Environmental risks - Surface water
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Introduction
The general protection goal for aquatic species is to protect biodiversity and ecosystems. The focus is on protecting aquatic species at the population level although the acute risk assessment for aquatic vertebrates may also seek to protect individuals.
The major routes of exposure of aquatic species to a pesticide are from spray drift or run- off from the treated area. The scope of the environmental assessment will depend on the potential groups of non-target species that could be exposed and that could be at risk.
The acute and chronic risks to aquatic species 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 aquatic species. 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 surface water and aquatic species (fish and shrimp) 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
The reader needs to be aware that a key issue for environmental risk assessment in relation to surface water and aquatic species 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 water organism (generally at the population level for different organism groups and including at the individual level for aquatic vertebrates), 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 end-points 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 assessment assumes the worst-case scenario of a direct overspray of a shallow aquatic habitat (15cm water depth). Methodology for higher tier runoff assessment is described in more detail in |
Risk assessment and acceptability criteria | The risk assessment compares the PEC to the RAC to arrive at a risk quotient. |
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 | 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 | 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 EEC in an appropriate water body scenario. For pesticides used multiple times in one season, the (cumulative) EEC is calculated assuming non-target species are exposed to the concentration immediately after the last application. The number of applications, half-life of the active ingredient, and time between applications are considered when determining the cumulative EEC. |
Risk assessment and acceptability criteria | RQs are calculated using the ratio of the EEC and the RAC. |
China
Aspect | Description |
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Links to risk assessment guidelines, manuals and science policy documents | |
Hazard assessment and end-point selection |
Higher tier assessments include Species Sensitivity Distribution (SSD) analysis and mesocosm studies. |
Setting of toxicological reference values and the use of assessment factors |
In Tier 1 assessment, for fish and daphnia acute study, the uncertainty factor is 100; for fish and daphnia chronic study and algae study, the uncertainty factor is 10. |
Exposure assessment |
China-PSEM model will be used to calculate the PECsw for dry land crop, this model is under development. |
Risk assessment and acceptability criteria |
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EU
Aspect | Description |
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Links to risk assessment guidelines, manuals and science policy documents | |
Hazard assessment and end-point selection | The following end-points are derived from the hazard assessment:
Detailed guidance on tiered acute and chronic effect assessment schemes for aquatic organisms is provided at |
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 for the aquatic environment is based on the FOrum for Co-ordination of pesticide fate models and their USe (FOCUS) methodology. The FOCUS simulation models and scenarios are used to calculate the concentrations of pesticides (PEC) in surface water. |
Risk assessment and acceptability criteria | The risk assessment compares the PEC to the RAC. Where the PEC is less than or equal to the RAC the the risks are considered to be low.
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USA
Aspect | Description |
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Links to risk assessment guidelines, manuals and science policy documents | |
Hazard assessment and end-point selection | The assessment of the ecotoxicological and other relevant data in line with the matters to be taken into account as set out in legislation, forms the basis for the hazard assessment Abbreviations: |
Setting of toxicological reference values and the use of assessment factors | n.a. |
Exposure assessment | The exposure assessment involves the calculation of the EEC. The screening level assessment assumes the worst-case scenario for a water body adjacent to the treated field and highly vulnerable to runoff or leaching. |
Risk assessment and acceptability criteria | The risk assessment compares the EEC to the acute and chronic toxicity values to calculate the RQ.
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Can the legislative criteria be applied in other countries?
The principles and policies followed in the hazard assessment and end-point selection for surface water and aquatic species is similar across regulatory frameworks and can be applied in any country.
The setting of toxicological reference values for fish and invertebrates is similar across regulatory frameworks, however different regulatory frameworks use different assessment factors when setting the toxicological reference values. Country or regional policy should determine which assessment factors should be applied in setting toxicological reference values depending on the specific protection goal to be achieved.
The exposure assessment involves estimating concentrations of the pesticide in surface water based on a water body scenario. Different regulatory frameworks use different scenarios which will impact the outcome of the assessment. Water body scenarios must be relevant to the country/agricultural area where the pesticide is to be used.
Screening-level/worst case exposure assessments used by some countries/regions may be applicable to other countries. It is important that the regulator understands the scope and limitations of models they intend to use. In many case the risk assessment methods and models used are generally are based on local cropping situations, ecosystems, soil characteristics and weather, particularly for higher tier risk assessments. Country/region specific models based on site-specific, local cropping situations, ecosystems, soil characteristics and weather may not readily be applied in other countries.
The risk assessment approach and acceptability criteria based on comparing the estimated environmental exposure to the toxicological reference value are similar across regulatory frameworks and can be applied in other countries. Some countries apply trigger values (levels of concern) that focus on specific protection goals and/or endangered species. Country or regional policy should determine whether and what trigger values/level of concern should be applied.