90-Tage-Inhalationstoxizitätsprüfung von Di-n-butylamin an Wistar(WU)-Ratten

Aim of the study was to investigate the potential toxic effects of di-n-butylamine (DBA) as an example of a skin and eye irritating compound after inhalation exposure over 91 days in rats [Crl: (WI) WU BR] with special emphasis on irritation of the respiratory tract. To check wether and to what degree the no observed (adverse) effect level (NO(A)EL) decreases with increasing study duration, serial sacrifices were performed after 3 and 28 days, respectively. Based on two dose range finding studies, the concentration for this study were determined with 0 (clean air), 50, 150, and 450 mg/m3. Animals were exposed for 5 days per week (6 hours/day) and killed after 3, 28, and 91 days, respectively. The results show that clear irritating effects could only be shown in the upper part of the respiratory tract, in the nasal cavities. While after 3 and 28 days effects were found only in the high dose group, slight adaptive effects, expressed as mucous (goblet) cell hyperplasia, could be diagnosed in the medium and low dose groups after 91 days of exposure. Pathological changes were most prominent after 3 days of exposure. In the lung, only marginal effects could be observed (increased relative lung weight only in females of the high concentration after 28 days, slight, not statistically significant histopathological effects, no effects on BAL).