62 research outputs found
Is Cumulative Fossil Energy Demand a Useful Indicator for the Environmental Performance of Products?
Expected Risk as basis for assessment of safe use of chemicals
This paper describes a straightforward modeling procedure to derive ‘expected risk’ (ER) of chemical substances. Starting from proposed use volumes, intended uses, physical and chemical substance properties and toxicity information, the procedure combines multimedia environmental fate modeling with species sensitivity modeling to derive the probability that exposure concentrations exceed critical effect concentrations. The procedure was tested on 1977 so-called mono-constituent organic chemicals that had been registered to be marketed in the EU, after ‘possibility to be used safely’ had been demonstrated by showing that the possible Risk Quotients (RQ) defined as PEC/PNEC ratios (Predicted Exposure Concentration & Predicted No Effect Concentration) were expected to remain below the value of 1, as required by REACH. It appears from this study that (i) RQ and ER of chemicals can be calculated readily, reliably, transparently and reproducibly, that (ii) both RQ and ER can be used to assess whether a new chemical may exceed a chosen acceptability level, but that (iii) in addition ER can be straightforwardly used to rank chemicals according to expected environmental safety. In conclusion, the paper states that modeling ER of chemicals (instead of estimating RQ values), could strengthen the scientific basis of environmental risk assessment for use in REACH. The paper further recommends that more robust environmental risk calculation can be done by using acute EC50, instead of chronic NOEC as critical effect concentration
QSAR-based estimation of SSD parameters - an exploratory investigation.
Ecological risk assessments are hampered by limited availability of ecotoxicity data. The present study aimed to explore the possibility of deriving SSD (species sensitivity distribution) parameters for non-tested compounds, based on simple physicochemical characteristics, known SSDs for data-rich compounds and a QSAR-type approach. The median toxicity of a data-poor chemical for species assemblages significantly varies with values of the physicochemical descriptors, especially when based on high quality SSD data (either from acute EC50 s or chronic NOECs). Beyond exploratory uses, we discussed how the precision of QSAR-based SSDs can be improved to construct models that accurately predict the SSD-parameters of data poor chemicals. The current models show that the concept of QSAR-based SSDs supports screening-level evaluations of the potential ecotoxicity of compounds for which data are lacking. This article is protected by copyright. All rights reserved
Species sensitivity distributions for use in environmental protection, assessment, and management of aquatic ecosystems for 12 386 chemicals
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Cellular uptake of nanoparticles as determined by particle properties, experimental conditions, and cell type
The increased application of nanoparticles (NPs) is increasing the risk of their release into the environment. Although many toxicity studies have been conducted, the environmental risk is difficult to estimate, because uptake mechanisms are often not determined in toxicity studies. In the present study, the authors review dominant uptake mechanisms of NPs in cells, as well as the effect of NP properties, experimental conditions, and cell type on NP uptake. Knowledge of NP uptake is crucial for risk assessment and is essential to predict the behavior of NPs based on their physical-chemical properties. Important uptake mechanisms for eukaryotic cells are macropinocytosis, receptor-mediated endocytosis, and phagocytosis in specialized mammalian cells. The studies reviewed demonstrate that uptake into nonphagocytic cells depends strongly on NP size, with an uptake optimum at an NP diameter of approximately 50nm. Increasing surface charges, either positive or negative, have been shown to increase particle uptake in comparison with uncharged NPs. Another important factor is the degree of (homo-) aggregation. Results regarding shape have been ambiguous. Difficulties in the production of NPs, with 1 property changed at a time, call for a full characterization of NP properties. Only then will it be possible to draw conclusions as to which property affected the uptake. Environ Toxicol Chem 2014;33:481-492. © 2013 SETAC
Definition and Applications of a Versatile Chemical Pollution Footprint Methodology
Because
of the great variety in behavior and modes of action of
chemicals, impact assessment of multiple substances is complex, as
is the communication of its results. Given calls for cumulative impact
assessments, we developed a methodology that is aimed at expressing
the expected cumulative impacts of mixtures of chemicals on aquatic
ecosystems for a region and subsequently allows to present these results
as a chemical pollution footprint, in short: a chemical footprint.
Setting and using a boundary for chemical pollution is part of the
methodology. Two case studies were executed to test and illustrate
the methodology. The first case illustrates that the production and
use of organic substances in Europe, judged with the European water
volume, stays within the currently set policy boundaries for chemical
pollution. The second case shows that the use of pesticides in Northwestern
Europe, judged with the regional water volume, has exceeded the set
boundaries, while showing a declining trend over time. The impact
of mixtures of substances in the environment could be expressed as
a chemical footprint, and the relative contribution of substances
to that footprint could be evaluated. These features are a novel type
of information to support risk management, by helping prioritization
of management among chemicals and environmental compartments
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