This month's column concludes a short refresher about industrial hygiene in critical cleaning. We have covered how the human body protects itself even if we don't protect ourselves. This material covers how chemicals used in cleaning, and other operations, can harm various organs in our bodies. It is a reminder of why we take the actions that we do.

Some chemical vapors, after being inhaled, are absorbed into the blood via the lungs. The absorbed chemical is then transported to the heart and other organs, stimulating the heart to abnormal activity levels in an effect termed cardiac sensitization—a condition so serious that there's an ASTM test for it.

Halogenated alkanes (trichloroethylene, fluorocarbons, 1,1,l-trichloroethane, perchloroethylene, and others) cause cardiac arrhythmia (an alteration in rhythm of the heartbeat either in time or force) and sudden death by altering cardiac sensitivity to endogenous catecholamines (drugs synthesized in the body that are released upon sympathetic nervous system activation). Sudden death has been reported from inhaling typewriter correction fluid containing 1,1,1-trichloroethane.

Benzene and chlorinated hydrocarbons may cause aplastic anemia, leukemia, and other similar disorders that prevent bone marrow from producing in all three types of blood cells if absorbed into the blood.
The liver stores vitamins and iron, regulates blood sugar levels, plays a vital role in digestion, and metabolizes foreign chemicals. Metabolism sometimes results in a chemical being changed into a more toxic material. This is one way in which chemicals can damage the liver.

As with other organs, liver toxins can be grouped together according to the kind of liver disease they cause, including acute hepatitis (inflammation of the liver) or chronic diseases such as cirrhosis and cancer. These diseases can also be caused by viruses such as hepatitis B. Chemicals that cause acute hepatitis include carbon tetrachloride, chloroform, dinitrophenol, dinitrobenzene, dioxin, polychlorobiphenyls, the pesticide DDT, chlorobenzenes, the anaesthetic halothane, the dye feedstock methylenedianiline, and the explosive TNT.