Download The `biological` component of bioavailability

The “biological” component of
bioavailability: the usage of
ecotoxicological tests
Jörg Römbke
ECT Oekotoxikologie GmbH, D-65439 Flörsheim, Germany
Brussels,
Running 2014
Title
Outline of this Talk
1.
Introduction
Soil ecology and ecotoxicology
2.
Selection of standard tests
General criteria and exposure
3.
Description of individual tests
Already required and potential methods
4.
Inclusion of bioavailability in ERA
Existing approaches
Focal compartment:
Soil
Focal organisms:
Soil invertebrates
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Background: Soil Ecology
Soils differ enormously in terms of
Macrofauna
their biological diversity, but also
regarding their abiotic properties.
Mesofauna + microbes
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Background: Soil Ecotoxicology
Chemicals
Invertebrates
Ecotoxicological
effects depend on the
class, fate and
availability of the
chemical, on the type
and behavior of the
species and on the
surrounding abiotic
Soil
Physical, chemical & microbiological properties
factors (e.g. soil
properties, climate)
Surely: clear protection goals are needed for assessing any risks.
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Title
Conceptual Basis: ISO 17402 (2008)
Methods to assess
bioavailability –
Chemical measurements
(available fractions)
soil/water
Relation between
chemical, biologi-
membrane
cal tests and
bioaccumulation
organism
Toxicity tests
Bioaccumulation
Biological
measurements
Conclusion: The only direct way of measuring bioavailability for
an organism to be protected is the use of that organism and to
measure the effect and/or the accumulation of a given chemical.
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Title
Selection of Standard Tests: Overview
So, soil biological tests are needed – but which ones?
25
20
Blue = Laboratory
Red = Semi-field
Yellow = Field
15
10
5
0
1980
1985
1990
1995
2000
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Selection of Standard Tests: Criteria
Regulatory needs
<==>
Problem: What was first?
Exposure pathways
==>
Minimum: pore water, soil ingestion
Species
==>
Different taxonomic / ecological groups
(often size: micro/meso/macrofauna)
Sensitivity
==>
Practicability of tests ==>
Chronic or behavioural endpoints
Simple, quick and cheap performance
Such tests are provided by two international organizations:
►
OECD (Chemicals Group): single-chemical testing before
market authorization  prospective protection of soil
►
ISO (Technical Committee 190): soils contaminated by a
mixture of chemicals  retrospective protection of soil
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Running 2014
Title
Selection of Standard Tests: Exposure I
OECD and ISO methods are often similar. But: soils are different.
Organic matter: 10%
OECD artificial soil:
 Prospective tests
Organic matter: 2-4%
Natural standard
Natural field soils:
LUFA soil
 Retrospective tests
Availability of chemicals in OECD and field soil (may) differ strongly.
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Title
Selection of Standard Tests: Exposure II
Exposure of soil organisms is determined by three factors:
1.
Exposure pathways:
►
Pore-water: main route for plants and (many) invertebrates
►
Ingestion of soil particles: relevant for saprophagous invertebrates
►
Inhalation of air: possible for all organisms but rarely (?) relevant
2.
Biology and ecology of species
►
Morphology: e.g. soft- versus hard-bodied organisms
►
Physiology: e.g. food uptake, i.e. with or without soil particles
►
Behavior: e.g. vertical distribution, including avoidance patterns
3.
Chemical properties
(Peijnenburg et al. 2012)
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Title
Selection of Standard Tests: Exposure II
Examples: Exposure of soft- und hard-bodied organisms
Soft: Uptake of oxygen, water and contaminants via the body surface (skin)
Both: Uptake of contaminants via food (with or without soil particles)
Hard: Specific organs for the uptake of oxygen, water and contaminants
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Title
Selection of Standard Tests: Battery
A minimum battery of laboratory tests with soil invertebrates is
required in prospective soil protection in the European Union:
Soft-bodied macrofauna:
Chronic Earthworm Test (Eisenia andrei/fetida)
OECD 222 (2004); ISO 11268-2 (1998)
Hard-bodied mesofauna:
Chronic Collembola Test (Folsomia candida)
OECD 232 (2009); ISO 11267 (1999)
Chronic Predatory Mite (Hypoaspis aculeifer)
OECD 226 (2008)
In addition, at least one plant and one microbial test are required.
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Running 2014
Title
Description of Individual Tests I
Name:
Earthworm reproduction test (OECD, ISO)
Substrate:
Artificial Soil or many field soils, e.g. LUFA
Duration:
56 days
Parameter:
Biomass, number of juveniles
Experience:
High for pesticides, veterinary drugs, REACH,
contaminated soils, often very sensitive
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Running 2014
Title
Description of Individual Tests II
Name:
Collembola reproduction test (OECD, ISO)
Substrate:
Artificial Soil or many field soils, e.g. LUFA
Duration:
28 days
Parameter:
Mortality of adults, number of juveniles
Experience:
High for pesticides and contaminated soils, less for
other chemicals, often very sensitive
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Title
Description of Individual Tests III
Name:
Predatory mite reproduction test (OECD)
Substrate:
Artificial Soil or field soils, e.g. LUFA
Duration:
28 days
Parameter:
Mortality of adults, number of juveniles
Experience:
High for pesticides, almost none for other chemicals,
or contaminated soils; rarely very sensitive
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Title
Which other Tests could be useful?
Using the same criteria, behavioral tests are missing, especially
for retrospective soil protection:
Soft-bodied macrofauna:
Earthworm Avoidance Test
(Eisenia andrei/fetida)
ISO 17512-1 (2008)
Hard-bodied mesofauna:
Collembola Avoidance Test
(Folsomia candida)
ISO 17512-2 (2011)
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Running 2014
Title
Further Standard Invertebrate Tests I
These standard tests are available but are rarely used in practice,
mainly in retrospective soil protection:
Snail Growth Toxicity Test (Helix aspersa)
ISO 15952 (2003)
Nematode Reproduction Test
(Caenorhabditis elegans) ISO 10872 (2011
Chronic Enchytraeid Test
(Enchytraeus albidus/crypticus)
OECD 220 (2004); ISO 16387 (2004)
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Title
Further Standard Invertebrate Tests II
Originally "invented" for retrospective soil protection, but also
useful in prospective soil protection: semi-field tests.
Terrestrial Model Ecosystems (TME): ASTM (1993), PERAS (2010)
►
Interaction of soil properties and the natural community of
microbes, invertebrates and plants
►
Undisturbed soils from crop sites or meadows
►
Usually about 16 weeks
►
Wide variety of fate and effect endpoints
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Title
Overview on Existing Tests: Plants I
Prospective soil protection:
►
Seedling emergence test. 6 – 10 crop species (or
"wild species") OECD 208 (2000). Exposure: mixing
chemicals into control soil; (e.g. LUFA "standard"
field soil). Endpoint: biomass, shoot length.
►
Vegetative vigor test. OECD 227 (2000): Like 208
But: Exposure: spraying the pesticide on
the emerging plants and soil surface.
Note: Currently, the inclusion of "lower" plants
(e.g. mosses, ferns) is proposed (EFSA 2011).
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Title
Overview on Existing Tests: Plants II
Retrospective soil protection:
►
Plant root growth test, usually grain species. ISO 11269-1 (1993)
Nowadays rarely used, considered to be not very robust
►
Emergence and plant growth test. Avena sativa, Brassica rapa.
ISO 11269-2 (2008): Mixing of contaminated soil (or wastes) with a
control soil (usually LUFA).
Plant test most often used
for contaminated soils.
►
Chronic plant test. ISO
22030 (2012): Like 11268-2.
But: Reproduction endpoints.
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Title
Overview on Existing Tests: Microbes
In contrast to other tests, in microbial studies usually the function (NOT
the structure) of the natural microbial community is tested, i.e. the
tests are performed in natural field soils.
Prospective soil protection:
Nitrogen transformation test:
OECD 217 (2000)
Retrospective soil protection (only few examples are given):
Respiration test (SIR):
ISO 14240-1 (1997)
Ammonium oxidation rapid test: ISO 15685 (2001)
Arthrobacter globiformis test:
ISO 18187 (2012)
Only single species microbial test in soil
Brussels,
Running 2014
Title
Inclusion of Bioavailability in ERA I
Prospective soil protection:
General impression: Bioavailability should be taken into account.
However, it is not yet clear how.
►
The existing biological tests (earthworms, springtails, mites, plants,
microbes) and the soil(s) used are under review (e.g. pesticides).
►
One possible addition: isopods (wood-lice)
(e.g. hard-bodied macrofauna feeding on litter)
►
Main focus: Modified exposure calculations
-
Exchange of total concentrations
in favor of pore-water concentrations.
-
Omisssion of bound residues
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Title
Inclusion of Bioavailability in ERA II
Retrospective soil protection:
Proposal based on draft
ISO Standard 19204 (2014):
TRIAD approach
Ecotoxicology
(laboratory
Testing is performed for each
tests)
Chemistry
(exposure,
bioaccumulation)
of these three areas in three
refinement levels, starting with
simple screening tests.
Availability is covered both in
Ecology
(monitoring,
field surveys)
Integrative
Evaluation
Chemistry and Ecotoxicology.
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Running 2014
Title
Inclusion of Bioavailiability in ERA III
Tier I (screening):
Chemistry: Refinement of soil screening values
Ecotoxicology: Arthrobacter test (ISO 18187); plant screening test (ISO
17126); earthworm or Collembola avoidance test (ISO 17512-1/2);
Tier II (refined screening):
Chemistry: Bioavailability methods, e.g. solid phase micro extraction.
Ecotoxicology: Chronic earthworm tests (ISO 11268-2), enchytraeids
(ISO 16387), springtails (ISO 11267); Plant growth test (ISO 11269-2).
Tier III (detailed assessment):
Chemistry: Modelling or simulation systems
Ecotoxicology: Multi-species test; Chronic plant test (ISO 22030).
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Title
Acknowledgements
Thanks a lot to all colleagues
who have been contributed to this talk!
In particular the Working Group 3 of ISO TC 190 SC 7!
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Title