Inhalation exposure to low levels of ethyl tertiary butyl ether: Its genetic effects were significantly modified by ALDH2 activity.

Previous experiments showed that high concentrations of ethyl tertiary butyl ether (ETBE) exposure (500-5,000 ppm) significantly resulted in DNA damages in aldehyde dehydrogenase 2 (Aldh2) knockout (KO) mice. This study was aimed to verify the genotoxic effects in three genetic types, Aldh2 KO, heterogeneous (HT), and wild type (WT), of mice exposed to lower concentrations of ETBE (50-500 ppm) by inhalation. Histopathology assessments in the livers, measurements of genotoxic biomarkers in blood and livers, and urinary 8-hydroxydeoxyguanosion (8-OH-dG) for the oxidative DNA damage of whole body were performed. Significant histopathological changes and DNA strand breaks both in hepatocytes and leukocytes were found in HT and KO male mice exposed to ≥200 ppm ETBE, but not in 50 ppm ETBE. 8-OH-dG levels either in liver or urine were higher in the HT and KO male mice exposed to ≥200 ppm ETBE. The pathological and genetic effects of ETBE were almost at the same extents for HT and KO mice. Thus, 50 ppm could be the no observed adverse effect level for ETBE in HT and KO male mice, which was far lower than the 500 ppm in WT mice. These results suggested that decrease and deficiency of ALDH2 activity would significantly increase the sensitivity to ETBE-induced genotoxicity as well as hepatotoxic effects after exposure even to low concentrations of ETBE. Environ. Mol. Mutagen. 60: 145-153, 2019. © 2018 Wiley Periodicals, Inc.