Applying a tiered environmental risk assessment framework to estimate the risk of pesticides to soil organisms in Latin America

Abstract

This work investigates the application of a tiered risk assessment scheme for soil organisms based on the risk quotient (RQ) and the toxicity exposure ratio (TER). Forty-five pesticides registered in Latin America were chosen and the ecotoxicological endpoints for earthworms, Collembola, and microorganisms were collated. Tier I assessment was made on conservative assumptions in which no refinements were applied. There, 14 pesticides (31%) exceed the RQ regulatory trigger indicating unacceptable risk, whereas 27 (60%) indicate unacceptable risk on the TER approach. In a Tier II evaluation when refinement options such as foliar interception, field half-life, and the dissipation following the peak estimated environmental concentration are considered, eight (18%) pesticides indicate unacceptable risk based on the RQ, and 15 (33%) indicate unacceptable risk based on the TER. A nonmetric multidimensional scaling evaluation was performed to understand the relevant characteristics involved in how each pesticide poses a risk to soil organisms. Based on the outcome of this analysis, we observed that, for a given pesticide, the combination of high persistence, low or no crop interception, and high toxicity are likely to require higher tier risk assessment. Refinement options can consider either or both the exposure and/or the effect side of the framework. Exposure refinements are potentially simpler and can be conducted with data already available to risk assessors, whereas effect refinements involving further testing with the organisms potentially at risk are still under discussion for intermediate and higher tiers. A sensitive, simple, and logical environmental risk assessment framework can be used to adequately identify risks based on the relevant protection goals that, in turn, will help to protect the desired soil multifunctionality of the ecosystem. We encourage academia and industry to further investigate these topics to provide the most scientifically robust and evidence-based information to decision makers.

Development of a soil exposure assessment for plant protection products in Brazil: Requirements, options, and recommendations

“…It is noted that the underpinning calculations supporting each of these techniques are consistent in the UK HSE spreadsheet, the Ctgb spreadsheet, and the ESCAPE model and would lead to the same exposure outcomes and risk characterization to support decision‐making. Illustrations are presented in Table 2 duplicating calculations presented for example compounds as summarized by Tincani, Cione, Casallanovo, Bottoms, Alvarez, et al (2023), but extending this to the parallel representation in the Ctgb spreadsheet and the ESCAPE model. This comparison includes a chemical with a very short DT 50 (Herbicide 4 as presented by Tincani, Cione, Casallanovo, Bottoms, Loutseti, et al, 2022), an example of a chemical with repeated applications (Insecticide 2 as presented by Tincani, Cione, Casallanovo, Bottoms, Loutseti, et al, 2022), and a chemical characterized by persistence with multiple annual applications (Fungicide 2 as presented by Tincani, Cione, Casallanovo, Bottoms, Loutseti, et al, 2022).…”