As more Americans color their hair, some wonder if they're sacrificing safety for vanity.
A new study offers comforting news for dye-hards. Elizabeth Holly, a researcher at the University of California at San Francisco, found hair color wasn't a factor in non-Hodgkins' lymphoma. The immune system cancer has been rising world-wide, and previous studies had suggested a link to dye use.
Dr. Holly's eight-year survey of 4,108 people found 56% of female patients and 56% of healthy volunteers colored their hair. Among men, 10% of patients and 9% of the control group used dye.
Retrospective case-control studies like this are open to questions of recall bias. Sick patients searching for a cause of their illness may recall product use better than controls, magnifying the appearance of risk. But here, dye usage was virtually identical in both groups. "It's quite reassuring," Dr. Holly says. "There's little convincing evidence of increased risk with normal use of hair-color products."
Despite no overall color-cancer link, there was one "little glitch" in that some men using semipermanent color showed slightly higher cancer incidence. But this finding wasn't consistent, she says, suggesting it was due to chance. The study, supported by a grant from the National Cancer Institute, is to be published Tuesday in the American Journal of Public Health.
ABOUT HALF OF all American women now color their hair, along with 10% to 12% of men, according to Bristol-Myers Squibb's Clairol unit in Stamford, Conn.
Manhattan stylist Frederic Fekkai says the trend is toward "more men -- it's amazing," he says. Executives increasingly use hair color as part of their image maintenance, he adds, though most still keep it under wraps.
At Mister Lee, a San Francisco salon, Robert Ross, a 43-year-old Marin County home builder, highlights his brown locks "just for fun." As for product safety, he says he faces far greater chemical exposures working at construction sites than perking up his palette in the salon.
But the specter of cancer has periodically resurfaced since the discovery in the 1970s that certain ingredients in hair dyes -- chemicals called aromatic amines and nitro compounds -- could cause cancer or mutations in lab animals fed large amounts.
These findings sparked two decades of human research. While some small studies found increased tumor incidence, the largest prospective research has failed to find clear causal relationships between hair color and cancer.
At Harvard University and Brigham and Women's Hospital in Boston, Charles Hennekens and his colleagues followed the health of 99,000 women in their Nurses Health Study, finding "no evidence of a positive association" between permanent hair dye and cancers such as leukemia, lymphoma or myeloma, which affects bone marrow.
In Atlanta, Michael Thun of the American Cancer Society, did a prospective study of over half a million women, finding no overall increase in risk of cancer among those who colored their hair. One shadow lurked among the cheerful data: women who had used black hair dye for 20 years had a small increase in lymphoma and myeloma. This fraction -- under 1% of dye users -- is being further scrutinized in studies due out next summer.
"If this relationship exists, it's a weak relationship," Dr. Thun says. For those trying to cut their risk of cancer, he suggests, "There are far more important things to worry about," such as smoking, which multiplies lung cancer risk 23-fold in men, and 12-fold in women.
"The totality of the evidence is much more reassuring than alarming," says Dr. Hennekens. Lab studies that indicted dyes featured animals who were tube-fed massive doses of dye, he notes, not the cosmetic-color exposure for humans.
AT THE National Cancer Institute, Sheila Zahm, director of cancer epidemiology, continues to investigate risks of dark-colored dyes. However, she said Dr. Holly's report is a "fine ... well-conducted study."
In 1980, under orders to affix a cancer warning to their dyes, hair-color manufacturers purged the carcinogen 4-MMPD from their product lines. "It just wasn't smart business to have properties that were alarming, even if the systemic exposure was very small," says John Corbett, a consultant to the Cosmetic Toiletry and Fragrance Association, a Washington-based trade group.
Today, industry giant Clairol has an "extensive safety program" and uses no carcinogens, says Sharma Raj, research director at Bristol-Myers Squibb Worldwide Beauty Care.
However, Drs. Thun and Zahm worry a quirk in the law hamstrings regulatory control of hair color. Currently, hair dyes fall under a 1938 "coal-tar exemption" in the Food, Drug and Cosmetic Act. This Depression-era provision, named for a dye source now supplanted by petrochemicals, basically exempts hair dyes from the certification process required of other cosmetic colors. It only requires the dyes to carry warnings of skin irritation or eye injury.
"Science changes, but the coal-tar exemption still exists," says FDA compliance officer Allen Halper. If fresh evidence of cancer-causing ingredients arose, he says, the law "could theoretically hamper the agency from taking action."
So while new studies suggest it is safe to go back to the salon, public health would be served by giving an old statute a makeover.
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