Formaldehyde and formaldehyde “releasers” are preservatives that can be found in many skincare products. It is not usually listed as an ingredient; formaldehyde “releasers” are listed on labels as:
Formaldehyde is a known carcinogen and is linked to skin irritation including scalp burns and hair loss. Formaldehyde releasers (and associated compounds) can also be problematic for aquatic life as they don’t always break down and have been found in lakes, streams, and seas.
According to the Obelis Group “Formaldehyde has been recommended to be classified as a mutagen of category 2 (may induce heritable mutations) and a category 1B carcinogen (presumed human carcinogen) by the European Chemical Agency (ECHA), since December 2012. This reclassification is to be adopted from the 1st of January 2016…” 
The U.S. state of California introduced AB 495, the “Toxic-Free Cosmetics Act” in 2019. It aims to ban asbestos, lead, formaldehyde, and 17 other toxic chemicals in cosmetics. The bill is still in process and would be the first of its kind in the United States if passed .
 State of California. AB 495, “Toxic-Free Cosmetics Act”. (2019). https://leginfo.legislature.ca.gov/faces/billTextClient.xhtml?bill_id=201920200AB495
 Obelis Group. Formaldehyde in Cosmetics – What You Should Know. (2016). https://www.obelis.net/news/formaldehyde-in-cosmetics-what-you-should-know
 Canada’s Cosmetic Ingredient Hotlist. (2019). https://www.canada.ca/en/health-canada/services/consumer-product-safety/cosmetics/cosmetic-ingredient-hotlist-prohibited-restricted-ingredients/hotlist.html#tbl1
 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). https://www.hsa.gov.sg/docs/default-source/hprg-cosmetics/annexes-of-the-asean-cosmetic-directive-(updated-july-2019).pdf
 Center For Disease Control. Medical Management Guidelines for Formaldehyde. https://www.atsdr.cdc.gov/mmg/mmg.asp?id=216&tid=39