Harvard medical experts have conducted an analysis of a recently published study that warns about the risk of breast cancer from permanent hair dye and chemical straighteners, indicating that the risk may be lower than initially thought, but remain a concern for certain women.
The study was first published in the International Journal of Cancer in December 2019, by researchers from the National Institute of Environmental Health Sciences (NIEHS), indicating that common hair dyes and straighteners often contain known cancer-causing agents, which appear to increase the risk of breast cancer by 9%.
Those researchers collected data from the Sister Study, which is a long-term research project in the U.S. and Puerto Rico involving over 50,000 participants to determine how the environment and genes affect women’s chances of getting breast cancer.
Part of the study involved participants answering questionnaires about hair products they used in the past year. More than half of the women reported using permanent hair dyes, and 75% of African-American participants reported using chemical straighteners.
Over an eight year period, researchers identified 2,794 cases of breast cancer from participants reporting having used or frequently using permanent hair dyes and chemical straighteners.
However, in a report published this month in Harvard Women’s Health Watch, another group of experts took a look at the study, and suggest that the findings may be somewhat overblown.
The Harvard researchers found that, while the chemicals in the hair dyes are definitely of concern, all of the women in the study were in a high-risk breast cancer group. They indicated this means the findings might not apply to the average population.
They also noted that the additional elevated risk detected among African American women were likely due to environmental factors, including differences in chemicals used in products marketed to that population. Therefore, they suggest there is likely no genetic factor making African American women more susceptible to these chemicals, but, more likely, the chemicals being used by hair dye manufacturers specifically marketed to African American women are more dangerous.
The researchers noted that previous studies have confirmed products sold to African American women sometimes have higher concentrations of hormone disrupting chemicals.
The findings of the original study are similar to a study published in 2017, which found that African American women who use dark hair dyes and Caucasian women who use relaxers and straighteners both face increased cancer risks.
Although researchers indicated there are many factors which play a role into the risks of developing breast cancer, hair products are known to contain on average more than 5,000 chemicals, including some that may damage DNA or interfere with the body’s endocrine system. Exposure to this wide array of chemicals could allow them to enter an individual’s blood stream and circulate through the body.
In this latest analysis, the Harvard experts determined that the NIEHS study’s findings could not be ignored, even if they may not be as damning as originally interpreted. They called for more research into the subject, and advised women to always reduce chemical exposure to potential carcinogens whenever possible.