Hair dyes are as common as lipstick, with nearly as many shades. But some researchers say these popular beauty products have an ugly flip side: They may cause cancer. The Medical Detective asked experts, �Should she, or shouldn�t she?� Read on to learn the truth about coloring hair, where the harshest chemicals lurk and how to tone down gray the healthy way...
Many women would rather face a root canal without Novocain than let their locks go gray.
�It�s important for my self-esteem,� says Gaynell Warcola, a 60-year-old Los Angeles social worker who�s been covering her gray for years. Her stylist touches up her brunette coif every 5-6 weeks.
�I don�t want to look like a skunk,� she says.
Nor do most women, who brave the possibility of cancer by frequently coloring their hair.
So, is all that dyeing� to die for?
It depends on the dye�s ingredients, how often you color and the hue you choose. Even your genetic composition makes a difference concerning toxicity, experts say.
The Medical Detective combed through published studies and talked to experts to untangle the truth about coloring hair. Here�s what we found.
Coloring Hair Risk #1: The Type of Dye
More than 5,000 chemicals are in hair dye, according to the National Cancer Institute.
In 2004, the Environmental Working Group (EWG), a nonprofit environmental research and advocacy agency, rated 117 personal-care hair dyes, and found about 80 had chemicals that might pose a cancer risk. Today the group rates 945 hair dyes for safety at the EWG website: http://www.ewg.org/skindeep/browse.php?
Here are some you�ll encounter in the four most common types of hair dyes:
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Permanent: These hair dyes, available in most major brands, including L�Oreal and Garnier Nutrisse, are used by about 80% of consumers. They cause lasting chemical changes in the hair shaft. Permanent dyes contain a cocktail of chemicals (the darker the hair dye, the higher the concentration that may cause cancer). Among them:
Para-phenylenediamine (PPD) creates dramatic color changes � going from blond to brunette, for example � but has caused cancer in animals, according to the Food and Drug Administration (FDA), which regulates some hair dyes. Women worried about hair dye�s cancer risk should �decrease their frequency of permanent hair dye use or use non-chemical-based or natural hair dye [without PPD],� advises Manuela Gago-Dominguez, M.D., Ph.D., assistant professor at the Keck School of Medicine and USC/Norris Comprehensive Cancer Center in Los Angeles.
Coal tar is a combination of chemicals that create longer-lasting colors than natural, vegetable dyes. It also caused cancer in laboratory animals, according to the FDA. Because of that, products with coal tar must include a warning saying some people may experience skin sensitivity; users should perform a skin test before use; they should follow instructions provided; and the product must not be used for dyeing eyelashes or eyebrows � to do so may cause blindness.
Hydrogen peroxide, a key ingredient in permanent dyes, removes your natural color and readies it for a new shade. Peroxide damages hair, and its sulfurous smell may cause eyes to sting.
Ammonia makes hair color last longer, but high exposure can irritate skin. Most more-expensive, at-home products, such as L�Oreal and Garnier, are ammonia-free.
Semi- and demi-permanent: These hair dyes add color but don�t lighten hair. Semi-permanent dyes last for about 6-12 shampoos; demi-permanent 24-26 shampoos. Both may contain some peroxide.
Temporary hair dye: Consisting of water, organic solvents and other agents, these cover the hair shaft but don�t penetrate it, according to the American Cancer Society (ACS). They come in rinses, gels and sprays and usually last 1-2 hair washings.
Natural hair dye: Henna � sold by Light Mountain, for example � is chemical-free and can last up to 6 weeks. It doesn�t do a great job of coloring gray, however, and needs to be refreshed every 2-4 weeks
Coloring Hair Risk #2: Frequency
The number of times you dye your hair may increase your cancer risk. Women who colored their hair with permanent dye at least once a month for a year or longer doubled their odds of developing bladder cancer over those who didn�t, according to a 2001 University of Southern California study.
The risk triples if you�ve used permanent dye for 15 years or more, and rises 50% if you�re a professional stylist or barber working with dyes for just a year. It�s five times as harmful for stylists with more than 10 years� exposure.
Bladder cancer isn�t the only illness to fear. Women who used dark permanent dyes and colored eight times a year or more for at least 25 years had double the risk of non-Hodgkin lymphoma (NHL), according to a four-year study published in 2004 in the American Journal of Epidemiology. Those who went blond showed no such risk increase.
Coloring Hair Risk #3: Your DNA
Your genetic makeup also may make you more susceptible to bladder cancer if you use permanent dyes, according to a 2011 study by the International Journal of Cancer.
The crucial factor was how fast women flushed out arylamines, which are derivatives of ammonia absorbed through the skin during the dyeing process. Permanent dyes contain more of the toxic compound than semi-permanent dyes, says Gago-Dominguez, a lead author of an earlier USC study with the same findings.
Researchers found one slow gene was associated with triple the risk of bladder cancer. There was a 6.8-fold risk increase for women with another type of slow gene.
Coloring Hair Risk #4: When You Started Dyeing
Started dyeing your hair before 1980? Then you have a 40% greater risk of Non-Hodgkin's lymphoma, according to a 2008 combined analysis of four case-control studies that included more than 4,000 women with NHL and about 5,800 women without the disease.
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