Protecting soils: the “Dutch
regulation case” with regard
to bioavailability
Willie Peijnenburg, 14 October 2014
RIVM / Centre for Safety of Substances and Products
Overview
• Policy frameworks
- Soil
- Sediment
- Water Framework Directive
• Bioavailability in soil policy
- Soil standards and soil type correction
- Clean up criteria & Risk assessment
• Modified soil type correction: background and background risk
• Bioavailability in 2nd tier assessment
Background levels and risks
• Natural and anthropogenic
• Potentially available and non available
• Chemically and/or biologically available
Struijs e.a. 1997
Current Dutch soil policy
• Law on soil protection (revised 1 januari 2006, now in process of
fundamental revision – new integrated law on sustainable environment)
• Prospective - Target values soil
- Target values groundwater
- Construction materials (leaching/composition): Decision on soil quality
- Storage tanks in subsoil
• Retroprospective - Intervention values
- Sanitation critera
- Maximum allowable values (Sanitation goals)
• Soil management - Generic maximum values
- Local (site specific) maximum values (region specific)
- Risk toolbox: actual soil quality
Current Soil Policy and bioavailability
• Preventive
- No implementation bioavailability
• Curative
- Implementation bioavailability desirable/possible
• Soil management
- Implementation bioavailability allowed, however……
Total content
(mg/kgdw)
Soil use ( decreasing “sensitivity”)
Playground Industrial Living +
Garden
Intervention
value
Sanitation criteria
Maximum
value
local Maximum
Values
Agriculture +
Small scale
home pharming
Target value
Standards in soil policy
NATURE “Green” / parc
+ Env. value
Soil function classes
Other legislative frames: sediment policy
• Policy on soil and sediment: separate trajectories
• 2008: Circular on sediment quality
• RINOWA, “Richtlijn Nader Onderzoek Waterbodems” (february
2008); yes/no urgent sanitation?
- Porewater (for instance CaCl2 + reference framework)
- Available (for instance tenax extraction)
- total
• Integral law on Water (2009): link to ecological and chemical
objectives WFD
Overview
• Policy frameworks
- Soil
- Sediment
- Water Framework Directive
• Bioavailability in soil policy
- Soil standards and soil type correction
- Clean up criteria & Risk assessment
• Modified soil type correction: background and background risk
• Bioavailability in 2nd tier assessment
Risk assessment and soil type correction
• Target values, background values, maximum allowable
values, intervention values
• Metals: (standard)l,om = (standard) l=25, h=10 x {{(A + (B x %
lutum) + (C x % organic matter)} / {(A +(B x 25) + (C x 10)}}
• Based on relationship between lutum/organic matter and
[metal] relatively undisturbed sites
• Organics: (standard)om = (standard) om=10 x (% organic
matter/10)
• Also: Lab tox data corrected to obtain value for standard soil
• Correction for background + fraction risk part of standard
(commonly: risk part = 1)
Sanitation criterion soil
• Yes/no urgency for clean up
Sanitation
criterion
Bioavailability:
Site specific assessment
Ecosystem risks: step 2 (2nd tier assessment)
Standard approach:
• Deduce msPAF 0.2 en 0.5 contour (previously HC50)
• Assess size of contaminated area
• Assess ecological sensitivity of contaminated area, for
instance:
• Industrial areas less sensitive
• Nature areas very sensitive
Site specific ecological risk assessment:
TRIADE approach; tier 3
• Three types of assessment methods, each with conceptual
uncertainties
• Purpose: pragmatic reduction of uncertainty
• Method:
- ‘Weight of evidence’
- Tiered approach
ecologytoxicology
riskeffect
chemistry
ecologytoxicology
riskeffect
chemistry
RIZA
TRIADE and test methods
Triad Aspect Parameter Zone A Zone B Zone C
Number of HC50 exceedances (Cr) 0 7 13
Chemistry Sum TP total metals antropogenic 0.00 0.83 0.97
Sum TP porewater 0.00 0.62 0.89
Risk 0.00 0.75 0.94
Toxicology Microtox 0.36 0.48 0.62
PAM-algae 0.00 0.00 0.00
Germination L.sativa 0.00 0.02 0.1
Risk 0.14 0.21 0.30
Ecology Biolog 0.00 0.35 0.44
PICT 0.00 0.47 0.71
Microbiology 0.00 0.25 0.42
Nematodes 0.00 0.15 0.32
Enchytraeids 0.00 0.00 0.68
Earthworms 0.00 0.15 0.24
Risk 0.00 0.24 0.50
Outcome chemistry: 0.00 0.75 0.94
Outcome toxicology: 0.14 0.21 0.30
Outcome ecology: 0.00 0.24 0.50
Judgement: 0.05 0.47 0.73
deviation 0.14 0.52 0.57
• Chemistry
• Toxicity
• Ecology
bioavailability
Standard setting in soil management: generic
and region/local specific
• Region/local specific: assess maximum alowable
values using the risk toolbox, especially developed for
this purpose
• Three soil use classes (generic) :
- Background
- Urban (lowest)
- Industrial sites
Always
applicable
Soil function:
urban
Soil function:
industrial
Not applicable
anywhere
Background values Maximum value
urban Maximum value
Industrial
Bioavailability in soil management
• Derivation of corrected local maximum allowable levels
for purpose of site/region specific policy making.
• Potential problem: (large) differences in bioavailability
among areas (Q: allowed to transport soil between areas
and subsequent differences soil properties differences
in bioavailability)
Foreseen role bioavailability in 2nd tier
assessment
Considerations
• Prevention non-needed actions + optimise means available
• Part of TRIADE, quickly showing differences between potentially (total content) and actual risk
• Possibly to be included in deriving local/regional soil standards
• When experts provide clear advises, then confidence among policy makers regarding actual implementation in policy making mobilisation of experts to agree on suited methods
Summary – Need for implementation BA
“Incorrect” prediction of risks
Too often indication risks, while ecosystem is not affected
Soil matrix and behavior of organisms influence the
potential effects of contaminants
Only bioavailable fraction is available to exert adverse
effects
Including BA reduction of false negatives and positives
Example of TENAX extraction
0.01
0.1
1
10
0.01 0.1 1 10 100
concentration in sediment (mg/kg OC)
co
nce
ntr
ati
on
in
org
an
ism
(mg
/kg
lip
id)
R2 = 0.9592
0
1
2
3
4
0 10 20 30 40 50 60
Fraction desorbed to Tenax in 6h (%)B
SA
F f
or
Lim
no
dri
lus
sp
. (k
g O
C/k
g lip
id)
Ten Hulscher et al., ET&C 22 (10), 2258-2265 (2003)
Total Concentrations vs Bioavailable
concentrations
General considerations implementation
BA Topic of scientific research for a large number of years
Legislators face the challenge to implement this
knowledge in present risk evaluations
The Netherlands aim to implement bioavailability in a
second tier risk evaluation for soils and sediments
Many of the developments in water compartment
Assumption: general principles in water do not differ from
those in soil and sediments
However: awareness of fact that behavior and effects of
contaminants on organisms in soil are more complex in
relation to in water
Methods under consideration (1)
Organic contaminants
Passive sampling
• Solid Phase Micro Extraction (SPME)
• Semi Permeable Membrane Devices (SPMD)
• Solid Phase Extraction Disks
• Stir Bar Sorptive Extraction (SBSE)
Tenax extraction
Cyclodextrine extractions
Supercritical fluid extraction
Methods under consideration (2) Heavy metals
Actions
Elaborate literature study
Workshop with national experts on BA
Selection criteria
1. Wide ranging applicability
2. Practical use
3. Added value compared to total content
4. Validity for ecotoxicity
5. Applicability for more than ecotoxicity
Method Selection criteria
1a 1b 1c 1d 2 3 4 5
Organic contaminants
Passive sampling
-SPME + + 0 + 0 + + +
-POM-SPE + + + + 0 + + +
-Silicone ubber + + 0 0 0 + 0 +
Tenax + + 0 + + + 0 +
Cyclodextrine + + + 0 + 0 0 +
Heavy metals
Acid extractions
-0.43 M HNO3 + + + + + + - +
-0.1 M HCl + + + + + 0 - +
Weak extractions
-0.01 M CaCl2 + + + + + + 0 +
-0.0025 M NaNO3 + + + + + + + +
Final outcome (1)
Not just one method!
Differentiate between potential available conc. and
actual available conc.
Heavy metals
Acid extractions (potential)
• 0.43 M HNO3 extraction
Weak extractions (actual)
• 0.01 M CaCl2 extraction
Final outcome (2)
Organic Contaminants
Passive sampling (actual)
• SPME
• POM-SPE
Tenax Extraction (potential)
Cyclodextrine extraction (potential)
Further actions
Design a policy framework in which BA can be
implemented without diminishing current protection
level
Relation measured conc. actual toxicity
Technical design and user protocol of the methods
Pilot study
Implementation issues – reference
framework
Preferred: relate extractable concentrations to
toxicity data on similar basis
Relate bioavailable concentrations to Critical Body
Burdens: non-polar narcosis
Relate measured bioavailable concentrations to
aquatic toxicity data
Concluding remark
Good that there is some
confirmation …..