1,4-Dioxane
Mostly found in products that have suds.
Not required to be listed on ingredient labels by the FDA.
The EPA "identified health risks, risks of liver toxicity, adverse effects in the olfactory epithelium, and cancer from inhalation or dermal exposures to 1,4-dioxane." [1]
A scholarly review discussed that while data on "human exposure and health effects are limited, animal studies have shown chronic exposure to cause carcinogenic responses in the liver across multiple species and routes of exposure." [2]
Butylated Hydroxyanisole (BHA)
Found in makeup and creams, as well as deodorant, sunscreen, and fragrance.
Look for "BHA" on the label.
According to the National Toxicology Program Report on Carcinogens, 15th edition, BHA "is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals." [3]
A study found that "high dose of BHA induce weak dysfunction and underdevelopment of reproductive system of male and female rats with the change of T4 and testosterone levels, sex organ weights and sexual maturation and histological lesions of thyroid gland." [4]
Formaldehyde
Used in makeup to prevent bacterial growth.
Also found in building materials.
Look for "formaldehyde" on the label.
The National Toxicology Program names formaldehyde as a known human carcinogen in their Fifteenth Edition of Report on Carcinogens. [3]
According to a study, formaldehyde "both initiates and promotes cancer." [5]
Triclosan
Found in creams and color cosmetics, as well as deodorant, whitening products, and antibacterial soaps.
According to the Cleveland Clinic, triclosan is an antibacterial chemical. Long term exposure may have health risks that "range from allergies to bacterial resistance." "Some animal studies have shown that exposure to high amounts of the ingredient may cause a decrease in certain thyroid hormones." Triclosan can also cross the placenta and is detected in breast milk. [6]
Acrylamide
Look for "polyacrylamide" and "acrylamide" on the label.
According to the National Toxicology Program Report on Carcinogens, 15th edition, acrylamide is "reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals." "Daily exposure to acrylamide through cosmetic products was estimated at 0.95 μg/kg of body weight per day." This is a higher exposure rate than individuals smoking a pack of cigarettes a day, "which would result in an average daily intake of 0.67 μg/kg of body weight per day." [3]
The European Commission opined that "lifelong use of cosmetic products containing polyacrylamide may represent an unacceptable high lifetime risk of cancer due to residual acrylamide in the polyacrylamide preparations." [7]
The Campaign for Safe Cosmetics (CSC) is a great resource if you want to dive deeper. "CSC is a program of Breast Cancer Prevention Partners (BCPP), a national science-based advocacy organization working to prevent breast cancer by eliminating environmental exposures linked to the disease." On their site you can find lists of chemicals found in various personal care products, including makeup. Each chemical lists a summary of where they are likely found in products, how to find these chemicals on labels, and summarized research studies with links on the health effects of these toxins.
References
[1] "Final Risk Evaluation for 1,4-Dioxane." Environmental Protection Agency, July 2023, https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/final-risk-evaluation-14-dioxane#findings. Accessed 15 January 2024.
[2] 1,4-Dioxane as an emerging water contaminant: State of the science and evaluation of research needs, Science of The Total Environment, Volume 690, 2019, Pages 853-866, ISSN 0048-9697, https://doi.org/10.1016/j.scitotenv.2019.06.443 (https://www.sciencedirect.com/science/article/pii/S0048969719330165)
[3] NTP (National Toxicology Program). 2021. Report on Carcinogens, Fifteenth Edition. Research Triangle Park, NC: U.S. Department of Health and Human Services, Public Health Service. https://ntp.niehs.nih.gov/go/roc15. DOI: https://doi.org/10.22427/NTP-OTHER-1003
[4] Jeong, Sang-Hee et al. “Effects of butylated hydroxyanisole on the development and functions of reproductive system in rats.” Toxicology vol. 208,1 (2005): 49-62. doi:10.1016/j.tox.2004.11.014
[5] Yoshida, Ikuma, and Yuko Ibuki. “Formaldehyde-induced histone H3 phosphorylation via JNK and the expression of proto-oncogenes.” Mutation research vol. 770 (2014): 9-18. doi:10.1016/j.mrfmmm.2014.09.003
[6] “Triclosan: What It Is & Effects.” Cleveland Clinic, my.clevelandclinic.org/health/articles/24280-triclosan. Accessed on 17 December 2023.
[7] “OPINION OF THE SCIENTIFIC COMMITTEE ON COSMETIC PRODUCTS AND NON-FOOD PRODUCTS INTENDED FOR CONSUMERS CONCERNING ACRYLAMIDE RESIDUES IN COSMETICS ADOPTED BY THE PLENARY SESSION OF THE SCCNFP OF 30 SEPTEMBER 1999.” European Commission Scientific Committees: Expert Panel on Effective Ways of Investing in Health, 30 Sept. 1999, ec.europa.eu/health/scientific_committees/consumer_safety/opinions/sccnfp_opinions_97_04/sccp_out95_en.htm.