A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment...
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![Page 1: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/1.jpg)
A practical approach to account for the
bioavailability of metals
Bruce BrownWCA Environment
REPRESENTING Eurometaux
November 25th 2010
![Page 2: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/2.jpg)
Slide 2
Metals EQSs are Evolving• Existing methods based on
total concentrations are poor predictors of potential environmental risk
• Need to monitor dissolved metals
• Biotic Ligand Models (BLMs) developed which predict toxicity extremely well
• BLMs appear complicated to implement – but are not!
![Page 3: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/3.jpg)
Slide 3
Why bother to account for bioavailability?
• Many new metals EQSs are based on high bioavailability
• Wide scale failure of EQSs derived for metals if only considering face-value comparison with monitoring data.
• Enables resources and money to be focussed at those sites at real risk of harm
![Page 4: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/4.jpg)
Slide 4
Perceived practical limitations when using biotic ligand
models (BLMs) in the WFD• Complexity of models• Input hungry• Resource intensity• Practical difficulties• How to use the outputs?
![Page 5: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/5.jpg)
Slide 5
Solutions to the practical problems of implementing bioavailability in a
regulatory frameworks• Development of screening tools –
only 3 inputs for Cu, Ni, Zn – DOC, pH and Ca)
• Tiered compliance assessment for metals
• Full automation possible within laboratory analytical system e.g. UK
• Outputs can be expressed as either bioavailable metal or site specific EQS
![Page 6: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/6.jpg)
Slide 6
Screening Tools
0
5
10
15
20
25
0 5 10 15 20 25
HC5 NiBLM µg l-1
HC5
Scre
enin
g too
l µg
l-1
Comparison of Ni screening tool performance against NiBLM performance (all concentrations in µg dissolved Ni l-1) data from sites across the England and Wales (n ≈ 112) .
![Page 7: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/7.jpg)
Slide 7
Limited input data
Output 1:Bioavailability-basedPNEC
Output 2:Site-specific risk characterization
![Page 8: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/8.jpg)
Slide 8
The Tiered Approach1. Comparison with generic EQSbioavailable
2. Use of screening tool
3. Consideration of local ambient background concentrations
4. Remedial measures
Class
ificati
onPr
ogra
mme o
f Me
asur
es
FAIL
FAIL
FAIL No fu
rther
actio
n nec
essa
ry Pass
Pass
Pass
![Page 9: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/9.jpg)
Slide 9
1. Comparison with generic EQSbioavailable
2. Use of screening tool
3. Consideration of local ambient background concentrations
4. Remedial measures
Class
ificati
onPr
ogra
mme o
f Me
asur
es
FAIL
FAIL
FAIL No fu
rther
actio
n nec
essa
ry Pass
Pass
Pass
![Page 10: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/10.jpg)
Slide 10
Nickel - Great Britain (n = 183)
1. Comparison with generic (100% bioavailable) EQS
2. Use of screening tool
FAIL
FAIL
Pass
Pass
Percentage pass rate = 97 %
(n =122) (n = 61)
(n =6)(n =116)
![Page 11: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/11.jpg)
Slide 11
Nickel - France (n = 249)
1. Comparison with generic (100% bioavailable) EQS
2. Use of screening tool
FAIL
FAIL
Pass
Pass
Percentage pass rate = 95 %
(n =29) (n = 220)
(n =12)(n =17)
![Page 12: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/12.jpg)
Slide 12
Nickel - Austria (n = 1779)
1. Comparison with generic (100% bioavailable) EQS
2. Use of screening tool
FAIL
FAIL
Pass
Pass
Percentage pass rate = 91 %
(n =646) (n = 1133)
(n =158)(n = 488)
![Page 13: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/13.jpg)
Slide 13
Data Requirements• Typically DOC, pH & Ca as minimum• Potential need for guidance on best
practice for producing DOC data?• Can estimate DOC from dissolved Fe
or UV absorbance but adds uncertainty
![Page 14: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/14.jpg)
Slide 14
DOC Estimation by UV
![Page 15: A practical approach to account for the bioavailability of metals Bruce Brown WCA Environment REPRESENTING Eurometaux November 25 th 2010.](https://reader035.fdocuments.in/reader035/viewer/2022062401/5a4d1b4f7f8b9ab0599a7272/html5/thumbnails/15.jpg)
Slide 15
Summary• Accounting for metal bioavailability provides a robust
metric by which to assess potential risks – and is linked to biology!
• Bioavailability can be applied within a tiered approach • Simplified screening tools are available that:
– Process large numbers of samples– Have only 3 inputs (in the case of Cu, Ni and Zn)– Fully automated
• Accounting for bioavailability does NOT present significant practical challenges
• Some changes to routine monitoring requirements probably needed e.g. Dissolved metals and DOC
• Implementation Guidance next year?