Limited data are available on the fate of clothianidin under realistic agricultural production conditions. The present study is the first large‐scale assessment of clothianidin residues in soil and bee‐relevant matrices from corn and canola fields after multiple years of seed‐treatment use. The average soil concentration from 50 Midwest US corn fields with 2 yr to 11 yr of planting clothianidin‐treated seeds was 7.0 ng/g, similar to predicted concentrations from a single planting of Poncho 250‐treated corn seeds (6.3 ng/g). The water‐extractable (i.e., plant‐bioavailable) clothianidin residues in soil were only 10% of total residues. Clothianidin concentrations in soil reached a plateau concentration (amount applied equals amount dissipated) in fields with 4 or more application years. Concentrations in corn pollen from these fields were low (mean: 1.8 ng/g) with no correlation to total years of use or soil concentrations. For canola, soil concentrations from 27 Canadian fields with 2 yr to 4 yr of seed treatment use (mean = 5.7 ng/g) were not correlated with use history, and plant bioavailability was 6% of clothianidin soil residues. Average canola nectar concentrations were 0.6 ng/g and not correlated to use history or soil concentrations. Under typical cropping practices, therefore, clothianidin residues are not accumulating significantly in soil, plant bioavailability of residues in soil is limited, and exposure to pollinators will not increase over time in fields receiving multiple applications of clothianidin. Environ Toxicol Chem 2016;35:311–321. © 2015 The Authors. Published by Wiley Periodicals, Inc. on behalf of SETAC.

A comprehensive multiyear monitoring program was conducted to assess the exposure, effects, and long-term risk of the fungicide bixafen to earthworms in cereal fields. The realistic exposure of bixafen in soil was assessed at 10 representative field sites in Germany after a period of up to 8 years of use with five different products containing bixafen, followed by annual measurements from 2017 to 2019. The measured exposure concentrations were compared with modeled predicted environmental concentrations in soil (PECsoil) that are derived in the context of the European risk assessment of plant protection products. It was shown that the model assumptions, in particular the kinetic parameters describing the background accumulation, provided a conservative description of the observed residue data. This demonstrates that the exposure modeling tools are adequate for use in soil risk assessment. Laboratory and field ecotoxicological studies were performed to provide a comprehensive risk assessment on the long-term use of bixafen-based fungicides in cereals. While a laboratory reproduction study with the earthworm Eisenia fetida indicated a potential risk at the Tier 1 risk assessment for the end-use product Skyway XPro ® , a 2.5-year field study showed no unacceptable long-term effects on natural earthworm populations. The exposure in this study exceeded the maximum recommended field rate of Skyway XPro ® by a factor of 3 and the maximum measured bixafen concentrations from exposure monitoring study by a factor of 5.2. Hence, an acceptable long-term risk of bixafen-based cereal fungicides is concluded for earthworms.