Curing of UV prints - Assessment of possible toxicological hazard for consumers

In an experimental setting a laboratory analysis of substances migrating from UV prints under mechanical stress into sweat and saliva simulant was performed. The influence of paper type and curing degree on UV prints was investigated. Five substances were identified at concentrations above the limit of detection in the simulants PPG-3 glyceryl triacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, 2/4-isopropylthioxanthone (ITX), and 2,4-diethylthioxanthone (DETX). Migration of the acrylates and photoinitiators into saliva and sweat simulants were increased when the UV inks were printed on uncoated paper in comparison to coated paper. With an exposure scenario considering a person to leaf through 80 pages of UV-printed paper per day while touching each page with a licked fingertip, Risk Characterisation Ratios (RCR) for oral exposure well below 1 were obtained for all five substances indicating no risk for the general population. The three acrylates are classified for skin sensitisation. The migrated amounts per skin surface area of these three were compared with the EC3 value for a hypothetical substance that could be categorised as strong sensitiser (EC3 = 0.1%). The results show that the risk of skin sensitisation even under worst case conditions can be considered as negligible.