Long-term chronic bioassays from

Long-term chronic bioassays from animal studies ... 

Results of the database surveys proposed that rats were more sensitive then mice and that tumorigeni-city detected in mice only was never the sole reason for regulatory action. Furthermore, findings in rats only were twice as frequent as in mice only all known human carcinogens were positive in rats. Therefore, it was proposed that normally one long-term study in one rodent species would suffice. The species should be the most appropriate and on practical convenience, the rat would be preferred. From the European point of view, one chronic bioassay in the rat would be sufficient. However from the US perspective, an additional short-term study was requested. The shortterm models are further explained later in this article. 

Results of chronic MTBE exposure studies are the most widely available of all studies on the ether-like fuel oxygenates (MTBE, ETBE, TAME, DIPE). Evidence from animal bioassays demonstrates that long-term, high-level exposures to MTBE by either ingestion or inhalation cause cancer in rodents. Inhalation exposure to MTBE produced an increased incidence of renal and testicular tumors in male rats and liver tumors in mice. Oral administration of MTBE produced an increased incidence of lymphomas and leukemias in female rats and testicular tumors in male rats. Chronic exposure to ethanol also produces cancers (e.g., esophageal) in laboratory animals. 

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