Reprinted from the ACJ - October, 1994
If you recall last month's article (me neither, but humor me), we spoke of the types of damage that explosives, flammables, corrosives, etc. inflict upon our poor bodies. We spoke of "point of contact" concerns, chemicals which cause their damage at the site where they are exposed. My analogy was that of car bombs, forest fires and that nasty flesh-eating virus. All are incidents that leave a visible, tangible scar wherever they touch (also, a somewhat sick feeling among readers of the article).
Now let us get a little more obscure. Consider the internal, psychological angst felt by the people of Northern Ireland. The deep fear mothers have about letting their children out of their sight after watching all the horror stories of abduction highlighted on the evening news, or the state of irrational panic fire can cause in the victim of a past house fire. All of these injuries were caused by specific incidents, but the damage manifests itself in indirect ways. Such is the circumstance with toxic materials.
Toxins are defined as hazards which cause an adverse reaction away from the contact site. If you breathe small amounts of lead dust and/or fumes over time, then your kidneys, nerves or blood may show signs of damage. But why? It is due to the ability of our bodies to manipulate and be manipulated by thousands of different chemicals. With lead, your lungs may not show signs of damage (site of contact) but the lead molecules react nicely with your blood cells, displacing iron and causing anemia. As the lead is filtered out of your system, it can also cause excessive wear and tear on your kidneys. Thus lead is considered a toxin. It causes its damage away from the exposure site.
Because of the unlimited types of reactions and chemicals coursing within our bodies, this idea of toxicity is not clear-cut. Some substances are beneficial to our systems until they accumulate or we intake a dose that overwhelms the body. Salt is one example. A little is necessary to support life, but if a 200-pound man were to consume a half pound of salt at a sitting he would most likely die of salt poisoning. But looking at the bright side, he would also keep well without refrigeration, like beef jerky.
This two-sided blade of helpful/harmful for a single substance is categorized by a ratio of how much is harmful to how much is helpful. This number is called the Therapeutic Index. The larger the Therapeutic Index number, the wider the safety margin between the amount that helps and the amount that harms. You know, that might not be a bad way of rating employees and coworkers. The point is, we shouldn't fear chemicals just because they are chemicals. It would be far more beneficial to understand their potential hazards and dangers and conduct our actions accordingly for safe handling.
This would probably be a good time to discuss toxin vs. hazard. Toxicity is defined as an amount of the substance that is dangerous. A hazard is defined not only by the substance involved, but by how it is handled. A substance can be toxic, but not necessarily a hazard.
For example, the ethanol in a bottle of vodka is toxic. But the vodka is not hazardous if sealed and locked in a safe. But open it up, set it next to a tumbler full of ice and a bowl of pretzels, and now it's a hazard. So it is obvious that our actions when dealing with toxic substances control the hazard to which we are exposed. If we wear gloves, goggles, respirators, etc. when the toxicity and manner of use require it, we are behaving in such a manner as to minimize the hazard.
The toxicity of a given substance is based on its ability to affect an organ system in our bodies, like the liver, kidneys or nerves. It also may be based on its ability to disrupt a bodily process such as blood clotting or reproduction. Both of these types of effects are away from the point of contact. Because of these remote effects it would be easy to downplay the seriousness of toxicity. If you don't get a burn, it must not be corrosive. If you don't get immediately sick, it must not be harmful. Out of sight, out of mind.
But we know better. We know that if we control every and all chances for exposure, we will eliminate the toxic effects on our body. So we wear our dust masks, respirators, gloves and goggles as well as any other personal safety equipment necessary whenever exposure to a toxic chemical is possible. Letting it go for even just one quick job shouldn't be tolerated. The toxic effect may be immediate (acute), such as nerve paralysis due to inhalation of certain pesticides. Or the effect may develop over the long term like cirrhosis of the liver due to extended (chronic) abuse of alcohol and other drugs. Remember the slogan we have used in the past: Control the acute exposures and you automatically control the chronic hazards.
One last point to make is that a given substance can be several of the hazards we have discussed. A compressed gas can be both an explosion hazard and flammable. A corrosive compound that causes a burn may also cause organ damage of some kind as it travels through your body.
Keep these things in mind, and always know the toxicity and the hazard of what you are working with. The MSDS is an excellent source of information on this subject. Then protect yourself with equipment and conduct your actions in a safe manner. That way your psychiatrist won't find any deep emotional scarring hidden in your psyche due to a long past bad shop experience involving tainted antifreeze or a pair of defective pliers.
The above article was written by David M. Brown, Chief Engineer of Johnson Manufacturing Company, Inc. and is published by JOHNSON with the expressed approval of the National Automotive Radiator Service Association and the Automotive Cooling Journal. Other reproduction or distribution of this information is forbidden without the written consent of JOHNSON and NARSA/ACJ. All rights reserved.
JOHNSON MANUFACTURING COMPANY
114 Lost Grove Road / PO Box 96 / Princeton, Iowa 52768-0096
Phone 563-289-5123 or Fax 563-289-3825