Myeloma and Hair Dyes #1

There's no strong link between the use of permanent hair dyes and an increased risk of cancer, says a major study to be published today in the prestigious Journal of the American Medical Association.

The authors, including Canadian pharmacy researcher Mahyar Etminan, undertook what is called a meta-analysis. Rather than do a new trial, they systematically searched the scientific literature for studies on possible links between hair dye and cancer, pooling data from 79 studies published between 1966 and January of this year.

The studies looked at risks for people who have their hair dyed, but not the professionals who did the dying. The same research team plans to conduct a future meta-analysis to see if people working in hair salons are at greater risk of developing cancers than their clients.

They concluded that "globally, there is no effect of personal hair dye use on the risk of breast and bladder cancer."

There was a "borderline" effect for the hematopoietic cancers or blood cancers such as multiple myeloma and leukemia.

"However, the evidence of a causal link effect is too weak to represent a major public health concern," the study concluded.

There was also a borderline effect for brain tumours and ovarian cancer, but the results were based on only two studies for each type of cancer. The researchers urged more study in these areas.

Some previous studies have found increased cancer risk related to permanent dyes, especially darker colours.

"An association between hair dyes and cancer would be an important public health concern since about one-third of women in Europe and North America, along with 10 per cent of men older than 40 years, use some type of hair dye. Permanent dyes, the most aggressive type, represent 70 per cent of the market share -- even more in Asia," said the study.

So far, research into the risks posed by hair dyes has been inconclusive, said Heather Logan, director of cancer control policy for the Canadian Cancer Society.

"This study is valuable because it looks at a large number of studies, she said. "Certainly, this is very reassuring."

© The Edmonton Journal 2005