Disclosures: The authors report no relevant financial disclosures.
December 28, 2021
2 min read

Hair dye, relaxer use associated with lower sex steroid levels during pregnancy

Disclosures: The authors report no relevant financial disclosures.
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The use of certain hair care products is linked to lower concentrations of sex steroid levels among pregnant women, likely due to the presence of endocrine-disrupting chemicals, according to data published in Environmental Research.

Zorimar Rivera-Núñez

“Many chemicals found in personal care products, including phthalates, phenols and parabens, are known endocrine disruptors,” Zorimar Rivera-Núñez, PhD, MS, assistant professor in the department of biostatistics and epidemiology at Rutgers School of Public Health in Piscataway, New Jersey, told Healio. “Women using hair care products, such as hair dyes, bleach, mousse and relaxers, had lower levels of sex steroid hormones compared to women not using these products. Sex steroid hormones are critical for fetal growth and pregnancy maintenance. Sociodemographic factors, such as income and education, influence frequency of use of personal care products.”

Sex steroid levels for women using hair dye
The use of hair dye is associated with decreased levels of estriol, progesterone and testosterone in women. Data were derived from Rivera-Núñez Z, et al. Environ Res. 2021;doi:10.1016/j.envres.2021.112376.

Rivera-Núñez and colleagues analyzed data from 1,070 pregnant women enrolled in Puerto Rico PROTECT, an ongoing prospective birth cohort initiated in 2010 to study environmental exposures among pregnant women and their children. Participants, who had not used oral contraceptives in the 3 months before pregnancy and did not use in vitro fertilization, underwent physical exams and completed a series of questionnaires assessing self-reported use of personal care products, including perfumes/cologne and soap, lotions, cosmetics, nail polish, shampoo and hair conditioners, shaving cream and mouth wash. Blood samples to measure levels of nine hormones (corticotropin-releasing hormone, sex hormone-binding globulin, estriol, progesterone, testosterone, thyroid-stimulating hormone, total triiodothyronine, total thyroxine and free thyroxine) were collected at the first visit (n = 910 samples) and third visit (n = 633 samples). The mean age of women providing samples was 28 years; 80% were never smokers. Researchers used linear mixed models to examine associations between personal care product use and serum hormone levels.

Use of hair products, such as hair dyes and bleach, relaxers and mousse, was associated with lower levels of all sex steroid hormones compared with nonuse, including SHBG (percentage change, –7.1; 95% CI, –12.4 to –1.8), estriol (percentage change, –23.2; 95% CI, –32.2 to –13), progesterone (percentage change, –21.5; 95% CI, –29.4 to –12.9) and testosterone (percentage change, –21.5; 95% CI, –33.1 to –7.8). Results persisted after adjustment for maternal age, education and pre-pregnancy BMI.

“Our findings suggest that household income and education level influence personal care product use among pregnant women in this study,” Rivera-Núñez told Healio. “Use of certain hair products was associated with lower concentrations of sex steroid hormones. Although there are limitations to questionnaire data, characterizing personal care product use is inexpensive and may represent exposure from multiple classes of chemicals, including chemicals that may not specifically appear on product labels and/or have not been tested for endocrine-disrupting potential, making it a useful complement to chemical biomarker data.”

Rivera-Núñez said alterations in hormone levels, especially during pregnancy, can have consequences beyond health at birth, including changes in infant and child growth and pubertal trajectories, and may influence development of hormone-sensitive cancers, such as breast, uterine and ovarian cancer.

“Primary care physicians and obstetricians should inform and offer guidance to reproductive-age women about the potential health impact of endocrine-disrupting chemicals such as those found in hair care products,” she said. “We should replicate this study in other populations. There is a strong culture of beauty influence among Latina women, but also other populations, including Black women. This will help us to identify populations at risk. Second, refining tools like frequency of use questionnaires by including brands and more time points will also be helpful to better assess exposure, and examining multiple personal care products at the same time will help assess the impact of multiple exposures.”

For more information:

Zorimar Rivera-Núñez, PhD, MS, can be reached at zr69@eohsi.rutgers.edu.