Draize Eye Scores and Eye Irritation Thresholds in Man Combined into one Quantitative Structure–Activity Relationship

Draize eye scores (DES) for 37 pure organic liquids have been converted into scores for the corresponding vapours, DES/Po, where Po is the liquid vapour pressure in ppm at 298 K. It is shown that there is a constant difference (0.66) between values of log(DES/Po) and log(1/EIT) where EIT is the eye irritation threshold in ppm of eight vapours towards human subjects. The 37 log(DES/Po) values can be combined with 17 log(1/EIT) values to give one quantitative structure-activity relationship, Log SP = -7.918 – 0.482 R2 + 1.420 p2 H   + 4.025 ∑aH 2   + 1.219 ∑b2 H   + 0.853 log L16          [i] n = 54, r2 = 0.928, r2 CV = 0.913, sd = 0.36, F = 124 where R2 is an excess molar refraction, p2 H is the compound polarizability/dipolarity, ∑aH 2 and ∑b2 H are the compound hydrogen-bond acidity and basicity, and L16 is the gas-hexadecane partition coefficient. The number of data points is n, the correlation coefficient is r, the standard deviation is sd, and F is the F-statistic. LogSP is then either [log(DES/Po) - 0.66], or log(1/EIT). It is suggested that equation i can be used to predict eye irritation of organic vapours and pure liquids as eye irritation thresholds