The Canadian Experience

Dr. Steve Mihok, Directorate of Environmental and Radiation Protection and Assessment

PROTECT Workshop – Vienna, June 27, 2007

Estimating Radiation Hazards to Biotaat Uranium Mines

2

Regulatory Framework – NSCA (2000)

CNSC - “Regulate … to prevent unreasonable risk to the environment…”, Applicant - “Make adequate provision for the protection of the environment …”, “… control releases …”

CNSC Regulatory Policy P-223- consistency with other Canadian policies, acts, … CEPA – legal framework for managing “toxic” substances CEAA – pre-licensing, assessment of likely, significant, adverse

effects for defined “projects” FTSMP – promotion of pollution prevention

MMER – As, Pb, Ni, Zn, Ra-226 … “permission to pollute”- CNSC license conditions for emerging issues (U, Mo, Se)- PSL2 decision on uranium as a “toxic substance” for biota at certain facilities, resultant MOU with Environment Canada

S-296, Environmental Management Systems ~ ISO 14001

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Hazard Assessment - How results are used

EMS - Programs and Procedures for Environmental Protection

- Context and predictions for spatial and temporal effects / ”aspects” - Needs for operational controls on quantities, timing and locations of releases

Effluent Monitoring Program

- Requirements for procedures to verify that controls are effective- Performance indicators / targets, administrative controls & action levels

Environmental Monitoring Program- Need for, and the scope of, activities to verify that releases are having the predicted effects (Pathways Contaminant Monitoring vs Biological Effects Monitoring)

Remediation of Contaminated Sites- Clean-up criteria and priorities for many historical sites $$$

Emerging issues at all sites- Long-term contamination of groundwater, sediments, unexpected pathways

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Uranium Mining in Canada – Geography

5

CNSC – Federal RegulatorSaskatchewan Environment – Provincial Regulator

JEB open pitMcClean Lake Mine

Northern Boreal Forest – MANY Lakes & Rivers

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Decommissioned & Abandoned Mines

Elliot Lake, OntarioQuirke TMA

Some sites with minimal Decommissioning

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Recent Mining-related EAs / ERAs

• New High Grade Ore Mine – Cigar Lake

• Operating Mines – McClean Lake Sue E, Key Lake, McArthur River, Rabbit Lake Pregnant Soln

• Decommissioning – Cluff Lake

• Historical Mines –Beaverlodge, Port Radium, Lorado, Gunnar, Madawaska, Dyno, ongoing …

• Remediation – Port Hope / Port Granby “Mounds”

• 2007+ – DeLoro (received), Midwest (guidelines)

Typical Consultants – e.g. SENES, Ecometrix

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CNSC Approach - Radiation Hazards for Biota

• Published by Environment Canada & Health Canada as a PSL2 Assessment in 2004 – Chemical Toxicity of Uranium

• Refined from literature reviews in the late 1990’s• Following Environment Canada’s risk quotient approach for

assessment of any hazardous substance (safety factors)• Simple, conservative dose coefficients and biota geometry

(Amiro, 1997), conservative alpha RBE 40, tritium RBE 3• Effects benchmarks chosen for the most sensitive species

using data on chronic reproduction or mortality effects, “similar” to UNSCEAR/IAEA except for fish

• Conservative in estimating exposure (benthos), secular equilibrium (30% Rn-222), choice of transfer factors …

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Licensee Approach - Delegation of Technical Work

• CNSC is not prescriptive - guidelines only, no standards• What has worked out well

- Risk is being identified to set priorities- Practical needs of licensing are being met- Data gaps are being addressed in “FUPs”

• What has not worked well- ERA “numerical” results are easy to manipulate, and hence, very tedious to review and interpret- There are many data gaps on exposure or effects- Physical models do often under-predict sediment levels - Pathways are still generic; exposure of wildlife is only just now starting to be verified with measured data

• Licensees still question ERA interpretation, prefer to react to “dead bodies” rather than prevent risk

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A “Typical” ERA – Predicting the future

Rabbit Lake• an old mill with

sites already at ecological risk

• proposal to mill Cigar “pregnant” solution from McClean Lake mill via a new haul road

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Valued Ecosystem Components

• Chosen to balance public interest and to capture exposure pathways, set in consultation with “Environmental Quality Committees”

• Similar logic for aquatic biota, fish species and benthos

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Typical Pathways – Water as a driverWatershed model calibrated via Kd

Interpretation of Beyer et al.

feces data

Kd or transfer factor approach

Almost no data

Whole fish data needed

Carex, the wrong

species“Muskrats do not eat roots”, and other nonsense

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Radiation Hazard – Common practices

• Conservative DCFs from Amiro (1997)• Discussion of RBE values, alpha from 5-40

Discussion of dose benchmarks, PSL2 vs others• Variable treatment of secular equilibrium, Thorium

may not be considered, Radon at 1%, 10%, 30% …• Benthos screening done against LEL/SELs, some

use of Thompson et al. recent benchmarks

• Considerable diversity in how uranium chemical toxicity is addressed, both exposure and effects

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Dealing with uncertainty

• SENES – probabilistic approach with mostly order of magnitude, log-normal distributions for transfer factors, many fixed parameters, occasionally using a tiered approach with further data collection

• ECOMETRIX –screening approach, use of expected and bounding / maximum scenarios

• ALL - minimal discussion of whole body versus organ doses, species-specific biology, review of toxicity literature, ecological context of impacts

“Adaptive Management” & FUPs

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Radiation effects – Rabbit Lake EASR (2006)

Po-210 and

benthos

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Reality Checks - Tissue Concentrations

• Waterfowl: Cluff Lake (5), Rabbit Lake (4), Elliot Lake (2), some very high levels on TMAs, almost no bone data

• Benthos: McClean Lake (2, creek), Cluff Lake (4, shallow lakes), Elliot Lake (2, lakes), Port Hope (harbour & creek)- dragonflies, crayfish, snails, tubificids, pooled samples…

• Fish: much better data, different trophic levels, small and large fish, some fish ageing data, recent whole body data, some flesh vs bone comparisons, almost no organ data

Analysis of Po-210 is expensive – often missingE.G. Wildlife – no request by regulator = no radionuclide data

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Reality Checks – Ecology

• Moose exposure/diet is adjusted for low density, and large home range to produce low, low risk… BUT, BUT…

• Aerial surveys of moose have all been done in winter - In summer some moose have literally fallen into TMAs

• Moose appear to live on macrophytes in early summer, this high level of sustained exposure is ignored in yearly averaging

• Fecal data from mule deer at a metal mine in BC indicate very high exposure to tailings, what happens at uranium mines?

Useful N =

Zero?

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Setting Priorities – Radionuclides or ???

U

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Uranium Chemical Toxicity

• No benchmark for birds (1 study with metallic form)• Mammalian physiological benchmarks approach

background based on kidney toxicity; chronic reproductive benchmark is at lowest level studied

• Bioavailability and environmental chemistry is poorly documented in soils, sediments, water

• Allometric scaling of CTV for wildlife species relative to mouse / rabbit greatly affects results [Sample et al. 1996 vs 1999 coefficients]

• Uranium OFTEN FLAGS FOR RISK at near-field siteS depending on how the model is set up

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Rabbit Lake Mine – Benthos & Uranium

Small lakes/ponds are often the first receiving water body.

Upper Link Lake is an “outlier” in the LEL/SEL statistical analysis; it greatly affects STATISTICS for Hyallela despite overall N = 20,000

Water to Benthos - Historical values and recent data/choices

1.E-05

1.E-04

1.E-03

1.E-02

1.E-01

1.E+00PH h

arbo

ur m

ostly

tubif

icids

'85

PH cree

k cra

yfish

'05

Blayloc

k '82

/ Bird

'96

Elliott

Lake

- sn

ails '

99

Elliott

Lake

- cr

ayfis

h '96

M/D

/M -

Thom

pson

'72

M/D

/M -

Sed K

d Ciga

r '02

R/M -

mos

tly d

rago

nflie

s

Gunna

r - E

PA '79

Cluff -

Poo

led '0

5 co

ntam

inate

d

Clulff

- Poo

led '0

5 co

ntro

l

Cluff '0

5 - B

enth

os=se

dimen

t

Bq

/g p

er B

q/m

3

Radium-226

Uranium

In the1990's, these were the only co-located data available from relevant environments in Canada

PSL2 did not use these data unless necessary, benthos set = sediment pore water concentration

First and last bars are calculated from dry weights assuming equal partitioning in sediments and tissues

Not shownSwanson

1982

Orders of Magnitude

RQ=1 or 10?

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Waterfowl / Benthos – TMAs / Pits

Rabbit Lake B-Zone 1992

Whole Body vs Tissues - Mallard and Ring-Necked Duck

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

breast thigh liver kidney flesh liver kidney bone GI tract

Bq

/g f

resh

wei

gh

t

Uranium Th-230 Ra-226 Pb-210 Po-210

Po-210Kidney!!

75% of total dose = Po-210Radon @10%, RBE=10

Importance of organ doses from Po-210 to waterfowl RQ>>1??

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The long term

Watershed models tell us that most far-field environments should return to background in about 100 years

What do we know about wildlife exposure now?

Bone doses may be critical ~ Ra = Rn? = Pb = Po

Dose from Radon: Ra vs Pb/Po - One Moose vs Many Fish

0.00001

0.0001

0.001

0.01

0.1

1

flesh liver kidney bone WS-f bone LW-f bone NP-f bone

Bq

/g f

resh

wei

gh

t

Uranium Th-230 Ra-226 Pb-210 Po-210

Cluff Moose WS= Cluff suckersLW= Lorado whitefish

NP= Key pike

BoneData

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ERA Interpretation – how to get a low RQ

Real examples of Muskrat exposure to Uranium

• ↓ 2x - use “default” sediment ingestion rate of 1%[ignore recent measured values (1.6-3.5%)]

• ↓ 2x adjust the CTV for a 28 g mouse to a “large” muskrat by the lowest of two allometric exponents suggested by Sample

• ↓ 5-10x have the muskrat only eat shoots of macrophytes (Carex!) and not roots, ignore literature and/or data

• ↓ 2-4x calibrate the watershed model to agree with shoots of macrophytes, present “fit” on a log scale to make it look good

• ↓ ?x – choose your transfer coefficients wisely …

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Putting it all together – A typical decision point

• Benchmark = 1 mGy/d, RBE = 10, Radon @30%• Whole body dose, Amiro (1997) DCFs• Probabilistic Transfer, beaver, moose etc. all with very low

RQs for radiation Coefficients• Generic diets, home range, exposure scenarios…• Highest RQ for near field = 0.43 (expected) for the scaup, =

1.54 (95th percentile), Muskrat hazards• BUT - Se, Mo flagging for risk, many species with RQs > 1

for NOAELs, effects extending into the far field for years

Proceed with licensing the project – YES or NO?

Set license conditions for improved effluent treatment?

Insist on a major Follow-up Program to measure actual risks?

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Future – Uranium @ $150+ per lb?

• High Grade Ores(predicting effects)

• Athabasca Basin(old mills, new mines)

• Northern Mines (Nunavut, Labrador)

• Climate Change(Wildlife, First Nations)

Woodland and BarrenGround Caribou