Do hair dyes increase cancer risk? – . Health Blog

Personal use of hair dye is very common. It is estimated that 50% or more of women and 10% of men over 40 color their hair. However, with social distancing guidelines in place amid the ongoing pandemic, many people have skipped their regular hairdressing appointments. When natural hair colors are ingrained, we come to a multi-faceted question: do permanent hair dyes increase the risk of cancer?

Decades of research, conflicting results

Hair dyes come in three main varieties: oxidative (permanent), direct (semi-permanent or temporary) and natural dyes. Most of the hair dyes used in the US and Europe – both home improvement and salon dyes – are permanent dyes. They react chemically and form pigments that deposit on the hair shafts and can be the greatest risk of cancer.

People are exposed to chemicals in hair dye through direct skin contact or by inhaling vapors during the dyeing process. Occupational exposure to hair dye, as experienced by hairdressers, has been classified as likely to be carcinogenic. However, it remains unclear whether personal use of permanent hair dye increases the risk of cancer or cancer-related death.

Many studies have examined the relationship between personal hair dye use and the risk of cancer or cancer-related death. Contradicting results are due to incomplete studies due to small study populations, short follow-up periods, inadequate classification of exposures (personal or professional) or hair dye type (permanent or non-permanent), and an incomplete consideration of cancer-specific risk factors for long-term use of hair dyes.

Permanent hair dye doesn't seem to increase the overall risk of cancer, according to a recent study

In a recent study by the BMJ, researchers at . Medical School looked at personal hair dye use and the risk of cancer and cancer-related death. The study authors analyzed survey data from 117,200 women who participated in the Nurses' Health Study, which was collected from 1976 over 36 years. They tabulated information such as age, race, body mass index, smoking status, alcohol consumption, natural hair color and permanent hair dye use (per user vs. never user, age at first use, duration of use, frequency of use) and risk factors for certain types of cancer.

Compared to non-hair dyes, participants who ever used permanent hair dyes did not have an overall higher risk of cancer or cancer-related death.

For certain types of cancer, the risk of basal cell carcinoma (the most common type of skin cancer) was slightly higher in all users compared to non-users. The risk of certain breast and ovarian cancers seemed to increase with longer-term use of permanent dye. Women with naturally dark hair appeared to be at increased risk for Hodgkin lymphoma, and women with naturally light hair were at higher risk for basal cell carcinoma.

The authors cautiously reported their results and concluded that further investigation is needed to better understand the associations identified. Furthermore, we should keep in mind that associations do not prove causality.

A well-designed study also had some limitations

This was a large, well-designed study with high response rates from participants. The researchers analyzed detailed data to find out to what extent the risk of cancer was due to personal constant use of hair dye, rather than other potential risk factors.

This study also had several limitations. First, the participants were mostly European nurses, which means that the results may not necessarily apply to men or other racial or ethnic groups. Next, the study failed to consider every single cancer risk factor (e.g. exposure to pesticides and other environmental chemicals). No data was collected on other hair care products other than hair dyes, and the subjects may have falsely reported using permanent hair dyes when they were actually using semi-permanent or natural dyes. Without specifying the actual color of the hair dyes used, the authors assumed that the color of the hair dyes correlated with the natural hair tones. This assumption can miscalculate true chemical exposures, as in the case of dark-haired users who had additional chemical exposures because they shed the natural darker pigment.

To dye or not to dye?

Once the pandemic restrictions are lifted, some may consider coloring their hair. The main highlights of this study are:

  • Personal permanent use of hair dye did not increase the risk of most cancers or death from cancer. This is reassuring, but continuous security monitoring is required.
  • Additional research is required to look at different racial and ethnic backgrounds, specific hair dye colors (light versus dark), cancer subtypes, and exposure levels (personal versus professional).
  • Although this study uncovered possible links between persistent hair dye use and increased risk of some cancers, there isn't enough new evidence to move the needle on recommendations for personal permanent hair dye use. Keep your personal and family experiences in mind until more is known, until you start using permanent hair dye. If in doubt, contact your doctor for more information.

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