The study was designed to investigate the biological effects of six mineral oils and three petroleum waxes representative of those used in food processing and food contact application. The oil samples were chosen to reflect differences in crude oil source (naphthenic or paraffinic origin), route of manufacture (acid or hydrogenated process) and viscosity. The waxes were selected on the basis of method of manufacture and melting point. An oil of biological origin (coconut oil) was included as a control material. Groups of 20 male and female Fischer 344 rats were fed diets containing one of six different white mineral oils (N15 (H), N70 (H), N70 (A), P15 (H), N10 (A), and P100 (H)) or one of three different mineral waxes (a low melting point wax, a high melting point wax and a high sulphur wax) at dose levels of 0.002%, 0.02%, 0.2% and 2.0% for 90 days. Groups of 60 males and 60 females were fed the control diet for the same period of time. A further group of 20 males and 20 females were fed diet containing 2% coconut oil as an oil of biological origin for comparison. These animals comprised the main study. Additional groups of 10 males and 10 females were fed diet containing test article at the 2% levels or coconut oil at the 2% level for 90 days followed by a 28 day period on control diet. Groups of 30 male and 30 female animals were fed control diet for the same period of time. These animals comprised the reversal study.