Numerical Benchmarks for protecting biota against radiation in the environment Methodology to derive benchmarks, selected methods used in PROTECT and Results PROTECT FP6-036425
Download ReportTranscript Numerical Benchmarks for protecting biota against radiation in the environment Methodology to derive benchmarks, selected methods used in PROTECT and Results PROTECT FP6-036425
Slide 1
Numerical Benchmarks for
protecting biota against
radiation in the environment
Methodology to derive benchmarks, selected
methods used in PROTECT and Results
PROTECT
FP6-036425
Slide 2
Methods to derive benchmarks (reminder)
3 main methodologies :
(1) Deterministic : based on application of Assessment
Factor to critical ecotoxicity data, or
(2) Probabilistic : based on Species Sensitivity
Distribution (SSD) approach associated with an
arbitrary cut-off value, usually set at a protection level of
95% of the species, and the use of an additional AF,
(3) a weight of evidence approach using effect data from
field exposures
(1) & (2) based on critical ecotoxicity values from tests in lab
e.g., EC10 (preferred to NOEC) : stressor level in a given medium giving 10% effect in the
exposed group in comparison to the control group for chronic exposure.
(1) to (3) usually applied for chemical substances to derive PNEC (e.g., TGD, 2003)
Concerning RAS:
(1) and (2) applied and compared within ERICA to derive PNEDR (Garnier-laplace et al., 2006)
(1) used by Environment Canada (2003) for radionuclides
(3) used by Thompson et al. (2005) for multipollution context (radionuclides + metals)
PROTECT
FP6-036425
Slide 3
Methods used within PROTECT
• Following PROTECT Consultation and
availability of various EDR10 values (from ERICA and
follow up), SSD method adopted when data sets
were adequate (quality and quantity)
(1) allow to make the best use of the available most relevant knowledge in a
transparent way,
(2) allow to quantify the associated uncertainty,
(3) easily allow to revise the outcoming values when new knowledge
becomes available
• Need to incorporate documented expert
judgement at various stages
(1) when selecting ecotoxicity data (EDR10 in our case),
(2) when selecting a cut-off value to estimate the Hazardous Dose Rate of
interest (HDR5),
(3) when applying an AF to obtain the final benchmark (PNEDR).
PROTECT
FP6-036425
Slide 4
The 3-step method used
STEP 1 – Compiling quality assessed exposure-effect data
FREDERICA
Radiation Effect Database
Effect (%)
Data sorted per ecosystem, per exposure condition, per
bibliographic reference and per test . Quality of data describing each
test was assessed against 3 criteria (dosimetry, exp. Design, stats).
Multi-rules applied to accept or reject each data set
STEP 2 – Building dose rate-effect relationships to
estimate critical ecotoxicity values EDR10
100 %
50 %
Dose-effect relationship was built for each accepted test.
The quality of the fitted model was judged before accepted
EDR10. Two models tested (logistic/hormetic)
10 %
EDR50
EDR10
Dose Rate (µGy/h)
PAF (% of Affected Species)
100
80
60
40
Dose Rate (µGy/h)
20
0
1
10
100 1000 10000
PROTECT
STEP 3 – Deriving benchmarcks
Application of SSD on the estimated toxicity values accepted
after step 2.
Application or not of the taxonomic weighted options
Application of an AF to the HDR5 to obtain the final benchmark
FP6-036425
Slide 5
EDR10 from logistic models
Data set for one test
(a test is defined as a consistent group of (dose or dose rate, effect) couples from a given species and a given
effect, examined under defined exposure conditions (duration, irradiation pathway)
Logistic model
The data set is made of:
at least 3 different couples (dose or dose rate, effect) including one for the control group (no dose(rate))
at least two different couples if the effect is analysed relatively to the control.
YES
Effect
Control
(response at dose rate 0)
NO
data set is rejected
The variation of effect with dose (or dose rate) is monotonous.
The pattern is consistent with the state-of-the-art on the tested effect
YES
NO
data set is rejected
The maximum effect value in case it was not reached during the test can be fixed theoretically if knowledge on such
effect is sufficient. The difference between the maximum effect value observed y(MaxObs) during the test and the
theoretical one y(MaxTheo) are used to calculate the extrapolation percentage needed to model dose-effect relationship
as follows : %Extrapol = 100 *(y(MaxObs) – y(MaxTheo))/(y(ControlObs) – y(Maxtheo)) where y(ControlObs) is the
effect value observed for the control group.
EDR10
Dose rate (µGy/h)
EDR10
YES
NO
data set is rejected
At least one couple is located within the 10 to 90% of the variation of effect observed. This latter is defined as
(y(ControlObs)-y(MaxObs))
YES
NO
data set is rejected
The Estimated ED50 or EDR10 are between two experimental couples.
YES
NO
data set is rejected
The Estimated ED50 or EDR10 can be used within a SSD analysis.
PROTECT
FP6-036425
Slide 6
EDR10 from hormetic models
Dose-response exhibiting an initial response stimulation or an effect minimisation
Curve shape
« Hormetic » model
NOEC definition
Inverted U shaped
curve
Selection criteria
Control
(response at dose rate 0)
NOEC definition
U shaped curve
EDR10
Exclusion criteria
Selection criteria
the highest dose with a response ≥ 90% of the control
- at least 5 dose-response data points (the minimal number to fit a
hormesis model with 4 parameters, requires fixing the lower limit to 0)
- 1 control data point
- at least 2 doses ≤ NOEC with a response numerically higher than the
control
- 1 NOEC
- at least 1 dose > NOEC with a response ≤ 90% of control
the highest dose with a response ≤ 110% of the control
- at least 6 dose-response data points (the minimal number to fit a
hormesis model with 5 parameters; lower and upper limit are different to
0)
- 1 control point
- at least 2 doses ≤ NOEC with a response numerically lower than the
control
- 1 NOEC
- at least 1 dose > NOEC with a response ≥ 110 % of control
(1) the absence of a relevant control;
(2) the incapacity to achieve responses greater than (or less than,
depending on end point) the control response (e.g., studies where the end
point was survival and the control response was 100% or where the end
point was tumour incidence and the control response was zero);
(3) at least two doses below the NOEC;
(4) at least one dose showing a priori criteria-based inhibition.
Dose rate (µGy/h)
PROTECT
FP6-036425
Slide 7
STEP 1 – EDR10 selection (1/4)
•ERICA : 82 EDR10 obtained for chronic g external exposure
meeting the previous criteria, covering 18 species (5 plants, 9
invertebrates, 10 vertebrates) and various effect endpoints
grouped as one geometric mean per effect category
(mortality, morbidity, reproduction) and per species (ie. for a
given species, a single value per category of effect (the GM)-> this allows to ignore
intra-species variation for the same effect category)
SSD on 24 GM -> HDR5=82 µGy/h [24-336]
•PROTECT : 104 EDR10 obtained for chronic g external
exposure meeting the previous criteria, covering 23 species (6
plants, 8 invertebrates, 9 vertebrates) and various effect
endpoints
PROTECT
FP6-036425
Slide 8
STEP 1 – EDR10 selection (2/4)
•Among those 104 EDR10,
•One single endpoint per species (the lowest value)
•Relevance for population sustainability but expert
discussion on ecological relevancy of some of them
•To illustrate the sensitivity of the SSD method and the derived
screening level dose rate, two sets of EDR10 selected:
« repro » list: most sensitive reproduction endpoint per
species (at the population level -i.e. include juvenile survival)
« ecol » list: most relevant with regard to « direct » ecological
interpretation
PROTECT
FP6-036425
Slide 9
STEP 1 – EDR10 selection (3/4)
« repro » list : 19 EDR10
ID
WildlifeGroup
Taxo
µGy/h
SpeciesL
EffectDescription
EDR10
Daphnia magna
Larval survival to starvation during 5 days, brood 1 (% survival when food lacks) - stress on stress
test of indirect effect on energy allocation to juveniles production
18537
Gilbin
Crustaceans
Invertebrates
1065
Crustaceans
Invertebrates
Daphnia pulex
Population birth rate (per day) Data read from graph
277633
247
Crustaceans
Invertebrates
Porcellio scaber
Mean number of offspring per tank per dose rate group
1030
Hertel-Aas
Annelid
Invertebrates
Eisenia foetida
Hatchlings per adult during the whole 13 weeks reproduction exposure period (F1/ Adult F0)
3369
296
Molluscs
Invertebrates
Mercenaria mercenaria
Survival of juvenile clams (%) on day 426. Dose = max. cumulative dose
119117
361
Annelid
Invertebrates
Ophryotrocha diadema
The percentage of worms in generation 3 surviving to day 62.
2359
326
Molluscs
Invertebrates
Physa heterostropha
Percentage of eggs that hatched
61229
523
841
Plants
Plants
Plants
Plants
Abies balsamea
Fagopyrum esculentum
Summary of mean fir characteristics for seven dose-rate catergories, Number of buds (1975),
Productivity in M3 generation (1979), Yield of seeds (g/sq m)
2945
X
40151
416
998
Plants
Plants
Plants
Plants
Pinus rigida
Triticum sinskjae
Effect of long term irradiation on seed development. Dose rate provided as average per day
Productive bush amount, % of the control value. N 13, K-48993 T. sinskjae var. Sinskajae
710
6434
X
998
Plants
Plants
Triticum monococcum
Productive bush amount, % of the control value. N 3, K-29602 T. monococcum var. Atriaristatum
8573
X
616
Egami
207
Mammals
Fish
Fish
Vertebrates
Vertebrates
Vertebrates
Mus musculus
Oryzias latipes
Pleuronectes platessa
Nº of litters per fertile female during 245 days (mean; SE).
Male mean gonad weight (mg)
Mean proportion of plaice testes occupied by different cell types irradiated for 197 days - sperm
26
19730
X
53
X
74
593
621
629
Fish
Mammals
Mammals
Mammals
Vertebrates
Vertebrates
Vertebrates
Vertebrates
Poecilia reticulata
Rattus norvegicus
Spanish goat
Sus crofa
Mean life time fecundity
A1 Spermatogonia ( % of control)
Total sperm production (% of control): 730 days irradiation
Testis weight (g) at 70 days of age (+- SE)
516
24
X
12
X
6.7
X
PROTECT
FP6-036425
Slide 10
STEP 1 – EDR10 selection (4/4)
« ecol » list : 14 EDR10
Omission of endpoints with difficult ecological interpretation (no direct
link with reproductive success) e.g., bud production, gonad weight,
µGy/h
sperm cell or spermagonia count
ID
WildlifeGroup
Taxo
SpeciesL
EffectDescription
EDR10
Gilbin
Crustaceans
Invertebrates
Daphnia magna
Larval survival to starvation during 5 days, brood 1 (% survival when food lacks) - stress on stress
test of indirect effect on energy allocation to juveniles production
18537
1065
Crustaceans
Invertebrates
Daphnia pulex
Population birth rate (per day) Data read from graph
277633
247
Crustaceans
Invertebrates
Porcellio scaber
Mean number of offspring per tank per dose rate group
1030
Hertel-Aas
Annelid
Invertebrates
Eisenia foetida
Hatchlings per adult during the whole 13 weeks reproduction exposure period (F1/ Adult F0)
3369
296
Molluscs
Invertebrates
Mercenaria mercenaria
Survival of juvenile clams (%) on day 426. Dose = max. cumulative dose
119117
361
Annelid
Invertebrates
Ophryotrocha diadema
The percentage of worms in generation 3 surviving to day 62.
2359
326
841
Molluscs
Plants
Invertebrates
Plants
Physa heterostropha
Fagopyrum esculentum
Percentage of eggs that hatched
Productivity in M3 generation (1979), Yield of seeds (g/sq m)
61229
40151
416
998
Plants
Plants
Plants
Plants
Pinus rigida
Triticum monococcum
Effect of long term irradiation on seed development. Dose rate provided as average per day
Fertility, % of the control value. N 15, K-23653 T. monococcum var. Hornemanni
710
9819
616
Mammals
Vertebrates
Mus musculus
Nº of litters per fertile female during 245 days (mean; SE).
26
74
622
204
Fish
Mammals
Fish
Vertebrates
Vertebrates
Vertebrates
Poecilia reticulata
Spanish goat
Oryzias latipes
Mean life time fecundity
Number born per female (in 5 consecutive gestation: see comment)
Number of surviving fish
516
1968
90861
PROTECT
FP6-036425
Slide 11
STEP 2 - SSD-fit to the selected list (1/3)
• Repro-list
SSWD - Log Normal
R² = 0.9583
KSpvalue = 0.500
Sp = unw eighted; TW: none
w m.lg = 3.24
w sd.lg = 1.41
100%
HDR5 = 8.4 µGy/h
CI 95% = [1.4;99]
Cumulative weighted probability
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
0,1
1
10
100
1000
10000
100000
1000000 10000000
Concentration
Dose
rate (µGy/h)
PROTECT
Best-Estimate
Centile 5%
Plants
Invertebrates
Centile 95%
Vertebrates
FP6-036425
Slide 12
STEP 2 - SSD-fit to the selected list (2/3)
• Ecol-list
SSWD - Log Normal
R² = 0.9625
KSpvalue = 0.500
w m.lg = 3.81
w sd.lg = 1.12
Sp = unw eighted; TW: none
HDR5 = 91 µGy/h
CI 95% = [11;710]
100%
Cumulative weighted probability
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
1
10
100
1000
10000
100000
1000000
10000000
Concentration
Dose
rate (µGy/h)
PROTECT
Best-Estimate
Centile 5%
Plants
Invertebrates
Centile 95%
Vertebrates
FP6-036425
Slide 13
STEP 2 - SSD-fit to the selected list (3/3)
Taxonomic weight options to fit SSD
Influence of the proportion of tested species from different taxonomic groups
(trophic levels) on the HDR5 while giving the same weight to each
trophic/taxonomic group
Repro
Ecol
Number of EDR10 Number of species Taxonomic Weight
19
19
No (5 P; 7 I; 7 V)
Yes (1 P; 1 I; 1 V)
14
14
No (3 P; 7 I; 4 V)
Yes (1 P; 1 I; 1 V)
HDR5
8.4
11
91
72
min
1.4
1.8
11
8.0
max
99
159
710
566
For the repro-list, applying the same weight for each TG means to decrease the
proportion of the most radiosensitive group from 37% (7/19) to 33% (equiprobability) ->
HDR5 increases slightly
Ecol-case : V from 28% to 33% -> HDR5 decreases
PROTECT
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Slide 14
STEP 3 - Screening generic dose rates
(in µGy/h)
Rounded to the nearest 10
Weight option
HDR5
min
max
AF
PNEDR
Generic Screening Value
Repro
No
8.4
1.4
99
1
8.4
10
Ecol
Yes
No
11
91
1.8
11
159
710
1
5
11
18
10
20
Yes
72
8.0
566
5
14
10
•AF= from 1 to 5 according to the TGD
- taxonomic coverage
- coverage of the inter-species sensitivity
- ecological relevancy of endpoints
- line of evidence from field
- final value compared to background
e.g., 0.1 to 6 µGy/h for marine organisms (Brown et al., 2004)
0.4 to 4 ________freshwater______________________
0.07 to 0.6______terrestrial________(Beresford et al. in press)
PROTECT
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Slide 15
STEP 3 - Screening generic dose rates
(in µGy/h)
Rounded to the nearest 10
Weight option
HDR5
min
max
AF
PNEDR
Generic Screening Value
Repro
No
8.4
1.4
99
1
8.4
10
Ecol
Yes
No
11
91
1.8
11
159
710
1
5
11
18
10
20
Yes
72
8.0
566
5
14
10
•For illustration purpose: AF=1 for the repro-list and 5 for the ecol-list
generic screening level recommended by PROTECT : 10 µGy/h
PROTECT
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Slide 16
STEP 3’ – Taxonomic screening dose rates
(in µGy/h)
•Data were insufficient to create an SSD for the 3 basic taxonomic groups (plants(5),
invertebrates(7), vertebrates(7))
•A limited sensitivity analyses of the overall SSD suggested that the only statistically
justifiable separation was to remove vertebrates leaving an SSD for plants and
invertebrates (with a total of 12 data points)
Weight option
Non-Vertebrates No (5 P;2 I-M;2 I-A; 3 I-C)
Yes (same weight per group)
HDR5
min
max
AF
PNEDR
Taxonomic Screening Value
449
166
1791
1
449
450
503
167
1858
1
503
500
•We suggest that a taxonomic screening level of 450 µGy/h be used for plants and
invertebrates in refined assessments if the results of the screening tier assessment
suggest this is required. For vertebrates, a taxonomic screening level of 10 µGy/h
(i.e. the generic screening level) is recommended.
PROTECT
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Slide 17
Regulatory action level
• The statistical extrapolation approach could be used to help in the
management decision making process by generating different levels
of potential impact (e.g. by taking the 50th percentile of the EDR10
distribution or 20th percentile of the EDR50 distribution etc).
• PROTECT will thus provide a range of tabulated effect levels and
percentiles which may prove to be useful to decision-makers
•Different percentiles of an unweighted SSD derived using EDRx values from the
repro-list as input and following the same derivation methodology as used for the
HDR5 values
Input data for SSD fit
Number of data
r2
HDR5
HDR10
HDR20
HDR50
PROTECT
EDR10
EDR25
EDR50
19
17
14
0.958
0.965
0.953
8
27
114
1741
30
85
302
3385
86
217
665
5641
FP6-036425
Slide 18
Summary of the proposed approach
and associated benchmarks (1/2)
•First tier of an ERA-type approach (simple – conservative)
The use of the proposed generic screening level should enable assessed sites for
which incremental dose rates are estimated as being below 10 µGy/h to be confidently
excluded from further assessment.
•Second tier of an ERA-type approach (less conservative)
The application of the 10 µGy/h screening dose rate for vertebrates
and 450 µGy/h for plants and invertebrates is likely to identify those sites which
pose an insignificant risk when used in such assessments.
•The generic and taxonomic screening values we have derived are within the range of
values suggested as being appropriate for population level protection by other
organisations using expert judgement.
•Suitable data we have identified are currently insufficient to enable the derivation of
more refined levels of taxonomic screening values (if these are required) using the SSD
approach.
PROTECT
FP6-036425
Slide 19
Summary of the proposed approach
and associated benchmarks (2/2)
•Regulatory action level
We have presented a SSD-based scientific analysis of the available data which
may help decision makers select a value appropriate to either planned or
existing situations in consultation with appropriate stakeholders.
PROTECT
FP6-036425
Numerical Benchmarks for
protecting biota against
radiation in the environment
Methodology to derive benchmarks, selected
methods used in PROTECT and Results
PROTECT
FP6-036425
Slide 2
Methods to derive benchmarks (reminder)
3 main methodologies :
(1) Deterministic : based on application of Assessment
Factor to critical ecotoxicity data, or
(2) Probabilistic : based on Species Sensitivity
Distribution (SSD) approach associated with an
arbitrary cut-off value, usually set at a protection level of
95% of the species, and the use of an additional AF,
(3) a weight of evidence approach using effect data from
field exposures
(1) & (2) based on critical ecotoxicity values from tests in lab
e.g., EC10 (preferred to NOEC) : stressor level in a given medium giving 10% effect in the
exposed group in comparison to the control group for chronic exposure.
(1) to (3) usually applied for chemical substances to derive PNEC (e.g., TGD, 2003)
Concerning RAS:
(1) and (2) applied and compared within ERICA to derive PNEDR (Garnier-laplace et al., 2006)
(1) used by Environment Canada (2003) for radionuclides
(3) used by Thompson et al. (2005) for multipollution context (radionuclides + metals)
PROTECT
FP6-036425
Slide 3
Methods used within PROTECT
• Following PROTECT Consultation and
availability of various EDR10 values (from ERICA and
follow up), SSD method adopted when data sets
were adequate (quality and quantity)
(1) allow to make the best use of the available most relevant knowledge in a
transparent way,
(2) allow to quantify the associated uncertainty,
(3) easily allow to revise the outcoming values when new knowledge
becomes available
• Need to incorporate documented expert
judgement at various stages
(1) when selecting ecotoxicity data (EDR10 in our case),
(2) when selecting a cut-off value to estimate the Hazardous Dose Rate of
interest (HDR5),
(3) when applying an AF to obtain the final benchmark (PNEDR).
PROTECT
FP6-036425
Slide 4
The 3-step method used
STEP 1 – Compiling quality assessed exposure-effect data
FREDERICA
Radiation Effect Database
Effect (%)
Data sorted per ecosystem, per exposure condition, per
bibliographic reference and per test . Quality of data describing each
test was assessed against 3 criteria (dosimetry, exp. Design, stats).
Multi-rules applied to accept or reject each data set
STEP 2 – Building dose rate-effect relationships to
estimate critical ecotoxicity values EDR10
100 %
50 %
Dose-effect relationship was built for each accepted test.
The quality of the fitted model was judged before accepted
EDR10. Two models tested (logistic/hormetic)
10 %
EDR50
EDR10
Dose Rate (µGy/h)
PAF (% of Affected Species)
100
80
60
40
Dose Rate (µGy/h)
20
0
1
10
100 1000 10000
PROTECT
STEP 3 – Deriving benchmarcks
Application of SSD on the estimated toxicity values accepted
after step 2.
Application or not of the taxonomic weighted options
Application of an AF to the HDR5 to obtain the final benchmark
FP6-036425
Slide 5
EDR10 from logistic models
Data set for one test
(a test is defined as a consistent group of (dose or dose rate, effect) couples from a given species and a given
effect, examined under defined exposure conditions (duration, irradiation pathway)
Logistic model
The data set is made of:
at least 3 different couples (dose or dose rate, effect) including one for the control group (no dose(rate))
at least two different couples if the effect is analysed relatively to the control.
YES
Effect
Control
(response at dose rate 0)
NO
data set is rejected
The variation of effect with dose (or dose rate) is monotonous.
The pattern is consistent with the state-of-the-art on the tested effect
YES
NO
data set is rejected
The maximum effect value in case it was not reached during the test can be fixed theoretically if knowledge on such
effect is sufficient. The difference between the maximum effect value observed y(MaxObs) during the test and the
theoretical one y(MaxTheo) are used to calculate the extrapolation percentage needed to model dose-effect relationship
as follows : %Extrapol = 100 *(y(MaxObs) – y(MaxTheo))/(y(ControlObs) – y(Maxtheo)) where y(ControlObs) is the
effect value observed for the control group.
EDR10
Dose rate (µGy/h)
EDR10
YES
NO
data set is rejected
At least one couple is located within the 10 to 90% of the variation of effect observed. This latter is defined as
(y(ControlObs)-y(MaxObs))
YES
NO
data set is rejected
The Estimated ED50 or EDR10 are between two experimental couples.
YES
NO
data set is rejected
The Estimated ED50 or EDR10 can be used within a SSD analysis.
PROTECT
FP6-036425
Slide 6
EDR10 from hormetic models
Dose-response exhibiting an initial response stimulation or an effect minimisation
Curve shape
« Hormetic » model
NOEC definition
Inverted U shaped
curve
Selection criteria
Control
(response at dose rate 0)
NOEC definition
U shaped curve
EDR10
Exclusion criteria
Selection criteria
the highest dose with a response ≥ 90% of the control
- at least 5 dose-response data points (the minimal number to fit a
hormesis model with 4 parameters, requires fixing the lower limit to 0)
- 1 control data point
- at least 2 doses ≤ NOEC with a response numerically higher than the
control
- 1 NOEC
- at least 1 dose > NOEC with a response ≤ 90% of control
the highest dose with a response ≤ 110% of the control
- at least 6 dose-response data points (the minimal number to fit a
hormesis model with 5 parameters; lower and upper limit are different to
0)
- 1 control point
- at least 2 doses ≤ NOEC with a response numerically lower than the
control
- 1 NOEC
- at least 1 dose > NOEC with a response ≥ 110 % of control
(1) the absence of a relevant control;
(2) the incapacity to achieve responses greater than (or less than,
depending on end point) the control response (e.g., studies where the end
point was survival and the control response was 100% or where the end
point was tumour incidence and the control response was zero);
(3) at least two doses below the NOEC;
(4) at least one dose showing a priori criteria-based inhibition.
Dose rate (µGy/h)
PROTECT
FP6-036425
Slide 7
STEP 1 – EDR10 selection (1/4)
•ERICA : 82 EDR10 obtained for chronic g external exposure
meeting the previous criteria, covering 18 species (5 plants, 9
invertebrates, 10 vertebrates) and various effect endpoints
grouped as one geometric mean per effect category
(mortality, morbidity, reproduction) and per species (ie. for a
given species, a single value per category of effect (the GM)-> this allows to ignore
intra-species variation for the same effect category)
SSD on 24 GM -> HDR5=82 µGy/h [24-336]
•PROTECT : 104 EDR10 obtained for chronic g external
exposure meeting the previous criteria, covering 23 species (6
plants, 8 invertebrates, 9 vertebrates) and various effect
endpoints
PROTECT
FP6-036425
Slide 8
STEP 1 – EDR10 selection (2/4)
•Among those 104 EDR10,
•One single endpoint per species (the lowest value)
•Relevance for population sustainability but expert
discussion on ecological relevancy of some of them
•To illustrate the sensitivity of the SSD method and the derived
screening level dose rate, two sets of EDR10 selected:
« repro » list: most sensitive reproduction endpoint per
species (at the population level -i.e. include juvenile survival)
« ecol » list: most relevant with regard to « direct » ecological
interpretation
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FP6-036425
Slide 9
STEP 1 – EDR10 selection (3/4)
« repro » list : 19 EDR10
ID
WildlifeGroup
Taxo
µGy/h
SpeciesL
EffectDescription
EDR10
Daphnia magna
Larval survival to starvation during 5 days, brood 1 (% survival when food lacks) - stress on stress
test of indirect effect on energy allocation to juveniles production
18537
Gilbin
Crustaceans
Invertebrates
1065
Crustaceans
Invertebrates
Daphnia pulex
Population birth rate (per day) Data read from graph
277633
247
Crustaceans
Invertebrates
Porcellio scaber
Mean number of offspring per tank per dose rate group
1030
Hertel-Aas
Annelid
Invertebrates
Eisenia foetida
Hatchlings per adult during the whole 13 weeks reproduction exposure period (F1/ Adult F0)
3369
296
Molluscs
Invertebrates
Mercenaria mercenaria
Survival of juvenile clams (%) on day 426. Dose = max. cumulative dose
119117
361
Annelid
Invertebrates
Ophryotrocha diadema
The percentage of worms in generation 3 surviving to day 62.
2359
326
Molluscs
Invertebrates
Physa heterostropha
Percentage of eggs that hatched
61229
523
841
Plants
Plants
Plants
Plants
Abies balsamea
Fagopyrum esculentum
Summary of mean fir characteristics for seven dose-rate catergories, Number of buds (1975),
Productivity in M3 generation (1979), Yield of seeds (g/sq m)
2945
X
40151
416
998
Plants
Plants
Plants
Plants
Pinus rigida
Triticum sinskjae
Effect of long term irradiation on seed development. Dose rate provided as average per day
Productive bush amount, % of the control value. N 13, K-48993 T. sinskjae var. Sinskajae
710
6434
X
998
Plants
Plants
Triticum monococcum
Productive bush amount, % of the control value. N 3, K-29602 T. monococcum var. Atriaristatum
8573
X
616
Egami
207
Mammals
Fish
Fish
Vertebrates
Vertebrates
Vertebrates
Mus musculus
Oryzias latipes
Pleuronectes platessa
Nº of litters per fertile female during 245 days (mean; SE).
Male mean gonad weight (mg)
Mean proportion of plaice testes occupied by different cell types irradiated for 197 days - sperm
26
19730
X
53
X
74
593
621
629
Fish
Mammals
Mammals
Mammals
Vertebrates
Vertebrates
Vertebrates
Vertebrates
Poecilia reticulata
Rattus norvegicus
Spanish goat
Sus crofa
Mean life time fecundity
A1 Spermatogonia ( % of control)
Total sperm production (% of control): 730 days irradiation
Testis weight (g) at 70 days of age (+- SE)
516
24
X
12
X
6.7
X
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Slide 10
STEP 1 – EDR10 selection (4/4)
« ecol » list : 14 EDR10
Omission of endpoints with difficult ecological interpretation (no direct
link with reproductive success) e.g., bud production, gonad weight,
µGy/h
sperm cell or spermagonia count
ID
WildlifeGroup
Taxo
SpeciesL
EffectDescription
EDR10
Gilbin
Crustaceans
Invertebrates
Daphnia magna
Larval survival to starvation during 5 days, brood 1 (% survival when food lacks) - stress on stress
test of indirect effect on energy allocation to juveniles production
18537
1065
Crustaceans
Invertebrates
Daphnia pulex
Population birth rate (per day) Data read from graph
277633
247
Crustaceans
Invertebrates
Porcellio scaber
Mean number of offspring per tank per dose rate group
1030
Hertel-Aas
Annelid
Invertebrates
Eisenia foetida
Hatchlings per adult during the whole 13 weeks reproduction exposure period (F1/ Adult F0)
3369
296
Molluscs
Invertebrates
Mercenaria mercenaria
Survival of juvenile clams (%) on day 426. Dose = max. cumulative dose
119117
361
Annelid
Invertebrates
Ophryotrocha diadema
The percentage of worms in generation 3 surviving to day 62.
2359
326
841
Molluscs
Plants
Invertebrates
Plants
Physa heterostropha
Fagopyrum esculentum
Percentage of eggs that hatched
Productivity in M3 generation (1979), Yield of seeds (g/sq m)
61229
40151
416
998
Plants
Plants
Plants
Plants
Pinus rigida
Triticum monococcum
Effect of long term irradiation on seed development. Dose rate provided as average per day
Fertility, % of the control value. N 15, K-23653 T. monococcum var. Hornemanni
710
9819
616
Mammals
Vertebrates
Mus musculus
Nº of litters per fertile female during 245 days (mean; SE).
26
74
622
204
Fish
Mammals
Fish
Vertebrates
Vertebrates
Vertebrates
Poecilia reticulata
Spanish goat
Oryzias latipes
Mean life time fecundity
Number born per female (in 5 consecutive gestation: see comment)
Number of surviving fish
516
1968
90861
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Slide 11
STEP 2 - SSD-fit to the selected list (1/3)
• Repro-list
SSWD - Log Normal
R² = 0.9583
KSpvalue = 0.500
Sp = unw eighted; TW: none
w m.lg = 3.24
w sd.lg = 1.41
100%
HDR5 = 8.4 µGy/h
CI 95% = [1.4;99]
Cumulative weighted probability
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
0,1
1
10
100
1000
10000
100000
1000000 10000000
Concentration
Dose
rate (µGy/h)
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Best-Estimate
Centile 5%
Plants
Invertebrates
Centile 95%
Vertebrates
FP6-036425
Slide 12
STEP 2 - SSD-fit to the selected list (2/3)
• Ecol-list
SSWD - Log Normal
R² = 0.9625
KSpvalue = 0.500
w m.lg = 3.81
w sd.lg = 1.12
Sp = unw eighted; TW: none
HDR5 = 91 µGy/h
CI 95% = [11;710]
100%
Cumulative weighted probability
90%
80%
70%
60%
50%
40%
30%
20%
10%
0%
1
10
100
1000
10000
100000
1000000
10000000
Concentration
Dose
rate (µGy/h)
PROTECT
Best-Estimate
Centile 5%
Plants
Invertebrates
Centile 95%
Vertebrates
FP6-036425
Slide 13
STEP 2 - SSD-fit to the selected list (3/3)
Taxonomic weight options to fit SSD
Influence of the proportion of tested species from different taxonomic groups
(trophic levels) on the HDR5 while giving the same weight to each
trophic/taxonomic group
Repro
Ecol
Number of EDR10 Number of species Taxonomic Weight
19
19
No (5 P; 7 I; 7 V)
Yes (1 P; 1 I; 1 V)
14
14
No (3 P; 7 I; 4 V)
Yes (1 P; 1 I; 1 V)
HDR5
8.4
11
91
72
min
1.4
1.8
11
8.0
max
99
159
710
566
For the repro-list, applying the same weight for each TG means to decrease the
proportion of the most radiosensitive group from 37% (7/19) to 33% (equiprobability) ->
HDR5 increases slightly
Ecol-case : V from 28% to 33% -> HDR5 decreases
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Slide 14
STEP 3 - Screening generic dose rates
(in µGy/h)
Rounded to the nearest 10
Weight option
HDR5
min
max
AF
PNEDR
Generic Screening Value
Repro
No
8.4
1.4
99
1
8.4
10
Ecol
Yes
No
11
91
1.8
11
159
710
1
5
11
18
10
20
Yes
72
8.0
566
5
14
10
•AF= from 1 to 5 according to the TGD
- taxonomic coverage
- coverage of the inter-species sensitivity
- ecological relevancy of endpoints
- line of evidence from field
- final value compared to background
e.g., 0.1 to 6 µGy/h for marine organisms (Brown et al., 2004)
0.4 to 4 ________freshwater______________________
0.07 to 0.6______terrestrial________(Beresford et al. in press)
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Slide 15
STEP 3 - Screening generic dose rates
(in µGy/h)
Rounded to the nearest 10
Weight option
HDR5
min
max
AF
PNEDR
Generic Screening Value
Repro
No
8.4
1.4
99
1
8.4
10
Ecol
Yes
No
11
91
1.8
11
159
710
1
5
11
18
10
20
Yes
72
8.0
566
5
14
10
•For illustration purpose: AF=1 for the repro-list and 5 for the ecol-list
generic screening level recommended by PROTECT : 10 µGy/h
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Slide 16
STEP 3’ – Taxonomic screening dose rates
(in µGy/h)
•Data were insufficient to create an SSD for the 3 basic taxonomic groups (plants(5),
invertebrates(7), vertebrates(7))
•A limited sensitivity analyses of the overall SSD suggested that the only statistically
justifiable separation was to remove vertebrates leaving an SSD for plants and
invertebrates (with a total of 12 data points)
Weight option
Non-Vertebrates No (5 P;2 I-M;2 I-A; 3 I-C)
Yes (same weight per group)
HDR5
min
max
AF
PNEDR
Taxonomic Screening Value
449
166
1791
1
449
450
503
167
1858
1
503
500
•We suggest that a taxonomic screening level of 450 µGy/h be used for plants and
invertebrates in refined assessments if the results of the screening tier assessment
suggest this is required. For vertebrates, a taxonomic screening level of 10 µGy/h
(i.e. the generic screening level) is recommended.
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Slide 17
Regulatory action level
• The statistical extrapolation approach could be used to help in the
management decision making process by generating different levels
of potential impact (e.g. by taking the 50th percentile of the EDR10
distribution or 20th percentile of the EDR50 distribution etc).
• PROTECT will thus provide a range of tabulated effect levels and
percentiles which may prove to be useful to decision-makers
•Different percentiles of an unweighted SSD derived using EDRx values from the
repro-list as input and following the same derivation methodology as used for the
HDR5 values
Input data for SSD fit
Number of data
r2
HDR5
HDR10
HDR20
HDR50
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EDR10
EDR25
EDR50
19
17
14
0.958
0.965
0.953
8
27
114
1741
30
85
302
3385
86
217
665
5641
FP6-036425
Slide 18
Summary of the proposed approach
and associated benchmarks (1/2)
•First tier of an ERA-type approach (simple – conservative)
The use of the proposed generic screening level should enable assessed sites for
which incremental dose rates are estimated as being below 10 µGy/h to be confidently
excluded from further assessment.
•Second tier of an ERA-type approach (less conservative)
The application of the 10 µGy/h screening dose rate for vertebrates
and 450 µGy/h for plants and invertebrates is likely to identify those sites which
pose an insignificant risk when used in such assessments.
•The generic and taxonomic screening values we have derived are within the range of
values suggested as being appropriate for population level protection by other
organisations using expert judgement.
•Suitable data we have identified are currently insufficient to enable the derivation of
more refined levels of taxonomic screening values (if these are required) using the SSD
approach.
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Slide 19
Summary of the proposed approach
and associated benchmarks (2/2)
•Regulatory action level
We have presented a SSD-based scientific analysis of the available data which
may help decision makers select a value appropriate to either planned or
existing situations in consultation with appropriate stakeholders.
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