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Ecotoxicology of Nanoparticles
Published in Suresh C. Pillai, Yvonne Lang, Toxicity of Nanomaterials, 2019
Traditional ecotoxicological risk assessment of pollutants starts with a clear knowledge of the nature and chemical identity of the pollutant of concern. This is usually a known chemical or effluent from a known source or an observed effect such as a fish kill leading to an investigation and identification of the source. The composition of the effluent can be characterized chemically, respective concentrations measured, and appropriate ecotoxicity studies carried out, even taking synergistic effects into account where necessary. In the case of nanomaterials, this approach is not possible. Firstly, as previously mentioned, the nanomaterials in use are not known (McGillicuddy, Murray, Kavanagh, Morrison, Fogarty, Cormican, Rowan, & Morris, 2016). Secondly, the behaviour of nanomaterials in the freshwater ecosystem is highly variable and dependent not only on the physico-chemical properties of the nanomaterials themselves, but also the water chemistry in the receiving environment (Bury, Shaw, Glover, & Hogstrand, 2002; Ellis, Baalousha, Valsami-Jones, & Lead, 2018; Handy, Von Der Kammer, Lead, Hassellöv, Owen, Crane, 2008). Thirdly, the predicted environmental concentration (PEC) in the receiving environment is often so low as to be below the limit of detection using current standard methods and therefore immeasurable (Blaser, Scheringer, MacLeod, & Hungerbühler, 2008; Boxall, Chaudhry, Sinclair, Jones, Aitken, Jefferson, & Watts, 2007; Fadri Gottschalk, Sondere, Schols, & Nowack, 2009; Giese, Klaessig, Park, Kaegi, Steinfeldt, Wigger, Gleich, & Gottschalk, 2018).
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:
Risk Assessment
Published in David Woolley, Adam Woolley, Practical Toxicology, 2017
In terms of legislation in Europe, the regulatory framework for environmental risk assessment is based on the risk quotient, which is the ratio of the predicted environmental concentration (PEC) to the predicted environmental no-effect concentration (PNEC). Typically, the PEC is modeled using data on expected market volume and usage data, together with estimations of diffuse or point-source introduction, degradation, distribution, and fate. In some cases, these predictions are supported by analytical measurement. The PNEC is then estimated by using empirically derived effect or no-effect data from laboratory experiments, applying safety factors of up to 1000 depending on the uncertainties inherent in the test data. A risk characterization ratio (the PEC divided by the PNEC) of less than 1 indicates low risk, while a ratio greater than 1 may indicate a relevant risk. The margins of safety (MOSs) are also considered; the risk decreases with increasing MOS. This process and the reasoning involved are nicely outlined in an environmental risk assessment of methyl tertiary butyl ether (MTBE) carried out by a team from the European Fuel Oxygenates Association (EFOA), WRc-NSF National Centre for Environmental Toxicology (NCET), and European Centre for Eco-toxicology and Toxicology of Chemicals (ECETOC). This assessment is summarized in Case Study 18.2.
Marine natural products as antifouling molecules – a mini-review (2014–2020)
Published in Biofouling, 2020
Ling-Li Liu, Chuan-Hai Wu, Pei-Yuan Qian
The predicted no-effect concentration (PNEC) of any new commercial AF substance should be higher than its predicted environmental concentration (Yoshikawa et al. 2007). In this regard, the acute toxicity of butenolide in several non-target organisms (microalgae, crustaceans and fish) was evaluated and the PNEC of butenolide was further determined. The PNEC of butenolide was 0.016 μg l−1, which was higher than that of most of the representative new biocides. Butenolide possessed apoptotic induction activity in zebrafish embryos and HeLa cells, whilst its activity in HeLa cells was mediated by JNK activation, Bcl-2 family members, caspases and proteasome/lysosome activation (Zhang, Xiao, et al. 2011).
Using existing knowledge for the risk evaluation of crop protection products in order to guide exposure driven data generation strategies and minimise unnecessary animal testing
Published in Critical Reviews in Toxicology, 2021
Paul Parsons, Elaine Freeman, Ryan Weidling, Gary L. Williams, Philip Gill, Neil Byron
The Risk21 plots for the acute and chronic exposure estimates for the use of a fungicide on wheat in the EU and the use of an SDHI on wheat in the EU indicated acceptable risk. In contrast to the US exposure predictions that included food and drinking water, the exposure predictions for the EU use scenarios were based on consumption data in the EFSA PRIMo only for raw and processed crop commodities in conjunction with residue data. In the EU, if the predicted environmental concentration (PEC) in ground water is <0.1 µg/L, then exposure from drinking water is considered “acceptable” and no further assessment is required.
Material-specific properties applied to an environmental risk assessment of engineered nanomaterials – implications on grouping and read-across concepts
Published in Nanotoxicology, 2019
Generally, environmental risk assessments require data and information on both hazard and exposure assessments in order to derive the predicted no-effect concentration (PNEC) and the predicted environmental concentration (PEC), respectively. The division of the PEC by the PNEC yields the risk characterization ratio (RCR). A result above one indicates a need for more detailed assessments, while a result below one indicates no immediate risk (ECHA 2016).