Some of us were born with beautiful locks, and some of us attain them through socially acceptable but drastic means. Believe me, I am not passing judgment here. I belong to the latter group. Perhaps knowing there are so many of “my kind” inhabiting the planet makes it easier to reconcile. But are the chemicals we bathe our tresses in exposing us—perhaps unnecessarily—to cancer?
For those of us who choose to alter our hair color for whatever reason (and we all have our own) it’s important to know about our choices. The news isn’t all bad. But to be upfront, some of that is simply because there hasn’t been enough of us using the chemicals in today’s hair dyes for long enough to know for certain if they cause cancer. Time will tell. In the mean time, here’s the scoop about hair dyes and some recommendations for people who are concerned about safety.
For starters, let’s classify modern hair dyes as permanent (the most popular variety because the color lasts until it is replaced by new growth) semi-permanent (the type that generally last for 5-10 washings), and temporary(lasting 1-2 washes).
Concern about cancer risk is largely limited to the semi-permanent dyes and permanent dyes. The darker dyes have higher concentrations of some potential cancer-causing chemicals so these products are of greatest potential concern. As a side note, I’m not sure if this has anything to do with rumors about blondes and the fun factor but it’s worthy of consideration.
Since so many of us use hair dyes—estimated to be one-third of U.S. and European women over age 18 and 10 percent of men over age 40 (this number has been increasing annually) numerous scientific studies have tried to determine if exposure to hair dye chemicals is associated with an increasing risk of cancer in humans. Some of these chemicals have caused cancer in animal studies.
I was surprised to learn the staggering number of chemicals—more than 5,000—that are used in contemporary hair dyes, though not every product contains them all. Given the widespread use of hair dye products, even a small increase in risk may have a considerable public health impact.
This was the case in the mid-to-late 1970s when hair dye formulas contained aromatic amines that caused cancer in animals, so manufacturers of hair dye products changed their chemical formula. Although investigative studies have shown some dye applied to an animal's skin is absorbed into the bloodstream, most have not found a link between skin application and cancer risk. It is not clear right now how these results might relate to people's use of hair dyes.
The majority of studies examining if hair dye products increase the cancer risk have focused on certain cancers: non-Hodgkin lymphoma, leukemia, bladder cancer, and breast cancer, and two groups of people: those who regularly use hair dyes and those are exposed to them at work. Over the years, some epidemiologic studies have found an increased risk of bladder cancer in hairdressers and barbers. A 2008 report of the Working Group of the International Agency for Research on Cancer (IARC) concluded that some chemicals these workers are exposed to occupationally are “probably carcinogenic to humans.”
Studies have linked the personal use of hair coloring products with increased risks of cancers of the blood and bone marrow, such as non-Hodgkin lymphoma and leukemia, though other studies have not. Studies of breast and bladder cancer have also produced conflicting results. The IARC considers personal hair dye use to be "not classifiable as to its carcinogenicity to humans," based on a lack of evidence from studies in people.
Aside from cancer, certain hair dye ingredients can cause allergic reactions leading to severe skin and eye irritation in some people. Eye irritation can seriously affect vision lead to blindness, though this is rare. Hair dyes can also actually cause hair loss in some people. The U.S. Food and Drug Administration offered these tips for anyone concerned about safety:
Never mix different hair dye products, because you may cause potentially harmful reactions.
Lynette Summerill is an award-winning writer who lives in Scottsdale, Arizona. In addition to writing about cancer-related issues for EmpowHER, her work has been seen in newspapers and magazines around the world.
Sources: International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Volume 57: Occupational Exposures of Hairdressers and Barbers and Personal Use of Hair Colourants; Some Hair Dyes, Cosmetic Colourants, Industrial Dyestuffs and Aromatic Amines. 1993. Accessed at http://monographs.iarc.fr/ENG/Monographs/vol57/index.php.
US Food and Drug Administration. Hair dye products. 1997. Accessed at www.fda.gov/cosmetics/productandingredientsafety/productinformation/ucm143066.htm. For Consumers: http://www.fda.gov/forconsumers/byaudience/forwomen/ucm118527.htm
Zhang Y, Sanjose S, Bracci PM, et al. Personal use of hair dye and the risk of certain subtypes of non-Hodgkin lymphoma. Am J Epidemiol. 2008;167:1321–1331. Abstract at http://www.medscape.com/viewarticle/578427.
National Cancer Institute. Hair dyes and cancer risk. 2009. Accessed at www.cancer.gov/cancertopics/factsheet/Risk/hair-dyes.
Reviewed June 7, 2011
Edited by Alison Stanton