Inks used for printing paper and cardboard are dispersions of synthetic organic pigments in a bonding agent system built up essentially of resins, vegetable oils and high-boiling-point mineral oil products (b.p. >250°C). The proportion of mineral oil material in the ink ranges between 20 and 30%. The more volatile mineral oil components slowly evaporate from the printed cardboard box and may migrate into the food product. They contaminated cereals and dry baby-food products at concentrations between 10 and 150 mg/kg.