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Hair dye linked to rheumatoid arthritis
16:10 17 September 01

http://www.newscientist.com/news/news.jsp?id=ns99991306

Women who dye their hair for 20 years or more have almost double the risk of developing rheumatoid arthritis, say Swedish researchers. However, the cause of the increased risk is unclear.

Rheumatoid arthritis is an autoimmune disease, caused when immune cells attack the body's own tissue. Para-phenylenediamine, a key ingredient of many hair dyes, is known to trigger allergic skin rashes in some people.

However the immune system cells that are over-activated in rheumatoid arthritis are not the same as those that are over-activated during an allergic response, points out Deborah Symmons, professor of rheumatology at Manchester University, UK.

The team at Linkoping University, Sweden, suspect that chemicals in hair dyes somehow damage the immune system, triggering the onset of rheumatoid arthritis.

"But they have grouped together hair dye and bleach," says Symmons. "It could be that the peroxide might somehow be more important than constituents of the dyes."

Bladder cancer
 

Permanent hair dyes have previously been linked to increased risks of disease. Earlier in 2001, researchers at the University of Southern California found that women who used permanent dyes could double or treble their risk of developing bladder cancer. Women who coloured their hair every month for 15 years were exposed to the greatest increase in risk.

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The Swedish team based their research on data from 422 people with rheumatoid arthritis who were seen at the university hospital between 1980 and 1995.

Their research also revealed that exposure to household mould significantly increased the risk of rheumatoid arthritis in men. In addition, they found that women with shorter "fertile periods" between periods were more likely to develop the disease.

"That's interesting," says Symmons. "There's a lot of evidence that oral contraceptives protect women against developing rheumatoid arthritis. The shorter the fertile period, the less time the women would be exposed to higher levels of oestrogen."

Journal reference: Annals of the Rheumatic Diseases (vol 60, p 934)

Emma Young

http://www.newscientist.com/news/news.jsp?id=ns99991306