Migration of di(2-ethylhexyl) maleate from cardboard boxes into foods

Di(2-ethylhexyl) maleate (DEHM) is a non-evaluated substance newly detected in the majority of the printed cardboard boxes used for food packaging. Concentrations in the board are often sufficient for a migration into food of around 1 mg/kg. This level was reached after storage over several months and in the absence of a functional barrier (such as a layer of aluminum). The maximum concentration determined in food was 1,500 mu g/kg, even though the end of the shelf life of the product was not reached. DEHM is probably the non-reacted starting material in di(2-ethylhexyl) sulfosuccinate, which is used at concentrations of several percent as an emulsifier for water-based varnishes. A minor contribution is from recycled fibers, presumably contaminated through the same route. DEHM was absent in printing inks and almost all adhesives tested. No toxicological facts are available for DEHM. Through comparison with similar substances, the German BfR Committee for Consumer Products recommended a temporary migration limit of 50 mu g/kg, whereas the Swiss Federal Office of Public Health concluded on a lower toxicity. The case shows that impurities in components used for printing cardboard may migrate at concentrations demanding substantial compliance work.