Subchronic oral methyl tertiary butyl ether (MTBE) exposure in male Sprague-Dawley rats and effects on health of MTBE exposed workers

Abstract

Methyl tertiary-butyl ether (MTBE) is used to reduce carbon monoxide and ozone in urban air and to boost fuel octane. There are yet no data on the toxicity and health effects of MTBE in China. To evaluate the possible toxicity of domestic MTBE, 40 male, 8-week-old Sprague-Dawley rats, weighing 180-200 g, were gavaged with different concentrations of MTBE. MTBE, dissolved in soybean oil, was administered at doses of 1000, 600 or 200 mg/kg b.w., and a control group with soybean oil, once daily, five days per week, for 90 days. There were no marked differences in body weight growth and food intake among the 4 groups. The results showed that MTBE significantly increased the weights of liver and kidneys, but the levels of serum enzymes and proteins were not greatly changed. No apparent pathological changes in the main organs (liver, kidneys, testes, and lungs) were found by light microscopy, but electron microscopy analysis showed significant changes in liver cells of all treatment groups, including cell nuclear condensation, fat drops and lysosomes in cells, and smooth endoplasmic reticulum (SER) dispersion. The effects on the health of 96 MTBE occupationally exposed workers and 102 controls were also investigated by a questionnaire, and we found that workers who reported health complaints in MTBE exposed group (62 cases, 64.6%) were significantly more numerous (P