An intriguing study published by the International Journal of Cancer looked at the breast cancer risk in relation to the use of hair dyes and chemical straighteners, after results of previous studies remain inconclusive. It’s estimated that around a third of women over 18 in the United States use hair dye and high correlations between hair dye use and breast cancer rates have been reported, with black women being the most affected in the study.

Breast cancer incidences remain high for all women in the United States, and current research has been trying to identify the environmental and genetic components that may play a part in increasing risk. Major factors that influence breast cancer development include; lifestyle factors, family, age, and breast density.

Some hair products are known to contain as many as 5000 chemicals, including some with mutagenic and endocrine-disrupting compounds that are thought to play a role in breast cancer formation, such as aromatic amines. One example is amine 4-aminobiphenyl (ABP) which can reach the breast tissue through the skin. A previous study found that women who used hair dye containing this compound within the past year were eight times more likely to have ABP-DNA damage detected in breast epithelial cells. Some chemical straighteners contain formulations where formaldehyde, a known carcinogen, is an active ingredient. Several products favoured by African American consumers have been found to contain more hormonally-active compounds.

The study recruited 47,650 women aged 35 to 74 who’s sisters had already been diagnosed with breast cancer. There was an overall 9% higher breast cancer risk in women who reported to regularly use permanent hair dye in the year prior to enrolling in the study than women who did not. In black women, this risk was as high as 45%. More specifically in black women, when permanent hair dye was used with a frequency of “every five to eight weeks or more” the risk rose to 60%. There was no risk found to be associated with using semi-permanent or temporary hair dye.

With chemical straightener use, there was an increased breast cancer risk of 18%, but the researchers stated that this may need to be replicated.

This study provided intriguing results, however it is clear more studies should be carried out to fully understand the risks that are involved in using hair dyes and chemical straighteners. We are constantly being told that many things could be potentially harmful and contribute to our cancer risk, so it is difficult to say whether the use of hair dyes and straighteners should be stopped altogether.

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