A study from the National Institutes of Health claimed that permanent hair dye and chemical hair straighteners could increase the risk of breast cancer among women.

The study published online on Dec. 4 in the International Journal of Cancer found that women who used permanent hair dye and chemical hair straighteners were 9% more likely to develop breast cancer than those who did not.

The NIH used a sample size of 46,709 women.

Researchers stressed that there was little to no increase in breast cancer risk for semi-permanent or temporary dye use.

"Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent," said corresponding author Alexandra White, Ph.D., head of the NIEHS Environment and Cancer Epidemiology Group. "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. "

While the study suggests an increased risk for women, these results need to be replicated in other studies to make a conclusion, the NIH said.

When asked if women should stop dyeing or straightening their hair, co-author Dale Sandler, Ph.D., chief of the NIEHS Epidemiology Branch, said, "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."