In a new study, researchers found women who use permanent hair dye products to color their hair at home do not experience greater risk of most cancers or greater cancer related mortality.
While this should provide general reassurance to users of permanent hair dyes, they say they did find a slight increase in risk of ovarian cancer and some cancers of the breast and skin.
Natural hair color was also found to impact on the likelihood of some cancers.
The use of hair dye is very popular, particularly among older age groups keen to cover up signs of grey.
For example, it is estimated that it is used by 50-80% of women and 10% of men aged 40 and older in the United States and Europe.
The most aggressive hair dyes are the permanent types and these account for approximately 80% of hair dyes used in the US and Europe, and an even greater proportion in Asia.
While the World Health Organization’s International Agency for Research on Cancer has classified occupational exposure to hair dyes as a probable carcinogen, there is no warning about personal use because existing evidence is inconclusive.
To gain a better understanding of the risk of cancer from the use of personal hair dye, the researchers analyzed data on 117,200 women from the Nurses’ Health Study, which includes assessments of hair dye exposure.
The women did not have cancer at the start of the study and were followed for 36 years.
The results showed no increased risk of most cancers or of cancer death in women who reported having ever used permanent hair dyes compared with those who had never used such dyes.
Use of hair dye did not increase the risk of cancers of the bladder, brain, colon, kidney, lung, blood and immune system, or most cancers of the skin (cutaneous squamous cell carcinoma and melanoma) or breast (estrogen receptor-positive, progesterone receptor-positive or hormone receptor-positive).
Ever use of permanent dyes was linked to a slightly increased risk of the basal cell carcinoma of the skin, and this risk was higher in women with naturally light hair.
An increased risk of three types of breast cancer—estrogen receptor-negative, progesterone receptor-negative, and hormone receptor-negative—and ovarian cancer was also linked to the use of permanent dyes, with risk rising according to the cumulative amount of dye women were exposed to.
An increased risk of Hodgkin lymphoma was also seen with the use of permanent hair dye but only for women with naturally dark hair.
The team says shades of permanent hair dyes are linked to the concentration of ingredients, with darker colors having higher concentrations.
These findings can offer some reassurance against concerns that personal use of permanent hair dyes might be linked to increased cancer risk or mortality.
However, they add that the positive associations for some cancers with different hair color types warrant a further test.
The study is published in The BMJ.
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