The expiratory bradypnea indicative of upper airway irritation in mice was evaluated during a 15-min oronasal exposure to increasing concentrations of sixteen aliphatic amines. The airborne concentration resulting in a 50% decrease in the respiratory rate of mice ( R D ~~) was calculated for each test compound. Moreover, the sixteen amines were tested for pulmonary irritation by measuring the decrease in respiratory rate of (nonanaesthetized) tracheally cannulated mice ( R D ~~ TC). The R D ~~ and R D ~ TC values and their ratios were related to n-octanouwater partition coefficients (log 0. The R D ~ values associated with exposure to saturated amines ranged from 17 to 300 ppm. The RDsoTC values for these saturated amines ranged from 35 to 489 ppm. The RD50 and R D ~~T C
values of saturated amines were closely related to the n-octanoywater partition coefficient, indicating that the more lipophilic amines are more irritant for the upper and lower respiratory tracts. The RD~oTC/RDSO values were much less closely related to the n-octanol/water partition coefficient.
Based on the results, tentative standards are suggested for the studied amines.
Chemicals
The sixteen amines tested included isopropylamine, n-propylamine, isobutylamine, diisopropylamine, nbutylamine, cyclohexylamine, di-n-propylamine, npentylamine, tert-octylamine, n-hexylamine, diisobutyl-