Dose Assessments for Wildlife in England & Wales
description
Transcript of Dose Assessments for Wildlife in England & Wales
Dose Assessments for Wildlife in England & Wales
Contents
Legislative framework Overview of the assessment framework
Staged approach (1, 2, 3 & 4) Assessing doses to wildlife
Current status
Legislative Framework
Europe: Habitats & Birds Directives On the conservation of natural habitats and of wild flora and fauna
Legislative Framework
Europe: Habitats & Birds Directives On the conservation of natural habitats and of wild flora and fauna
UK: Conservation (Natural Habitats) Regulations 1994
Implements the Habitats Directive in the UK. Requires steps to maintain and restoration to favourable conservation status of habitats and species of Community level interest
The Environment Agency’s Role We have a duty to comply with the EU Birds and Habitats
Directives
The Environment Agency’s Role We have a duty to comply with the EU Birds and Habitats
Directives The Agency’s obligations are to review:
Existing authorisations, consents, licences and permissions for chemicals
All requests for variations to existing or new applications
Ensure that no Agency-authorised activity or permission results in an adverse effect, either directly or indirectly on the integrity of identified European sites (Natura 2000 sites)
The Environment Agency’s Role We have a duty to comply with the EU Birds and Habitats
Directives The Agency’s obligations are to review:
Existing authorisations, consents, licences and permissions for chemicals and radioactive substances
All requests for variations to existing or new applications
Ensure that no Agency-authorised activity or permission results in an adverse effect, either directly or indirectly on the integrity of identified European sites (Natura 2000 sites)
Pressure is from conservation not radiological protection
The Environment Agency’s Role
Given the requirement to assess the impacts of consents and authorisations affecting Natura 2000 sites:
We took the view, based on legal advice and with the support of English Nature (statutory consultee), that these assessments should include ionising radiation
Natura 2000 sites
About 430 Natura 2000 sites in England & Wales
Include Special Areas of Conservation (SAC) and Special Protection Areas (SPA)
Natura 2000 sites
About 430 Natura 2000 sites in England & Wales
Include Special Areas of Conservation (SAC) and Special Protection Areas (SPA)
Note the approach taken aims to be conservative in order to be protective
Timetable
Natura 2000 sites categorised by conservation agencies into:
High priority sites by 2004
Medium priority sites by 2006
Low priority sites by 2008
How does the assessment work?
How does the assessment work?
In stages...
Stage 1
Review of likelihood that discharges from an authorised site could reach a Natura 2000 site
e.g. inland freshwater Natura 2000 site v coastal discharge
Simple rules used authorised aerial discharges within 1km authorised freshwater discharges within 50km
Stage 2
Stage 2
Dose per unit release values calculated for reference organisms (µGy h-1 per TBq) - how?
2001 - R&D 128
R&D 128 provided a:
Review of the latest research on the biological effects of ionising radiation
Simplified approach to determining exposure (through dose calculations) for a set of organisms which were representative of freshwater, marine and terrestrial ecosystems for a limited set of radionuclides
2001 - R&D 128
Radionuclides: 3H, 14C , 32P, 35S, 60Co, 99Tc, 90Sr,
106Ru, 125I, 129I, 131I, 137Cs, 210Po, 226Ra, 234Th, 238U, 239+240Pu, 241Am, 85Kr, 41Ar
Uses concept of “reference” organism
Reference Organism Concept
Key points: (Simplified) geometric shape for dosimetry calculations
Reference Organism Geometries
Reference Organism Concept
Key points: Selected to represent different trophic levels (to enable
transfer of radionuclides to be determined/estimated) Selected to represent different exposure pathways - e.g.
immersed in soil or water, surrounded by air etc. Doses calculated to whole organism
Reference Organisms in R&D 128
Freshwater Estuarine/marine Terrestrial
BacteriaMacrophyte
PhytoplanktonZooplankton
Benthic MolluscSmall BenthicCrustacean
Large BenthicCrustaceanPelagic FishBenthic FishAmphibian
DuckAquatic Mammal
BacteriaMacrophyte
PhytoplanktonZooplankton
Benthic MolluscSmall BenthicCrustacean
Large BenthicCrustaceanPelagic FishBenthic Fish
Fish EggSeabird
SealWhale
BacteriaLichen
Tree, Shrub, HerbSeed
FungusCaterpillar
AntBee
WoodlouseEarthworm
Herbivorous MammalCarnivorous Mammal
RodentBird & Bird Egg
Reptile
Assessment Methodology
REFERENCE ORGANISM
IMPACTIMPACT
Assessment Methodology
ECOLOGICAL PARAMETERS
REFERENCE ORGANISM
RADIONUCLIDE SOURCE
IMPACTIMPACT
PATHWAY OF EXPOSURE
Assessment Methodology
ECOLOGICAL PARAMETERS
REFERENCE ORGANISM
RADIONUCLIDE SOURCE
IMPACTIMPACT
TOTAL ABSORBED
DOSE
PATHWAY OF EXPOSURE
Application of a weighting factor
for RBE
Compare predicted dose to known biological or
ecological effects & guideline values
Simplifying assumptions
External doses calculated from simple infinite or semi-infinite contaminated media formulae, with modifications for self shielding by the organism
Short lived radionuclides assumed to be in secular equilibrium with longer lived parent
Equilibrium between environmental media assumed - so that concentrations in organisms can be estimated from simple concentration factors/ratios
Terrestrial Environment
extitotal
soilisurfacesoil
iitotal
soili
soili DPUCCffDPUCCFCH ,
int, 5.0)(
where:
i
represents summation over all nuclides;
Csoil is the concentration of the radionuclide in surface soil;
CFsoil is the concentration factor for the organism referenced to soil;
fsoil is the fraction of time the organism spends under the soil surface; andfsurface is the fraction of time the organism spends on the ground surface.
2001 - R&D 128
Enter water, air, soil or biota concentrations to calculate dose rates (Gy/h)
Provides advice on practical use of methodology, and states assumptions and constraints
2001 - R&D 128
2001 - R&D 128
Stage 2
Using R&D 128 & some simple dispersion modelling the dose per unit release values were calculated for reference organisms (µGy h-1 per TBq)
Assume discharge at permit limits and impact from combined discharges (air, sewer, river, coastal waters)
Resulting doses compared to screening level of 5 µGy h-1 as agreed with (then) English Nature
Stage 2 - results
Approximately 100 authorisations have been identified that exceed the screening level at 51 Natura 2000 sites & thus require Stage 3 assessment
Stage 2 - results
Approximately 100 authorisations have been identified that exceed the screening level at 51 Natura 2000 sites & thus require Stage 3 assessment Note this is mainly due to choice of analogue
Initial use of other alpha and other beta/gamma categories
Expert judgement may be used to match on half-life and radiation type/energy
Stage 3
Stage 3
Dose per unit release values calculated for reference organisms and feature species and habitats
Threshold of 40 Gy h-1 agreed with English Nature, below which it can be concluded that there will be no adverse effect on habitat site integrity
Feature species & habitats
Feature Species (e.g.): Avocet, Bar-tailed Godwit, Bittern, Black-tailed Godwit, Curlew, Dunlin, Gadwall, Golden plover, Grey plover, Hen Harrier, Knot, Lapwing, Little tern, Marsh Harrier, Oystercatcher, Redshank, Ringed plover, Ruff, Sanderling, Scaup, Shelduck, Snipe, Tufted duck, Wigeon
Feature Habitats (e.g.): Birds of uplands, Birds of lowland heaths and brecks, Birds of lowland freshwaters and their margins, Birds of open sea and offshore rocks, Birds of lowland wet grasslands, Birds of farmland, Birds of coastal habitat, Birds of estuarine habitats
Determine authorisations affecting Natura 2000 site (from
Stage 2)
Obtain Natura 2000 site information
Having identified a feature species, determine
concentration factors and occupancy factors
Determine authorisations affecting Natura 2000 site (from
Stage 2)
Obtain Natura 2000 site information
Having identified a feature species, determine
concentration factors and occupancy factors
Identify any predator/prey for indirect effects
Determine authorisations affecting Natura 2000 site (from
Stage 2)
Obtain Natura 2000 site information
Having identified a feature species, determine
concentration factors and occupancy factors
Identify any predator/prey for indirect effects
Determine which reference organism
geometry can be used to approximate the feature
species geometry
DPUC calculations
Uncertainty typically <10%
Technetium vs. area/volume
y = 1E-09x1.103
R2 = 0.9953
1.E-08
1.E-07
1.E-06
1.E-05
1.E-04
1.E+01 1.E+02 1.E+03 1.E+04area/volume (m-1)
DP
UC
NewtBird
Bat
Caesium vs. area/volume
y = 0.0002x0.0736
R2 = 0.981
1.E-04
1.E-03
1.E+01 1.E+02 1.E+03 1.E+04area/volume (m-1)
DP
UC
NewtBird
Bat
Ecosystem Species Equivalent geometry(R&D Publication 128)
Coastal Avocet, Bar-tailed Godwit, Black-tailed Godwit,Brent Goose, Curlew, Gadwall, Great CrestedGrebe, Gulliemot, Hen Harrier (male andfemale), Kittewake, Lesser Black-backed Gull(male and female), Manx Shearwater, MarshHarrier, Mediterranean Gull, Oystercatcher,Pintail, Puffin, Razorbill, Redshank, RingedPlover, River Lamprey, Sandwich Tern,Shelduck (female), Storm Petrel, Teal, TuftedDuck (female), Turnstone, Wigeon
Benthic Fish
Allis Shad, Atlantic Salmon, Common Scoter,Common Tern, Dunlin, Gannet, Golden Plover,Grey Plover, Knot, Little Tern, Otter (female),Peregrine, Ruff, Sanderling, Sea Lamprey,Shelduck (male), Snipe, Tufted Duck (male),Twaite Shad, White-Fronted Goose
Seabird
Bewicks Swan, Bittern, Chough, Common Seal,Cormorant, Lapwing, Otter (male), Pink-FootedGoose, Scaup, Whooper Swan
Seal
Grey Seal Whale
Ecosystem Species Equivalent geometry(R&D Publication 128)
Coastal Avocet, Bar-tailed Godwit, Black-tailed Godwit,Brent Goose, Curlew, Gadwall, Great CrestedGrebe, Gulliemot, Hen Harrier (male andfemale), Kittewake, Lesser Black-backed Gull(male and female), Manx Shearwater, MarshHarrier, Mediterranean Gull, Oystercatcher,Pintail, Puffin, Razorbill, Redshank, RingedPlover, River Lamprey, Sandwich Tern,Shelduck (female), Storm Petrel, Teal, TuftedDuck (female), Turnstone, Wigeon
Benthic Fish
Allis Shad, Atlantic Salmon, Common Scoter,Common Tern, Dunlin, Gannet, Golden Plover,Grey Plover, Knot, Little Tern, Otter (female),Peregrine, Ruff, Sanderling, Sea Lamprey,Shelduck (male), Snipe, Tufted Duck (male),Twaite Shad, White-Fronted Goose
Seabird
Bewicks Swan, Bittern, Chough, Common Seal,Cormorant, Lapwing, Otter (male), Pink-FootedGoose, Scaup, Whooper Swan
Seal
Grey Seal Whale
Determine authorisations affecting Natura 2000 site (from
Stage 2)
Obtain Natura 2000 site information
Having identified a feature species, determine
concentration factors and occupancy factors
Identify any predator/prey for indirect effects
Determine which reference organism
geometry can be used to approximate the feature
species geometry
Run Assessment
Stage 4
Stage 4
Regulatory action required to reduce the potential impact
Not yet implemented in either chemicals or radioactive substances regulation
Currently the approach is being worked up in consultation with Natural England Need for proportionality, transparency, fairness
Current Status
Timetable - current status
Natura 2000 sites categorised by conservation agencies into:
High priority sites by 2004(completed and reviewed with English Nature in April 04)
Medium priority sites by 2006(completed and reviewed with English Naturein March 06)
Low priority sites by 2008(currently on target)
Current status
All habitat sites to date <40Gy/h, except Ribble Estuary Ribble & Alt Estuary Natura 2000 site assessment is
690Gy h-1 due to Th-234 & short lived alpha emitters discharged from Westinghouse Springfields
Current status
All habitat sites <40Gy/h, except Ribble Estuary Ribble & Alt Estuary Natura 2000 site assessment is
690Gy h-1 due to Th-234 & other short lived alpha emitters discharged from Westinghouse Springfields
Entering Stage 4 of the Habitats Assessment process (Regulatory) Action to be taken by March 2008
Current status
All habitat sites <40Gy/h, except Ribble Estuary Ribble & Alt Estuary Natura 2000 site assessment is
690Gy h-1 due to Th-234 & other short lived alpha emitters discharged from Westinghouse Springfields
Entering Stage 4 of the Habitats Assessment process (Regulatory) Action to be taken by March 2008
What form should this take, what actions should be taken?
Current status
All habitat sites <40Gy/h, except Ribble Estuary Ribble & Alt Estuary Natura 2000 site assessment is
690Gy h-1 due to Th-234 & other short lived alpha emitters discharged from Westinghouse Springfields
Entering Stage 4 of the Habitats Assessment process (Regulatory) Action to be taken by March 2008
What form should this take, what actions should be taken?
However reduction in limits is already planned due to change in operations and recent review of discharges
So…
Discussions have been held with Springfields and the following actions undertaken:
So…
Discussions have been held with Springfields and the following actions undertaken: Review of the data entered into the
spreadsheets
So…
Discussions have been held with Springfields and the following actions undertaken: Review of the data entered into the
spreadsheets Using Springfields environmental data water
concentrations in the Ribble have been modelled (using site specific models)
So…
Discussions have been held with Springfields and the following actions undertaken: Review of the data entered into the
spreadsheets Using Springfields environmental data water
concentrations in the Ribble have been modelled (using site specific models)
Previous levels of discharge identified at the agreed new permit limits and the monitoring data from this period collated
So…
Discussions have been held with Springfields and the following actions undertaken: Review of the data entered into the
spreadsheets Using Springfields environmental data water
concentrations in the Ribble have been modelled (using site specific models)
Previous levels of discharge identified at the agreed new permit limits and the monitoring data from this period collated
Assessment re-run using ERICA tool (part of our move to update R&D128
So…
“Risk of exceeding 40 uGy h-1 is negligible for any species likely to be present in the estuary”
Finally
We are currently reviewing this work Meeting in a weeks time
Finally
We are currently reviewing this work Meeting in a weeks time
Some issues identified E.g. assessment focuses only on radionuclides
discharged from Springfields, may need to consider radionuclides from other sources…
Finally
We are currently reviewing this work Meeting in a weeks time Still planning to undertake a scientific programme
of research in the estuary to identify any potential biological impacts
Finally
We are currently reviewing this work Meeting in a weeks time Still planning to undertake a scientific programme
of research in the estuary to identify any potential biological impacts
Regulatory action required?