A new study conducted by Rutgers University denotes a link between use of certain hair dyes and hair relaxers and a higher risk of developing breast cancer in women. The study also finds a difference in the relationship between black and white women.
Breast cancer is the second most common cancer worldwide. In the U.S., breast cancer is the second biggest cause of death from cancer for all women. Each year in the U.S. around 220,000 women are diagnosed with breast cancer, with approximately 40,000 dying from the disease.
The risk of developing breast cancer is related to some factors, many of which cannot be changed. However, many of these risk factors, such as cigarette smoking, can be avoided. This research shows that use of certain hair care products may also need to be avoided.
The study, conducted by researchers at Rutgers University in New Brunswick, NJ, was published in the journal Carcinogenesis. The case for the study is that there is conflicting evidence on whether the use of hair products, some of which contain cancer-causing chemicals, can raise the risk of breast cancer in women. The Rutgers team noted that some studies have looked at the relationship through animal testing. Others have used human populations with a focus on hair dyes. The Rutgers study says the results were mixed, hence the desire to do this new research.
The new study
For this new research, the Rutgers team analyzed data on 4,285 women who were a part of the Women’s Circle of Health Study, whose goal was to study breast cancer in black women. In that study, 2,280 of the women had breast cancer (1,508 black and 772 white women), and 2,005 didn’t (1,290 black and 715 white women).
The Women’s Circle of Health Study allowed for various social and economic background factors that could affect risks, such as family health history, hormone use, physical activity, smoking, and hair product use.
The Rutgers team looked specifically at the links between raised risk of breast cancer and use of hair products. It placed particular focus on the use of hair dyes, hair-straightening products, and creams containing cholesterol or placenta for deep conditioning of the hair.
When looking at the data, the Rutgers team noted that among the women who did not have breast cancer, the use of hair dyes was more common in white women than black women (58 percent and 30 percent, respectively), whereas the use of relaxers was less common in white women (5 percent compared with 88 percent of black women), as was use of deep conditioner (6 percent compared with 59 percent).
When the Rutgers team analyzed the data, they found links between raised risk for breast cancer and the use of hair dyes and chemical hair relaxers. The patterns differed between white and black women.
In black women, the new study found that use of dark shades of hair dye was linked to an overall higher risk of breast cancer (odds ratio compared to non-use was 1.51). There was an even higher correlation with estrogen positive breast cancer (odds ratio of 1.71).
In white women, although the use was lower, the risks were even higher. White women using relaxers either alone or together with hair dyes had a higher risk of breast cancer (odds ratios were 1.74 and 2.40, respectively). With dark hair dyes, there was a raised risk of estrogen positive breast cancer (odds ratio of 1.54) and raised the risk of estrogen negative breast cancer with the use of relaxers (odds ratio of 2.56).
In its final summary, the Rutgers team suggested that their findings merit increased the direct study of the links between hair dyes and relaxers and their possible links to breast cancer.