Tosylamide/formaldehyde resin

TSFR is produced by condensing (often impure, containing ) with formaldehyde. It consists of a mixture of short oligomers with repeating unit , terminated by or groups. ==Allergenicity==

Nail polishes containing TSFR were first introduced in 1939, becoming a major cause of allergic contact dermatitis of the eyelids, face, and neck. Allergic responses are caused by the water-soluble contaminants 5-tosyl-1,3,5-dioxazinane () and 3,5-ditosyl-1,3,5-oxadiazinane (), rather than formaldehyde, which is only present in trace quantities (<0.5%). Since the early 2010s, the prevalence of allergic reactions to TSFR has decreased, due to the widespread use of hypoallergenic alternatives such as tosylamide/epoxy resin (first introduced in the late 1980s), cellulose acetate butyrate, and polyester resins (e.g. –isophthalic acid–trimellitic anhydride). ==References==