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As well as storing vitamins and iron, regulating blood sugar levels and its role in digestion, the liver metabolises foreign chemicals. Metabolism sometimes results in a chemical being changed into a more toxic metabolite, and 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 like cirrhosis and cancer. These diseases can also be caused by viruses such as hepatitis B, an important risk for health care workers, as well as non-occupational factors.

Chemicals that cause acute hepatitis include carbon tetrachloride, chloroform, dinitrophenol, dinitrobenzene, dioxin, polychlorobiphenyls, the pesticide DDT, chlordecone, chlorobenzenes, the anaesthetic halothane, the dye feedstock methylenedianiline and the explosive TNT. Symptoms of acute hepatitis include headache, nausea, vomiting, dizziness and drowsiness.

As well as alcohol, cirrhosis is also caused by arsenic and vinyl chloride. Vinyl chloride is well known for causing liver angiosarcoma, a rare kind of cancer. After clusters of cases were reported in the 1970s, studies were done in vinyl chloride plants which found high levels of this liver cancer. Vinyl chloride is metabolised in the liver to an epoxide that causes the cancer. As well as a Maximum Exposure Limit, a yearly exposure limit of 3 ppm applies to exposed workers.

High levels of chronic liver disease have been reported in refrigeration engineers, chemists, dry cleaners, rubber manufacturers, and workers exposed to carbon tetrachloride and plutonium (Levy and Wegman).

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