Effects of subchronic methyl tert-butyl ether ether exposure on male Sprague-Dawley rats

Abstract

Methyl tert-butyl ether (MTBE) is an additive used to oxygenate gasoline to improve air quality by reducing tailpipe emissions of carbon monoxide and ozone precursors. Although several toxicity studies in rats have been conducted to examine the acute, subchronic, and chronic toxicities by employing various routes of exposure to MTBE, few data were available on the effects of MTBE exposure on blood. In this study, MTBE was administered to rats at dose levels of 0, 400, 800, and 1600 mg/kg/day, respectively. After 2- or 4-weeks treatment period, rats were euthanized and blood was collected for the assay of hematological indicators and blood biochemistry indicators. Some organs, including brain, heart, liver, spleen, lung, kidneys, testes, epididymis, thymus, and prostate, were immediately removed and weighed. Possible subchronic health effects of MTBE exposure by gavage were evaluated on mortality, body weight, relative organ weight, hematology, and blood biochemistry indicators in male Sprague-Dawley rats. The results indicated that MTBE did not disrupt the growth rate of rats. Relative organ weight showed change in heart, liver, kidney, testes, thymus, and prostate. In the 2-week treatment, MTBE exerted toxicity on white blood cell count, including lymphocyte, granulocyte, and eosinophil. This finding was especially strong at 1600 mg/kg/day MTBE. In the 4-week treatment, hemoglobin at high dose MTBE significantly increased. The results of the assay for the biochemistry indicators and relative organ weight indicated that MTBE could impair liver and kidney functions and also have adverse effects on lipid metabolism and immune system. It was conducted that subchronic MTBE exposure induced the adverse effects occurring in the relative organ weight, the hematological indicators, and the biochemistry indicators under high MTBE dose.

Relationship between Methyl Tertiary Butyl Ether Exposure and Non-Alcoholic Fatty Liver Disease: A Cross-Sectional Study among Petrol Station Attendants in Southern China

“…At the same time, there was no significant association between MTBE exposure and the prevalence of NAFLD separately in men and women ( p > 0.05, as shown in Table 2). Therefore, although the acute, subchronic, and chronic toxic effects of MTBE, such as lipid disorder [11], abnormal liver function [11], and oxidative stress [6,7,8], etc., were found in animal tests, there is no significant evidence showing an association between MTBE exposure and the prevalence of NAFLD in humans in our study. Of course, there were some limitations to this study, the first being that the exposure concentrations of MTBE among the subjects were relatively low (did not exceed the ACGIH TLV® of MTBE, 50 ppm); thus, it can hardly shed light on the association between relatively high exposure concentrations of MTBE and the prevalence of NAFLD.…”

“…Epidemiological investigation revealed that there was a significant positive correlation between ambient air concentrations and blood levels of MTBE [2,5]. The acute, subchronic, and chronic toxicities of MTBE have been explored, and the toxic effects of oxidative stress [6,7,8], DNA damage [5,6,7,8], DNA adducts [9,10], lipid disorder [11], abnormal liver functions [11], vascular lesions [12], and malignant tumors [13] induced by MTBE were found in animal tests. However, there is apparent uncertainty in the extrapolation of animal data to effects on humans [1,14,15].…”

“…However, there was not sufficient evidence showing the reliable links between MTBE exposure and these complaints [17,18,19,20]. Because MTBE can cause the adverse effects of oxidative stress [6,7,8], lipid disorder [11], and abnormal liver functions [11] in animal models, we are interested in whether MTBE exposure is a risk factor for non-alcoholic fatty liver disease (NAFLD) in humans, which has not been reported.…”

Interaction of insulin with methyl tert -butyl ether promotes molten globule-like state and production of reactive oxygen species

“…There are many reports that MTBE causes leukemia, liver, kidney, and Leydig cells testicular tumors [4][5][6][7][8][9]. In addition, limited epidemiological and clinical examinations show that MTBE adversely affects human health, and causes several symptoms including aversion to the smell, headache, dizziness, nasal and ocular irritation when individuals are exposed to gasoline-containing MTBE [10][11][12].…”