Study Finds Possible Link Between Hair Dye, Straighteners, and Breast Cancer

A study from researchers at the National Institute of Health (NIH) found that women who used permanent hair dye and chemical hair straighteners had a higher risk of breast cancer than women who didn’t use them. The study was published December 4, 2019 in the International Journal of Cancer.

This is the latest study to look at possible links between cancer and chemical hair products. Previous studies have had mixed results. The NIH study looked at data from 46,709 women in the Sister Study. Participants are American women who did not have cancer when they enrolled in the study but who had a sister diagnosed with breast cancer.

Researchers observed that women who regularly used permanent hair dye during the year before they enrolled in the Sister Study had a 9% higher risk of developing breast cancer. Women who used semi-permanent or temporary hair dye had little or no increased risk.

Greater risk among African-American women

Among African-American women, using permanent dyes was associated with a 45% increased risk of breast cancer, compared with a 7% increased risk for white women. The study authors suggest this may be because hair products marketed to black women contain different chemicals than those marketed to white women. Among black women (but not white women), using the products more often was also linked to a greater increase in risk.

"Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent," said corresponding author Alexandra White, PhD, in a statement. "In our study, we see a higher breast cancer risk associated with hair dye use, and the effect is stronger in African-American women, particularly those who are frequent users."

Straightener use was also linked with a higher breast cancer risk. Use of straighteners was much more common among black women than white women.

Putting it into context

Researchers found an association between permanent hair dye use and women getting breast cancer, but they did not conclude that using permanent hair dye causes breast cancer. More and other types of research are needed.

Also, the results of this study need to be viewed in the context of other studies that have looked at this issue. Previous studies have had mixed results: some have shown a possible link between hair dyes and breast cancer, but others have not. This means there’s still no clear answer for women who are concerned about a possible increase in the risk of breast cancer (or other cancers) from coloring their hair.

Co-author Dale Sandler, PhD, said in a statement, "We are exposed to many things that could potentially contribute to breast cancer, and it is unlikely that any single factor explains a woman’s risk. While it is too early to make a firm recommendation, avoiding these chemicals might be one more thing women can do to reduce their risk of breast cancer."

Breast cancer risk factors

The American Cancer Society recommends women who want to lower their risk for developing breast cancer make lifestyle changes that have strong evidence showing they have an effect.

• Get to and stay at a healthy weight. Being overweight or obese increases breast cancer risk. This is especially true after menopause and for women who gain weight as adults.
• Exercise regularly. Evidence is growing that regular physical activity reduces breast cancer risk, especially in women past menopause.
• Limit or avoid alcohol. Even small amounts of alcohol can increase breast cancer risk.
• Avoid or limit hormone replacement therapy (HRT) to help control night sweats, hot flashes, and other symptoms of menopause. Postmenopausal women who take a combination of estrogen and progestin are more likely to develop breast cancer. If you do decide to try HRT, it is best to use it at the lowest dose that works for you and for as short a time as possible.