Why should you take precautions when working with chemicals?

When working with reagents, one should proceed from the fact that any chemical substances, even the most “harmless” ones, are more or less poisonous. Especially dangerous is the systematic ingestion of even minute amounts of compounds into the body for a long time, which causes chronic poisoning. The severe consequences of chronic poisoning are aggravated by the fact that their symptoms at the first stage are not pronounced (general weakness, drowsiness, decreased performance, etc.) and do not cause particular alarm until further penetration of poisons into the body leads to serious intractable lesions.
Precautions must be taken to prevent the ingestion of chemical compounds on the skin, mouth, and respiratory tract.