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Introduction
The procedures of risk characterisation are described according to the present state of knowledge. In this tiered assessment framework, potential risk for birds and mammals is identified on the basis of responses of individual organisms observed in controlled laboratory experiments, noting that the abundance and persistence of populations of organisms are potentially more relevant as endpoints for assessment than are responses of individual organisms. The proposed approach is justified on the ground that too little is known about the responses of populations to chemical exposure to support regulatory decisions on that basis; however, population modelling can be considered in higher tier assessments when sufficient information is available. Risk assessors have to consider, at least qualitatively, that if only a small fraction of a population is exposed (spatial scale) risks associated with the use of the pesticide product may be small even if some individuals would be affected. That does not preclude, that appreciable mortality without population level consequences may be judged unacceptable.
The standard risk assessment is based on the field scale and not landscape scale, ie the risk to non-target birds and mammals frequenting the treated field is assessed. No consideration is made of the risk from applications of the same pesticide to neighbouring fields. If concern is raised (ie RQ >1.0) then the risk can be refined appropriately. When refining the risk it may be appropriate to consider such issues as suitability of the standard scenarios, scale of use and potential impact on populations. However, no deviations from worst case assumption should be made unless they are justified