UC San Diego

Draize eye scores (DES) of 37 pure organic liquids have been converted into scores for the corresponding vapors, DES/P⁰, where P⁰ is the liquid vapor pressure in atmospheres at 298K. It is shown that there is a constant difference of 6.7 between values of log(DES/P⁰) and log(1/ET), where ET is the eye irritation threshold in ppm of eight vapors for human subjects. The 37 log(DES/P⁰) values can be combined with log(1/ET) values for 17 vapors into one QSAR for sensory potency (SP) using our general solvation equation,

logSP = -7.979 + 1.016(pi)₂ ^H + 3.678 ∑(alpha)₂ ^H +1.730 ∑(beta)₂ ^H + 0.838 logL¹⁶

n = 54,            r2 = 0.924,                         sd = 0.369,      F = 149.3,

where (pi)₂ ^H is the compound polarizability-dipolarity, ∑(alpha)₂ ^H and ∑(beta)₂ ^H are the compound hydrogen-bond acidity and basicity, and logL¹⁶ is the gas-hexadecane partition coefficient. n is the number of data points, r the correlation coefficient, sd the standard deviation, and F the F-statistic. LogSP is then either log(DES/P⁰ - 6.7), or log(1/ET), confirming the result for the eight common compounds. It is suggested that eq. i can be used to predict eye irritancy of organic vapors and pure liquids. It is further suggested that for the compounds in the data set, the main process in eye irritation is transfer of the compound from the vapor or pure liquid to a biological phase, and a number of chemical properties of the biological phase have been mapped out through eq. i. These properties are consistent with corresponding properties for a number of organic liquid phases.