Scientists have found a link between regular use of hair dye and elevated risk of breast cancer in women.
While the finding seems rather odd, scientists at the Rutgers School of Public Health in Piscataway, New Jersey, say their findings show a link between the two and that people should be aware of the exposure when they use different products. The study of 4,285 African-American and white women was the first to find a significant increase in breast cancer risk among black women who used dark shades of hair dye and white women who used chemical relaxers.
The study included adult women from New York and New Jersey, surveyed from 2002 through 2008, who had been diagnosed with breast cancer, plus women of similar age and race but without a history of cancer. Women were asked if they had ever used permanent hair dye at least twice a year for at least a year. They were also asked if they had ever chemically relaxed or straightened their hair for at least a year.
While the vast majority – 88 percent – of blacks had used chemicals to relax their hair, only 5 percent of whites reported using relaxers. For dark hair dye, the numbers flipped, though the differences were not as dramatic. While 58 percent of whites said they regularly dyed their hair dark shades, only 30 percent of blacks did.
The most striking results showed increased risk in the minority of black women who used dark hair dye and white women who used chemical relaxers. Black women who used chemical straighteners and white women who used dark hair dyes were also at higher risk for breast cancer, but that might have been due to chance. James-Todd said that because so many of the black women used chemical relaxers and so many of the white women used dark hair dye, links would have been hard to detect.
Black women who reported using dark hair dye had a 51 percent increased risk of breast cancer compared to black women who did not, while white women who reported using chemical relaxers had a 74 percent increased risk of breast cancer, the study found.
The risk of breast cancer was even higher for white women who regularly dyed their hair dark shades and also used chemical relaxers, and it more than doubled for white dual users compared to white women who used neither dark dye nor chemical straighteners.
“A lot of people have asked me if I’m telling women not to dye their hair or not to use relaxers,” she said in a phone interview. “I’m not saying that. What I think is really important is we need to be more aware of the types of exposures in the products we use.”
There’s no reason to believe that chemical relaxers and hair dyes would increase the risk for women of one race and not of another, she said. She believes the association stems not from genetics but from cultural norms. It could also boil down to products, and women from different cultures might use different straighteners and dyes. But the study did not ask women to specify the products they used.