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 41 Tier overview for module Concentration models.
Name EFSA 2012 Optimistic EFSA 2012 Pessimistic - Acute EFSA 2012 Pessimistic - Chronic EC 2018 Tier 1 EC 2018 Tier 2

Default concentration model

Empirical

NonDetectSpikeLogNormal

NonDetectSpikeLogNormal

Empirical

Empirical

Include MRL fallback model

false

true

true

false

false

Non-detects replacement

ReplaceByZero

ReplaceByLOR

ReplaceByLOR

ReplaceByLOR

ReplaceByLOR

Sample based

true

true

true

true

true

Impute missing values from available values (if unchecked, missing values are imputed with 0)

false

true

true

true

true

Correlate imputed values with sample potency

false

true

true

true

false

Use occurrence frequencies for imputation

false

true

true

Parametric uncertainty

false

true

false

false

false

Restrict LOR imputation to authorised uses

false

false

false

false

Factor f (f x LOR)

1

1

0.5

0.5

MRL Factor (f x MRL)

1

1

Apply occurrence pattern percentages

false

true

Substance conversion method

UseMostToxic

DrawRandom

Retain all allocated substances after active substance allocation

true

true

Account for substance authorisations in substance conversions

false

true

Use extrapolation rules

true

true

Threshold for extrapolation

10

10

Restrict extrapolations to equal MRLs

true

true

Restrict extrapolations to authorised uses

true

true

Impute water concentrations

true

true

Water concentration value (µg/kg)

0.1

0.05

Restrict water imputation to the five most toxic substances

true

true

Restrict water imputation to authorised uses

false

false

Scale up use frequency to 100%

true

Restrict use percentage up-scaling to authorised uses

true

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

EFSA 2012 Optimistic

Use the optimistic model settings according to the EFSA Guidance 2012. Non-detects and missing values are replaced by zero.

Table 42 Tier definition for EFSA 2012 Optimistic.
Name Setting

Default concentration model

Empirical

Include MRL fallback model

false

Non-detects 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 Pessimistic - Acute

Concentration model settings for acute pessimistic dietary exposure assessments according to the EFSA Guidance 2012. A non-detect spike lognormal model is fitted to the positive residue values and non-detects 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 43 Tier definition for EFSA 2012 Pessimistic - Acute.
Name Setting

Default concentration model

NonDetectSpikeLogNormal

Include MRL fallback model

true

Restrict LOR imputation to authorised uses

false

Non-detects replacement

ReplaceByLOR

Factor f (f x LOR)

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 Pessimistic - Chronic

Concentration model settings for acute pessimistic dietary exposure assessments according to the EFSA Guidance 2012. A non-detect spike lognormal model is fitted to the positive residue values and non-detects 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 44 Tier definition for EFSA 2012 Pessimistic - Chronic.
Name Setting

Default concentration model

NonDetectSpikeLogNormal

Include MRL fallback model

true

Restrict LOR imputation to authorised uses

false

Non-detects replacement

ReplaceByLOR

Factor f (f x LOR)

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 Tier 1

Table 45 Tier definition for EC 2018 Tier 1.
Name Setting From input tier In module
Default concentration model Empirical
Include MRL fallback model false
Restrict LOR imputation to authorised uses false
Non-detects replacement ReplaceByLOR
Factor f (f x LOR) 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 Tier 1 Occurrence patterns
Substance conversion method UseMostToxic EC 2018 Tier 1 Concentrations
Retain all allocated substances after active substance allocation true EC 2018 Tier 1 Concentrations
Account for substance authorisations in substance conversions false EC 2018 Tier 1 Concentrations
Use extrapolation rules true EC 2018 Tier 1 Concentrations
Threshold for extrapolation 10 EC 2018 Tier 1 Concentrations
Restrict extrapolations to equal MRLs true EC 2018 Tier 1 Concentrations
Restrict extrapolations to authorised uses true EC 2018 Tier 1 Concentrations
Impute water concentrations true EC 2018 Tier 1 Concentrations
Water concentration value (µg/kg) 0.1 EC 2018 Tier 1 Concentrations
Restrict water imputation to the five most toxic substances true EC 2018 Tier 1 Concentrations
Restrict water imputation to authorised uses false EC 2018 Tier 1 Concentrations

EC 2018 Tier 2

Table 46 Tier definition for EC 2018 Tier 2.
Name Setting From input tier In module
Default concentration model Empirical
Include MRL fallback model false
Restrict LOR imputation to authorised uses false
Non-detects replacement ReplaceByLOR
Factor f (f x LOR) 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 Tier 2 Occurrence patterns
Scale up use frequency to 100% true EC 2018 Tier 2 Occurrence patterns
Restrict use percentage up-scaling to authorised uses true EC 2018 Tier 2 Occurrence patterns
Substance conversion method DrawRandom EC 2018 Tier 2 Concentrations
Retain all allocated substances after active substance allocation true EC 2018 Tier 2 Concentrations
Account for substance authorisations in substance conversions true EC 2018 Tier 2 Concentrations
Use extrapolation rules true EC 2018 Tier 2 Concentrations
Threshold for extrapolation 10 EC 2018 Tier 2 Concentrations
Restrict extrapolations to equal MRLs true EC 2018 Tier 2 Concentrations
Restrict extrapolations to authorised uses true EC 2018 Tier 2 Concentrations
Impute water concentrations true EC 2018 Tier 2 Concentrations
Water concentration value (µg/kg) 0.05 EC 2018 Tier 2 Concentrations
Restrict water imputation to the five most toxic substances true EC 2018 Tier 2 Concentrations
Restrict water imputation to authorised uses false EC 2018 Tier 2 Concentrations

EFSA 2012 Pessimistic

Note

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

Concentration model settings for pessimistic dietary exposure assessments according to the EFSA Guidance 2012. A non-detect spike lognormal model is fitted to the positive residue values and non-detects 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 Pessimistic.
Name Setting

Default concentration model

NonDetectSpikeLogNormal

Include MRL fallback model

true

Restrict LOR imputation to authorised uses

false

Non-detects replacement

ReplaceByLOR

Factor f (f x LOR)

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