Decal temporary tattoos, when legally sold in the United States, have had their color additives approved by the U.S. Food and Drug Administration (FDA) as cosmetics --- the FDA has determined these colorants are safe for “direct dermal contact.” While the FDA has received some accounts of minor skin irritation, including redness and swelling, from this type of temporary tattoo, the agency has found these symptoms to be “child specific” and not significant enough to support warnings to the public. Unapproved pigments, however, which are sometimes used by non-US manufacturers, can provoke allergic reactions in anyone. Understanding the types of temporary tattoos available to consumers, knowing where they are manufactured, and ensuring they come from a reliable source are keys to determining whether temporary tattoos are safe.
The word tattoo, or tattow in the 18th century, is a loanword from the Samoan word tatau, meaning "to strike". The Oxford English Dictionary gives the etymology of tattoo as "In 18th c. tattaow, tattow. From Polynesian (Samoan, Tahitian, Tongan, etc.) tatau. In Marquesan, tatu." Before the importation of the Polynesian word, the practice of tattooing had been described in the West as painting, scarring or staining.