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diff --git a/vignettes/web_only/NAFTA_examples.Rmd b/vignettes/web_only/NAFTA_examples.Rmd new file mode 100644 index 00000000..26a9240a --- /dev/null +++ b/vignettes/web_only/NAFTA_examples.Rmd @@ -0,0 +1,243 @@ +--- +title: "Evaluation of example datasets from Attachment 1 to the US EPA SOP for the NAFTA guidance" +author: "Johannes Ranke" +date: "`r Sys.Date()`" +output: + html_document: + toc: true + toc_float: + collapsed: false + mathjax: null + fig_retina: null +references: +- id: usepa2015 + title: Standard Operating Procedure for Using the NAFTA + Guidance to Calculate Representative Half-life Values and Characterizing + Pesticide Degradation + author: + - family: US EPA + type: report + issued: + year: 2015 + url: https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/standard-operating-procedure-using-nafta-guidance +vignette: > + %\VignetteIndexEntry{Example evaluation of FOCUS Laboratory Data L1 to L3} + %\VignetteEngine{knitr::rmarkdown} + %\VignetteEncoding{UTF-8} +--- + +# Introduction + +In this document, the example evaluations provided in Attachment 1 to the SOP +of US EPA for using the NAFTA guidance [@usepa2015] are repeated using mkin. +The original evaluations reported in the attachment were performed using PestDF +in version 0.8.4. Note that PestDF 0.8.13 is the version distributed at the US +EPA website today (2019-02-26). + +The datasets are now distributed with the mkin package. + +```{r, include = FALSE} +library(knitr) +opts_chunk$set(tidy = FALSE, cache = FALSE, fig.height = 7) +library("mkin", quietly = TRUE) +``` + +# Examples where DFOP did not converge with PestDF 0.8.4 + +In attachment 1, it is reported that the DFOP model does not converge for these +datasets when PestDF 0.8.4 was used. For all four datasets, the DFOP model can +be fitted with mkin (see below). The negative half-life given by PestDF 0.8.4 +for these fits appears to be the result of a bug. The results for the other +two models (SFO and IORE) are the same. + +## Example on page 5, upper panel + +```{r p5a} +p5a <- nafta(NAFTA_SOP_Attachment[["p5a"]]) +plot(p5a) +print(p5a) +``` + +## Example on page 5, lower panel + +```{r p5b} +p5b <- nafta(NAFTA_SOP_Attachment[["p5b"]]) +plot(p5b) +print(p5b) +``` + +## Example on page 6 + +```{r p6} +p6 <- nafta(NAFTA_SOP_Attachment[["p6"]]) +plot(p6) +print(p6) +``` + +## Example on page 7 + +```{r p7} +p7 <- nafta(NAFTA_SOP_Attachment[["p7"]]) +plot(p7) +print(p7) +``` + +# Examples where the representative half-life deviates from the observed DT50 + +## Example on page 8 + +For this dataset, the IORE fit does not converge when the default starting values +used by mkin for the IORE model are used. Therefore, a lower value for the rate +constant is used here. + +```{r p8} +p8 <- nafta(NAFTA_SOP_Attachment[["p8"]], parms.ini = c(k__iore_parent_sink = 1e-3)) +plot(p8) +print(p8) +``` + +# Examples where SFO was not selected for an abiotic study + +## Example on page 9, upper panel + +```{r p9a} +p9a <- nafta(NAFTA_SOP_Attachment[["p9a"]]) +plot(p9a) +print(p9a) +``` + +In this example, the residuals of the SFO indicate a lack of fit of this model, +so even if it was an abiotic experiment, the data do not suggest a simple +exponential decline. + +## Example on page 9, lower panel + +```{r p9b} +p9b <- nafta(NAFTA_SOP_Attachment[["p9b"]]) +plot(p9b) +print(p9b) +``` + +Here, mkin gives a longer slow DT50 for the DFOP model (17.8 days) than +PestDF (13.5 days). Presumably, this is related to the fact that +PestDF gives a negative value for the proportion of the fast degradation +which should be between 0 and 1, inclusive. This parameter is called +f in PestDF and g in mkin. In mkin, it is restricted to the interval from +0 to 1. + +## Example on page 10 + +```{r p10} +p10 <- nafta(NAFTA_SOP_Attachment[["p10"]]) +plot(p10) +print(p10) +``` + +Here, a value below N is given for the IORE model, because the data +suggests a faster decline towards the end of the experiment, which +appears physically rather unlikely in the case of a photolysis study. +It seems PestDF does not constrain N to values above zero, thus +the slight difference in IORE model parameters between PestDF and +mkin. + +# The DT50 was not observed during the study + +## Example on page 11 + +```{r p11} +p11 <- nafta(NAFTA_SOP_Attachment[["p11"]]) +plot(p11) +print(p11) +``` + +In this case, the DFOP fit reported for PestDF resulted +in a negative value for the slower rate constant, which is +not possible in mkin. The other results are in agreement. + +# N is less than 1 and the DFOP rate constants are like the SFO rate constant + +In the following three examples, the same results are obtained with mkin as +reported for PestDF. As in the case on page 10, the N values below 1 are deemed +unrealistic and appear to be the result of an overparameterisation. + + +## Example on page 12, upper panel + +```{r p12a} +p12a <- nafta(NAFTA_SOP_Attachment[["p12a"]]) +plot(p12a) +print(p12a) +``` + +## Example on page 12, lower panel + +```{r p12b} +p12b <- nafta(NAFTA_SOP_Attachment[["p12b"]]) +plot(p12b) +print(p12b) +``` + +## Example on page 13 + +```{r p13} +p13 <- nafta(NAFTA_SOP_Attachment[["p13"]]) +plot(p13) +print(p13) +``` + +# DT50 not observed in the study and DFOP problems in PestDF + +```{r p14} +p14 <- nafta(NAFTA_SOP_Attachment[["p14"]]) +plot(p14) +print(p14) +``` + +The slower rate constant reported by PestDF is negative, which is not +physically realistic, and not possible in mkin. The other fits give the same +results in mkin and PestDF. + +# N is less than 1 and DFOP fraction parameter is below zero + +```{r p15a} +p15a <- nafta(NAFTA_SOP_Attachment[["p15a"]]) +plot(p15a) +print(p15a) +``` + +```{r p15b} +p15b <- nafta(NAFTA_SOP_Attachment[["p15b"]]) +plot(p15b) +print(p15b) +``` + +In mkin, only the IORE fit is affected (deemed unrealistic), as the fraction +parameter of the DFOP model is restricted to the interval between 0 and 1 in +mkin. The SFO fits give the same results for both mkin and PestDF. + +# The DFOP fraction parameter is greater than 1 + +```{r p16} +p16 <- nafta(NAFTA_SOP_Attachment[["p16"]]) +plot(p16) +print(p16) +``` + +In PestDF, the DFOP fit seems to have stuck in a local minimum, as mkin finds +a solution with a much lower $\chi^2$ error level. As the half-life from the +slower rate constant of the DFOP model is larger than the IORE derived half-life, +the NAFTA recommendation obtained with mkin is to use the DFOP representative +half-life of 8.9 days. + +# Conclusions + +The results obtained with mkin deviate from the results obtained with PestDF +either in cases where one of the interpretive rules would apply, i.e. the +IORE parameter N is less than one or the DFOP k values obtained with PestDF are +equal to the SFO k values, or in cases where the DFOP model did not converge, +which often lead to negative rate constants returned by PestDF. + +Therefore, mkin appears to suitable for kinetic evaluations according to the +NAFTA guidance. + +# References |