Evaluation and Application of the RD sub(50) for Determining Acceptable Exposure Levels of Airborne Sensory Irritants for the General Public

Application of the concentration inducing a 50% decrease in respiratory frequency (RD sub(50)) for determining acceptable exposure levels of airborne sensory irritants for the general public was evaluated. Exposure guidelines to protect workers and the public focused on mild irritating signs or symptoms. The availability of RD sub(50)s in male mice for 89 chemicals, and their correlation with occupational exposure levels (OELs) suggested potential applicability to air exposure guidelines for the public. A strong correlation was found between RD sub(50)s and lowest observed adverse effect levels (LOAELs), threshold limit values (TLVs), and California reference exposure levels (RELs). The correlation remained close to 0.8 after conducting various subanalyses, indicating that the strains of mice or the RD sub(50) exposure time did not substantially affect the correlation.