Millions of people worldwide dye their hair. In fact, one-third of women and 10% of men over 40 in North America and Europe use some type of hair dye. Getting your hair dyed is a simple activity that can be done quickly in just about any hair salon. But is the use of hair dye risk-free? There is growing concern that people who regularly use hair dye may be increasing their risk of cancer.

The connection between hair dye and cancer dates back to the 1970’s when certain dye ingredients were banned after they were found to be carcinogenic (cancer-causing) in rodents. This action, however, did not completely resolve the issue. A number of more recent studies have suggested a cancer risk, and in 2004, based on a study linking hair dye to ]]>bladder cancer]]> , the Scientific Committee on Cosmetic Products and Non-Food Products released an opinion paper stating that bladder cancer may be caused by possible carcinogens in hair dye solutions.

Because of the widespread use of hair dye, the possibility of a relationship between it and cancer is quite alarming. The data is inconclusive though, with some studies supporting a relationship and other studies finding no increase in risk. A study published in the May 25, 2005 issue of the Journal of the American Medical Association conducted a systematic evaluation of the last 40 years of published scientific evidence in an attempt to tease out the relationship between hair dye use and cancer risk.

About the Study

In this study, the authors conducted a meta-analysis of the literature to obtain their data. In a meta-analysis, researchers review and combine the data from published studies that meet pre-established specified criteria. In this study, the two main criteria were exposure to personal hair dye products and an outcome of cancer at any anatomical site.

The authors included almost 80 studies spanning nearly 40 years of research. The types of cancers looked at included blood-borne (40 studies), ]]>breast]]> (14), bladder (10), ]]>brain]]> (two), ]]>skin]]> (two), ]]>ovarian]]> (two), ]]>cervical]]> (two) and one study for each of the following cancer sites: salivary gland, endometrium, vagina, oral cavity, soft tissue sarcoma, digestive system, respiratory system.

The researchers used the data to examine the association between personal hair dye use and the relative risk of cancer. Separate analyses were carried out for each cancer, and when possible, the researchers performed additional analysis to determine the effect of permanent dyes on cancer, as well as their extensive use (defined as >200 dye uses/lifetime).

The Findings

The authors found no strong evidence of a link between personal hair dye use and an increase in cancer risk. For bladder cancer and breast cancer, the results indicate that there was no effect of hair dye use on cancer risk. However, with blood-borne cancers, which include leukemia, multiple myeloma, ]]>Hodgkin’s]]> and ]]>non-Hodgkin’s]]> disease, there was a borderline increase in risk, which was more pronounced in male hair dye users. But, the authors feel that evidence of a causal effect is too weak to represent a major health concern.

For the cancers with only one or two studies included in the analysis, several showed an increase in risk. Risk of salivary cancer increased three times in hair dye users and risk of brain and ovarian cancer almost doubled. However, there was not enough data to draw any firm conclusions.

How Does This Affect You?

Given that millions of people worldwide use hair dye, the possibility of a risk associated with hair dye use is a major public health concern. Although the results of this study were mostly reassuring, they do not go far enough to completely quell all apprehension. If a risk exists at all, however, it is probably small.

If you are concerned about the risk, you can minimize your exposure to hair dye by:

  • Wearing gloves if you are applying the dye yourself
  • Applying hair dye less frequently
  • Using lighter colors (some studies have found an increase in risk with darker colors)
  • Using semi-permanent color (some studies have found an increase in risk with permanent color)