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 …..