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AGNS home JECFAThe archiveStatistical Evaluation
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Software-based workbook for statistical evaluation of residue depletion data for veterinary drugs
Background
JECFA has used on several occasions a statistical approach for the evaluation
of marker residue depletion data when estimating MRLs. The approach is primarily
based on linear regression analysis and statistical estimation of one-sided
upper tolerance limits for the marker residue depletion in the individual target
tissues. An iterative procedure is then used to calculate for different time
points on the depletion curve the intake of residues of concern in the food
basket. The calculated intake of residues is compared with the ADI and the
time point of depletion below the ADI is selected to determine the MRLs.
At the 62nd meeting of JECFA the FAO Joint Secretariat proposed to the Committee
an Excel-based workbook facilitating the complex calculations required to use
this approach. The Committee investigated the workbook and recommended that
the Secretariat should continue with its development. In order to take the
necessary steps, the Secretariat requested comments from interested parties
on both the features and the documentation of the tool. Comments were received
from Argentina, Canada, the European Medicines Agency (EMEA) and the International
Federation for Animal Health. The Committee reviewed all comments at its 66
th meeting and noted that all respondents agreed that the mathematical/statistical
approach was scientifically sound. Some comments analysed the advantages and
the limitations of the use of the workbook.
The Committee concluded at the 66 th meeting that the workbook would primarily
be of value in assisting the experts to statistically evaluate available depletion
data during the development of MRL recommendations. The Committee also concluded
that it would use the statistical approach in future whenever it was appropriate
and the experts drafting the working documents should explain to the Committee
the reasons when not using it.
Features of the work-book
Linear regression analysis of data describing the terminal depletion
of a suitable marker residue in edible tissues following the (last)
administration of the drug under approved conditions of use;
Subsequent use of the results of the regression analysis for the estimation
of upper limits of the 95% (alternatively, 99%) confidence interval
(CI) for the upper one-sided tolerance limit on the 95th (alternatively, 99th)
percentile of the population sampled;
Iterative calculation of statistical limits, such as a function of time
over the whole phase of terminal elimination of the marker residue;
The statistical method includes a mechanism for the derivation of MRLs
for veterinary drugs from a set of data.
Files for download
Please dowload the tool,
the files that contain examples,
and the documentation as
separate zip files.
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