Comparative assessment of exposure tools to estimate pesticide concentrations in rice paddies: a discussion of the Brazilian context.

Abstract

Estimating pesticide concentrations in paddy rice systems is challenging due to unique cultivation methods and water management practices. Various models, ranging from simple exposure calculators to complex scenario-dependent tools, have been developed globally to address this issue (PADDY, MED-Rice, RICEWQ, PFAM). In Brazil, pesticides are used in paddy rice production, and there is a potential risk of these compounds reaching waterbodies. Legislative changes in 2023 made environmental risk assessment mandatory for pesticide registration in Brazil. However, Brazil has not officially adopted a specific modelling tool for paddy rice systems. This critical review evaluates (i) the strengths and limitations of pesticide exposure models for paddy rice most commonly used in Europe, North America, Asia and Latin America; (ii) it reviews the tools used in a regulatory context outside Brazil; (iii) it discusses exposure tools used in lower tiers and then proceeds to a discussion of more sophisticated tools used in higher tiers; (iv) provides and overview of paddy rice production system in Brazil, (v) performs a comparative analysis of the features of each exposure tool against the characteristics of the Brazilian paddy rice production system, and finally, this review (vi) discusses which exposure tools may be most appropriate for integration into a prospective regulatory ERA framework in Brazil. The goal of this review is to contribute to the ongoing regulatory changes and discussions by identifying appropriate models that can effectively assess the environmental risks associated with pesticide use in Brazilian paddy rice cultivation.