What's so special about Chemical Hazards?

A common question I get when teaching people about chemical safety is :

Are chemicals dangerous to work with?

There are two key words in this question :

• dangerous : what does that really mean?
• chemicals : what makes chemical hazards different from other hazards?

The word "dangerous" is a little ambiguous (means a different thing to different people), and it doesn't indicate a way to analyze the situation and prevent incidents - which is what we want to do. So in Safety and Health Management, we distinguish between hazard, probability of exposure and risk :

• the HAZARD is the adverse effect ("harm") to our health that we could possible experience as a result of the activity in question. It is a property of the equipment or chemicals involved in the activity. Example : a well-known hazard of concentrated sulfuric acid is that it is extremely corrosive. Sulfuric acid is therefore an extreme corrosion hazard. It has several other hazards : it reacts violently with water (and many other substances), it activates strong inorganic oxidizers to become even more powerful oxidizers, etc. Sometimes, we can make a task safer by using a less hazardous chemical.

• but sulfuric acid in a closed bottle sitting quietly on a bench is not going to harm us. For it to harm us, the hazard has somehow to reach our body. When that happens, we say that there is exposure. So it is important that we know how likely or probable that is to happen. That is why we need to factor in the LIKELIHOOD or PROBABILITY OF EXPOSURE. The likelihood of exposure will depend on what we exactly do with the sulfuric acid, on how we handle it, and that may be different in different activities or tasks. So the likelihood of exposure is task specific. Reducing the likelihood of exposure is what we most of the time do to make a task safer.

• The RISK is defined as the probability or likelihood to experience adverse effects ("harm") from the activity or task. It is a combination of the hazard AND the likelihood of exposure within a given task. Typically, professional Risk Assessors will rate hazards and likelihood of exposure for a given task with a number between for example 1 and 5, and then calculate a risk rating by multiplying these numbers :

RISK = HAZARD x LIKELIHOOD OF EXPOSURE

So the proper question is :

What risk does this given task involving this given chemical pose to my health ?

These concepts form the basis of a Chemical Health Risk Assessment. (note that actually every risk assessment method uses a similar logic)

Having said all this, what makes chemical hazards so special as compared to other hazards? Lets have a look at the more common hazards that we are all familiar with. By either instinct or childhood education we know how to recognize and control hazards like :

Now think for a second about the last one : crossing a busy road. Doing that safely may look trivial to us adults, but it certainly was not when we had to learn it as a child. The hazard is very significant : one can get seriously injured or even killed when hit by a car. If you are a parent, you know that it takes long and careful explanation, teaching and demonstration of the proper road crossing techniques before you dare to let your child cross the road without your supervision. The child needs to learn :

• that getting hit by a car can get you killed or seriously injured
• the relevant traffic rules of road-crossing, traffic lights etc.
• that cars can come from any possible direction
• that one car can hide another car or a motorbike
• that drivers are not always disciplined and may break the rules
• to concentrate and not be diverted by play or daydreaming
• to constantly watch all the traffic while crossing
• etc...

This is complex, but you had no trouble learning it during your childhood (or, possibly, you wouldn't be reading this). Also note that we can normally detect these hazards by using our nature-given senses : sight, hearing, sense of heat, smell (how we avoid eating spoiled food) etc.

The key lessons from this are :

• our body is equipped to help us recognize these common hazards

• controlling common hazards is something we do all the time in our daily life. Every person of normal intelligence can learn how to do this. We can learn - and our parents knew how to teach us - how to recognize and control these hazards.

• we face and control hazards on a daily basis, it is a fact of life, and we shouldn't expect this not to be the case.

When we now apply a similar analysis to chemical hazards, we note that :

• in most cases, our body is NOT naturally equipped to recognize chemical hazards. After all, sulfuric acid looks like water. So does a deadly poisonous cyanide solution. And what happens when you mix these two is certainly something we don't expect instinctively (evolution of the extremely poisonous hydrogen cyanide gas)

• we normally do NOT learn how to recognize and manage chemical hazards in our childhood. Many parents wouldn't know how to do that either. Depending on your background, you may not have learned enough about it in school either.

So how do we overcome this knowledge and education gap? The answer is : BACK TO THE SCHOOL BENCH! OSH Training in other words.

Is this need for education anything to be worried about or should it put you off? No, not really. There is a lot to learn about chemical hazards and how to control them, and different jobs require different levels of knowledge. But everybody in a given job can certainly learn whatever he needs to know to do the job safely all his working life long, and be able to happily retire without having suffered any harm from the work he performed or the chemicals he worked with. That is, after all, one of the key objectives of OSH Management.