The data was collected from participants in the Sister Study, a nationwide effort by the US National Institute of Environmental Health Sciences (NIEHS) to learn how the environment and genes may affect the chances of developing breast cancer.
The researchers, including those from the NIEHS, said women who used hair straighteners at least every five to eight weeks were about 30 per cent more likely to develop breast cancer.
While the association between straightener use and breast cancer was similar in African American and white women, its use was much more common among African American women, they said.
“In our study, we see a higher breast cancer risk associated with hair dye use, and the effect is stronger in African American women, particularly those who are frequent users,” study co-author Alexandra White from NIEHS said.
The findings of the study, published in the International Journal of Cancer, also noted that women who regularly used permanent hair dye in the year prior to enrolling in the study were 9 per cent more likely than women who didn’t use hair dye to develop breast cancer.
Although there is prior evidence suggesting the association of breast cancer with chemical straighteners, these results need to be replicated in other studies, the researchers cautioned.
“We are exposed to many things that could potentially contribute to breast cancer, and it is unlikely that any single factor explains a woman’s risk. While it is too early to make a firm recommendation, avoiding these chemicals might be one more thing women can do to reduce their risk of breast cancer,” said study co-author Dale Sandler from NIEHS.