Hair products and their possible role

The chemicals products for hair straightening may be associated with a higher risk of uterine cancer.
The uterus consists of two main parts:

• The upper part called the body of the uterus;
• The lower end called the neck or cervix.

Uterine cancer develops in the lower part of the uterus, the site where the embryo is received and develops during pregnancy.
According to the “Global Cancer Statistics 2020” report, compiled in collaboration between the American Cancer Society (ACS) and the International Agency for Research on Cancer (IARC), uterine cancer ranks as the fourth most common cancer in women and accounts for 6.5 % of all cancers that are diagnosed in women.

A new study by the National Institutes of Health (NIH), published Oct. 17, 2022 in the Journal of the National Cancer Institute, found that women who use chemicals to make their hair smooth may be at higher risk of this cancer than those who did not use them; in fact, hair products may contain chemicals with carcinogenic effects.
Previous studies have found that the use of hair products is associated with an increased risk in the development of certain cancers, such as breast or ovarian cancer; to date, no study has examined the possible correlation between the use of certain hair products and straighteners and uterine cancer.
This research activity, through the Sister Study, aims to examine the association between the use of such products and the risk of developing this disease.
The Sister Study is a type of study that monitored a cohort of 50,884 U.S. women aged 35 to 74 years between 2003-2009. Within this group certain women were then excluded, for example some had had their uterus removed previously because they already had this cancer.
In this cohort, results were observed that showed a higher rate of uterine cancer for women who reported always or frequently using hair smoothing products and treatments, compared with those who did not.
Participants were asked to complete a questionnaire on their use of hair products in the previous 12 months reporting the frequency of use of specific hair products, such as straighteners, bleaches, or permanent dyes.
“We estimated that 1.64% of women who never used hair straighteners would go on to develop uterine cancer by the age of 70; but for frequent users, that risk goes up to 4.05%” said Alexandra White, a researcher who took part in the study.

Several chemicals that are components of hair straightening products could contribute to the increased incidence of uterine cancer.
In particular the exposure to certain chemicals through the use of hair products, especially straightening products, could be of greater concern than other personal care products. In fact, greater absorption of chemicals has been observed at the scalp than at other areas of the skin such as the forearm, palm, and abdomen.
The use of these specific products can cause injury and burns to the scalp by facilitating the permeability of chemicals.

The results obtained were compared with those of previous studies, and it was found that:

• The use of hair straightening products may increase the risk of developing cancers related to hormonal imbalances in women; however, this association is not yet so clear, when compared, for example, to that between smoking and cancer;
• This is a potential target for more attention and action to try to reduce the potential risk of developing such cancer.

Further research will be needed in the future both to replicate the results obtained in other contexts and to identify the specific chemical components and if possible further clarify this possible correlation.