Dose Assessments for Wildlife in England

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Dose Assessments for Wildlife in England Wales
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Contents

• Legislative framework
• Overview of the assessment framework
• Staged approach (1, 2, 3 4)
• Assessing doses to wildlife
• Current status

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Legislative Framework

• Europe Habitats Birds Directives On the
  conservation of natural habitats and of wild
  flora and fauna

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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

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The Environment Agencys Role

• We have a duty to comply with the EU Birds and
  Habitats Directives

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The Environment Agencys Role

• We have a duty to comply with the EU Birds and
  Habitats Directives
• The Agencys 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)

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The Environment Agencys Role

• We have a duty to comply with the EU Birds and
  Habitats Directives
• The Agencys 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

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The Environment Agencys 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

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Natura 2000 sites

• About 430 Natura 2000 sites in England Wales
• Include Special Areas of Conservation (SAC) and
  Special Protection Areas (SPA)

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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

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Timetable

• Natura 2000 sites categorised by conservation
  agencies into
• High priority sites by 2004
• Medium priority sites by 2006
• Low priority sites by 2008

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How does the assessment work?
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How does the assessment work?

• In stages...

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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

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Stage 2
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Stage 2

• Dose per unit release values calculated for
  reference organisms (µGy h-1 per TBq) - how?

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2001 - RD 128

• RD 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

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2001 - RD 128

• Radionuclides
• 3H, 14C , 32P, 35S, 60Co, 99Tc, 90Sr, 106Ru,
  125I, 129I, 131I, 137Cs, 210Po, 226Ra, 234Th,
  238U, 239240Pu, 241Am, 85Kr, 41Ar
• Uses concept of reference organism

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Reference Organism Concept

• Key points
• (Simplified) geometric shape for dosimetry
  calculations

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Reference Organism Geometries
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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

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Reference Organisms in RD 128
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Assessment Methodology
REFERENCE ORGANISM
IMPACT
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Assessment Methodology
PATHWAY OF EXPOSURE
RADIONUCLIDE SOURCE
ECOLOGICAL PARAMETERS
REFERENCE ORGANISM
IMPACT
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Assessment Methodology
PATHWAY OF EXPOSURE
RADIONUCLIDE SOURCE
ECOLOGICAL PARAMETERS
REFERENCE ORGANISM
Application of a weighting factor for RBE
TOTAL ABSORBED DOSE
Compare predicted dose to known biological or
ecological effects guideline values
IMPACT
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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

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Terrestrial Environment
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2001 - RD 128

• Enter water, air, soil or biota concentrations to
  calculate dose rates (mGy/h)
• Provides advice on practical use of methodology,
  and states assumptions and constraints

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2001 - RD 128
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2001 - RD 128
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Stage 2

• Using RD 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

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Stage 2 - results

• Approximately 100 authorisations have been
  identified that exceed the screening level at 51
  Natura 2000 sites thus require Stage 3
  assessment

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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

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Stage 3
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Stage 3

• Dose per unit release values calculated for
  reference organisms and feature species and
  habitats
• Threshold of 40 mGy h-1 agreed with English
  Nature, below which it can be concluded that
  there will be no adverse effect on habitat site
  integrity

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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

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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
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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
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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
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DPUC calculations

• Uncertainty typically lt10

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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
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Stage 4
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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

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Current Status
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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)

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Current status

• All habitat sites to date lt40mGy/h, except Ribble
  Estuary
• Ribble Alt Estuary Natura 2000 site assessment
  is 690mGy h-1 due to Th-234 short lived alpha
  emitters discharged from Westinghouse Springfields

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Current status

• All habitat sites lt40mGy/h, except Ribble Estuary
• Ribble Alt Estuary Natura 2000 site assessment
  is 690mGy 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

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Current status

• All habitat sites lt40mGy/h, except Ribble Estuary
• Ribble Alt Estuary Natura 2000 site assessment
  is 690mGy 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?

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Current status

• All habitat sites lt40mGy/h, except Ribble Estuary
• Ribble Alt Estuary Natura 2000 site assessment
  is 690mGy 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

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So

• Discussions have been held with Springfields and
  the following actions undertaken

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So

• Discussions have been held with Springfields and
  the following actions undertaken
• Review of the data entered into the spreadsheets

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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)

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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

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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 RD128

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So

• Risk of exceeding 40 uGy h-1 is negligible for
  any species likely to be present in the estuary

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Finally

• We are currently reviewing this work
• Meeting in a weeks time

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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

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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

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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?