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(070) Ecological Relative Risk (EcoRR): A method for ranking environmental risks of agricultural pesticides. Sánchez-Bayo, Francisco1, Baskaran, Sundaram2, Kennedy, Ivan1, 1 2 ABSTRACT- A methodology was developed to rank and compare the ecological risk that several agricultural pesticides may introduce in a particular environment. The Ecological Relative Risk (EcoRR) is based on standard frameworks for risk assessment (PEC/toxicity), but includes features related to the fate and persistence of residues as well as the diversity of ecosystems. The exposure assessment considers the predicted environmental concentrations of a substance, its persistence, bioaccumulation and probability of exposure in a given environmental compartment (water, soil, vegetation, etc). The toxicity assessment takes into account the biodiversity of the ecosystem, whereby the endpoints used are weighted by the contribution of each taxa (i.e. proportion of species per taxon) in a given environment. Thus, EcoRR values are estimated by the quotient exposure/toxicity for each affected area, enabling to pinpoint the compartments most at risk Essentially, EcoRR results in a relative index for ranking risks amongst different pesticides in a given area. A cotton farm development adjacent to a wetlands nature reserve provided a case study to evaluate the ability of EcoRR for ranking risks of 12 pesticides, using model predictions for exposure data. A validation of the exposure data is currently under way. Results for the aquatic environment were also compared to other traditional assessments using quotients. It is concluded that EcoRR rankings reflect adequately the risk of those chemicals in such an environment, while the EcoRR expression is less dependent on toxicity to sensitive species than the simple quotient. This methodology can be used with both field measured and model predicted data, so management options for new chemicals can be tested prior to their application on crops. Key words: risk, ranking, index, pesticides |
