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Comprehensive framework for human health risk assessment of nanopesticides

Abstract

Nanopesticides are not only in an advanced state of research and development but have started to appear on the market. Industry and regulatory agencies need a consolidated and comprehensive framework and guidance for human health risk assessments. In this perspective we develop such a comprehensive framework by exploring two case studies from relevant product types: an active ingredient delivered with a nanocarrier system, and a nanoparticle as an active ingredient. For a nanocarrier system, three entities are tracked during the assessment: the nanocarrier–active ingredient complex, the empty nanocarrier remaining after the complete release of the active ingredient, and the released active ingredient. For the nanoparticle of pure active ingredient, only two entities are relevant: the nanoparticle and the released ions. We suggest important adaptations of the existing pesticide framework to determine the relevant nanopesticide entities and their concentrations for toxicity testing. Depending on the nature of the nanopesticides, additional data requirements, such as those pertaining to durability in biological media and potential for crossing biological barriers, have also been identified. Overall, our framework suggests a tiered approach for human health risk assessment, which is applicable for a range of nanopesticide products to support regulators and industry in making informed decisions on nanopesticide submissions. Brief summaries of suitable methods including references to existing standards (if available) have been included together with an analysis of current knowledge gaps. Our study is an important step towards a harmonized approach accepted by regulatory agencies for assessing nanopesticides.

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Fig. 1: The three stage of human exposure to pesticides.
Fig. 2: Decision tree considering case 1: a polymer NC associated with a pesticide AI.
Fig. 3: Decision tree considering case 2: metal or metal oxide NPs releasing ions over time.

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Acknowledgements

We are grateful to several experts who made contributions to the early stages of this project, including D. Anderson, P. Demokritou, G. Mahler, L. Parsons, A. Byro, D. McShan, P. Reeves, A. Tobia, U. Nasini, S. Qu, G. Walker, H. Xiao and B. Xing. The development of this framework was facilitated by financial support from IUPAC via a project on Human Health Risk Consideration of Nano-enabled Pesticides for Industry and Regulators (project number 2017-035-2-600).

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Correspondence to Melanie Kah.

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Kah, M., Johnston, L.J., Kookana, R.S. et al. Comprehensive framework for human health risk assessment of nanopesticides. Nat. Nanotechnol. 16, 955–964 (2021). https://doi.org/10.1038/s41565-021-00964-7

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