At the Juan Juan beauty salon in Beverly Hills, colorist Jennifer Jahanbigloo had to calm a client who phoned the other day "in a panic" about reports of a possible link between permanent hair dyes and bladder cancer. She advised the woman to check with her doctor.
At other hair salons, clients have been asking about the newest study but haven't been deterred from coming in for their usual color treatment. As Jahanbigloo puts it, "We live in a vain city."
The study in question, published in a medical journal earlier this month, suggested that using permanent hair dyes for long periods could significantly increase the risk of developing bladder cancer. The risk was greatest for hairdressers and others who use the dye in their work, the study found.
While that sounds a bit alarming, experts point out that the study's findings suggest a relationship, but do not establish absolutely that permanent dyes are causing bladder cancer. And even though the study found the risk to be elevated, experts point out that bladder cancer accounts for about 2% of cancers in women and 6% of cancers in men. That's something for women to keep in mind before they toss their at-home coloring kits or cancel their salon appointments.
Moreover, some prior studies have not found any link between the dyes and bladder cancer.
"We're the first to say these [results] need to be confirmed with other studies," said Dr. Manuela Gago-Dominguez, principal author of the study that appeared in the International Journal of Cancer's February issue. "We don't have the precise information to make recommendations."
The chance of developing bladder cancer, which will strike an estimated 54,300 Americans this year, is fairly low and most heavily linked to smoking, although occupational exposure to chemicals also is a factor. So in assessing potential risk for the average healthy nonsmoker, "if you start out low and multiply that by two or three, you're still low," said Dr. Mimi C. Yu, a study co-author.
The team of preventive medicine researchers at USC's Keck School of Medicine found that women who used permanent hair dyes at least once a month for a year or more experienced about double the bladder cancer risk of nonusers. Those who used the dyes for more than 15 years tripled their risk. Hairdressers and barbers with more than 10 years of experience quintupled their risk. (Previous studies have also found elevated bladder cancer risk among barbers and hairdressers, although researchers still haven't nailed down the reason. Scientists do know that the skin absorbs some of the chemicals, which eventually pass through the bladder before being eliminated in urine.)
The statistical association between permanent dyes and the cancer was drawn from bladder cancer patients' recollections about using all types of hair dyes--permanent, semi-permanent and temporary rinses, and from comparisons with healthy subjects. The findings did not implicate the semi-permanent and temporary formulas, which rinse out with repeated shampooing.
Stirring up worries was never the intent of the study, originally designed to look at bladder cancer risks, says Yu.
"I would not advocate going out there with a public message and telling all these women to go gray," Yu said. "We certainly do not have the hard evidence to back up such advice."
Even though the study only suggested a relationship with permanent dyes, Yu said she's not comfortable proclaiming semi-permanent dyes completely safe. They contain the same chemicals, just in lower concentrations.
Hair dyes contain arylamines--a generic term that covers thousands of chemical complexes--that can't be deciphered from labels. They're found in permanent and semi-permanent products and their derivatives are in temporary rinses. Basically, the darker the shade, the greater the concentration of the chemicals.
Although the USC study found an association with bladder cancer, some other large studies of permanent hair dyes have not, said Dr. Michael Thun, head of epidemiology research for the American Cancer Society in Atlanta. Among them is an epidemiologic study released in February 1994 by the FDA and the American Cancer Society involving 573,000 women. It found no link between the use of permanent hair dye and death from bladder cancer. The USC study, in contrast, looked more broadly at bladder cancer cases, not just the 20% or so that result in death.
Said Thun: "I think the overall evidence suggests that if there is a risk from hair dyes, it's exceedingly small, so on one's list of things to worry about, this should be low."