Department Environmental Chemistry

Bioaccumulation in chemical risk assessment

Internal body concentrations are the driver of toxicological effects. Previous field studies monitoring micropollutant concentrations in aquatic invertebrates revealed tissue concentrations of many compounds to be substantially higher than predicted from models based on laboratory studies. This was especially the case for (semi-) polar compounds including pharmaceuticals and systemic pesticides. Such deviations can lead to crucial underestimations in environmental risk assessment.

In this project, we investigate processes that could increase the bioaccumulation in the field. Using a field campaign as well as toxicokinetic modelling, we investigate the applicability of laboratory-derived data to the field on the example of Gammarus species. In detail, we study the following processes:

  • Dietary uptake pathway
  • Particle bound uptake
  • Difference in biotransformation

Publications

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      authors => protected'Lauper, B. B.; Anthamatten, E.; Raths, J.; Arlos, M
         .; Hollender, J.' (97 chars)
      title => protected'Systematic underestimation of pesticide burden for invertebrates under field
          conditions: comparing the influence of dietary uptake and aquatic exposure 
         dynamics' (160 chars)
      journal => protected'ACS Environmental Au' (20 chars)
      year => protected2022 (integer)
      volume => protected2 (integer)
      issue => protected'2' (1 chars)
      startpage => protected'166' (3 chars)
      otherpage => protected'175' (3 chars)
      categories => protected'aquatic invertebrates; gammarids; pesticides; toxicokinetics; bioaccumulatio
         n; field study; dietary uptake; modeling' (116 chars)
      description => protected'Pesticides used in agriculture can end up in nearby streams and can have a n
         egative impact on nontarget organisms such as aquatic invertebrates. During 
         registration, bioaccumulation potential is often investigated using laborato
         ry tests only. Recent studies showed that the magnitude of bioaccumulation i
         n the field substantially differs from laboratory conditions. To investigate
          this discrepancy, we conducted a field bioaccumulation study in a stream kn
         own to receive pollutant loadings from agriculture. Our work incorporates me
         asurements of stream pesticide concentrations at high temporal resolution (e
         very 20 min), as well as sediment, leaves, and caged gammarid analyses (ever
         y 2-24 h) over several weeks. Of 49 investigated pesticides, 14 were detecte
         d in gammarids with highly variable concentrations of up to 140 ± 28 ng/g<s
         ub>ww</sub>. Toxicokinetic modeling using laboratory-derived uptake and depu
         ration rate constants for azoxystrobin, cyprodinil, and fluopyram showed tha
         t despite the highly resolved water concentrations measured, the pesticide b
         urden on gammarids remains underestimated by a factor of 1.9 ± 0.1 to 31 ±
          3.0, with the highest underestimations occurring after rain events. Includi
         ng dietary uptake from polluted detritus leaves and sediment in the model ex
         plained this underestimation only to a minor proportion. However, suspended 
         solids analyzed during rain events had high pesticide concentrations, and up
         take from them could partially explain the underestimation after rain events
         . Additional comparison between the measured and modeled data showed that th
         e pesticide depuration in gammarids is slower in the field. This observation
          suggests that several unknown mechanisms may play a role, including lowered
          enzyme expression and mixture effects. Thus, it is important to conduct suc
         h retrospective risk assessments based on field investigations and adapt the
          registration accordingly.' (1926 chars)
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      doi => protected'10.1021/acsenvironau.1c00023' (28 chars)
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Systematic underestimation of pesticide burden for invertebrates under field conditions: comparing the influence of dietary uptake and aquatic exposure dynamics

Pesticides used in agriculture can end up in nearby streams and can have a negative impact on nontarget organisms such as aquatic invertebrates. During registration, bioaccumulation potential is often investigated using laboratory tests only. Recent studies showed that the magnitude of bioaccumulation in the field substantially differs from laboratory conditions. To investigate this discrepancy, we conducted a field bioaccumulation study in a stream known to receive pollutant loadings from agriculture. Our work incorporates measurements of stream pesticide concentrations at high temporal resolution (every 20 min), as well as sediment, leaves, and caged gammarid analyses (every 2-24 h) over several weeks. Of 49 investigated pesticides, 14 were detected in gammarids with highly variable concentrations of up to 140 ± 28 ng/gww. Toxicokinetic modeling using laboratory-derived uptake and depuration rate constants for azoxystrobin, cyprodinil, and fluopyram showed that despite the highly resolved water concentrations measured, the pesticide burden on gammarids remains underestimated by a factor of 1.9 ± 0.1 to 31 ± 3.0, with the highest underestimations occurring after rain events. Including dietary uptake from polluted detritus leaves and sediment in the model explained this underestimation only to a minor proportion. However, suspended solids analyzed during rain events had high pesticide concentrations, and uptake from them could partially explain the underestimation after rain events. Additional comparison between the measured and modeled data showed that the pesticide depuration in gammarids is slower in the field. This observation suggests that several unknown mechanisms may play a role, including lowered enzyme expression and mixture effects. Thus, it is important to conduct such retrospective risk assessments based on field investigations and adapt the registration accordingly.
Lauper, B. B.; Anthamatten, E.; Raths, J.; Arlos, M.; Hollender, J. (2022) Systematic underestimation of pesticide burden for invertebrates under field conditions: comparing the influence of dietary uptake and aquatic exposure dynamics, ACS Environmental Au, 2(2), 166-175, doi:10.1021/acsenvironau.1c00023, Institutional Repository