Contamination of animal feed and food from animal origin with mineral oil hydrocarbons

Oils and fats used for the production of animal feed can become contaminated with mineral oil material originating from gas oils (C18-C35) or synthetic oils (poly-alpha olefins, C-25 to beyond C-45). An important cause is assumed to be the discharge of waste oils, such as motor oil and hydraulic oils. Mineral oil material was analysed by on-line LC-GC-FID directly in the fat or in a raw extract from animal feed or foodstuffs. In Switzerland in summer/autumn 1999 concentrations in oils and fats for feed production were often found to be between 100 and 1000 mg/kg. In the feeds, the average concentration was around 100 mg/kg with values ranging up to a maximum of 1000 mg/kg; few samples were free of contamination. In animal body fat, the average concentration determined in summer 1999 was 25 mg/kg, with a maximum of 150 mg/kg, although in samples from December 1999, contamination was substantially lower. In the fat phase of eggs, the average concentration was 30 mg/kg, with a maximum of 80 mg/kg. Paraffin oil is used for feed production, which may account for part of the contamination problem (e.g. eggs).