Chapter 4 - Hazard awareness

Abstract

A person working in the chemical laboratory and dealing with hazardous chemicals should completely understand their physical and chemical properties. Gas cylinders, explosive chemicals, reactive chemicals, flammable chemicals, oxidizing chemicals, corrosive chemicals, organic peroxides, cryogenic liquids, and dry ice are classified as hazardous chemicals. Various chemicals are classified as carcinogens, toxins, teratogens, mutagens, autotoxins, sensitizers, etc. based on their potential hazardous effects on organism and environment. The extent and type of toxic effect depend upon the exposure conditions and the individual exposed to chemicals. The rate of absorption of a chemical through body depends upon its chemical and physical properties. Once the chemical gets absorbed in the body, its physical and chemical characteristics will affect whether it would produce systemic effect, metabolized by enzymes to any further toxic metabolite, stored in the body, or excreted. Physical properties of chemical such as physical state (solid, liquid, or gas) or particle size affects its absorption. Gas particles usually get absorbed through inhalation, while solids and liquids get absorbed via ingestion or absorption through eyes or skin. Smaller size particles would deposit in the lungs. Chemical properties including water and lipid solubility and pH also affect absorption. If a chemical is primarily lipid soluble, it can easily cross the biological membranes and gets absorbed, while if it is water soluble, it can easily be absorbed in the lungs. pH also affects absorption. If a strong acid or base is inhaled, ingested, or applied locally, it will not get absorbed in the blood but rather produce a local effect.