Workplace Hazardous Materials Information System

Here are some of the hilarious, interesting, or scary tidbits that I wrote down when I took my WHMIS training in Feb 2011.

Compressed Gas

Many of the pictures the presenter showed us were actually taken during lab inspections at McGill. The first of these was a picture of a compressed gas cylinder with a backpack hanging from part of the regulator assembly on top of the cylinder.

One litre of liquid nitrogen can displace 700 litres of air. There is a risk of asphyxiation if you are in a small room.


The flash point of a material is the temperature at which it releases enough vapour that it can be ignited. I have definitely heard the term flash point used in a very different sense (in common usage), such as referring to the temperature at which a material will suddenly explode or burst into flame.

There was a fire/explosion at the Montreal Neurological Institute because someone left some sort of chemical on a hot plate and left the lab. The teacher suggests a rule: If you are working with volatile things, unplug all the hotplates nearby.

Domestic refrigerators and freezers can sometimes create small internal sparks during their operation. This means that if you store volatile substances in these places, you can end up with an explosion. Buy things that are certified for storing volatile products (they won’t spark internally, among other things).

The teacher talks about how dangers peroxide crystals can be. They can form in many different ways, and are susceptible to heat, friction, and shock. Any of these things might make them suddenly explode. This is a good reason to keep an eye on expiry dates on chemicals that can form peroxide crystals. The recommendation is that you don’t keep chemicals around for more than a year.

Never store oxidizing agents together with flammable materials.

Chemical Sensitization

Repeated exposure to chemicals can cause sensitization. This means that you become more sensitive to exposure as time goes on. This reminds me of what some friends of mine told me when they were talking about their experience with sick building syndrome. For them, even a whiff of a cleaning chemical used on a hospital floor might be enough to make them physically ill.

Acids, etc

Pour acid into water, not water into acid.

Never store organic acids with oxidizing agents.

Hydrofluoric acid needs special consideration. There is a special cream that you must always keep with the hydrofluoric acid bottle. Why? Hydrofluoric acid will attack calcium in the blood. Within a very short amount of time there is a very high risk of cardiac arrest. Must apply cream to exposed area. You should then have enough time to go to the hospital. Cream is actually kept attached to bottle of hydrofluoric acid in some labs due to this serious health concern.

Karen Wetterhahn and dimethylmercury safety

We were told a very scary story about the late Professor Karen Wetterhahn at Dartmouth college. She was a highly-regarded expert in the area of heavy metal poisoning and she was abiding by all prescribed safety procedures in the lab when she was exposed. During a lab procedure, she dropped some dimethylmercury on her hand (which was covered in a glove). She died less than a year after exposure due to the massive dose of mercury that she had received, but was unaware of for the first six months.

Her accident set off a study that investigated whether the safety procedures were effective. This is when it was discovered that the latex gloves are ineffective at protecting from dimethylmercury. It turns out that dimethylmercury penetrates through latex gloves in less than 15 seconds.

Material Safety Data Sheets

If you are exposed to a chemical, bring the MSDS with you when you get medical help.

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