Table 1: Summary of ET50 values. The proportional data were arcsine square root transformed and the ET50 calculated using maximum-likelihood probit or logit analysis. WW1–WW5: samples of watercress wash water. P1–P5: samples of PEITC solution.

SampleET50 (minutes)95% confidence intervals

WW177*73–85
WW2106*103–110
WW38978–102
WW58472–93
P14838–56
P2119108–133
P38577–92
P54020–56

*Calculated using logit model—all others with probit.