Solvents include aliphatic and aromatic hydrocarbons, alcohols, aldehydes, ketones, chlorinated hydrocarbons and carbon disulphide. The vapours of organic solvents may be toxic. Occupational exposure can occur in many different processes, such as the decreasing of metals in the machine industry, the extraction of fats or oil in the chemical or food industry, in dry-cleaning, in painting, in the plastics industry, and in the viscose-rayon industry. Solvent vapours enter the body mainly by inhalation, although some skin absorption may occur. The vapours are absorbed from the lungs into the blood, and are distributed mainly to tissues with a high content of fat and lipids, such as the central nervous system, liver, and bone marrow. Most solvent vapours have an anaesthetic effect on the central nervous system. Some solvents may, in addition, cause damage to the liver and kidneys (carbon tetrachloride) or to the blood-forming organs (benzene), or contribute to early atherosclerosis.
The action on the central nervous system causes nervous symptoms, such as fatigue, headache and vertigo. Unconsciousness and death may result from short-term exposure to high concentrations. Toxicity to the liver and kidneys may cause jaundice and uraemia. Prolonged exposure to benzene may cause leukaemia and anaemia. Carbon disulphide may contribute to a high incidence of atherosclerosis and possibly to ischaemic heart disease; and may also cause severe nervous symptoms, including psychoses.
A group of 70 Scottish women claim they have developed cancers and serious reproductive illnesses after working at a microchip manufacturer. It was reported in 1999 that they are seeking millions of dollars in compensation. Chemicals, gases, and acids used in the production process of microchips are being blamed for their damaged health.