Study finds increased risk but no direct cause

Published: December 20, 2019 | Updated: September 19, 2024

The link between chemicals and cancer is often in question. The latest is a study that found a higher risk of developing breast cancer among women who used permanent hair dye or hair straighteners. This higher risk also affected women who apply the products to others’ hair.

The study, published in the International Journal of Cancer, found that women using permanent dye had a 9% higher risk of breast cancer. However, the risk went up 45% for black women who used dye in the past year, and 60% with dye use every five to eight weeks. Straightener was associated with an 18% higher risk for one-time use, and 31% higher risk when used every five to eight weeks.

It’s important to realize that these increases represent a relative risk. Women overall have a 12% risk of developing breast cancer. If you increase that 45% (increase in risk for black women using dye within the last year), the overall risk becomes 17.4%.

“While the study had some interesting findings, this does not show that using these products causes cancer — it simply increased the risk among women in the study,” said Laila S. Agrawal, M.D., hematologist and oncologist with Norton Cancer Institute. “There are risk factors every woman has based on personal history.

“We also know that there are lifestyle changes everyone can make to reduce the risk of breast cancer. This includes consistent exercise, maintaining a healthy weight, not smoking, and limiting alcohol.”

While the U.S. Food and Drug Administration does not have “reliable evidence” of a link between cancer and “coal-tar” hair dye, it continues to review data to watch for any issues.

If you are going to use hair dye or straighteners, the American Cancer Society offers some suggestions:

• Follow package directions and only leave dye on your head the amount of time listed in the directions — not longer.
• Wear gloves when using dye.
• Do a patch test every time before you dye your hair.
• Rinse well with water.
• Never mix different hair dyes together.

Hair dye is only for your scalp, not eyebrows or eyelashes.