Sunday, December 14, 2008


27. Toxicity

*Early in any teaching situation, and absolutely before teaching my students about glazing, I give them a version of the following talk about toxicity.

There’s a lot of concern in our culture today about toxicity, about what’s toxic and what’s not, and about being safe. This can be particularly important for potters since we work with so many chemicals and we tend to have a lot of dust in our studios.
To begin, I want to talk about the dangers of distilled water. If you breathe in too much distilled water (and I don’t know just how many ounces that is) you’ll die. We call that, “drowning.” You can also kill yourself with water just by drinking it. In this case, the lethal dose is something over three gallons, and we know this because some poor eating disordered woman in Florida ran the experiment on herself. Apparently all that extra water so messed up the chemistry of her blood that her cells just couldn’t function properly. I don’t know how long your skin has to be wet for the effects to be ‘toxic’ but I once fell asleep in a bath and it hurt like hell when I woke up and toweled off.
The point is, for a chemical to hurt you it must get into your body, either through the lungs (inhalation), through the stomach (ingestion), or through the skin (contact). Further, dosage matters. There is no particle of plutonium so small that once lodged in your lungs it will fail to kill you. You may not die right away but your fatal cancer is inevitable. We can call that, “most toxic.” On the other hand, the Dutch chemist who discovered cyanide learned what it could do by picking up a little on his little finger and tasting it. He woke up on his floor twelve hours later. He was lucky. He had a ‘sub-lethal’ dose.
When scientists test the toxicity of a substance on animals they come up with something called, “LD 50.” This is the dosage level that killed 50% of the test animals.
One of the problems with most toxicity warnings you encounter is that they don’t generally tell you the warning signs of a sub-lethal exposure level. Barium Carbonate, for instance, is a classically “toxic” ingredient used (less and less often) in some matte glazes. I’ve seen the ‘toxic’ amount shown next to a dime for scale. But you may have to do some research to find out that it interferes with nerve function and that headaches and tremors are your warning symptoms.
Some partial exposures are more dangerous than others, too, because of what it takes for your body to remove the toxin. Some toxins your body simply can not remove. Any further exposure you permit is simply added to the dosage already in your system until, of course, your total dosage becomes too high to bear.
So, what can you do?
First, don’t be stupid. Everything is toxic, it’s just a matter of dosage and exposure. The lungs are the most vulnerable, followed by the digestive system, followed by the skin. So, don’t breathe the dirt, don’t eat the dirt, don’t get the dirt on your skin (or let it stay there) unnecessarily. Wear dust masks (or better) in dusty situations (mixing clay, mixing glazes, or sweeping up) or when spraying glazes. Do what you can to minimize your dusty situations. The books all recommend wet mopping your workspace regularly. No one ever does it, but maybe you could start a trend. Don’t breathe the dirt!
Second, absolutely no food or drink in a glazing area. You shouldn’t have food or drink in a clay studio at all, but that’s probably unrealistic. One tip; just eat it or drink it and be done. Don’t let time conspire to add undesirable elements to your lunch. Do not put food and drink where foreign elements can fall into them. Further, do not put food or drink where they can fall into other things. Nothing in your studio will be improved by having food bits rotting in them. Don’t eat the dirt!
Third, wash your hands a lot. Even just regular old “non-toxic” clay will dry out your skin. My first semester in clay my sub-lethal contact exposure symptoms included knuckles so badly chapped they bled. Use lotion. Use gloves where that seems appropriate. Skin is great stuff, but you have to take care of it. Don’t be stupid.
So, I don’t want to hear a lot of questions about, “Is this toxic?” Of course it’s toxic, but the things that are toxic in small amounts are labeled, “TOXIC.” Read the labels, read the books, and don’t eat the dirt. Keep a clean studio. Wear dust masks when doing dusty jobs and use ventilation systems. Wash your hands and use lotion. Protect yourself and protect each other by establishing good habits and good studio hygiene.

No comments: