The in vitro activity of carboxylesterase recovered from the nasal mucosal tissue of B6C3F1/CrlBR mice toward several agents known to cause olfactory epithelial lesions when inhaled by rodents was determined. Apparent Vmax and Km values were obtained for mouse nasal carboxylesterase using ethylene glycol monomethyl ether acetate (EGMEAc), ethylene glycol monoethyl ether acetate (EGEEAc), propylene glycol monomethyl ether acetate (PGMEAc), methyl acrylate (ME), ethyl acrylate (EA), and butyl acrylate (BA) as substrates. The short straight-chained glycol ethers, EGMEAc and EGEEAc, appeared to be relatively good substrates for nasal carboxylesterase under enzyme saturating and subsaturating conditions as indicated by their high Vmax and Vmax/Km values. The short-chained acrylate esters MA and EA were also hydrolyzed to a greater extent than BA at enzyme-saturating levels; however, the reverse was true at subsaturating levels as indicated by the relatively high Vmax/Km ratio obtained for BA. MA and BA were observed to cause a loss of carboxylesterase activity at enzyme saturation levels while EA caused a loss of enzyme activity at only one-half Km concentration. Using EGMEAc as a substrate, no sex differences in nasal carboxylesterase activity were observed in mice or rabbits. The specific activity of nasal carboxylesterase was found to be equivalent to that of the liver and greater than that of the kidney, lung, or blood. Mice and dogs were found to have similar nasal carboxylesterase activities which were slightly higher than that found in rats and about six-fold higher than that found in rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)