Formation of Methanol and Formate in Wistar Rats after Oral Administration of Methylated Rapeseed Oil: A Fuel for Lamps

Abstract

Low viscosity, low surface tension and low volatility are features of lamp oils contributing to chemical pneumonia that can occur after ingestion. Because lamp oils with such physico-chemical properties have been forbidden in the European Community from July 2000 onward, industry has developed different products, mostly based upon rapeseed oil. The fatty acids of these oils are methylated. The goal of this study is to demonstrate whether methanol is released in Wistar rats after oral administration of these new lamp oils. Applying a dose of 1 ml/kg body weight lamp oil, peak levels of methanol were reached at 1 h (54.6 ± 18.6 μg/ml), methanol was not detectable at 8 h. After the instillation of 4 ml/kg of lamp oil peak levels occurred at 2 h (189.2 ± 24.9 μg/ml). The metabolite formate increased with time, and was highest at 8 h after the administration of 1 ml/kg body weight lamp oil (32.9 ± 2.9 μg/ml). Starvation before the administration of 1 ml/kg body weight lamp oil decreased the methanol serum concentrations, but the differences were not significant. Based upon these experimental data in rats, it can be concluded that in humans small amounts of methanol will be released after ingestion of these lamp oils. As these products are mainly ingested accidentally by toddlers in low quantities, the risk of a methanol intoxication seems to be very low.