- This study analyzed the hormonal activity of six leave-in hair care products commonly used by Black women: one hair lotion, two leave-in conditioners, two hair oils and one root stimulator
- The testing evaluated how the products affected four hormones that are important to normal body functioning in women and men: estrogen, testosterone, progesterone and hydrocortisone
- All six hair care products elicited hormonal activity; in general, the type of activity varied by product, with some adding to natural hormone activity and others blocking it
- The leave-in conditioners and one of the hair oils had the highest degree of hormonal activity—they added to the activity of estrogen and progesterone and blocked the activity of testosterone and hydrocortisone
- Future research should address whether use of such products contributes to certain hormone-related diseases and racial/ethnic disparities in disease risk
Chemicals in women's hair care products have been linked to multiple hormone-related conditions, including early puberty, preterm birth, obesity and diabetes. Researchers at Brigham and Women's Hospital previously found that African-American and African-Caribbean women are more likely than white women to use all types of hair products and to use them more frequently, as reported in the Journal of Immigrant and Minority Health.
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Now, Tamarra James-Todd, MD, MPH, of the Connors Center for Women's Health and Gender Biology at Brigham and Women's Hospital, Shruthi Mahalingaiah, MD, MS, reproductive endocrinologist in the Department of Obstetrics & Gynecology at Massachusetts General Hospital, and colleagues have examined the specific hormonal activity of leave-in hair products commonly used by Black women. They present their concerns in the Journal of Exposure Science & Environmental Epidemiology.
In the previous study, African-American, African-Caribbean, Hispanic and white women were recruited between 2004 and 2006 in the New York City area from community settings such as churches, hair salons and laundromats. They completed a detailed survey about their current and past use of hair care products.
The researchers identified six product brand names mentioned by >10% of the African-American and African-Caribbean participants and being used more than once per week. In 2012 the products were sent for independent laboratory testing: one hair lotion, two leave-in conditioners, two hair oils and one root stimulator.
The new paper reports how the products affected four hormones: estrogen, testosterone, progesterone and hydrocortisone.
- All six products displayed hormonal activity
- Three products resulted in additive estrogen activity
- Five products had anti-androgen activity
- Four products disrupted progesterone and hydrocortisone
- One of the leave-in conditioners and one of the hair oils displayed activity on all four hormone tests, potentially indicating that use of these products is particularly problematic with regard to hormone-related disease
Putting the Findings in Context
Black women spend more money on hair products than any other racial/ethnic group, partly because of pressure to have eurocentric hairstyles in the workplace and other settings. These products are often left on the hair and scalp for days or weeks, potentially allowing chemicals to enter the body through the scalp.
The four hormone receptor binding pathways analyzed here are involved in numerous biological processes, which when disrupted, might lead to premature pubertal transition, diabetes, cardiovascular disease, adverse reproductive health outcomes and other diseases. For example, at least two past studies have linked the use of hair dyes and chemical relaxers with increased breast cancer risk in both Black and white women.
The health implications of hormone-altering chemicals might be particularly adverse when hair care products are used frequently and/or in combination. However, the design of this study does not permit conclusions about whether the hormonal activity of the products contributes to certain hormone-related diseases or racial/ethnic disparities in disease risk.
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