Controlled Ethyl tert-Butyl Ether (ETBE) Exposure of Male Volunteers: II. Acute Effects

The aim of this study was to evaluate acute effects of ethyltert-butyl ether (ETBE) in man after short-term exposure. ETBEmay in the future replace methyl tert-butyl ether, a widelyused oxygenate in unleaded gasoline. Eight healthy male volunteerswere exposed to ETBE vapor for 2 h at four levels (0, 5, 25,and 50 ppm) during light physical exercise. The subjects ratedirritative symptoms, discomfort, and central nervous systemeffects in a questionnaire. Ocular (eye redness, tear film break-uptime, conjunctival epithelial damage, and blinking frequency),nasal (acoustic rhinometry and analysis of inflammatory markersand cells in nasal lavage fluid), and pulmonary (peak expiratoryflow, forced expiratory volume in 1 s, forced vital capacity,vital capacity, and transfer factor) measurements were performed.Significantly increased ratings of solvent smell (p = 0.001,repeated-measures ANOVA) were seen during exposures and correlatedto exposure levels. Furthermore, significantly elevated ratingsof discomfort in throat and airways were seen during and after50 ppm compared to the control exposure (p = 0.02). Increasednasal swelling (p = 0.001) and blinking frequency (p = 0.01)were noted at all exposure levels, but their magnitudes werenot related to exposure levels. A slightly impaired pulmonaryfunction was seen at 25 and 50 ppm, since forced vital capacity(p = 0.02) and vital capacity (p = 0.04) differed significantlyfrom the clean air exposure. Although the impairments seemedto fall within normal inter- and intraindividual variation andhave no clinical relevance as such, it cannot be excluded thatother individuals may react more severely than eight healthymale volunteers in this study.