Women who use hair straightening chemicals are at higher risk for uterine cancer than those who don't, according to a new study by the National Institutes of Health.

The study, which included 33,497 women aged 35-74, found that participants who used hair straightening products more than four times a year were more than twice as likely to develop uterine cancer.

After 11 years of studying the women participating in the study, the researchers reported that 378 cases of uterine cancer had been diagnosed.

Commenting on the research, Dr. Alexandra White, 'It is estimated that 1.64 percent of women who do not use hair straightening chemicals will get uterine cancer by the age of 70. However, we did not expect this risk ratio to reach 4.05 percent for women who frequently use hair straightening chemicals.' said.

Researchers note that other hair products, such as hair dyes, bleaches, lighteners, or perms, that women report use have not been associated with uterine cancer.