April 4, 2000 (San Francisco) -- In Los Angeles County -- a place where "the natural look" often means a good dye job from a Beverly Hills salon -- as many as 19% of the cases of bladder cancer in women could be linked to the use of permanent hair dyes, cancer researchers say.
Researcher Manuela Gago-Dominguez, MD, PhD, tells WebMD that the risk is greatest among women who "use the dye 12 or more times a year for 15 years or longer." She says that women who dye their hair at that rate are almost three times more likely to get bladder cancer than those who don't dye their hair or dye it less frequently.
But this increased risk is not as great as that associated with smoking. A 40-year-old woman who smokes is five times more likely to be diagnosed with bladder cancer than a non-smoking woman of the same age, says Gago-Dominguez, who is with the Norris Cancer Center at the University of Southern California.
Hairdressers and barbers have an even greater risk, Gago-Dominguez says, and "the occupational risk is the same for men and women. Persons who worked 10 or more years as hairdressers or barbers were five times more likely to be diagnosed with bladder cancer." That occupational risk has been reported in previous studies, but Gago-Dominguez says her study is the first to link "the personal use of hair dye by women to bladder cancer risk."
Gago-Dominguez and other researchers compared use of hair dye among 203 bladder cancer patients and 203 healthy women of the same age. A total of 124 of the women with bladder cancer said they used hair dye, and 92 of them used permanent dye. That compares with 111 healthy women who used dye, with 66 using permanent dyes.
Earlier studies, she says, found no increased risk associated with personal use of hair dye. "But those studies failed to discriminate among the different types of dye," she says. "The risk is only seen in persons who use permanent dyes." Permanent dyes have many chemicals that are considered cancer-causing, she says, and some of these dyes have been shown to cause genetic changes in lab experiments.
Susan S. Devesa, PhD, an epidemiologist with the National Cancer Institute, tells WebMD that Gago-Dominguez's study is interesting but that it needs to be put in context. First, she says, women have a low risk of bladder cancer. The American Cancer Society reports that while there are almost 40,000 new cases of bladder cancer each year, only 15,100 of those are in women, she says. So while the possibility of an increased risk should not be ignored, such a risk can "only represent a small number of cases."
"And I think we need to consider that the use of hair dye has been increasing since the beginning of the last century, but there has not been a concordant increase in bladder cancer," Devesa says.
Gago-Dominguez says that more studies are needed to confirm her findings. But she says that women who use permanent hair dye might want to think about switching to a semi-permanent dye.