Medical Health Encyclopedia

It is still not clear why the immune system responds abnormally. Some experts believe that environmental factors, such as a virus or chemical, may trigger the response in individuals with genetically abnormal immune systems.

Oxygen-Free Radicals and Abnormal Metal Accumulation. Another focus for researchers involves an observation that in scleroderma, as blood vessels narrow and become inflamed, destructive particles known as oxygen-free radicals are produced. Oxygen free radicals are unstable molecules produced by the natural chemical processes in the body. They cause harm in the following way:

• Because oxidants are missing an electron, they tend to bind with other molecules in the body.
• Environmental toxins, infections, and other factors may produce excessive amounts of these oxygen free radicals.
• In such cases, overproduction can set off a chemical chain reaction that damages any type of cell in the body, including nerve cells in the brain, and even interferes with their DNA.

Researchers have detected abnormal molecules in these damaged cells that appear to occur only with abnormally high levels of certain metals, particularly zinc, iron, and copper. Researchers postulate that these defective molecules may be the antigens targeted by some of the autoantibodies that trigger the development of scleroderma.

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Chemicals. Occupational exposure to certain chemicals can cause blood vessel constriction and Raynaud's phenomena. Although some cases of actual scleroderma are believed to be occupationally induced, no specific factors have been proven to cause the disorder itself. Industrial and pharmaceutical chemicals being investigated include the following:

• Silica. Silicone is derived from silica. Silicone breast implants have been under intense scrutiny as a possible trigger of autoimmune diseases, including scleroderma. Evidence to date is inconclusive about breast implants, although silica dust in stone quarries or other settings is associated with a high risk of scleroderma in workers.
• Plastic materials such as epoxy resins and vinyl chloride.
• Detergents.
• Herbicides.
• Organic solvents such as trichloroethane, benzene, and carbon tetrachloride.
• Various drugs such as bleomycin, amphetamine, cocaine, amfepramone, docetaxel, pentazocine, and penicillamine.
• Asbestos.