"Cosmetics often contain formaldehyde or a formaldehyde releasing substance. The formaldehyde acts as a preservative in the cosmetics. In the United States many cosmetics contain Quaternium 15, which is a formaldehyde releasing agent. Quaternium 15 and other formaldehyde releasing materials are found in shampoos, conditioners, deodorant soap, hairspray, styling mousse, fluoride toothpastes, mouthwash, mascara, talcum powders,haircolors, makeup foundations, firming facial creams and fingernail polish. Even "Natural" cosmetics such as those marketed by Garden Botanika™ contain diazolidinyl urea, which is another formaldehyde-releasing preservative." (Source Link
Formaldehyde Cosmetics. What you do not know can hurt you!
*Formaldehyde is a carcinogen. I.e. causes cancer. That is why the sciences no longer use the chemical in preservation of tissues, etc.. Further, Formaldehyde is used to preserve clothings shelf life. This is why it is vital one wash new clothes before wearing them! Also, this chemical is one of the culprits at work in "Contact Dermatitis"