Revising Environmental Quality Standards: Lessons Learned.

An environmental quality standard (EQS) is a threshold value applied in regulatory monitoring for retrospective environmental risk assessment. However, an EQS may vary with time and between countries with shared water bodies, challenging coherent risk management. This study aimed to analyze the underlying reasons for changes in EQS values following a revision of previously derived EQSs for 62 substances. Relevant data were retrieved from publicly accessible databases, available literature, registration dossiers, and, in some cases, provided by manufacturers. Ecotoxicological data were assessed regarding reliability and relevance. As in previous studies, EQS derivation followed the European Union guideline. Overall, 61 annual average EQSs (AA-EQS) and 58 maximum acceptable concentration EQSs (MAC-EQS) were derived. Size and completeness of data sets generally increased due to the revision. AA-EQSs increased in 13 cases and decreased in 21 cases. MAC-EQSs increased in 22 cases and decreased in 11 cases. Most EQSs were derived using the deterministic assessment factor (AF) method. The number of substances for which EQSs were derived probabilistically by reference to the species sensitivity distribution (SSD) method increased from 2 to 5 AA-EQSs and from 6 to 11 MAC-EQSs. For AA-EQS derivation, AFs were reduced in 14 cases and increased in 6 cases. For MAC-EQS derivation, AFs were reduced in 9 cases and increased in 2 cases. Results demonstrate that the revisions did not generally lead to either lower or higher EQSs. The majority of EQSs (>93%) changed less than 10-fold. Clearly, EQSs based on small or incomplete data sets with large AFs were more prone to considerable changes in their numeric values when revised than EQSs based on SSDs. Thus, revision can reduce uncertainty and increase robustness of an EQS. In this study, however, available data continued to be insufficient to construct SSDs for the majority of substances. This was mostly due to a lack of reliable data. Integr Environ Assess Manag 2019;00:1-13. © 2019 SETAC.

Criteria for Reporting and Evaluating ecotoxicity Data (CRED): comparison and perception of the Klimisch and CRED methods for evaluating reliability and relevance of ecotoxicity studies.

BACKGROUND: The regulatory evaluation of ecotoxicity studies for environmental risk and/or hazard assessment of chemicals is often performed using the method established by Klimisch and colleagues in 1997. The method was, at that time, an important step toward improved evaluation of study reliability, but lately it has been criticized for lack of detail and guidance, and for not ensuring sufficient consistency among risk assessors. RESULTS: A new evaluation method was thus developed: Criteria for Reporting and Evaluating ecotoxicity Data (CRED). The CRED evaluation method aims at strengthening consistency and transparency of hazard and risk assessment of chemicals by providing criteria and guidance for reliability and relevance evaluation of aquatic ecotoxicity studies. A two-phased ring test was conducted to compare and characterize the differences between the CRED and Klimisch evaluation methods. A total of 75 risk assessors from 12 countries participated. Results show that the CRED evaluation method provides a more detailed and transparent evaluation of reliability and relevance than the Klimisch method. Ring test participants perceived it to be less dependent on expert judgement, more accurate and consistent, and practical regarding the use of criteria and time needed for performing an evaluation. CONCLUSIONS: We conclude that the CRED evaluation method is a suitable replacement for the Klimisch method, and that its use may contribute to an improved harmonization of hazard and risk assessments of chemicals across different regulatory frameworks.

The 2015 Annual Meeting of SETAC German Language Branch in Zurich (7-10 September, 2015): Ecotoxicology and environmental chemistry-from research to application.

This report provides a brief review of the 20th annual meeting of the German Language Branch of the Society of Environmental Toxicology and Chemistry (SETAC GLB) held from September 7th to 10th 2015 at ETH (Swiss Technical University) in Zurich, Switzerland. The event was chaired by Inge Werner, Director of the Swiss Centre for Applied Ecotoxicology (Ecotox Centre) Eawag-EPFL, and organized by a team from Ecotox Centre, Eawag, Federal Office of the Environment, Federal Office of Agriculture, and Mesocosm GmbH (Germany). Over 200 delegates from academia, public agencies and private industry of Germany, Switzerland and Austria attended and discussed the current state of science and its application presented in 75 talks and 83 posters. In addition, three invited keynote speakers provided new insights into scientific knowledge 'brokering', and-as it was the International Year of Soil-the important role of healthy soil ecosystems. Awards were presented to young scientists for best oral and poster presentations, and for best 2014 master and doctoral theses. Program and abstracts of the meeting (mostly in German) are provided as Additional file 1.

CRED: Criteria for reporting and evaluating ecotoxicity data.

Predicted-no-effect concentrations (PNECs) and environmental quality standards (EQSs) are derived in a large number of legal frameworks worldwide. When deriving these safe concentrations, it is necessary to evaluate the reliability and relevance of ecotoxicity studies. Such evaluation is often subject to expert judgment, which may introduce bias and decrease consistency when risk assessors evaluate the same study. The Criteria for Reporting and Evaluating Ecotoxicity Data (CRED) project attempts to address this problem. It aims to improve the reproducibility, transparency, and consistency of reliability and relevance evaluations of aquatic ecotoxicity studies among regulatory frameworks, countries, institutes, and individual assessors. In the present study, the CRED evaluation method is presented. It includes a set of 20 reliability and 13 relevance criteria, accompanied by extensive guidance. Risk assessors who participated in the CRED ring test evaluated the CRED evaluation method to be more accurate, applicable, consistent, and transparent than the often-used Klimisch method. The CRED evaluation method is accompanied by reporting recommendations for aquatic ecotoxicity studies, with 50 specific criteria divided into 6 categories: general information, test design, test substance, test organism, exposure conditions, and statistical design and biological response. An ecotoxicity study in which all important information is reported is more likely to be considered for regulatory use, and proper reporting may also help in the peer-review process.

Erratum to: Criteria for Reporting and Evaluating ecotoxicity Data (CRED): comparison and perception of the Klimisch and CRED methods for evaluating reliability and relevance of ecotoxicity studies.

[This corrects the article DOI: 10.1186/s12302-016-0073-x.].

Acclimation of Chlamydomonas reinhardtii to ultraviolet radiation and its impact on chemical toxicity.

The toxicity of chemical pollutants can be modulated under stressful environmental conditions, such as increased temperature, salinity or ultraviolet radiation (UVR), due to the interaction of effects during simultaneous stressor exposure. However, organisms may acclimate to such conditions by activation of physiological and biochemical defence mechanisms. In sequential exposures, organisms acclimated to environmental stressors may display an increased sensitivity or co-tolerance towards chemical pollutants. It has been suggested that co-tolerance might be expected for similarly acting stressors due to common defence mechanisms. To test this for combinations of UVR and chemical stressors, we first acclimatized the model green alga Chlamydomonas reinhardtii to UVR and subsequently compared the sensitivity of UVR pre-exposed and control algae towards chemicals. Selected chemicals all act on photosynthesis and thus share a common physiological target, but display distinct toxicity mechanisms. Results showed that UVR pre-exposure for four days partially inhibited algal growth and photosynthesis, but also increased algal tolerance to higher UVR levels, confirming UVR acclimation. HPLC analysis of algal pigments indicated that UVR acclimation might in part be explained by the protective function of lutein while the contribution of UVR absorbing compounds was less clear. Challenge exposure to chemicals in the absence of UVR showed that acclimated algae were co-tolerant to the photosensitizer rose bengal, but not to the herbicides paraquat and diuron, suggesting that the fast physiological and biochemical defence mechanisms that conferred tolerance of algae towards higher UVR levels were related to singlet oxygen defence. The presented study suggests that knowledge of the molecular toxicity mechanisms of chemicals, rather than their general physiological target, is needed in order to predict co-tolerance between environmental and chemical stressors.

Multiple stressor effects in Chlamydomonas reinhardtii--toward understanding mechanisms of interaction between effects of ultraviolet radiation and chemical pollutants.

The effects of chemical pollutants and environmental stressors, such as ultraviolet radiation (UVR), can interact when organisms are simultaneously exposed, resulting in higher (synergistic) or lower (antagonistic) multiple stressor effects than expected based on the effects of single stressors. Current understanding of interactive effects is limited due to a lack of mechanism-based multiple stressor studies. It has been hypothesized that effect interactions may generally occur if chemical and non-chemical stressors cause similar physiological effects in the organism. To test this hypothesis, we exposed the model green alga Chlamydomonas reinhardtii to combinations of UVR and single chemicals displaying modes of action (MOA) similar or dissimilar to the impact of UVR on photosynthesis. Stressor interactions were analyzed based on the independent action model. Effect interactions were found to depend on the MOA of the chemicals, and also on their concentrations, the exposure time and the measured endpoint. Indeed, only chemicals assumed to cause effects on photosynthesis similar to UVR showed interactions with UVR on photosynthetic yield: synergistic in case of Cd(II) and paraquat and antagonistic in case of diuron. No interaction on photosynthesis was observed for S-metolachlor, which acts dissimilarly to UVR. However, combined effects of S-metolachlor and UVR on algal reproduction were synergistic, highlighting the importance of considering additional MOA of UVR. Possible mechanisms of stressor effect interactions are discussed.

Ultraviolet radiation dose calculation for algal suspensions using UVA and UVB extinction coefficients.

Although the biological importance of ultraviolet light (UVR) attenuation has been recognised in marine and freshwater environments, it is not generally considered in in vitro ecotoxicological studies using algal cell suspensions. In this study, UVA and UVB extinction were determined for cultures of algae with varying cell densities, and the data were used to calculate the corresponding extinction coefficients for both UVA and UVB wavelength ranges. Integrating the Beer-Lambert equation to account for changes in the radiation intensity reaching each depth, from the surface until the bottom of the experimental vessel, we obtained the average UVA and UVB intensity to which the cultured algal cells were exposed. We found that UVR intensity measured at the surface of Chlamydomonas reinhardtii cultures lead to a overestimation of the UVR dose received by the algae by 2-40 times. The approach used in this study allowed for a more accurate estimation of UVA and UVB doses.

GLK transcription factors coordinate expression of the photosynthetic apparatus in Arabidopsis.

Chloroplasts of photosynthetic organisms harness light energy and convert it into chemical energy. In several land plants, GOLDEN2-LIKE (GLK) transcription factors are required for chloroplast development, as glk1 glk2 double mutants are pale green and deficient in the formation of the photosynthetic apparatus. We show here that glk1 glk2 double mutants of Arabidopsis thaliana accumulate abnormal levels of chlorophyll precursors and that constitutive GLK gene expression leads to increased accumulation of transcripts for antenna proteins and chlorophyll biosynthetic enzymes. To establish the primary targets of GLK gene action, an inducible expression system was used in combination with transcriptome analysis. Following induction, transcript pools were substantially enriched in genes involved in chlorophyll biosynthesis, light harvesting, and electron transport. Chromatin immunoprecipitation experiments confirmed the direct association of GLK1 protein with target gene promoters, revealing a putative regulatory cis-element. We show that GLK proteins influence photosynthetic gene expression independently of the phyB signaling pathway and that the two GLK genes are differentially responsive to plastid retrograde signals. These results suggest that GLK genes help to coregulate and synchronize the expression of a suite of nuclear photosynthetic genes and thus act to optimize photosynthetic capacity in varying environmental and developmental conditions.