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Luhnstedt, Germany

Nendza M.,Analytisches Laboratorium | Muller M.,Fraunhofer Institute for Molecular Biology and Applied Ecology
SAR and QSAR in Environmental Research | Year: 2010

Aquatic bioconcentration factors are critical in PBT assessment of industrial chemicals under REACH. Reliable indicators based on physico-chemical properties and molecular attributes of chemicals with low bioconcentration potential have been searched to de-prioritize non-accumulative chemicals in order to avoid unnecessary biotests that do not produce risk-relevant information. Developed to screen drug candidates, Lipinski's 'Rule of 5' identifies chemicals with poor oral absorption based on criteria in partitioning, molecular weight and hydrogen bonding. This parameter ensemble has been supplemented with molecular diameter and tested for its adequacy to filter chemicals with low bioconcentration potential. Perhaps (not) surprisingly, the application of the 'Rule of 5' fails to protectively identify non-accumulative compounds because other processes dominate the uptake in aquatic environments as compared with oral absorption. No robust evidence was found for cut-offs in bioconcentration related to molecular size. However, pragmatic thresholds in molecular weight (>650 g mol-1) and lipophilicity (logKOW < 3 or >10) have been verified to securely de prioritize 30-40% of chemicals of low concern with regard to the B criterion. © 2010 Taylor & Francis. Source


Nendza M.,Analytisches Laboratorium | Klaschka U.,Ulm University of Applied Sciences | Berghahn R.,Umweltbundesamt
Environmental Sciences Europe | Year: 2013

Background: Infochemical effects have been defined as the manipulation of the odour perception of organisms by anthropogenic substances which may result in ecologically relevant behavioural disorder. However, the environmental relevance of infochemical effects has not yet been confirmed by experimental observations. This project aims to test for infochemical effects on chemical communication in water bodies with systematic experimental investigations. The first crucial step is to select suitable test substances. Repellents (PT 19 biocides) and odourants may be assumed to affect the response of aquatic populations and communities. These mostly polar and stable compounds may disturb chemical communication between organisms and may cause organismic effects like drift (downstream dislocation of e.g. crustacean and insect larvae in streams). Repellents enter surface waters mainly indirectly via wastewater discharges from sewage treatment plants or directly by being washed off from the skin and clothes of bathers. Results: In this literature study, suitable chemicals were selected for confirmatory assessments of suspected infochemical effects by laboratory tests in a subsequent second part of the project. The use pattern and physico-chemical properties of the substances selected, in combination with their limited biological degradability, indicate potential aquatic relevance with possible chronic impact caused by disturbed communication. After due consideration of advantages and limitations, three PT 19 repellents appear suitable test compounds for proof of concept in the subsequent experimental part of the project: DEET (CAS 134-62-3) Icaridine (CAS 119515-38-7) EBAAP (CAS 52304-36-6) Another promising candidate for infochemical effects is isophorone (CAS 78-59-1), a natural attractant and an anthropogenic high production volume solvent. Conclusions: Four chemicals were selected with the expectation that they may be suitable test substances for experimental proof of concept of infochemical effects in the subsequent part of the project. The experimental results may then help to answer the question of whether PT 19 biocides and other odourants entering aquatic ecosystems give rise for concern about potential infochemical effects. © 2013 Nendza et al.; licensee Springer. Source


Nendza M.,Analytisches Laboratorium | Muller M.,Fraunhofer Institute for Molecular Biology and Applied Ecology | Wenzel A.,Fraunhofer Institute for Molecular Biology and Applied Ecology
SAR and QSAR in Environmental Research | Year: 2014

Functional similarity of chemicals combines toxicological knowledge (which toxicity pathways can happen in which species under which exposure conditions) with chemical expertise (which parts of the chemical structures and physico-chemical properties are involved in which interactions) to discriminate between baseline and excess toxicants. The objective is to identify as many baseline toxicants as possible because their acute fish toxicities can be predicted with sufficient accuracy from their log Kow. Established tools like structural alerts are used to indicate modes of action (MOAs) that are typical causes of excess toxicity. Verhaar classifications are supplemented with additional chemical attributes and physico-chemical property thresholds to cover a larger range of compounds within the baseline toxicity domain. Our approach is precautionary to avoid false negatives with a sensitivity of 96.3%. It classifies 57.1% of the compounds of the EPA Fathead Minnow Acute Toxicity Database (EPAFHM) as baseline toxicants and suggests that more than 50% of acute fish toxicity testing could be replaced by reliable QSAR predictions. Furthermore, functional similarity can support the MOA classification of chemicals in different species. Toxicity profiles with fish, Daphnia and algae reveal specific targets for the compounds and, particularly for chemicals with multiple MOA, identify the most sensitive species. © 2014 Taylor & Francis. Source


Lombardo A.,Laboratory of Environmental Chemistry and Toxicology | Roncaglioni A.,Laboratory of Environmental Chemistry and Toxicology | Benfenati E.,Laboratory of Environmental Chemistry and Toxicology | Nendza M.,Analytisches Laboratorium | And 5 more authors.
Environmental Research | Year: 2014

To satisfy REACH requirements a high number of data on chemical of interest should be supplied to the European Chemicals Agency. To organize the various kinds of information and help the registrants to choose the best strategy to obtain the needed information limiting at the minimum the use of animal testing, integrated testing strategies (ITSs) schemes can be used. The present work deals with regulatory data requirements for assessing the hazards of chemicals to the aquatic pelagic environment. We present an ITS scheme for organizing and using the complex existing data available for aquatic toxicity assessment. An ITS to optimize the choice of the correct prediction strategy for aquatic pelagic toxicity is described. All existing information (like physico-chemical information), and all the alternative methods (like in silico, in vitro or the acute-to-chronic ratio) are considered. Moreover the weight of evidence approach to combine the available data is included. © 2014 Elsevier Inc. Source


Nendza M.,Analytisches Laboratorium | Herbst T.,Analytisches Laboratorium
SAR and QSAR in Environmental Research | Year: 2011

Physico-chemical properties related to the bioavailability of xenobiotics in aquatic environments have been tested for their ability to identify chemicals with low bioconcentration potential. Cut-offs in lipophilicity (log KOW <3 or> 10), solubility and volatility (log Henry constant < -11 [atm (mol L-1)-1]), degradability (ready biodegradability, hydrolysis) and ionisation (>5% ionisation at pH 7) have been adopted and combined into a decision tree based on 382 industrial chemicals. The five-parameter classification scheme was externally validated with 49 pesticides and successfully confirmed with 83 bioaccumulative compounds. The applicability domain of the model has been described in terms of chemical classes (excluding polybrominated compounds (>4 Br), organometallics, compounds with perfluorinated fragments, substances with an acyclic alkyl moiety (chain length>C7) and thiols) and ranges of physico-chemical properties. The present tool allows to securely de-prioritize more than 50% chemicals of low concern with regard to the B criterion (BCF <2000). Bioassays with compounds with these physico-chemical constraints may be waived because testing may be technically not possible and does not appear scientifically necessary in persistent, bioaccumulative, toxic (PBT) substances and risk assessments. © 2011 Taylor & Francis. Source

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