Scientific evidence from multiple research approaches confirms that chemicals from personal care products are readily absorbed through the skin and can be detected throughout the body.
Researchers have measured cosmetic ingredients including phthalates, parabens, bisphenol A, and triclosan in urine from Swedish mothers and children, with levels correlating to personal care product use [1]. Adolescent girls who reported daily makeup use had significantly higher urinary concentrations of monoethyl phthalate, methyl paraben, and propyl paraben compared to those who rarely used such products [2]. A nationally representative Korean study found that urinary concentrations of parabens steadily increased as the cumulative number of personal care products used increased [3].
Tissue analysis: Multiple studies have detected phthalate metabolites, benzophenone-type UV filters, parabens, triclosan, and triclocarban in human hair, nails, urine, blood, and breast tissue [4].
Controlled exposure studies: When healthy male subjects applied cream containing diethyl phthalate, dibutyl phthalate, and butyl paraben to their whole body, metabolites peaked in urine 8-12 hours after application, with measurable amounts excreted over 24 hours, demonstrating systemic absorption and circulation [5].
Regional skin permeability: Studies show greater chemical penetration occurs in the face, neck, and genital area compared to other body regions, differences explained by variations in stratum corneum thickness, hair follicle density, hydration levels, and blood flow [6]. Classic research demonstrated that the scrotum has the highest absorption rates among tested sites, followed by facial regions, while the forearm showed the lowest absorption [7]. Genital skin exhibits increased permeability due to higher hydration levels, thinner epithelium, and reduced keratinization compared to other body sites [8].
Bottom line: Multiple lines of scientific evidence demonstrate that cosmetic ingredients penetrate the skin barrier and enter systemic circulation, with absorption rates varying by body location and product formulation.
References
[1] Larsson, Kristin, Karin Ljung Björklund, Britta Palm, Marie Wennberg, Lotta Kaj, Christian H. Lindh, Bo A. G. Jönsson, and Marika Berglund. “Exposure Determinants of Phthalates, Parabens, Bisphenol A and Triclosan in Swedish Mothers and Their Children.” Environment International 73 (December 2014): 323–333.
[2] Harley, Kim G., Anna M. Berger, Kimberly Kogut, Kathleen Parra, Robert H. Lustig, Robert B. Greenspan, Dana B. Barr, et al. “Personal Care Product Use as a Predictor of Urinary Concentrations of Certain Phthalates, Parabens, and Phenols in the HERMOSA Study.” Journal of Exposure Science & Environmental Epidemiology 29, no. 1 (January 2019): 21–32.
[3] Kho, Younsun, Ji-Eun Lim, Kyungho Choi, and Eunmi Kwon. “The Associations between Personal Care Products Use and Urinary Concentrations of Phthalates, Parabens, and Triclosan in Various Age Groups: The Korean National Environmental Health Survey Cycle 3 2015–2017.” Science of The Total Environment 742 (November 2020): 140640.
[4] Zhou, Yi, Hongliang Jia, Hongwen Sun, Tao Zhang, Huike Dong, Hongyu Chen, Yang Liu, et al. “Distribution of Phthalate Metabolites, Benzophenone-Type Ultraviolet Filters, Parabens, Triclosan and Triclocarban in Paired Human Hair, Nail and Urine Samples.” Environmental Pollution 330 (October 2023): 121745.
[5] Janjua, Nadeem R., Bent Mortensen, Anne Marie Andersson, Birger Kongshoj, Niels E. Skakkebaek, and Hanne E. Wulf. “Urinary Excretion of Phthalates and Paraben after Repeated Whole-Body Topical Application in Humans.” International Journal of Andrology 31, no. 2 (April 2008): 118–130.
[6] Chedik, Lucie, Samat Baybekov, Frédéric Cosnier, Gilles Marcou, Alexandre Varnek, and Claire Champmartin. “An Update of Skin Permeability Data Based on a Systematic Review of Recent Research.” Scientific Data 11, no. 1 (February 2024): 224.
[7] Feldmann, Robert J., and Howard I. Maibach. “Regional Variation in Percutaneous Penetration of 14C Cortisol in Man.” Journal of Investigative Dermatology 48, no. 2 (February 1967): 181–183.
[8] Farage, Miranda A., Kenneth W. Miller, Howard I. Maibach, and Miranda A. Farage. “Sensitive Skin in the Genital Area.” Frontiers in Medicine 6 (April 2019): 96.