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Ecological Risk Assessment
Published in Ted W. Simon, Environmental Risk Assessment, 2019
Regarding Step 2, the Process Document indicates that risk is estimated by comparing maximum concentrations detected with the ecotoxicity screening benchmarks collected in Step 1. This results in a set of hazard quotients for the chemicals detected at the site. The Process Document also prescribes a scientific management decision point (SMDP) at the conclusion of Step 2. At the conclusion of Step 2, the risk manager and risk assessment team will decide that either the screening level ecological risk assessment is adequate to determine that ecological threats are negligible, or whether the process should continue to a more detailed ecological risk assessment.
Cultivation of Artemisia annua—The Environmental Perspective
Published in Tariq Aftab, M. Naeem, M. Masroor, A. Khan, Artemisia annua, 2017
Karina Knudsmark Sjøholm, Bjarne W. Strobel, Cedergreen Nina
As A. annua is cultivated in fields, and artemisinin released directly to the environment, we use the risk assessment paradigm that exist for pesticides. In this type of risk assessment, the first tier is hazard identification. In hazard identification, the physicochemical properties of the chemical are evaluated in relation to environmental fate, and exposure scenarios are considered. Ecotoxicity of the compound of interest is also evaluated, and the most vulnerable species in exposed environmental compartments are identified. The environmental fate evaluation yields a predicted environmental concentration (PEC), and the effect evaluation produces a predicted no-effect concentration (PNEC) value. The PNEC is the lowest available ecotoxicity value divided by a safety factor. The magnitude of the safety factor (10–1000) depends on the level of certainty on which the data are obtained. From these, the hazard quotient (HQ) is calculated:
Determination
Published in David Woolley, Adam Woolley, Practical Toxicology, 2017
It seems probable that in the longer term, the ecotoxicological impact of genetically modified crops could be more significant than their immediate adverse effects on consumers. At this point, the extent of or scope for interaction of chemicals and the natural world, of which we are a part, becomes a topic of concern. The precise definition of ecotoxicity therefore becomes important. Clearly, if there are widespread effects on beneficial (or desirable) insect populations due to insecticidal gene expression in crops, this is a toxic manifestation of the crop and can be classified as ecotoxicity. Loss of a species is a clear-cut event with imponderable impact; if an effect is limited to a shift in populations of plants or animals due to cross-breeding, it may be more difficult to describe it as toxicity, although such an event may indeed be entirely adverse environmentally.
Characterizing the effects of titanium dioxide and silver nanoparticles released from painted surfaces due to weathering on zebrafish (Danio rerio)
Published in Nanotoxicology, 2021
Krittika Mittal, Arshath Abdul Rahim, Saji George, Subhasis Ghoshal, Niladri Basu
In recent years, there have been calls to improve the relevancy of ecotoxicity studies in terms of environmental plausibility, biological realism, and regulatory connection (Staveley and Wentsel 2016; Rudén et al. 2017). For ENPs in particular, there is a need for studies that better reflect realistic exposure scenarios (Holden et al. 2016; Selck et al. 2016), and thus a need for studies that evaluate weathered ENPs at environmental concentrations. Additionally, there is also a push to replace traditional whole animal tests with alternatives to animal testing strategies such as in vitro and early life stage (embryo) methods, and to better characterize perturbations at the molecular level rather than characterizing apical endpoints such as growth and survival (NRC 2007). For aquatic models, there are established cell lines such as the zebrafish liver cell line (Bols et al. 2005; Chen et al. 2011), and standardization of the fish embryotoxicity test (FET) by the Organization for Economic Co-operation and Development (OECD; test guideline 236) has facilitated their use in aquatic toxicity studies. Developing a testing system using these alternative methods for ENPs released from painted surfaces could serve to speed up the testing process while providing a more in-depth understanding of their toxic effects.
Rationale and decision rules behind the ECETOC NanoApp to support registration of sets of similar nanoforms within REACH
Published in Nanotoxicology, 2021
Gemma Janer, Robert Landsiedel, Wendel Wohlleben
All these existing frameworks, together with the ECHA Guidance documents have been taken into consideration during the development of the ECETOC NanoApp. But we took a step forward by proposing rules to systematically evaluate similarity in the context of generating sets of similar nanoforms. These rules were based on pairwise similarity to overcome the limitations of pre-defined categories. The rules were defined taking into consideration current evidence on the role of different intrinsic and extrinsic properties on exposure, toxicokinetics, fate, and (eco)toxicity, and ultimately on risks to environment and humans. Current datasets do not allow a comprehensive validation of the rules that we developed, for several reasons: (i) nanoforms have rarely been characterized with all descriptors required by the NanoApp, (ii) a low number of (comparable) in vivo studies for human health endpoints exist for variants of nanoforms for a same substance, (iii) ongoing discussions on adequacy of standard ecotoxicological tests (designed to test soluble substances) for nanoforms. The legal requirement to register nanoforms will considerably increase these datasets and will allow the future reassessment of the thresholds that we have proposed.
Nanotoxicology data for in silico tools: a literature review
Published in Nanotoxicology, 2020
Irini Furxhi, Finbarr Murphy, Martin Mullins, Athanasios Arvanitis, Craig A. Poland
The majority of the reviewed studies extracted data from peer-reviewed literature sources as demonstrated in Section 3.1. Available computational approaches were not built as much on recognized databases such as S2NANO, NIOSH, OCHEM, NBI etc., while one study used data from eNanoMapper (Helma, Rautenberg, and Gebele 2017). This can be attributed to the fact that most of those databases are, for the moment, not nano-specific, e.g. the OCHEM database contains nano and non-nano experimental data. ENanoMapper is an ongoing project, integrating research data from various relevant projects and literature, expected to deliver results in the near future. Most endpoints derived from databases were used for modeling ecotoxicity. This indicates that there are more data publicly available suitable for ecotoxicity endpoints than human health hazard endpoints. Over 200 in vivo assessments for NP toxicity in embryonic zebrafish model can be found in the NBI. Almost all database derived data regard metal and metal oxide NPs.