Polyacrylamide is a polymer that is used in a wide variety of cosmetics and personal care products due to its ability to form a thin coating on the skin, hair, or nails.
Polyacrylamide is a polymer (long chain) of acrylamide monomers. The only commercially important polyacrylamide is poly(2-propenamide) which is simply called polyacrylamide or PAM. It is a non-ionic, water-soluble, and biocompatible polymer that can be tailored to meet a broad range of applications. Polyacrylamide can be synthesized as a simple linear-chain structure or cross-linked. In the cross-linked form, the possibility of the monomer (acrylamide) being present is reduced.
One of the largest uses for polyacrylamide is to flocculate solids in a liquid. Polyacrylamide is also used in water, sewage and waste treatment, oil recovery, ore processing paper making, and to make permanent-press fabrics, to synthesize dyes, contact lenses, and in the construction of dams, tunnels and sewers. Polyacrylamide is also present in cigarette smoke.
Polymers, such as polyacrylamide, are often used to change the rheology of water-based formulations, which means they help to increase viscosity, thicken, or gel products. In cosmetics and personal care products, polyacrylamide is used in the formulation of many product types including skin cleansers, moisturizers, lotions and creams, sunscreens, makeup, hair care products, and nail care products.
Polyacrylamide is used in cosmetics and personal care products in two different forms. One is its cross-linked form, which forms a soft gel that is highly water-absorbent. The other is the straight-chain form that functions as a thickener and suspending agent.
When polyacrylamide dries it forms a thin coating on the skin, hair, or nails. In makeup, this function helps to hold together the ingredients of a compressed tablet. In sunscreen products, polyacrylamide aids in keeping the active ingredients of the sunscreen on the skin after immersion in water. Small polyacrylamide beads may be used as an abrasive in skin cleansing and exfoliating products. In hair care products, polyacrylamide helps hair hold its style by inhibiting the hair’s ability to absorb moisture.
Polyacrylamide is a controversial ingredient because acrylamide is a known neurotoxin. While polyacrylamide itself is relatively non-toxic, it is known that commercially available polyacrylamide contains minute residual amounts of acrylamide remaining from its production, usually less than 0.05%.
Polyacrylamide polymers do not penetrate the skin due to their large size, according to a safety report by the International Journal of Toxicology. However, this safety report does state that acrylamide monomer residues do penetrate the skin.
The Food and Drug Administration (FDA) allows polyacrylamide (with less than 0.2% acrylamide monomer) to be used as a film former in the imprinting of soft-shell gelatin capsules. In addition, the FDA also allows polyacrylamide to be used as a denture adhesive which is considered a medical device.
The Cosmetic Ingredient Review (CIR) Expert Panel had previously published a review of the safety of polyacrylamide, concluding that it was safe as a cosmetic ingredient as currently used. However, in 2003 the CIR Expert Panel reassessed the safety of this ingredient because of concern regarding potential effects of residual acrylamide monomer. The CIR Expert Panel reaffirmed the safety of polyacrylamide as a cosmetic ingredient in the practices of use and concentrations, and they recommended that acrylamide monomer in cosmetic and personal care products should be less than 5 ppm. The CIR Expert Panel acknowledged that acrylamide is a demonstrated neurotoxin in humans and a carcinogen in animal tests, but that neurotoxic levels could not be attained by use of cosmetics.
Polyacrylamide was not carcinogenic in several chronic animal studies. Human skin tolerance tests performed to evaluate the irritation of 5% (w/w) polyacrylamide indicated that the compound was well tolerated. According to EWG, polyacrylamide has received a rating of 4 on a 1 to 10 scale, with 1 being the lowest health hazard and 10 being the highest. The highest health concerns are contamination and bioaccumulation, while moderate concerns are organ system toxicity.
References: Polymer Properties Database, “Polyacrylamides”, Wikipedia, “Polyacrylamide”, Campaign for Safe Cosmetics, “Polyacrylamide”, Polymer Solutions, “Polymers and Cosmetics”, Cosmetics Info, “Polyacrylamide”, Int J Toxicol. 2005;24 Suppl 2:21-50, EWG’s Skin Deep Cosmetic Database, “Polyacrylamide”.