Butoxyethanol can be a solvent (helps chemicals dissolve) or a surfactant (create foam/bubbles).
Butoxyethanol is generally found in hair + nail products. It may cause reproductive/developmental toxicity and/or endocrine disruption. It is also a petrochemical, of which are automatically disqualified from MadeWith’s inventory due to their hazardous impact on the environment and human health.
While not banned outright, Butoxyethanol is considered an irritant by the governments of the United States, Canada, and the European Union. The use of this ingredient in personal care products is 10% or less. The Association for Southeast Asian Nations has determined concentration should not exceed 2-4%, depending on the product, and it is not allowed in any aerosol form [2].
[1] The Government of Canada’s “Hot List” https://www.canada.ca/en/health-canada/services/consumer-product-safety/cosmetics/cosmetic-ingredient-hotlist-prohibited-restricted-ingredients/hotlist.html#t2b
[2] ASEAN (Association for Southeast Asian Nations). Annex II Part 1 – List of substances which must not form part of the composition of cosmetic products. Updated (2019). Page 108. https://www.hsa.gov.sg/docs/default-source/hprg-cosmetics/annexes-of-the-asean-cosmetic-directive-(updated-july-2019).pdf
[3] Endocrine Disruption TEDX List of Potential Endocrine Disruptors https://endocrinedisruption.org/popup-chemical-details?chemid=1025
[4] NIH. NCBI. Effects of Subchronic Exposure of Rats to 2-methoxyethanol or 2-butoxyethanol: Thymic Atrophy and Immunotoxicity. (1991). https://pubmed.ncbi.nlm.nih.gov/1715831/
[5] Center For Disease Control. Butoxyethanol warnings. https://www.cdc.gov/niosh/topics/butoxyethanol/default.html