UC San Diego

To increase our understanding of the olfactory and trigeminal (i.e., sensory irritation) impact of chemical mixtures we have studied the binary mixture butyl acetate/toluene. First, we measured complete concentration-response (i.e., psychometric) functions for the odor, nasal pungency, and eye irritation detectability of the single chemicals. Second, we selected fixed detectability levels between chance (p=0.0) and perfect (p=1.0) detection (e.g., p=0.6). Finally, we compared the detection of the single chemicals at the concentration producing these selected levels with the detection of binary mixtures at proportions that, if a rule of dose additivity were to hold, should be as detectable as the single chemicals. The outcome revealed that the degree of dose additivity is larger for the irritation modalities than for the odor modality.