With over 97 per cent of hair relaxers said to contain a cancer-causing impurity called 1,4-dioxane, there is mounting concern that the products could not only cause lesions and scalp burns but also create more serious, cancerous, effects.
As manufacturers are not legally required to list all ingredients in hair relaxants, consumers may be unaware of the potential risk of using the products.
However, there is no direct link between the thousands of African American women who use hair relaxers and a higher incidence of breast cancer, according to research carried out at the Slone epidemiology center at Boston University and reported on in the Cancer Epidemiology Biomakers and Prevention journal.
The Black Women's Health Study was conducted on 59,000 African-American women across the US with information on hair relaxer use collected in 1997. A total of 48,167 women were studied through to 2003 for incident related breast cancer.
Researchers analysed each female for duration of use, frequency of use, age at first use, number of burns experienced during use, or type of relaxer used, and found 574 cases of breast cancer.
When hair relaxant products are used at least seven times a year for 20 or more years relative to use for less than a year, the incidence rate ratio of cancer was 0.98 per cent, indicating that the link was not related to the hair relaxant products.
The inclusion of 1,4-dioxane in personal care products has been causing concern in the personal care industry, with a recent study carried out by lobby group the Environmental Working Group (EWG) highlighting the amount of cosmetic products that contain the hazardous chemical.
The group claimed that despite the fact that the impurity is easily removed during processing, it appears that many companies are neglecting to do so, putting consumers at risk.
According to its statistics 80 per cent of cosmetic and personal care products sold in the country contain one or more of around 24 known impurities that have been linked to cancer.
As an integral part of its campaigns EWG has consistently stressed the fact that the FDA does not systematically enforce the testing of cosmetic ingredients for such impurities and is unable to enforce safety testing of finished cosmetic products, a situation the lobby group is working towards changing.
"As a start, we recommend that consumers choose products free of carcinogenic impurities," the group said in a statement. "To avoid 1,4-dioxane, read ingredient labels and avoid any of the 56 cosmetic ingredients that include the clauses 'PEG,' 'xynol,' 'ceteareth', and 'oleth'."