Toxicity Profile for Methyl tert-butyl ether (1997)

Abstract

Neat methyl tert-butyl ether (MTBE) was slightly irritant to the skin and eyes of rabbits. The vapour caused eye irritation in rats and mice, and inflammation of the upper respiratory tract in rats. Repeated injection of a dilute solution did not induce sensitization in guinea-pigs. MTBE was of low acute toxicity to laboratory animals when administered orally, dermally or by inhalation. Single doses given by the oral, inhalation or injection routes have affected the central nervous system and blood circulation in laboratory animals. Repeated oral or inhalation administration to rats and mice produced effects on the central nervous system, liver, lungs, blood and kidney (including hyaline droplet formation in male rats). Inhalation by pregnant mice resulted in foetal toxicity and malformations, effects which were not observed in similar studies in rats and rabbits. In long-term inhalation studies, MTBE induced kidney tumours in male rats, and liver tumours in mice, whilst a dietary study in rats yielded equivocal carcinogenicity findings (in the testes and, in females, the blood and lymphatic system). MTBE has generally shown no genotoxic activity in rodents exposed orally or by inhalation, in mammalian cells treated in culture, or in mutagenicity assays in bacteria (Ames tests), yeast and fruit flies.

In humans, there have been anecdotal reports of headaches, nausea, dizziness and respiratory irritation in garage workers or commuters exposed to MTBE in petrol, but these observations have not been confirmed in studies using controlled conditions of exposure to pure MTBE. The use of MTBE in the treatment of gall stones by direct instillation into the gall bladder has produced transient side effects (including nausea, vomiting and sedation).