Carcinogenesis and carcinogens

Workers come in contact with a large number of chemical substances in work areas, as does the general public. The commonly found chemical carcinogens are grouped under (1) polycyclic aromatic hydrocarbons (PAHs), (2) nitroso compounds, (3) halogenated hydrocarbons (solvents e.g., carbon tetrachloride, chloroform, trichloroethylene, and methylene chloride), (4) inorganic metals and minerals (beryllium, cadmium, nickel, cobalt, chromium, asbestos and arsenic), and (5) naturally occurring chemical substances (aflatoxins). 

Halogenated hydrocarbons. Several of these compounds are commonly used as solvents. Examples include carbon tetrachloride, chloroform, trichloroethylene, and methylene chloride. 

Inorganic metals and minerals. Several carcinogens are known among metals or their salts. Examples of these include beryllium, cadmium, nickel. 

Cancer, in fact, has afflicted humans around the world and throughout recorded history. The origin of the word cancer is credited to the Greek physician Hippocrates (460-370 Bc), considered the father of medicine. Hippocrates used the terms car-cinos and carcinoma to describe non-ulcer-forming and ulcer-forming tumors. Bernardino Ramazzini, an Italian doctor, reported in 1713 the high incidence of breast cancer in nuns. Percival Pott of Saint Bartholomew s Hospital in London described in 1775 an occupational cancer in chimney sweeps, cancer of the scrotum, caused by soot collection under the scrotum of workers. 

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