Letterflex photoprepolymer sensitization in newspaper printers due to penta erythritol tetrakis 3 mercaptopropionate and 3 mercaptopropionic acid.

The Letterflex urethane photopolymer mixture contains eight components. The curing agent penta erythritol-tetrakis-3 mercaptopropionate and an auxiliary substance present separately, namely 3 mercaptopropionic acid, gave positive reactions in five patients suffering from occupational contact allergic dermatitis. The mixture contains a third substance to which contact sensitization in a single patient has been described in the literature. This substance did not play any role in the patients' dermatitis. The ways in which the workers come into contact with the liquid form of the prepolymer, which is the sensitizing form of the mixture, are described. Safety measures and complete labelling are advised.