Table 10. Comparison of Experimental Log KOC Values with Experimental and Estimated Log KOW Values as well as Minimum Log DOW Values (pH 4–9) for Neutral and Ionizable Substancesa.
| M Substances | Not M substances | ||||||
|---|---|---|---|---|---|---|---|
| chemical category | log KOC < 4, log KOW/DOW < 4.5 | log KOC ≥ 4, log KOW/DOW ≥ 4.5 | overall efficiency | linear regression | r2 | rmse | |
| neutral nonpolar | exp. log KOW | 88% | 91% | 89% | log KOC = (0.77 ± 0.02) log KOW + (0.01 ± 0.06) | 0.78 | 0.73 |
| (n = 689 with 82% log KOC ≤ 4.0) | est. log KOW | 85% | 98% | 87% | log KOC = (0.63 ± 0.01) log KOW + (0.33 ± 0.05) | 0.81 | 0.68 |
| neutral polar | exp. log KOW | 92% | 79% | 91% | log KOC = (0.74 ± 0.01) log KOW + (0.06 ± 0.04) | 0.74 | 0.88 |
| (n = 1032with 92% log KOC ≤ 4.0) | est. log KOW | 91% | 90% | 91% | log KOC = (0.57 ± 0.01) log KOW + (0.30 ± 0.04) | 0.67 | 0.99 |
| anionic or ionizes to anion | exp. log KOW | 98% | 57% | 95% | log KOC = (0.27 ± 0.03) log KOW + (1.29 ± 0.07) | 0.19 | 1.36 |
| (n = 487 with 93% log KOC ≤ 4.0) | est. log KOW | 100% | 29% | 95% | log KOC = (0.20 ± 0.02) log KOW + (1.84 ± 0.07) | 0.19 | 1.36 |
| cationic or ionizes to cation | exp. log KOW | 96% | 51% | 93% | log KOC = (0.53 ± 0.03) log KOW + (0.64 ± 0.07) | 0.37 | 1.59 |
| (n = 607 with 93% log KOC ≤ 4.0) | est. log KOW | 100% | 7% | 93% | log KOC = (0.34 ± 0.02) log KOW + (2.00 ± 0.09) | 0.26 | 1.74 |
| zwitterionic/amphoteric | exp. log KOW | 100% | 14% | 91% | log KOC = (0.22 ± 0.09) log KOW + (1.31 ± 0.25) | 0.07 | 2.04 |
| (n = 68 with 91% log KOC ≤ 4.0) | est. log KOW | 100% | 0% | 80% | log KOC = (−0.04 ± 0.06) log KOW + (1.08 ± 0.30) | 0.01 | 2.11 |
a
Shown are log–log regression statistics and the statistical performance of a log KOW or log DOW < 4.5 as a screening parameter for the UBA proposed Mobility (M) criteria of log KOC < 4.0. rmse = root mean square error.