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BookletJECFA Toolbox for Veterinary Drug Residues Risk Assessment
Section 4.1. JECFA’s approach for assessing dietary exposure to veterinary drug residues: Estimating total residues for use in dietary exposure assessment
2024By this point, you will understand the roles of both the total residue and marker residue depletion studies. Consult the guidance document to: • review how the M:T ratios are calculated in edible tissues at any time point after drug administration; and• see how total residue estimates are calculated based on the marker residue depletion and M:T data. This publication is part of the FAO JECFA Toolbox for Veterinary Drug Residue Risk Assessment. The toolbox provides practical guidance on the principles, modalities and technical requirements of JECFA in assessing the risks of veterinary drug residues in food and in recommending MRLs. -
BookletJECFA Toolbox for Veterinary Drug Residues Risk Assessment
Section 3.2. Marker residues and the marker to total residue ratio
2024Regulatory authorities need to monitor for residues of veterinary drugs in food. Monitoring laboratories cannot easily quantify “total” drug residues. To detect total residues, the monitoring laboratory would need assays that detect and quantify all residue components (i.e. every metabolite). Rather than attempting to monitor total residues in food, the regulatory agencies instead monitor for a marker residue (MR). Consult the guidance document to learn about:• the characteristics of a suitable MR with examples for different types of MRs; • the relationship between marker residues and total residues, particularly how the ratio of marker to total (M:T) residues varies between edible tissues and over time; and• alternative approaches to total residue assessment, such as the residue of concern (RoC) and related concepts like bioavailability and bioaccessibility.This publication is part of the FAO JECFA Toolbox for Veterinary Drug Residue Risk Assessment. The toolbox provides practical guidance on the principles, modalities and technical requirements of JECFA in assessing the risks of veterinary drug residues in food and in recommending MRLs. -
BookletJECFA Toolbox for Veterinary Drug Residues Risk Assessment
Section 3.4. Estimating median and tolerance limit values for marker residues
2024To estimate human dietary exposure to veterinary drug residues and establish maximum residue limits (MRLs), derivation of median residue concentration and upper tolerance limit (UTL) is necessary. The first value represents a typical residue concentration for the entire dataset of concentrations measured in samples (e.g. tissue, milk, eggs) from individual animals over a range of time periods. UTL values are calculated to consider those samples in which marker residues are present at concentrations higher than average levels, potentially posing a higher risk to consumers.Consult the guidance document on median and tolerance limit values for marker residues to: • plot the residue concentrations graphically and determine the median residue concentrations in edible tissues at any time point after drug administration, using the hypothetical data set provided; • learn about the concept of UTL residues (95/95 UTL, the upper limit of the one-sided 95% confidence interval over the 95th percentile of marker residue concentrations); and• see how the design of the marker residue depletion study influences the resulting 95/95 UTL, with subsequent impacts on the derivation of maximum residue levels.This publication is part of the FAO JECFA Toolbox for Veterinary Drug Residue Risk Assessment. The toolbox provides practical guidance on the principles, modalities and technical requirements of JECFA in assessing the risks of veterinary drug residues in food and in recommending MRLs.
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