Black women who use permanent hair dyes and chemical hair
straighteners are at a higher risk of developing breast cancer than
those who don’t use these products, a new study has shown.
The study, titled “Hair dye and chemical straightener use and breast
cancer risk in a large US population of black and white women,”
examined the relationship between hair dye and chemical
relaxer/straightener use and breast cancer risk by ethnicity.
The research was conducted in the US using 46,709 black and white
women — between the ages of 35 and 74 — recruited between 2003 and
2009, who had no personal history of breast cancer, but had a sister
diagnosed with the disease.
Findings from the study, published in the International Journal of
Cancer, showed “a higher breast cancer risk associated with any
straightener use and personal use of permanent dye, especially among
black women” which suggests “that the chemicals in hair products may
play a role in breast carcinogenesis.”
The researchers also stated that “many hair products contain
endocrine-disrupting compounds and carcinogens potentially relevant to
breast cancer,” adding that “products used predominately by black
women may contain more hormonally-active compounds.”
“We evaluated the relationship between hair dye and straightener use
with breast cancer risk and found that women who used permanent dye or
straighteners, or applied straighteners to others, in the 12 months
before enrolment were at a higher breast cancer risk,” said the study.
The link was particularly evident in black women as their use of
permanent dye was associated with 45 per cent higher breast cancer
risk, while white women faced a seven per cent higher risk.
“The association with permanent hair dye was particularly evident in
black women, for whom we observed a 45% higher breast cancer risk.
Overall, these results support the hypothesis that hair dye and
straightener use, which are highly prevalent exposures, could play a
role in breast carcinogenesis,” it added.
“The study also implicated hair straighteners, finding a 30 percent
increase in the risk of breast cancer among women of all races who
reported regular use of the products. African-American women were much
more likely than white women to use hair straighteners.
Head of the National Institute of Environmental Health Sciences
Environment and Cancer Epidemiology Group, Alexandra White, also took
to her social media page to summarise the findings of the study.
“The risk associated with permanent dye was small for white women
(<10%) but for Black women was much higher (45%) suggesting the type
or amount of dye used or application method varies substantially and
influences risk,” she wrote on Twitter.
Paul Pharoah, a professor of cancer epidemiology at the University of
Cambridge, also urged women to remember that correlation does not mean
causation.
“While these results are intriguing, they do not provide good evidence
that hair dyes or chemical straighteners are associated with a
meaningful increase in risk of breast cancer or that any increased
risk association is causal,” said Pharoah.
