Environmental risks - Soil organisms
Table of contents | |
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Introduction
The general protection goal is to protect biodiversity and ecosystems. The focus is on the protection and maintenance of populations taking into account both soil function and organisms (invertebrates, micro-organisms) important for proper soil function and nutrient cycle conservation.
The major route of exposure is direct exposure at time of application. Other routes of exposure include treated substrate for growing crops disposed on land and plant material, treated with pesticide prior to planting.
The acute and chronic risks to soil organisms are generally assessed using a tiered approach. An initial (screening) level risk assessment assumes a worst-case scenario and identifies those pesticides and associated uses that do not pose a risk to soil organisms. When acceptable risk cannot be determined at the initial (screening ) level then more refined higher tier risk assessments are undertaken and/or risk mitigation measures applied.
What this page contains
This table summarises the principles applied during the risk assessment to determine whether the environmental risks in relation to soil ( earthworms, other soil macro-organisms and soil micro-organism) are acceptable. The focus is on the screening level assessment. The screening level assessment identifies those pesticides and uses where no further testing or analysis is required. Where available, links to documents that describe the more complex higher tier assessment in more detail are provided.
Summary analysis
As for surface water and aquatic species, the reader needs to be aware that a key issue for environmental risk assessment in relation to soil and soil organisms is the limitations inherent in extrapolation from a limited number of test species to a comparatively large number of potential species at risk. Some regulatory frameworks more precisely describe the setting of specific protection goals for soil organism (for example, earthworms), while others rely on the problem formulation component of the risk assessment to identify the specific protection goal and suitable indicator species.
Australia
Aspect | Description |
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Links to risk assessment guidelines, manuals and science policy documents |
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Hazard assessment and end-point selection | The following endpoints are derived from the hazard assessment:
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Setting of toxicological reference values and the use of assessment factors | The RAC is calculated for acute and chronic exposure scenarios using the following assessment factors:
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Exposure assessment | The exposure assessment involves the calculation of the PEC. The screening level risk assessment assumes the works-case scenario of a direct overspray of soil without interception. |
Risk assessment and acceptability criteria | The risk assessment compares the PEC to the RAC to arrive at a risk quotient: RQ= PEC/RAC |
Canada
Aspect | Description |
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Links to risk assessment guidelines, manuals and science policy documents |
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Hazard assessment and end-point selection | Canada does not require data on soil micro-organisms.
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Setting of toxicological reference values and the use of assessment factors |
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Exposure assessment | The EEC is calculated based on a direct application (soil depth 15cm and soil density of 1.5g/cm3). |
Risk assessment and acceptability criteria | The risk to earthworms is determined by dividing the EEC in soil by the toxicological reference value to calculate a RQ. The LOC is 1. |
China
Aspect | Description |
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Links to risk assessment guidelines, manuals and science policy documents | |
Hazard assessment and end-point selection | n.a. |
Setting of toxicological reference values and the use of assessment factors | The PNEC based on endpoints and an uncertainty factor is calculated.
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Exposure assessment | • "PECsoil_SFO_30Y"(an Excel spreadsheet) is used as a 1st tier exposure model. China-PEARL model can be used as a higher tier exposure model |
Risk assessment and acceptability criteria | n.a. |
EU
Aspect | Description |
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Links to risk assessment guidelines, manuals and science policy documents |
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Hazard assessment and end-point selection | The following end-points are derived from the hazard assessment:
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Setting of toxicological reference values and the use of assessment factors | n.a. |
Exposure assessment | The exposure assessment involves the evaluation of fate and behaviour of the pesticide and transformation products in soil and the calculation of PECs. |
Risk assessment and acceptability criteria | For earthworms and soil macro-organism risk is characterised using a TER. For soil micro-organisms the magnitude of effect is assessed.
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USA
Aspect | Description |
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Links to risk assessment guidelines, manuals and science policy documents | The US does not routinely require data on terrestrial soil organisms. |
Hazard assessment and end-point selection | n.a. |
Setting of toxicological reference values and the use of assessment factors | n.a. |
Exposure assessment | n.a. |
Risk assessment and acceptability criteria | n.a. |
Can the legislative criteria be applied in other countries?
In some countries risks to soil (earthworms, other soil macro-organisms and soil micro-organisms) is only considered on a case-by-case basis. Some countries only assess data in relation to earthworms while other countries or regions will conduct a comprehensive risks assessment of soil (macro- and micro-organisms). Country or regional policy should determine whether, and what, they will include soil organisms as an environmental protection goal.
Where environmental risks in relation to soil are assessed, the criteria for assessing the risks are not consistent across regulatory frameworks Thus hazard assessment and end-point selection for soil organisms vary across regulatory frameworks. Some, but not all regulatory frameworks, set toxicological reference values for soil organisms.
The exposure assessment involves estimating concentrations of the pesticide in soil based on the user of scenarios, however different regulatory frameworks use different scenarios which will impact the outcome of the assessment.
Screening level assessments based on laboratory studies using standard test organisms and soils may be suitable for application in other countries. For higher tier risk assessments is important that the regulator understands the scope and limitations of models they intend to use. Higher tier risk assessment methods and models used are generally are based on local cropping situations, ecosystems, soil characteristics and weather. Country/region specific models based on site-specific, local cropping situations, ecosystems, soil characteristics and weather may not readily be applied in other countries.
Some regulatory frameworks use a risk quotient approach comparing the estimated environmental exposure to the toxicological reference value to determine whether risks are acceptable. Other regulatory frameworks use a toxicity to exposure ratio and compare these to trigger values (levels of concern) set out in legislation. Country or regional policy should determine whether to use a risk quotient approach or a toxicity to exposure ratio approach and what trigger values (levels of concern), if any, to apply