Two common beauty products -- permanent hair dyes and chemical straighteners -- may be associated with an elevated risk for breast cancer.
The study published in the International Journal of Cancer tracked more than 46,000 women over several years.
Overall, women using permanent dye had a 9% higher risk of developing breast cancer.
Black women who used permanent dye had a 45 percent higher risk of breast cancer, compared to non-users.
And those who used these products every eight weeks or more often had a 60 percent higher risk.
The study was funded by the National Institutes of Health and recruited breast-cancer free women whose sisters had been diagnosed with the disease.
Women in the study ranged in age from 35 to 74.
Researchers say more research is needed.