Are there scary things in your school this Halloween? October 29 2014, 0 Comments

Halloween has been turned into a time for scary things, although I much prefer celebrating the harvest and honoring the dead. There is one scary thing that could be hiding in your school, however, and so I recommend that you check to see if it is present. The scary thing is hazardous chemicals.

When the original experiments for the Great Lessons were created, the awareness of health risk from chemical exposure had not yet come about. Even when I was in high school (OK, so that was more than 4 decades ago), we observed evaporation with the chemical benzene, which is now known to be a potent carcinogen. Chemists knew that benzene was hazardous, but that information had not trickled down to schools.

The experiments for the Great Lessons originally had colorful compounds such as potassium dichromate, which now has a health hazard rating of 4, the highest risk level. This is because of the chromium-containing ion is highly carcinogenic. It is also corrosive to skin and eyes, and a cause of dermatitis and genetic damage. The hexavalent chromium ion is to blame. This is also present in the ammonium dichromate volcano demonstration. Lead salts were another ingredient for colorful demonstrations. They are too toxic to be in a school setting. Disposing of these chemicals can contaminate water and harm wildlife.

You may have switched to safer chemicals years ago, but are any of those old scary compounds still hiding in a box or cabinet somewhere in your school? Now is a great time to look carefully, and if you find dangerous chemicals, call your hazardous waste disposal facility or your county public health department and get that scary stuff out of your school.

If you find a compound and don’t know if it is dangerous, do an Internet search with the name of the chemical and “MSDS” which stands for material safety data sheet. The MSDS has the information you need for working with the chemical and disposing of it safely.

Note: I have heard it argued that lead compounds and dichromates were necessary to inspire children and that those chemicals can be handled safely in a school. I do not accept either of these ideas. Children are inspired by stories, not by specific chemicals. All sorts of reactions can be modeled with a variety of safe compounds. Greg MacDonald of the Hershey Training Institute has written a set of experiments with safe substances. You can reach him at

Meanwhile, I wish you Happy Halloween and experiments that are safe and inspiring.