Seasonal dynamics of the macrophyte test species Myriophyllum spicatum over two years in experimental ditches for population modelling application in risk assessment

Toxicokinetic-toxicodynamic (TKTD) modelling is essential to make sense of the time dependence of toxic effects, and to interpret and predict consequences of time-varying exposure. These advantages have been recognised in the regulatory arena, especially for environmental risk assessment (ERA) of pesticides, where time-varying exposure is the norm. We critically evaluate the link between the modelled variables in TKTD models and the observations from laboratory ecotoxicity tests. For the endpoint reproduction, this link is far from trivial. The relevant TKTD models for sub-lethal effects are based on Dynamic-Energy Budget (DEB) theory, which specifies a continuous investment flux into reproduction. In contrast, experimental tests score egg or offspring release by the mother. The link between model and data is particularly troublesome when a species reproduces in discrete clutches, and even more so when eggs are incubated in the mother's brood pouch (and release of neonates is scored in the test). This situation is quite common among aquatic invertebrates (e.g., cladocerans, amphipods, mysids), including many popular test species. We discuss these and other issues with reproduction data, reflect on their potential impact on DEB-TKTD analysis, and provide preliminary recommendations to correct them. Both modellers and users of model results need to be aware of these complications, as ignoring them could easily lead to unnecessary failure of DEB-TKTD models during calibration, or when validating them against independent data for other exposure scenarios.

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Glyceria maxima as new test species for the EU risk assessment for herbicides: a microcosm study

Ecotoxicology ◽

10.1007/s10646-014-1379-3 ◽

2014 ◽

Vol 24 (2) ◽

pp. 309-320 ◽

Cited By ~ 1

Author(s):

S. Mohr ◽

J. Schott ◽

L. Hoenemann ◽

M. Feibicke

Keyword(s):

Risk Assessment ◽

Test Species ◽

Microcosm Study ◽

The Eu

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Interspecific sensitivity of European amphibians towards two pesticides and comparison to standard test species

Environmental Sciences Europe ◽

10.1186/s12302-021-00491-1 ◽

2021 ◽

Vol 33 (1) ◽

Author(s):

Elena Adams ◽

Christoph Leeb ◽

Alexis P. Roodt ◽

Carsten A. Brühl

Keyword(s):

Risk Assessment ◽

Model Organism ◽

Bufo Bufo ◽

Standard Test ◽

Lower Sensitivity ◽

Amphibian Species ◽

Surrogate Species ◽

Test Species ◽

Uncertainty Factor ◽

Hyla Arborea

Abstract Background Although debates about the assessment of potential effects of pesticides on amphibians are ongoing, amphibians are not yet considered in the current EU environmental risk assessment of pesticides. Instead, the risk assessment of potential effects on aquatic amphibian life stages relies on use of data of surrogate species like the standard temperate fish species rainbow trout (Oncorhynchus mykiss). This assumption is mainly based on the comparison to amphibian species not native to Europe such as the aquatic African clawed frog (Xenopus laevis). It remains unclear whether these surrogate species cover semi-aquatic Central European amphibian sensitivities. Therefore, we assessed the acute sensitivity of aquatic stages of eight European amphibian species native in Germany (Bufo bufo, Bufotes viridis, Epidalea calamita, Hyla arborea, Pelobates fuscus, Pelophylax sp., Rana dalmatina, R. temporaria) towards commercial formulations of the fungicide folpet (Folpan® 500 SC, Adama) and the insecticide indoxacarb (Avaunt® EC, Cheminova). The determined acute sensitivities (median lethal concentration, LC50) were included in species sensitivity distributions and compared to experimentally determined LC50 values of X. laevis and literature values of O. mykiss. Results The results showed that native amphibian sensitivities differed between the tested pesticides with a factor of 5 and 11. Depending on the pesticide, X. laevis was five and nine times more tolerant than the most sensitive native amphibian species. Comparing literature values of O. mykiss to the experimentally determined sensitivities of the native amphibian species showed that the O. mykiss sensitivity was in the same range as for the tested amphibians for the formulation Folpan® 500 SC. The comparison of sensitivities towards the formulation Avaunt® EC showed an eight times lower sensitivity of O. mykiss than the most sensitive amphibian species. Conclusions A risk assessment using the 96-h LC50 values for fish covers the risk for the assessed aquatic stages of European amphibians after the application of the recommended uncertainty factor of 100 and thus may be adequate for lower tier risk assessment of the studied pesticides. If aquatic amphibian testing will be required for pesticide risk assessment nevertheless, acute tests with the model organism X. laevis and the application of an appropriate uncertainty factor might be a promising approach.

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Bioaccumulation assessment of nanomaterials using freshwater invertebrate species

Environmental Sciences Europe ◽

10.1186/s12302-020-00442-2 ◽

2021 ◽

Vol 33 (1) ◽

Author(s):

Sebastian Kuehr ◽

Verena Kosfeld ◽

Christian Schlechtriem

Keyword(s):

Risk Assessment ◽

Bioconcentration Factor ◽

Assessment Process ◽

Production Volume ◽

Worst Case ◽

Test Species ◽

Suitable Test ◽

Invertebrate Species ◽

Freshwater Invertebrate ◽

Test Organisms

Abstract Background The high production volume of engineered nanomaterials (ENMs) may lead to high pressure on the environment, and a scientific assessment of ENMs that bioaccumulate in organisms and biomagnify in the food web is necessary. Within the regulation of chemicals in several jurisdictions, such as the European regulation REACH, the bioconcentration factor is the standard endpoint. The bioconcentration factor is mostly determined by flow-through fish tests. However, nanomaterials tend to agglomerate, which may lead to sedimentation in aquatic environments. The bioavailability of the tested nanomaterials may be thus impaired for pelagic species, including fish, in comparison to benthic or filtrating species. Several risk assessment regulations allow the usage of data gained during tests using invertebrates and such data may allow a waiver of further tests using vertebrates. The aim of this study was to elucidate the potential of different freshwater invertebrate species to be used in laboratory bioaccumulation studies on ENMs and to give some guidance for the use of bioaccumulation endpoints derived from studies using aquatic invertebrate species in the risk assessment process for ENMs. Results The existing literature related to the testing of nanomaterial bioaccumulation with freshwater invertebrates was screened and reviewed to find suitable test species with regard to their ecology and physiology, as well as laboratory test systems allowing to investigate the bioavailability/bioaccumulation of nanomaterials with the respective species. Bivalvia, gastropoda, isopoda, amphipoda, and branchiopoda were reviewed and their suitability for bioaccumulation testing was assessed. Amphipods and bivalves represent worst-case scenarios and show clear advantages to be used as test organisms. However, only amphipods allow the examination of two clearly independent exposure pathways (water and diet). Conclusion Amphipods are suitable test organisms for bioaccumulation testing of ENMs. The results from amphipod bioconcentration and biomagnification tests can be included in a tiered assessment suggested at the end of this study allowing a clear grading of the tested nanomaterials as “bioaccumulative” or “non bioaccumulative.” Due to the worst-case scenario of the amphipod test, this approach may allow a waiver of further vertebrate tests.

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