Hair colouring with chemical laden hair dye enhances the possibility of breast cancer among women. A new research by National Institute of Environmental Health Science(NIEHS) has revealed that women who use chemical hair straighteners and permanent hair dye have higher risk of developing this ailment. Researchers studied the data from 46,709 women, the study was conducted between 2003 and 2009 on woman in the age group of 35 to 75 years. Women who had used permanent hair dye one year prior to the study were found to be 9% more likely to develop breast cancer. Among the various ethnic groups African American woman who used coloured dyes seem to be at highest risk. African American women who died their hair were found to have a 60% higher risk of developing breast cancer compared to white women who displayed 8% enhanced risk of developing this disease. Reason for higher risk among Afro-American women is there higher frequency of use of permanent hair dyes. Chemical hair straightener too you are not safe option as researchers found that those women who use these in 5 to 8 weeks are 30% more likely to develop this affliction. Formaldehyde a unknown carcinogen is sometimes included in hair straightening chemicals is thought to be one of the reasons why hair straightening chemical could lead to cancer.