Jan Ahlers

Acute to chronic ratios in aquatic toxicity--variation across trophic levels and relationship with chemical structure.

For fish, daphnids, and algae, acute to chronic ratios (ACRs) have been determined from experimental data regarding new and existing chemicals. Only test results in accord with the European Union Technical Guidance Document (TGD) and validated by authorities were considered. Whereas the median ACRs of 10.5 (fish), 7.0 (daphnids), and 5.4 (algae) are well below the ACR safety factor of 100 as implied by the TGD, individual ACRs vary considerably and go up to 4400. The results suggest that a safety factor of 100 is not protective for all chemicals and trophic levels. Neither a correlation between ACR and baseline toxicity as modeled through the logarithmic octanol-water partition coefficient nor an ACR correlation across trophic levels exists. Narcosis is associated with a preference for a low ACR; nevertheless, low ACRs are frequently obtained for nonnarcotics. Analysis of chemical structures led to the derivation of structural alerts to identify compounds with a significantly increased potential for a high ACR, which may prove to be useful in setting test priorities. At present, however, life-cycle tests are the only way to conservatively predict long-term toxicity.

Integrated testing and intelligent assessment-new challenges under REACH.

Background, aim and scopeDue to a number of drawbacks associated with the previous regime for the assessment of new and existing chemicals, the European Union established a new regulation concerning the registration, evaluation, authorisation and restriction of chemicals (REACH). All relevant industrial chemicals must now be assessed. Instead of the authorities, industry itself is responsible for the risk assessment. To achieve better and more efficient assessments while reducing animal testing, all information—standard, non-standard and non-testing—has to be used in an integrated manner. To meet these challenges, the current technical guidance documents for risk assessment of new and existing chemicals had to be updated and extended considerably. This was done by experts in a number of REACH Implementation Projects. This paper presents the most relevant results of the expert Endpoint Working Group on Aquatic Toxicity in order to illustrate the change of paradigm in the future assessment of hazards to the aquatic environment by chemical substances.Main features and challengesREACH sets certain minimum data requirements in order to achieve a high level of protection for human health and the environment. It encourages the assessor to use alternative information instead of or in addition to standard one. This information has to be equivalent to the standard information requirement and adequate to draw overall conclusions with respect to the regulatory endpoints classification and labelling, persistent, bioaccumulative and toxic (PBT) assessment and predicted no-effect concentrations (PNEC) derivation. The main task of the expert working group was to develop guidance on how to evaluate the toxicity of a substance based on integration of information from different sources and of various degrees of uncertainty in a weight of evidence approach.Integrated testing and intelligent assessmentIn order to verify the equivalence and adequacy of different types of information, a flexible sequence of steps was proposed, covering characterisation of the substance, analysis of modes of action, identification of possible analogues, evaluation of existing in vivo and in vitro testing data as well as of QSAR results. Finally, all available data from the different steps have to be integrated to come to an overall conclusion on the toxicity of the substance. This weight of evidence approach is the basis for the development of integrated testing strategies (ITS), in that the available evidence can help to determine subsequent testing steps and is essential for an optimal assessment. Its flexibility helps to meet the different requirements for drawing conclusions on the endpoints classification and labelling, PNEC derivation as well as PBT assessment. The integration of all kinds of additional information in a multi-criteria assessment reduces the uncertainties involved with extrapolation to the ecosystem level. The weight of evidence approach is illustrated by practical examples.Conclusions and perspectivesREACH leads to higher challenges in order to make sound decisions with fewer resources, i.e. to move away from extensive standard testing to an intelligent substance-tailored approach. Expert judgement and integrated thinking are key elements of the weight of evidence concept and ITS, potentially leading to better risk assessments. Important sub-lethal effects such as endocrine disruption, which are not covered by the current procedure, can be considered. Conclusions have to be fully substantiated: Risk communication will be an important aspect of future assessments.

Ökotoxikologie soll endlich wissenschaftliches Fach werden

Umweltbundesamt, Bismarckplatz 1, 14193 Berlin 2 Universit~it Bremen, Zentrum f0r Umweltforschung und Umwelttechnologie (UFT), 28359 Bremen a Universit&t Bayreuth, Lehrstuhl f0r Umweltchemie und s 95440 Bayreuth 4 Fraunhofer-lnstitut Molekularbiologie und Angewandte Oekologie, 57392 Schmallenberg s Technische Universit&t Dresden, Institut for Hydrobiologie AG (3kotoxikologie, 01062 Dresden 8 UFZ-Umweltforschungszentrum Leipzig-Halle GmbH, Sektion Chemische s 04318 Leipzig

Environmental risk assessment of existing chemicals.

AbstractMost of the existing chemicals of high priority have been released into the environment for many years. Risk assessments for existing chemicals are now conducted within the framework of the German Existing Chemicals Program and by the EC Regulation on Existing Substances. The environmental assessment of a chemical involves:a)exposure assessment leading to the derivation of a predicted environmental concentration (PEC) of a chemical from releases due to its production, processing, use, and disposal. The calculation of a PEC takes into account the dispersion of a chemical into different environmental compartments, elimination and dilution processes, as well as degradation. Monitoring data are also considered.b)effects assessment. Data obtained from acute or long-term toxicity tests are used for extrapolation on environmental conditions. In order to calculate the concentration with expectedly no adverse effect on organisms (Predicted No Effect Concentration, PNEC) the effect values are divided by an assessment factor. This assessment factor depends on the quantity and quality of toxicity data available. In the last step of the initial risk assessment, the measured or estimated PEC is compared with the PNEC. This “risk characterization” is conducted for each compartment separately (water, sediment, soil, and atmosphere). In case PEC > PNEC an attempt should be made to revise data of exposure and/or effects to conduct a refined risk characterization. In case PEC is again larger than PNEC risk reduction measures have to be considered.

Yeast as an unicellular model system in ecotoxicology and xenobiochemistry

Abstract The effects of 57 phenols, anilines and aliphates on yeast growth rate as well as on structural and functional properties of the plasma membrane have been examined. The different systems correlated with each other and with data from higher eucaryotic organisms. Close relations between the activity of the chemicals in the different biological test systems and structural parameters, especially hydrophobicity, were observed.

The EU existing chemicals regulation: A suitable tool for environmental risk assessment and risk management?

The legal framework for the risk assessment of chemicals was established in the EU by a directive carried out during the beginning of the 1980s which was transformed into a national chemical acts by the member states. It describes the extent of information industry has to present before marketing a newly synthesised substance. Since 1993 in the European Union, a regulation on the evaluation and control of existing substances ensures that a uniform and mandatory procedure is applied for the assessment of existing chemicals in all member states as well. Due to the large number of these chemicals (100,000 are compiled in the European Inventory of Existing Commercial Substances, EINECS), a risk assessment can only be performed for those substances which have been identified as being of high priority in a priority setting process.

Anforderungen aus Sicht der regulatorischen Ökotoxikologie

Das Umweltbundesamt hat vor knapp zwei Jahren eine Diskussion zur Verbesserung der Ausbildungssituation in der Okotoxikologie angestof~en. Der Grund dafiir war die Beobachtung, dass der Bedarf an Umweltchemikern und Okotoxikologen in Beh6rden, in Unternehmen und in Forschungseinrichtungen durch die Ausbildungskapazit~iten und die Ausbildungsausrichtungen an den Universit~iten nicht ausreichend gedeckt wird. Insbesondere mit der Einffihrung des REACH-Systems (Registration, Evaluation and Authorisation of Chemicals) in der EU werden neue und erweiterte Anforderungen an die Ausbildung yon Okotoxikologen gestellt.

Environmental risk assessment of airborne trichloroacetic acid--a contribution to the discussion on the significance of anthropogenic and natural sources

In environmental risk assessments the question has to be answered, whether risk reduction measures are necessary in order to protect the environment. If the combination of natural and anthropogenic sources of a chemical substance leads to an unacceptable risk, the man-made emissions have to be reduced. In this case the proportions of the anthropogenic and natural emissions have to be quantified. Difficulties and possible solutions are discussed in the scope of the OECD- and EU-risk assessments of trichloroacetic acid (TCA) and tetrachloroethylene. In the atmosphere, TCA is formed by photo-oxidative degradation of tetrachloroethylene (PER) and 1,1,1-trichloroethane. The available data on atmospheric chemistry indicate that tetrachloroethylene is the more important pre-cursor. With its high water solubility and low volatility, TCA is adsorbed onto aerosol particles and precipitated during rainfalls. Extended monitoring in rainwater confirmed the global distribution of airborne TCA. TCA reaches soils by dry and wet deposition. In addition formation of TCA from tetrachloroethylene in plants was observed. Consequently, high concentrations were detected in needles, leaves and in forest soil especially in mountain regions. The effect assessment revealed that plants exposed via soil are the most sensitive species compared to other terrestrial organisms. A PNECsoil of 2.4 microg/kg dw was derived from a long-term study with pine and spruce seedlings. When this PNEC is compared with the measured concentrations of TCA in soil, in certain regions a PEC/PNEC ratio >1 is obtained. This clearly indicates a risk to the terrestrial ecosystem, with the consequence that risk reduction measures are deemed necessary. To quantify the causes of the high levels of TCA in certain soils, and to investigate the geographical extent of the problem, intensive and widespread monitoring of soil, air and rainwater for TCA and tetrachloroethylene would be necessary to be able to perform a full mass balance study at an appropriate number of sites. In addition, measurements of the 14C content in TCA isolated from soil could clarify whether a significant proportion of the TCA occurs from natural sources. The possible formation of TCA in soil can also be tested by incubation of isotope enriched inorganic chloride with subsequent mass spectrometry of TCA.

Strategies for risk assessment of existing chemicals in soil

In the risk assessment of industrial chemicals, an assessment of the risk to soil should be performed whenever relevant inputs occur via the following pathways: application of sewage sludge, wet or dry deposition, application as a pesticide constituent (e.g. solvent or metabolite), irrigation. An evaluation of the results for 34 chemicals from the first EU priority list showed that only 35% of the risk assessments for the terrestrial compartment were performed on the basis of at least 2 valid tests with soil organisms. In the vast majority of cases, the equilibrium partitioning method was used to extrapolate from aquatic to soil toxicity. However, no indications exist for a correlation between aquatic and terrestrial toxicity. Moreover, the exposure routes for soil organisms (uptake via pore water, air included in soil pores, ingestion of soil particles) are much more complex than those for aquatic organisms. As a new approach, it is therefore suggested that, in cases of relevant exposure (e.g. estimated or measured concentrations of >10 µg/kg), an assessment should generally be performed on the basis of valid terrestrial tests rather than on an extrapolation from the aquatic toxicity. It is recommended that prolonged exposure tests should be used already for an initial assessment of substances that have a strong tendency to adsorb on soil particles and thus a long residence time in soil. A decision scheme for the risk assessment of industrial chemicals in soil is presented, trigger values, testing strategies as well as assessment factors for derivation of a Predicted No Effect Concentration (PNECsoil) are discussed. An example of a terrestrial risk assessment for substances from the first EU priority list is given in order to illustrate current practice.

Application of the criteria for classification of existing chemicals as dangerous for the environment

The criteria for classification and labelling of substances as “dangerous for the environment” agreed upon within the European Union (EU) were applied to two sets of existing chemicals. One set (sample A) consisted of 41 randomly selected compounds listed in the European Inventory of Existing Chemical Substances (EINECS). The other set (sample B) comprised 115 substances listed in Annex I of Directive 67/548/EEC which were classified by the EU Working Group on Classification and Labelling of Existing Chemicals. The aquatic toxicity (fish mortality,Daphnia immobilisation, algal growth inhibition), ready biodegradability and n-octanol/water partition coefficient were measured for sample A by one and the same laboratory. For sample B, the available ecotoxicological data originated from many different sources and therefore was rather heterogeneous. In both samples, algal toxicity was the most sensitive effect parameter for most substances. Furthermore, it was found that, classification based on a single aquatic test result differs in many cases from classification based on a complete data set, although a correlation exists between the biological end-points of the aquatic toxicity test systems.