General characteristics of pesticide risk indicators
Pesticide risk indicators, as specified in the National Action Plans of the EU Member States, are all associated with a goal expressed in terms of volume, frequency of use or risk and impact. Some indicators have adopted quantified and time-bound targets, while some have not. The general trend has been to move away from volume reduction goals towards reduction in use, environmental impact and risk. A major constraint of volume reduction targets is that they do not take into account the replacement of lower-dose pesticides with newer and more potent ingredients (Barzman and Dachbrodt‐Saaydeh, 2011).
Pesticide risk indicators are mathematical equations that consider data inputs such as application rates, toxicity levels of a pesticide´s active ingredient, meteorological data, the soil characteristics of farm fields, and other information to generate potential risk scores for pesticide applications. These risk scores represent the best estimate of a pesticide´s impact on the surrounding environment and can be used to evaluate and quantify mitigation measures.
Pesticide risk indicators are generally based on models that predict the environmental impact of certain pesticides. Studies to evaluate and validate the indicators in the field are rare. The lack of validation studies of indicators also hampers the evaluation of mitigation measures (Greitens and Day, 2007).
There are three principal areas at issue for pesticide environmental indices, namely: the criteria and standards chosen to assess the environmental impact of pesticides; the methods used to estimate their environmental impact (including the aggregation of diverse data); and the data used (e.g. their accessibility and reliability). The choice of parameters and methods by which to assess the types and range of impacts is the starting point for indicator development (Falconer, 2002).
Work on pesticide indices and ranking models has been driven by a wish to compare different chemicals as a step towards more sustainable crop protection strategies. There is currently a significant information gap, for farmers and policy-makers, with regard to the relative merit or dis-merit of different pesticides from an environmental perspective.
Shortcomings and challenges of risk indicators for pesticides
There are many conceptual and practical challenges to indicator development and application, especially with regard to assessment of indirect environmental effects, given the multi-dimensionality of pesticide usage, properties and impacts. A significant problem lies in obtaining sufficient and accurate input data, coupled with the lack of knowledge and understanding of the links between pesticide use, emissions, environmental concentrations and any adverse effects.
Furthermore, data on eco-toxicological effects have to be collected using standardised testing protocols if they are to be comparable across different circumstances. New products are emerging onto the market constantly, but there are only limited data on the effects of these, and the problems of data-set incompleteness need acknowledgement in indicator development if they are to be used as real decision-making bases.
Pesticide indicators are inevitably partial, given that they are based on selected components of interest, and on a particular configuration of preferences where parameters relating to disparate impacts are aggregated. In this sense, indicators are unavoidably biased (Falconer, 2002).
Spatial scale issues need consideration, and the potential biases of aggregation must be at least acknowledged, if not overcome. Risks and impacts are likely to vary spatially, implying that assessment models should be differentiated between regions, in terms of their structure or the data on which they are calibrated.
Finally, an important issue for indicators of all types is the timescale over which a pesticide's environmental burden is assessed. Adverse environmental effects may be separated from pesticide application by long time lags, especially in the case of chronic health effects. A major disadvantage of indicators based on current usage is that they exclude consideration of impacts arising from past usage of persistent compounds.
Characterisation of the most frequently used/most important pesticide risk indicators
Annex 5 in »FAIRWAY Project Deliverable 3.1 gives a compilation of pesticide risk indicators used in Europe, including specific targets of Member States and level of spatial applicability. The large number and diversity of pesticide risk indicators can be explained by
- Role of indicators in EFSA admission process for active substances,
- Diversity of active substances,
- Diversity in products/formulations/combination,
- Diversity of target organisms/environmental compartiments,
- Problems in direct detection in environment.
As shown in Annex 5, European countries use very diverse and different indicators for their pesticide monitoring and reduction aims according to regulation (EC) No 1185/2009. Below, the most frequently used/important indicators for pesticide risks are further explained. These indicators refer not only to leaching risks, but in many cases focus on other environmental and health risks.