The chemical relaxers used to straighten hair weren’t linked to an increased risk of breast cancer in African American women. A study of more than 59,000 African American women found those who used the hair relaxers seven or more times a year for at least 20 years had the same risk of developing breast cancer as those who used the product for less than a year.

“This is good news,” said Dr. Lynn Rosenberg, the study’s lead investigator and a Boston University epidemiology professor.

The results appear in the May issue of Cancer Epidemiology, Biomarkers & Prevention. It was conducted by researchers from Boston and Howard University Cancer Center.