Researchers have found a link between the use of chemically based hair treatments and breast cancer. The findings, published in the International Journal of Cancer in December, suggest women who use permanent hair dyes and straighteners could have a higher risk of breast cancer compared with those who don’t use the products.

Researchers at the National Institutes of Health analyzed data from over 46,000 women to conduct the study. They found women who used permanent hair dyes were 9% more likely to develop breast cancer than women who did not. The increased risk was greater among African American women, who had a 60% increased risk if they used permanent dyes regularly. For white women, the increased risk was 8%.

The researchers also found a 30% increased risk of breast cancer among women who used hair-straightening treatments every five to eight weeks. The risk was similar for both African American and white women, but straightening treatments are more common among African American women.

Although the study’s findings indicate an increased risk of cancer, the researchers caution that this does not conclude that permanent hair dyes and straighteners cause cancer. Many of the women who participated in the study had a higher risk of breast cancer due to family history. Similar studies will need to be conducted to see if the results are replicated before any conclusions can be made.

What can women take away from the study? The researchers suggest women limit their exposure to these products, or have hair permanently dyed or straightened in a salon or similar professional setting, where exposure to chemicals is minimized.