The process of dyeing hair at home is so familiar that we don’t even look at the instructions. We
assume we know everything about hair colors, because our grandmother, and mother, and sister, and
celebrity stylist—everybody—is doing it, so we guess it’s just fine. It’s not.
How does chemical hair color work? First of all, we have to blend a tube of coloring solution with
a mixture of hydrogen peroxide and ammonia. Most permanent hair colors first remove the original
color of the hair and then deposit a new color. Ammonia opens the hair cuticle to allow for the
penetration of hydrogen peroxide, and it also increases the penetration of this potent bleach. No
matter which shade you choose, a dark mahogany or light ash blond, every time you color your hair,
hydrogen peroxide removes the original color and then the new color is deposited. Peroxide breaks
chemical bonds in hair, releasing sulfur. When the color is gone, a new permanent color is injected
into the hair shaft. After we have washed off the excess color, we use a silicone-based conditioner to
close and seal the cuticle.
Here’s what is happening to our body as we apply the hair color. Hydrogen peroxide, sulfur, and
ammonia, well-known respiratory tract irritants, fill our lungs. Pigment-forming chemicals, known as
aromatic amines, particularly phenylenediamines and aminophenols, are known to penetrate the skin
and enter the bloodstream. We usually apply the coloring solution directly to the scalp, nearest the
root, and most of us also stain our forehead, neck, and ears. The scalp is where the blood supply is
the richest in the entire human body. This rich blood supply carries carcinogenic components right
into the bloodstream, spreading them across the body, accumulating toxins in lymph tissue, and
dumping them into the bladder.
No wonder bladder cancer, non-Hodgkin’s lymphoma, and bone marrow cancers have a higher
incidence in hair care professionals who work with hair dyes daily for long periods of time (Bolt,
Golka 2007). In 2008, scientists of Yale University, reporting in the American Journal of
Epidemiology, observed that “increased risk of non-Hodgkins lymphoma associated with hair-dye
use was observed among women who began using hair dye before 1980” (Zhang et al. 2008). In
1995, the European Journal of Cancer Prevention found that hairstylists and colorists also have a
higher risk of developing breast cancer (LaVecchia, Tavani 1995). But, while hairstylists are usually
exposed to the fumes of hair dyes (mind you, they are wearing gloves!), the carcinogenic cocktail of
chemicals is applied directly to our skin, exposing us to significantly higher amounts of toxins. In one
study, the risk increased with more prolonged exposure to darker, more concentrated, permanent dyes
(Miligi et al. 2005).
Many experts still prefer to insist that hair dyes may not be harmful at all. Most often, these experts
have strong ties to the cosmetic industry or perform research that was paid for by cosmetic
corporations. For example, in 2008, an industrial consultancy firm Exponent performed a study of
studies on hair dyes and made a verdict that hair dyes are safe: “No association was found between
any personal use of hair dye and bladder cancer among women” (Kelsh et al. 2008). To achieve these
conclusions, scientists “compared, updated, and expanded the analyses of two previous meta-
analyses” on hair dyes. No independent, scientifically sound research was done to support the
optimism about hair dyes.
Writing about hair dyes is very painful for me. My mother continues dyeing her hair every two
weeks despite all my pleas to stop or at least to switch to safer, less chemical dyes. Until five years
ago, I couldn’t be without the darkest brown dyed hair, heavily styled with petrochemically laden
foams and sprays. So instead of crying wolf, let’s see what real science has said recently about the
troubling relationship between hair dyes and cancer.