A new study has found that chemical "relaxers" used to straighten hair are not associated with an increased risk of developing breast cancer among African-American women.
Hair relaxers can enter the body through cuts or lesions in the scalp. These products are not fully monitored by the Food and Drug Administration, and thus could contain potentially harmful compounds.
The study named 'Black Women's Health Study' was conducted by a team of researchers led by Lynn Rosenberg at the Boston University and Howard University Cancer Center.
Previous research has shown that breast cancer incidence is higher among African-American women age 40 or younger than among Caucasian women of the same age, and this increased risk is not fully explained by known risk factors, such as race and family history. At all ages, African-American women are more likely to die of breast cancer than are Caucasian women.
"Because hair relaxers are more widely used by younger African-American women than they are used by older African-American women, a connection with increased risk of breast cancer in younger women seemed possible. Also, millions of African-American women use hair relaxers, and substances that are used by millions of women over a span of many years should be monitored for safety," Rosenberg said.
As part of this study researchers followed 48,167 participants out 59,000 women who completed an initial questionnaire. More than 80 percent answered follow-up questions every two years since, including questions about use of hair relaxers.
Researchers found that younger women used hair relaxers more than older women did. They also discovered that the majority of women used hair relaxers before age 20 and a third used the chemicals at least seven times a year. But when they examined the association between use of hair relaxers and breast cancer, based on 574 newly diagnosed cases of breast cancer identified during the follow-up period, they found no connection between use of relaxers and breast cancer incidence overall or among the younger women, even if use had been frequent and of long duration.
"This is good news. The present study is definitive that hair relaxers don't cause breast cancer, as much as an epidemiologic study can be," Rosenberg said.
The findings of the study were published in the May issue of Cancer Epidemiology, Biomarkers & Prevention.