26-27 Jan 2005

1. FOCUS Kinetics training workshop Chapter 7 Recommended Procedures to Derive Endpoints for Parent Compounds Practical Exercise - Answers Ralph L. Warren, Ph.D.DuPont Crop ProtectionDelaware, USA Page 1 26-27 Jan 2005

2. FOCUS Kinetics training workshop Goal of the exercise The goal of this exercise is to calculate the 2 error and to conduct a visual assessment for kinetic model fits to measured levels of parent compound in soil. Based on this information, the most appropriate kinetic model and endpoints for comparison with regulatory triggers and for use in regulatory exposure modelling should be identified. • You will need • ModelMaker 4 results from this morning for Example 1 and Example 2. Try Example 3 if time allows (you will need to first do the optimization using MM4). • Excel file “Parent degradation kinetic training unprotected.xls” • Excel file “t_test.xls” • Excel file “DFOP_DT50.xls” Page 2 26-27 Jan 2005

3. FOCUS Kinetics training workshop • General instructions for the exercise • Follow the parent only flow chart for triggers, then the flow chart for modelling to determine which fits are needed. • Generate optimized results from ModelMaker (record necessary information!) • Create plots for observed versus fitted values and for residuals using Excel (record necessary information!) • Calculate the 2 error percentages using Excel (record!). • Decide which kinetic model and endpoints to use for triggers and for modelling. • Record your conclusions and be prepared to report them to the class. In the interest of time, we will not iteratively modify the fitting routines (e.g. excluding outliers, constraining MO, weighting). Also assume that there are no experimental artifacts (e.g. microbial die off). Page 3 26-27 Jan 2005

4. FOCUS Kinetics training workshop Triggers flowchart 26-27 Jan 2005 Page 4

5. FOCUS Kinetics training workshop Modelling flowchart Page 5 26-27 Jan 2005

6. EXAMPLE 1 – SFO Page 6

7. EXAMPLE 1 - SFO Draw the fitted line to the observed data points.Does the fitted line adequately describe the data? Yes Are there obvious over or under predictions? No Does the line cross the y-axis near the Day 0 data? Yes Other comments? Draw in the residual points (approximate).Do the residuals have a distinct pattern? No Are most of the residual points above or below 0? No Are the residual magnitudes large? Only at early time points. Other comments? Points randomly scattered about the 0 line. Page 7

8. EXAMPLE 1 - FOMC Page 8

9. EXAMPLE 1 - FOMC Draw the fitted line to the observed data points.Does the fitted line adequately describe the data? Yes Are there obvious over or under predictions? No Does the line cross the y-axis near the Day 0 data? Yes Other comments? Draw in the residual points (approximate).Do the residuals have a distinct pattern? No Are most of the residual points above or below 0? No Are the residual magnitudes large? Only at early time points. Other comments? Points randomly scattered about the 0 line. Page 9

10. FOCUS Kinetics training workshop Conclusions – Example 1 Triggers flowchart Most appropriate kinetic model (SFO, FOMC, other): SFO Most appropriate endpoint values (days): DT50 = 13.6 DT90 = 45.4 Modelling flowchart Most appropriate kinetic model (SFO, FOMC, other): SFO Most appropriate endpoint values (days): DT50 = 13.6 Page 10 26-27 Jan 2005

11. EXAMPLE 2 - SFO Page 11

12. EXAMPLE 2- SFO Draw the fitted line to the observed data points.Does the fitted line adequately describe the data? No Are there obvious over or under predictions? Yes Does the line cross the y-axis near the Day 0 data? No, low Other comments? Fitted line under predicts much of the data points, especially after Day 20. Draw in the residual points (approximate).Do the residuals have a distinct pattern? Yes Are most of the residual points above or below 0? Yes, below Are the residual magnitudes large? Yes, most >5% Other comments? Page 12

13. EXAMPLE 2 - FOMC Page 13

14. EXAMPLE 2- FOMC Draw the fitted line to the observed data points.Does the fitted line adequately describe the data? Yes Are there obvious over or under predictions? No Does the line cross the y-axis near the Day 0 data? Yes Other comments? Draw in the residual points (approximate).Do the residuals have a distinct pattern? No Are most of the residual points above or below 0? Trend > 0 Are the residual magnitudes large? Only at early time points. Other comments? Page 14

15. EXAMPLE 2 - DFOP Page 15

16. EXAMPLE 2- DFOP Draw the fitted line to the observed data points.Does the fitted line adequately describe the data? Yes Are there obvious over or under predictions? Slight Does the line cross the y-axis near the Day 0 data? Yes Other comments? Slight under prediction at the last two time points, which are below 10% of the initial measured value. Draw in the residual points (approximate).Do the residuals have a distinct pattern? No Are most of the residual points above or below 0? No Are the residual magnitudes large? Only at early time points. Other comments? Slight trend for residuals to be negative after Day 60. However, the associated magnitude of the residuals is small (5% or less). Page 16

17. FOCUS Kinetics training workshop Conclusions – Example 2 Triggers flowchart Most appropriate kinetic model (SFO, FOMC, other): FOMC Most appropriate endpoint values (days): DT50 = 4.8 DT90 = 47.0 Modelling flowchart Most appropriate kinetic model (SFO, FOMC, other): FOMC Most appropriate endpoint values (days): DT50 = 47.0/3.32 = 14.2 Page 17 26-27 Jan 2005

18. EXAMPLE 3 - SFO Page 18

19. EXAMPLE 3 - SFO Draw the fitted line to the observed data points.Does the fitted line adequately describe the data? Yes Are there obvious over or under predictions? Day 0? Does the line cross the y-axis near the Day 0 data? Yes Other comments? Day 0 could be under predicted. Check Day 0 recoveries from the study (e.g. application monitor data) to rationalize. If ~85% confirmed then okay. If ~100% supported then consider constraining M0 in the fitting. Draw in the residual points (approximate).Do the residuals have a distinct pattern? No Are most of the residual points above or below 0? No Are the residual magnitudes large? Several, up to Day 125. Other comments? Keep in mind that this is a field study, which typically have more variable data than lab studies. This variability is reflected in the residual magnitude. The residual pattern is okay. Page 19

20. EXAMPLE 3 - FOMC Page 20

21. EXAMPLE 3 - FOMC Draw the fitted line to the observed data points.Does the fitted line adequately describe the data? Yes Are there obvious over or under predictions? Day 0? Does the line cross the y-axis near the Day 0 data? Yes Other comments? Day 0 could be under predicted. Check Day 0 recoveries from the study (e.g. application monitor data) to rationalize. If ~85% confirmed then okay. If ~100% supported then consider constraining M0 in the fitting. Draw in the residual points (approximate).Do the residuals have a distinct pattern? No Are most of the residual points above or below 0? No Are the residual magnitudes large? Several, up to Day 125. Other comments? Keep in mind that this is a field study, which typically produce more variable data than lab studies. This variability is reflected in the residual magnitude. The residual pattern is okay. Page 21

22. FOCUS Kinetics training workshop Conclusions – Example 3 Triggers flowchart Most appropriate kinetic model (SFO, FOMC, other): SFO Most appropriate endpoint values (days): DT50 = 40.3 DT90 = 134 Modelling flowchart Most appropriate kinetic model (SFO, FOMC, other): SFO Most appropriate endpoint values (days): DT50 = 40.3 Page 22 26-27 Jan 2005