Do Hair Dyes Cause Cancer?

Permanent hair dyes produced before 1980 contained ingredients that are now known to cause cancer. These were eliminated from dyes produced in the United States in 1979 when industry-wide changes in the formulation of hair dyes were instituted.

It has generally been assumed that personal use of today's hair dyes is safe, even though there is some evidence that at least one cancer causing agent - known as 4-ABP - can be present in some dyes or dye-lots. It is not a deliberate ingredient, but an unintentional by-product of the manufacturing process. Another problematic chemical - known as 2,3-Naphthalenediol - has recently been banned from hair dyes in Europe but may be present in some US hair products.

Because of continued concerns about the potential risks of such chemicals, along with the observation that the incidence of a type of cancer known as lymphoma has doubled in the last 20 years - while the popularity of permanent hair dyes has also increased - scientists have investigated whether hair dye increases the risk of lymphoma.

The term "lymphoma" refers to cancers of the lymphatic system, including Hodgkin's disease, non-Hodgkin lymphoma, and multiple myeloma. More that 60,000 people in the United States were diagnosed with lymphoma in 2005, and about half of all lymphoma diagnoses and deaths are among women. However, many more women than men use hair dyes.

A study published in July, 2006 looked at the relationship between the use of hair dye and development of lymphoma among almost 5,000 people living in 6 European countries. ¹ The researchers determined how many of the lymphoma patients had a history of using hair dyes, compared to a similar population that did not have lymphoma.

Many of the media stories about this research - with headlines like "Study Links Hair Dyes to Cancer" were misleading, considering the actual findings that were reported. The strongest relationship that the researchers found is a 62% higher risk of lymphoma among people who said they had dyed their hair before 1980 but not after. The next strongest is a 37% higher risk among those whose use of hair dyes started before 1980 and continued after that date. Even though these percentages may sound large, they actually represent extremely small increases in individual and population risk. One way to keep this in perspective is to remember that more than 80% of the people who developed lymphoma said they had never used permanent hair dye. Only 4% of those who did have lymphoma used hair dyes prior to 1980.

Results of previous studies on this topic have been inconsistent. A few have found small increases in risk, but the most convincing ones have not. The results of the current study, however, do underscore the greater toxicity of older dyes compared to newer ones. At least for the time being, the bottom line for personal users of permanent hair dyes appears to be that if use of modern hair dyes increases the risk of lymphoma, that increase appears to be extremely small for any individual woman.