common toxic gasses) and you generate much more during a simple barbecue or woodfire than during a normal lab experiment (I read in some paper that in a standard wood fire, for every Kg wood that is burned, about 30g of CO is produced. However for some reason people freak out around small amounts of CO in a lab, and happily stand over a barbecue. Ever felt a little dizzy or just little tired when standing over a barbecue making meat for half an hour? I do, just slightly, and I think it is the effects CO.
When you know how much you make with at least mediocre ventilation, no problem. Although I don't advice mixing a liter of H2SO4 with a liter of formic acid ;)

The WiZard is In - 15-2-2011 at 08:04

Quote: Originally posted by Jor  

Yes CO can't be smelled, but I don't consider it dangerous in a lab setting. You need very high concentrations to get you down ( far more than other common toxic gasses) and you generate much more during a simple barbecue or woodfire than during a normal lab experiment (I read in some paper that in a standard wood fire, for every Kg wood that is burned, about 30g of CO is produced. However for some reason people freak out around small amounts of CO in a lab, and happily stand over a barbecue. Ever felt a little dizzy or just little tired when standing over a barbecue making meat for half an hour? I do, just slightly, and I think it is the effects CO.
When you know how much you make with at least mediocre ventilation, no problem. Although I don't advice mixing a liter of H2SO4 with a liter of formic acid ;)


Toxicity of Carbon Monoxide
J. Gas. Lighting, 1902, 82, [4602]. 1334
In:— The Journal of the Society of Chemical Industry
23 [21] 1465. December 15, 1902.

With a view of determining the exact proportion of carbon monoxide which, when
inhaled with atmospheric air. would prove fatal to man. U. Mosso has carried out
experiments in an iron chamber of 203 cubic feet capacity, lighted by a glass
window, hermetically closed by a door, and provided with inlets for the poisonous
gas. An experiment, in which the subject lost consciousness, and artificial
respiration and the use of compressed oxygen had to be resorted
to, showed that the proportion of carbon monoxide in air fatal to
man is 1-233rd or 0.43 per cent.


Wonder I — what is the limit of detection of cat spray?