Towards a protection of species at the population level: derivation of PNEDR values by modelling population responses to ionizing radiations Emilie Lance,
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Towards a protection of species at the population level: derivation of PNEDR values by
modelling population responses to ionizing radiations
Emilie Lance, Frédéric Alonzo, Jacqueline Garnier-Laplace
Direction de l’Environnement et de l’InterventionService d’Etude du Comportement des Radionucléides dans les EcosystèmesLaboratoire de Modélisation Environnementale
EMRAS Meeting, 26-27/01/2010, Vienna, Austria
- Titre Partie/Dir/Service – Page 2
Evaluation of environmental risk from ionizing radiations
IAEA : standards for environmental radioprotection
ICRP : recommendation of similar method than for chemical substances, 2005 Sept
Background on ERICA and PROTECT: recommendation
FASSET (2001-2004) 5th PCRD
ERICA (2004-2007) 6th PCRD
PROTECT (2006-2008) 6th PCRD
European projects:
Risk assessment screening dose or dose rate, « benchmarks » for the protection of wild species againts impact of ionizing radiations.
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 3
FREDERICA database : effects of ionizing radiations on non-human organisms
• Ecotoxicity data
• 25000 couples (dose or dose rate, effect) from 1040 references
• 16 pseudo-taxonomic groups
• 3 ecosystems
Vertebrates
Invertebrates
Primary producers
Ecosystems
terrestrial
freshwater
marine
Biologicalcomplexity
Background on ERICA and PROTECT: data set
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 4
Effects observed at the individual and sub-individual level
Which data for the derivation of benchmarks ?
On the first hand, data on chronic exposure to gamma radiation, external radiation exposure (µGy.h-1)
4 categories: - (1) morbidity: growth rate, immune system, behavior (impact on the central nervous system),
- (2) mortality: also mutations that affect life expectancy
- (3) reproductive capacity: fertility, fecundity, hatching/survival of embryos…
- (4) mutations of somatic and reproductive cells
Background on ERICA and PROTECT: data set
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 5
Radiotoxicity data relative to life-history traits (protection of the population)
Dose (rate)-effect relationships: critical data, EDR10 (dose rate inducing 10% of effect on the endpoint in comparison with controls)
For a given species, if an EDR10 is available for several endpoints, the most sensitive is selected
Derivation of criteria for the protection of populations
Effect (%)
Dose (Gy)Dose rate (µGy/h)
ED10EDR10
ED50EDR50
10
Regression modelExperimental data
Background on ERICA and PROTECT: method
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 6
Background on ERICA and PROTECT: method
Extrapolation model « Species Sensitivity Distribution » (SSD)
HDR5 = Dose rate protecting 95% of species (95% are affected at maximum 10% of effect in comparison with controls)
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 10 100 1000 10000 100000 1000000
Dose Rate (µGy/h)
Percentage of AffectedFraction
Best-Estimate Centile 5% Centile 95%
Vertebrates Plants Invertebrates
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 10 100 1000 10000 100000 1000000
Dose Rate (µGy/h)
Percentage of AffectedFraction
Best-Estimate Centile 5% Centile 95%
Vertebrates Plants Invertebrates
Best-Estimate Centile 5% Centile 95%
Vertebrates Plants Invertebrates
5%
HDR5
Garnier-Laplace et al. (2008)
HDR5 / safety factor = PNEDR (Predicted No Effect Dose Rate)
Derivation of criteria for the protection of populations
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 7
Background on ERICA and PROTECT: possible improvements
Biochemical level
Whole organism level
Physiological level
Population level
Community level
Ecosystem level
Time scale
Life-history traits: survival, growth, fecundity
Sensitivity of the population growth rate to impact on individuals endpoints
Life history strategies
dynamics
impact
Hypothesis: the toxicity at the individual level is comparable between species and endpoints
Ecotoxicity data at the individual level
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 8
age
Abundance
time
1) Population structured per age classes
2) Cohorts vary over time depending on survival and fecundity
12 3…
iagemax
Ni+1 = Pi Ni
at time t + 1
iN1 = Fi Ni
Ni
at time t
Eggs, juveniles(future cohort N1)
Modeling population size in number Determination of population growth rate
Population dynamic depending on survival and reproduction in each life stage
Fecundity rate Fi
Survival rate Pidepending on age i
Background on ERICA and PROTECT: possible improvements
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 9
Reduction in survival
Reduction in fecundity
Delay in reproduction0.0
1.0
2.0
3.0
0% 20% 40% 60% 80%
Individual level effect
0.0
1.0
2.0
3.0
0% 20% 40% 60% 80%
Dela
y in
pop
ula
tion
gro
wth
(rela
tive t
o g
en
era
tion
tim
e T
)
T = 10 days T = 12 weeks
Sensitivity of population depends on individual endpoints
Sensitivity of population depends on life history strategy of different species
Comparison of population sensitivity to changes in different endpoints and different species
Eisenia fetidatoxicité chronique de radiations gamma externes (Co-60)
Daphnia magnatoxicité chronique de U et Am-241 dissous et radiations gamma externes (Cs-137) Alonzo et al., 2008
Background on ERICA and PROTECT: possible improvements
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 10
Simulation of population dynamics of each species in control conditions and with 0 to 100% decrease in each life-history trait
Method and required data: a first theoretical step
Toward a protection of species at the population level
Hypothesis of the modelEnclosed systemNo density-dependenceOptimum environnemental conditions
Relative sensitivity of the population to different individual endpoints for a species
Population dynamic
0 15 6030 45
25000
50000
0
75000
100000
time (days)ta
ille
de p
op
ula
tion
To understand and compare life-history strategies between different species
• age sexual maturity • survival at each stage• fecundity at each stage(number of eggs, hatching %, juveniles survival…)
Bibliography
modélisation
Pop-EDR10: Dose rate inducing 10% decrease in population growth rate
Dose rate (µGy/h)ED10
EDR10
10
Effect (%)
%
Dose rate ?
-10% on thepopulation growth rate
2nd step: utilization of data from FREDERICA
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 11
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 10 100 1000 10000 100000 1000000
Dose Rate (µGy/h)
Percentage of AffectedFraction
Best-Estimate Centile 5% Centile 95%
Vertebrates Plants Invertebrates
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
1 10 100 1000 10000 100000 1000000
Dose Rate (µGy/h)
Percentage of AffectedFraction
Best-Estimate Centile 5% Centile 95%
Vertebrates Plants Invertebrates
Best-Estimate Centile 5% Centile 95%
Vertebrates Plants Invertebrates
5%
HDR5
Derivation of benchmarks
Extrapolation model « Species Sensitivity Distribution » (SSD) with pop-EDR10 = at the population level
New HDR5 = Dose rate protecting population dynamics for 95% of species (decrease in population growth rate of less than 10% in comparison with controls)
Pop-EDR10
Toward a protection of species at the population level
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
- Titre Partie/Dir/Service – Page 12
Thanks for your attention
// more informations on…
European program ERICARisques des substances radioactives pour l’environnementhttp://www.erica-project.org
European program PROTECTProtection of the environment from ionising radiation in a regulatory context http://www.ceh.ac.uk/protect/
FREDERICA Radiation Effects Database http://87.84.223.229/fred/mainpage.asp
http://www.irsn.org/CIPR http://www.icrp.orgNEA http://www.nea.fr
EMRAS Meeting, 2010-01-26/27, Vienna, Austria
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