reminder of protect objective within wp3

FP6-036425FP6-036425PROTECT PROTECT

PROTECT: First Proposed Levels for Environmental

Protection against Radioactive Substances

Definitions, Derivation Methods to Determine Thresholds, Available Effects Data, Preliminary Reasoning and Results


Reminder of PROTECT objective within WP3

• To derive and propose numerical target values for an extended list of ecological targets and protection levels,…

explore the possibility for the application of advanced statistical methods that :

(1) allow the best use of the available knowledge when this is represented by small data sets,

(2) allow quantification of the associated uncertainty,(3) easily allow revision of resultant values when

new knowledge becomes available.


Definition

• Protection goals:For the ecological target(s) of interest, combination of :

(1) the targeted level of biological organisation(e.g., a population of a given ecosystem, taxonomic group, species)

(2) the targeted level of protection that may take into account legal requirements(e.g., each individual for an endangered species, 95% of species for a taxonomic group or a community)

-> a range of protection goals can be listed-> a range of numerical thresholds can be derived to assure compliance to those environmental protection goals

Ecosystem:structure & function

Communities:Populations of species

Species:Population

Individual (sub)


Numerical Thresholds (1/3)

Definition:a limit quantifying the interface between an acceptable stressor level (e.g., in a given medium, in biota) and an unacceptable level [« acceptable » being related to the protection goal]

Applications :(1) Ecological Risk Assessment – used as Screening

Values, associated with a tiered RA scheme;Exceeding means « do more » to better understand the risk(e.g., the screening value in ERICA)

(2) Regulation – used as Action Values, i.e. « legally » binding criteria (or standards) to meet the « legal » requirements;Exceeding means « act »(e.g., an EQS)



• Application:

Planned and existing situations for which environmental impact/risk needs to be assessed (e.g., chronic (routine) releases).

Existing situations such as contaminated sites, for which a threshold may be defined to identify serious risk level triggering an immediate action/intervention (e.g., clean up a site).

• Unit :

Dose Rates in Gy per unit time (e.g., µGy/h) that may be converted into activity concentrations in media (water, sediment, soil, air)



In SummaryScreening Values-> to trigger further investigation in a tiered risk assessmentAction Values -> to make a final decision about acceptability, trigger a regulatory action

Both categories of thresholds may be:

(1) Applied to the context of chronic radioactive substances releases due to planned or existing situations.(2) Designed to be protective at a pre-defined

level, of different ecological targets that are potentially exposed to radioactive substances (ecosystems (terrestrial,

marine and freshwater), communities or wildlife taxonomic groups, populations of a species, individuals of a specific population of a species).


• Existing (chemical) approaches are based on available critical ecotoxicity data, typically ED50 for acute exposure conditions (short-term) and EDR10 for chronic exposure conditions (long-term).

Methods for deriving thresholds (1/5)

Exposure-response relationship from ecotoxicity tests(stressor, species, endpoint)

Effect (%)

Regression model

100 %

50 %

10 %

ED10

EDR10

Dose (Gy)Dose Rate (µGy/h)

ED50

EDR50

Observed data

EDR10: Dose Rate giving 10% effect in the exposed group in comparison to the control


AF

LowestEDRPNEDR 10

• Methods recommended by EC for chemicals (Technical Guidance Document (2003)) – easily adaptable to radioactive substances when ED50 or EDR10 are available

(1) The Assessment Factor Method for small data sets

Available ecotoxicity data SF to obtain

chronic PNEDR

At least one short-term ED50 from each of

three trophic levels (plant, invertebrate, vertebrate)

1000

One long-term EDR10 (either vertebrate or invertebrate)

100

Two long-term EDR10 from species representing two trophic levels among (plant, invertebrate, vertebrate)

50

Long-term EDR10 from at least three species (Plant, invertebrate, vertebrate) representing three trophic levels

10


Case not usedProblem of Unit


statistical extrapolation models to address variation between species in their sensitivity to a stressor.

The species for which results are known are representative, in terms of sensitivity, of the totality of the species in the ecosystem.The endpoints measured in laboratory tests are indicative of effects on populations in the field.

(2) The Species Sensitivity Distribution (SSD) Method

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Dose Rate (µGy/h)

PAF (%)

5%

HDR5% : Dose rate giving 5% of the

species affected to a 10% effect

Calculation of a dose rate that is assumed to protect a given % of species

In the Technical Guidance Document (2003): the agreed concentration is the hazardous concentration affecting 5 % of species to a 10%. When it remains other extrapolation issues, the TGD recommends to apply an additional AF (1-5)

AF

HDRPNEDR 5


EDR10


(3) a weight of evidence approach using data from field exposures (field measurements of biodiversity indexes co-occurring with stressor(s) levels)

->Concerning radioactive substances, such data series may be available for some specific sites(e.g., uranium mining sites and long-term ecological surveillance – SQGs for ERA of metals and radionuclides)




• In summary

3 main methodologies may be used (combined) for deriving thresholds (methods 1 & 2

reviewed/compared during ERICA): (1) the Assessment Factor method when few ecotoxicity data are available, or (2) the Species Sensitivity Distribution (SSD) approach associated with an arbitrary cut-

off value, which is usually set at a protection level of 95% of the species when the available data set is more robust.

(3) a weight of evidence approach using data from field exposures

based on critical ecotoxicity values - i.e., stressor level in a given medium giving 10% effect in the exposed group in comparison to the control group for chronic exposure (or 50% effect for acute exposure conditions).


Chronic effects data from FREDERICA

• Only data devoted to effects induced by external irradiation pathway were quantitatively adequate to be mathematically structured in terms of dose-effect relationships.

• In Protect, we have included an analysis of dose-effects relationships exhibiting an hormetic pattern.

• To apply any of the methods in a robust way, comparable critical ecotoxicity endpoints are needed i.e. EDR10 for chronic exposure.

• To meet this aim, a meta-analysis of effects data has been initiated and applied in ERICA to reconstruct dose-effect relationships exhibiting a logistic pattern.


Dose-effect relationships reconstruction(examples)

EDR10 = 7.42

Synechococcus lividus(Cyanobacteria)Response : growth (number of cells)(ID:804)

EDR10 = 123.14

Sus scrofa(mammal, pig)Response : reproduction (number of germ cells in female %of control)(ID:629)

Logistic Hormetic


Data set (EDR10 in µGy/h) obtained forchronic external exposure

Hormetic relationship

Trophic level Taxonomic group Species Effect category number of primary EDR10 Geometric meanTerrestrial Plants Plants Canopy cover - numerous species Morbidity 3 17540

Pinus rigida Morbidity 1 710Triticum monococcum Reproduction 15 10881

Morbidity 2 12868Abies balsamea Morbidity 1 2945

Fagopyrum esculentum Peterm Reproduction 1 40151

Moss/lichen Moss/lichen Morbidity 1 166553Terrestrial Invertebrates Soil fauna Porcellio scaber Reproduction 1 1030

Morbidity 1 7931Terrestrial Vertebrates Birds Gallus gallus Reproduction 2 13316

Mammals Mus musculus Mortality 8 12746Reproduction 6 512

Rattus norvegicus Reproduction 6 349Capra hircus Reproduction 3 303

Sus scrofa Morbidity 1 1667Reproduction 4 31.3

Mus musculus Morbidity 1 19754Morbidity 1 5364

Freshwater Invertebrates Crustaceans Daphnia pulex Mortality 3 441815Reproduction 2 461491

Daphnia pulex Morbidity 1 27763Mollusks Physa heterostropha Reproduction 3 66578

Freshwater Vertebrates Fish Poecilia reticulata Reproduction 1 516Oryzias latipes Reproduction 2 54672

Marine Plants Algae (cyanobacteria) Synechoccus lividus Morbidity 2 5.5Marine Invertebrates Annelids Neanthes arenaceodentata Reproduction 4 443

Ophryotrocha diadema Mortality 3 5157Reproduction 2 10893

Molluscs Mercenaria mercenaria Mortality 2 114973Marine Fish Fish Pleuronectes platessa Reproduction 5 217


Chronic critical radiotoxicity valuesSummary and « possible » SSD-cases

• Only obtained for external exposure conditions

• EDR10 – geometric means per species and effect category and per model (logistic/hormetic)

Total number of EDR10 : 80 (logistic) + 8 (hormetic)Total number of geometric means: 24 + 6Number of species: 18 + 3

taxonomic group with EDR10 number of species number of geometric means number of primary EDR10 SSD on EDR10geomplants 6 7 24 Yes

invertebrates 1 2 2 Novertebrates 5 9 32 Yes

mammals 4 8 30 Yesbirds 1 1 2 No

Terrestrial Ecosystems 12 18 58 Yesplants 1 1 2 No

invertebrates 5 8 20 Yesarthropods 1 3 6 No

non arthropods 4 5 12 No-bad fitvertebrates 3 3 8 No

Fish 3 3 8 No

Aquatic Ecosystems 9 12 30 Yes


First Proposed Thresholds & Reasoning for use

• Protection goals:Ecosystem (structure & function) 95% of species + AF for a high degree of conservatism

Taxonomic groups (one or several) 95% of species+ AF for small datasets 0

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100

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Dose Rate (µGy/h)

PAF (%)

5%

HDR5%Application

Category of thresholdHDR5 – protective criterion in µGy/h

ERAScreening Values

Highly Conservative values.HDR5 + AF of 5 from SSD- EDR10 ecosystems.BELOW -> StopABOVE -> Refine the risk assessment (exposure, effect and risk)

Potential RegulationAction Values

Realistic values. HDR5 + AF of 5 (or 1-5) from SSD- taxonomic groups.

BELOW-> Manage the risk (e.g., monitoring)ABOVE -> Act to reduce the dose rate


First Proposed Thresholds (1/3)

• Ecological target : Ecosystem (structure & function)SSWD - Log NormalSp = w eighted; TW: none

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 10 100 1000 10000 100000 1000000 10000000

Concentration

Cum

ulat

ive

wei

ghte

d pr

obab

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Best-Estimate Centile 5% Centile 95%

Vertebrates Plants Invertebrates

R² = 0.9657KSpvalue = 0.500

w m.lg = 3.63 w sd.lg = 1.20

HDR5 = 45 µGy/hCI 95% = [8.8;207]

All data (n=30)

Proposed Screening value: Application of a max AF (5)-> 10 or 20 µGy/h

HDR5 = 109 µGy/hCI 95% = [36;374]

Without the lowest data (n=29)


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Aquat

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HDR5 (µGy/h) Best estimate and CI95%

Taxonomic groupswithout enough chronic data

without the lowest data




HDR5 SV

Generic Ecosystems 45 9

109 22

Terrestrial Ecosystems 127 25

Aquatic Ecosystems 11 2

86 17

HDR5 =AV if AF=1 AV if AF=5

Terrestrial Plants 664 133

Aquatic Plants

All Plants 27 6

664 133

Terrestrial Invertebrates

Aquatic Invertebrates 722 144

All Invertebrates 399

Terrestrial Vertebrates 34 7

Aquatic Vertebrates

All Vertebrates 33 7

Screening Values (SV)Application of AF of 5

Action Values (AV)Application of AF (1-5) possible

Lowest value included


Issues for discussion (not exhaustive!)• Application of an additional AF to generate Screening

values for ecosystems (SV<<AV)• Application of a taxonomic weight on Plants, Invertebrates

and vertebrates to establish the SSD at the ecosystem-level

• Use of extrapolation empirical models to fill the gaps for taxonomic groups (Acute-to-Chronic relationships on sensitivity distributions)

• Use of other groupings (e.g., plants, invertebrates)• Use of an additional standard for « contaminated sites » to

trigger a remediation action (i.e. HDR50% or dose rate affecting 50% of species to a 10% effect)e.g., HDR50 SSD-All EDR10 - Ecosystem = 4.2 mGy/h

• …

reminder of protect objective within wp3

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