Concentration models tiers

In addition to the possibility for users to work with their own choices for all settings, MCRA implements four tiers from two documents:

The optimistic and pessimistic basic assessments from the EFSA 2012 Guidance on the Use of Probabilistic Methodology for Modelling Dietary Exposure to Pesticide Residues (EFSA (2012)).
Tier 1 and 2 from the European Commission working document SANTE-2015-10216 rev. 7 (2018) on risk management aspects related to the assessment of cumulative exposure (EC (2018)).

Overview

Table 45 Tier overview for module Concentration models.
Name	EFA 2012 Optimistic	EFA 2012 Acute Pessimistic	EFA 2012 Chronic Pessimistic	EC 2018 Tier I	EC 2018 Tier II	EFSA 2022 Tier I	EFSA 2022 Tier II
Default concentration model	Empirical	NonDetectSpikeLogNormal	NonDetectSpikeLogNormal	Empirical	Empirical	Empirical	Empirical
Include MRL fallback model	false	true	true	false	false	false	false
Censored values replacement	ReplaceByZero	ReplaceByLOR	ReplaceByLOR	ReplaceByLOR	ReplaceByLOR	ReplaceByLOR	ReplaceByLOR
Sample based	true	true	true	true	true	true	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	false	true	true	true	true	true	true
Correlate imputed values with sample potency	false	true	true	true	false	true	false
Use occurrence frequencies for imputation	false			true	true	true	true
Parametric uncertainty	false	true	false	false	false	false	false
Restrict LOR imputation to authorised uses		false	false	false	false	false	false
Factor f (f x LOR or f x LOD or LOD + f x (LOQ - LOD)		1	1	0.5	0.5	0.5	0.5
MRL Factor (f x MRL)		1	1
Apply occurrence pattern percentages				false	true	false	true
Substance conversion method				UseMostToxic	DrawRandom	UseMostToxic	DrawRandom
Retain all allocated substances after active substance allocation				true	true	true	true
Account for substance authorisations in substance conversions				false	true	false	true
Fix duplicate substance allocation inconsistencies				false	false	false	false
Use extrapolation rules				true	true	false	false
Threshold for extrapolation				10	10
Restrict extrapolations to equal MRLs				true	true
Restrict extrapolations to authorised uses				true	true
Impute water concentrations				true	true	true	true
Water concentration value (µg/kg)				0.1	0.05	0.1	0.05
Restrict water imputation to the five most toxic substances				true	true	true	true
Restrict water imputation to authorised uses				false	false	false	false
Restrict water imputation to approved substances				false	false	true	true
Scale up use frequency to 100%					true		true
Restrict use percentage up-scaling to authorised uses					true		true
Use substance conversion rules						true	true

The sections below describe the settings specified by each tier in detail.

EFSA 2012 Dietary exposure assessment - Optimistic

Concentration model settings according to the optimistic scenario of the EFSA 2012 methodology for dietary exposure assessments. Censored values and missing values are replaced by zero.

Table 46 Tier definition for EFSA 2012 Dietary exposure assessment - Optimistic.
Name	Setting
Default concentration model	Empirical
Include MRL fallback model	false
Censored values replacement	ReplaceByZero
Sample based	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	false
Correlate imputed values with sample potency	false
Use occurrence frequencies for imputation	false
Parametric uncertainty	false

EFSA 2012 Acute dietary exposure assessment - Pessimistic

Concentration model settings according to the pessimistic scenario of the EFSA 2012 methodology for acute dietary exposure assessments. A censored value spike lognormal model is fitted to the positive residue values and censored values are replaced by the LOR. When the number of positives is smaller than 2, the maximum residue limit (if available) is used instead. Missing values are imputed.

Table 47 Tier definition for EFSA 2012 Acute dietary exposure assessment - Pessimistic.
Name	Setting
Default concentration model	NonDetectSpikeLogNormal
Include MRL fallback model	true
Restrict LOR imputation to authorised uses	false
Censored values replacement	ReplaceByLOR
Factor f (f x LOR or f x LOD or LOD + f x (LOQ - LOD)	1
MRL Factor (f x MRL)	1
Sample based	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	true
Correlate imputed values with sample potency	true
Parametric uncertainty	true

EFSA 2012 Chronic dietary exposure assessment - Pessimistic

Concentration model settings according to the pessimistic scenario of the EFSA 2012 methodology for chronic dietary exposure assessments. A censored value spike lognormal model is fitted to the positive residue values and censored values are replaced by the LOR. When the number of positives is smaller than 2, the maximum residue limit (if available) is used instead. Missing values are imputed.

Table 48 Tier definition for EFSA 2012 Chronic dietary exposure assessment - Pessimistic.
Name	Setting
Default concentration model	NonDetectSpikeLogNormal
Include MRL fallback model	true
Restrict LOR imputation to authorised uses	false
Censored values replacement	ReplaceByLOR
Factor f (f x LOR or f x LOD or LOD + f x (LOQ - LOD)	1
MRL Factor (f x MRL)	1
Sample based	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	true
Correlate imputed values with sample potency	true
Parametric uncertainty	false

EC 2018 Dietary CRA Tier I

Table 49 Tier definition for EC 2018 Dietary CRA Tier I.
Name	Setting	From input tier	In module
Default concentration model	Empirical
Include MRL fallback model	false
Restrict LOR imputation to authorised uses	false
Censored values replacement	ReplaceByLOR
Factor f (f x LOR or f x LOD or LOD + f x (LOQ - LOD)	0.5
Sample based	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	true
Correlate imputed values with sample potency	true
Use occurrence frequencies for imputation	true
Parametric uncertainty	false
Apply occurrence pattern percentages	false	EC 2018 Dietary CRA Tier I	Occurrence patterns
Substance conversion method	UseMostToxic	EC 2018 Dietary CRA Tier I	Concentrations
Retain all allocated substances after active substance allocation	true	EC 2018 Dietary CRA Tier I	Concentrations
Account for substance authorisations in substance conversions	false	EC 2018 Dietary CRA Tier I	Concentrations
Fix duplicate substance allocation inconsistencies	false	EC 2018 Dietary CRA Tier I	Concentrations
Use extrapolation rules	true	EC 2018 Dietary CRA Tier I	Concentrations
Threshold for extrapolation	10	EC 2018 Dietary CRA Tier I	Concentrations
Restrict extrapolations to equal MRLs	true	EC 2018 Dietary CRA Tier I	Concentrations
Restrict extrapolations to authorised uses	true	EC 2018 Dietary CRA Tier I	Concentrations
Impute water concentrations	true	EC 2018 Dietary CRA Tier I	Concentrations
Water concentration value (µg/kg)	0.1	EC 2018 Dietary CRA Tier I	Concentrations
Restrict water imputation to the five most toxic substances	true	EC 2018 Dietary CRA Tier I	Concentrations
Restrict water imputation to authorised uses	false	EC 2018 Dietary CRA Tier I	Concentrations
Restrict water imputation to approved substances	false	EC 2018 Dietary CRA Tier I	Concentrations

EC 2018 Dietary CRA Tier II

Table 50 Tier definition for EC 2018 Dietary CRA Tier II.
Name	Setting	From input tier	In module
Default concentration model	Empirical
Include MRL fallback model	false
Restrict LOR imputation to authorised uses	false
Censored values replacement	ReplaceByLOR
Factor f (f x LOR or f x LOD or LOD + f x (LOQ - LOD)	0.5
Sample based	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	true
Correlate imputed values with sample potency	false
Use occurrence frequencies for imputation	true
Parametric uncertainty	false
Apply occurrence pattern percentages	true	EC 2018 Dietary CRA Tier II	Occurrence patterns
Scale up use frequency to 100%	true	EC 2018 Dietary CRA Tier II	Occurrence patterns
Restrict use percentage up-scaling to authorised uses	true	EC 2018 Dietary CRA Tier II	Occurrence patterns
Substance conversion method	DrawRandom	EC 2018 Dietary CRA Tier II	Concentrations
Retain all allocated substances after active substance allocation	true	EC 2018 Dietary CRA Tier II	Concentrations
Account for substance authorisations in substance conversions	true	EC 2018 Dietary CRA Tier II	Concentrations
Fix duplicate substance allocation inconsistencies	false	EC 2018 Dietary CRA Tier II	Concentrations
Use extrapolation rules	true	EC 2018 Dietary CRA Tier II	Concentrations
Threshold for extrapolation	10	EC 2018 Dietary CRA Tier II	Concentrations
Restrict extrapolations to equal MRLs	true	EC 2018 Dietary CRA Tier II	Concentrations
Restrict extrapolations to authorised uses	true	EC 2018 Dietary CRA Tier II	Concentrations
Impute water concentrations	true	EC 2018 Dietary CRA Tier II	Concentrations
Water concentration value (µg/kg)	0.05	EC 2018 Dietary CRA Tier II	Concentrations
Restrict water imputation to the five most toxic substances	true	EC 2018 Dietary CRA Tier II	Concentrations
Restrict water imputation to authorised uses	false	EC 2018 Dietary CRA Tier II	Concentrations
Restrict water imputation to approved substances	false	EC 2018 Dietary CRA Tier II	Concentrations

EFSA 2022 Dietary CRA Tier I

Table 51 Tier definition for EFSA 2022 Dietary CRA Tier I.
Name	Setting	From input tier	In module
Default concentration model	Empirical
Include MRL fallback model	false
Restrict LOR imputation to authorised uses	false
Censored values replacement	ReplaceByLOR
Factor f (f x LOR or f x LOD or LOD + f x (LOQ - LOD)	0.5
Sample based	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	true
Correlate imputed values with sample potency	true
Use occurrence frequencies for imputation	true
Parametric uncertainty	false
Apply occurrence pattern percentages	false	EFSA 2022 Dietary CRA Tier I	Occurrence patterns
Use substance conversion rules	true	EFSA 2022 Dietary CRA Tier I	Concentrations
Substance conversion method	UseMostToxic	EFSA 2022 Dietary CRA Tier I	Concentrations
Retain all allocated substances after active substance allocation	true	EFSA 2022 Dietary CRA Tier I	Concentrations
Account for substance authorisations in substance conversions	false	EFSA 2022 Dietary CRA Tier I	Concentrations
Fix duplicate substance allocation inconsistencies	false	EFSA 2022 Dietary CRA Tier I	Concentrations
Use extrapolation rules	false	EFSA 2022 Dietary CRA Tier I	Concentrations
Impute water concentrations	true	EFSA 2022 Dietary CRA Tier I	Concentrations
Water concentration value (µg/kg)	0.1	EFSA 2022 Dietary CRA Tier I	Concentrations
Restrict water imputation to the five most toxic substances	true	EFSA 2022 Dietary CRA Tier I	Concentrations
Restrict water imputation to authorised uses	false	EFSA 2022 Dietary CRA Tier I	Concentrations
Restrict water imputation to approved substances	true	EFSA 2022 Dietary CRA Tier I	Concentrations

EFSA 2022 Dietary CRA Tier II

Table 52 Tier definition for EFSA 2022 Dietary CRA Tier II.
Name	Setting	From input tier	In module
Default concentration model	Empirical
Include MRL fallback model	false
Restrict LOR imputation to authorised uses	false
Censored values replacement	ReplaceByLOR
Factor f (f x LOR or f x LOD or LOD + f x (LOQ - LOD)	0.5
Sample based	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	true
Correlate imputed values with sample potency	false
Use occurrence frequencies for imputation	true
Parametric uncertainty	false
Apply occurrence pattern percentages	true	EFSA 2022 Dietary CRA Tier II	Occurrence patterns
Scale up use frequency to 100%	true	EFSA 2022 Dietary CRA Tier II	Occurrence patterns
Restrict use percentage up-scaling to authorised uses	true	EFSA 2022 Dietary CRA Tier II	Occurrence patterns
Use substance conversion rules	true	EFSA 2022 Dietary CRA Tier II	Concentrations
Substance conversion method	DrawRandom	EFSA 2022 Dietary CRA Tier II	Concentrations
Retain all allocated substances after active substance allocation	true	EFSA 2022 Dietary CRA Tier II	Concentrations
Account for substance authorisations in substance conversions	true	EFSA 2022 Dietary CRA Tier II	Concentrations
Fix duplicate substance allocation inconsistencies	false	EFSA 2022 Dietary CRA Tier II	Concentrations
Use extrapolation rules	false	EFSA 2022 Dietary CRA Tier II	Concentrations
Impute water concentrations	true	EFSA 2022 Dietary CRA Tier II	Concentrations
Water concentration value (µg/kg)	0.05	EFSA 2022 Dietary CRA Tier II	Concentrations
Restrict water imputation to the five most toxic substances	true	EFSA 2022 Dietary CRA Tier II	Concentrations
Restrict water imputation to authorised uses	false	EFSA 2022 Dietary CRA Tier II	Concentrations
Restrict water imputation to approved substances	true	EFSA 2022 Dietary CRA Tier II	Concentrations

EFSA 2012 Dietary exposure assessment - Pessimistic

Note

This tier is deprecated and has been replaced by separate acute/chronic tiers.

Concentration model settings according to the pessimistic scenario of the EFSA 2012 methodology for dietary exposure assessments. A censored value spike lognormal model is fitted to the positive residue values and censored values are replaced by the LOR. When the number of positives is smaller than 2, the maximum residue limit (if available) is used instead. Missing values are imputed.

Table 53 Tier definition for EFSA 2012 Dietary exposure assessment - Pessimistic.
Name	Setting
Default concentration model	NonDetectSpikeLogNormal
Include MRL fallback model	true
Restrict LOR imputation to authorised uses	false
Censored values replacement	ReplaceByLOR
Factor f (f x LOR or f x LOD or LOD + f x (LOQ - LOD)	1
MRL Factor (f x MRL)	1
Sample based	true
Impute missing values from available values (if unchecked, missing values are imputed with 0)	true
Correlate imputed values with sample potency	true
Parametric uncertainty	true