Interpretation of sexual secondary characteristics (SSCs) in regulatory testing for endocrine activity in fish.

Secondary sexual characteristics (SSCs) are important features that have evolved in many fish species because of inter-individual competition for mates. SSCs are crucial not only for sexual selection, but also for other components of the reproductive process and parental care. Externally, they are especially clear in males (for instance, tubercles, fatpad, anal finnage, colouration) but are also externally present in the females (for instance, ovipositor). These characters are under hormonal control and as such there has been much interest in incorporating them as measures in fish test methods to assess the potential endocrine activity of chemicals. Here we describe the external SSCs in typical laboratory test species for endocrine testing - fathead minnow (Pimephales promelas), Japanese medaka (Oryzias latipes), zebrafish (Danio rerio) and the three-spined stickleback (Gasterosteus aculeatus L.). We also provide some examples and discuss the utility of SSC responses to the endocrine activity of chemicals in the field and the laboratory. This paper is not aimed to provide a comprehensive review of SSCs in fish but presents a view on the assessment of SSCs in regulatory testing. Due to the current regulatory importance of establishing an endocrine mode-of-action for chemicals, we also consider other, non-endocrine factors that may lead to SSC responses in fish. We conclude with recommendations for how the assessment of SSCs in fish could be usefully incorporated into the endocrine hazard and risk assessment of chemicals

Biological impact of organotin compounds on mollusks in marine and freshwater ecosystems

Organotin compounds, like tributyltin (TBT) and triphenyltin (TPT), degrade only slowly in the environment. Today, TBT is known to evoke a variety of effects in animals, even at very low environmental concentrations. In terms of sensitivity, none rivals that of two virilisation phenomena-intersex and imposex-in prosobranch gastropods. The effects of TBT and TPT on various marine and freshwater snails were investigated in newly developed sediment biotests in the laboratory. Most tested species showed very low effect concentrations for both organotin compounds (e. g. the freshwater mudsnail Potamopyrgus antipodarum with an EC10 of 0.03 μg TPT as Sn/kg and 0.98μg TBT as Sn/kg for the reduction of fertility). In order to assess the actual TBT contamination of coastal sediments, extensive surveys were carried out in France and Ireland, indicating that there is still a continuing threat for sensitive marine organisms. To obtain information on the contamination of fluvial and estuarine sediments in Germany, an effect monitoring was conducted using the biotests with the netted whelk Nassarius reticulatus and P. antipodarum. From our investigations we may conclude that a variety of benthic mollusks is strongly affected by low concentrations of organotin compounds in aquatic ecosystems. Due to their persistence in the environment, a continuing impact on aquatic wildlife has to be expected

Validation of the OECD reproduction test guideline with the New Zealand mudsnail Potamopyrgus antipodarum using trenbolone and prochloraz

The Organisation for Economic Cooperation and Development (OECD) provides several standard test methods for the environmental hazard assessment of chemicals, mainly based on primary producers, arthropods, and fish. In April 2016, two new test guidelines with two mollusc species representing different reproductive strategies were approved by OECD member countries. One test guideline describes a 28-day reproduction test with the parthenogenetic New Zealand mudsnail Potamopyrgus antipodarum. The main endpoint of the test is reproduction, reflected by the embryo number in the brood pouch per female. The development of a new OECD test guideline involves several phases including inter-laboratory validation studies to demonstrate the robustness of the proposed test design and the reproducibility of the test results. Therefore, a ring test of the reproduction test with P. antipodarum was conducted including eight laboratories with the test substances trenbolone and prochloraz and results are presented here. Most laboratories could meet test validity criteria, thus demonstrating the robustness of the proposed test protocol. Trenbolone did not have an effect on the reproduction of the snails at the tested concentration range (nominal: 10-1000 ng/L). For prochloraz, laboratories produced similar EC10 and NOEC values, showing the inter-laboratory reproducibility of results. The average EC10 and NOEC values for reproduction (with coefficient of variation) were 26.2 µg/L (61.7%) and 29.7 µg/L (32.9%), respectively. This ring test shows that the mudsnail reproduction test is a well-suited tool for use in the chronic aquatic hazard and risk assessment of chemicals

Hazard/Risk Assessment AQUATIC TOXICITY TESTS WITH SUBSTANCES THAT ARE POORLY SOLUBLE IN WATER AND CONSEQUENCES FOR ENVIRONMENTAL RISK ASSESSMENT

Abstract-Aquatic toxicity tests with substances that are poorly soluble in water have been conducted using different methods, and estimates of toxicity have varied accordingly. The present study illustrates differences in toxicity values resulting from variation in test designs and solution preparation methods, and offers guidance on the best way to conduct these tests. Consequences for environmental risk assessment and classification are also discussed. The present study mainly considers active ingredients of plant protection products, but is also considered relevant to other chemicals. It is recommended that toxicity tests be conducted only up to the saturation limit, dispersants avoided, and solvents used only if necessary to support handling and speed of dissolution. Analytical measurements of exposure concentrations should reflect what organisms are exposed to. If acute toxicity testing at the saturation limit yields no adverse effects, further testing should not normally be required; the toxicity value of the endpoints should be considered as the saturation limit and adverse classification should not be required. Chronic testing, if required, should then be conducted at the practical saturation limit as this is the most realistic worst-case exposure scenario. If no adverse effects occur, the risk should be acceptable because higher aqueous exposure cannot occur. This could be substantiated by testing additional species. Assessment factors on no observed effect concentration (NOEC) values at the saturation limit require careful consideration in the risk assessment to avoid unnecessarily low regulatory acceptable concentrations. Environ. Toxicol. Chem.# 2012 SETA

Robust multi-proxy data integration, using late Cretaceous paleotemperature records as a case study

In paleoclimate studies, multiple temperature records are often compared and combined to evaluate temperature trends. Yet, no standardized approach for integrating proxy-derived paleotemperature records exists. In addition, paleotemperature data are often reported without uncertainty estimates (prediction errors), and raw data are not always available. This complicates the quantification of, for example, temperature trends and the magnitude of warming events. Here we propose a robust quantitative approach for multi-proxy analysis in paleoclimate studies. To demonstrate this, we study the latest Maastrichtian warming event (LMWE) in the ODP 174AX Bass River core (New Jersey), and integrate five independent paleotemperature proxies covering the last million years of the Cretaceous. Our integrated temperature reconstruction suggests that, after a climatically stable period, a latest Cretaceous warming of 3.9 ± 1.1 °C occurred between ∼450 and 100 kyr before the K–Pg boundary. The error on this reconstructed temperature should be considered the absolute minimum error, as poorly constrained or unknown uncertainties cannot be fully propagated. The warming event was followed by a gradual cooling to pre-warming conditions towards the end of the Cretaceous. Furthermore, the record suggests multiple warming pulses during the LMWE. The results of this integrated approach are consistent with other latest Cretaceous temperature records, suggesting that the trend described here represents a global signal

Robust multi-proxy data integration, using late Cretaceous paleotemperature records as a case study

© 2018 Elsevier B.V. In paleoclimate studies, multiple temperature records are often compared and combined to evaluate temperature trends. Yet, no standardized approach for integrating proxy-derived paleotemperature records exists. In addition, paleotemperature data are often reported without uncertainty estimates (prediction errors), and raw data are not always available. This complicates the quantification of, for example, temperature trends and the magnitude of warming events. Here we propose a robust quantitative approach for multi-proxy analysis in paleoclimate studies. To demonstrate this, we study the latest Maastrichtian warming event (LMWE) in the ODP 174AX Bass River core (New Jersey), and integrate five independent paleotemperature proxies covering the last million years of the Cretaceous. Our integrated temperature reconstruction suggests that, after a climatically stable period, a latest Cretaceous warming of 3.9 ± 1.1 °C occurred between ∼450 and 100 kyr before the K–Pg boundary. The error on this reconstructed temperature should be considered the absolute minimum error, as poorly constrained or unknown uncertainties cannot be fully propagated. The warming event was followed by a gradual cooling to pre-warming conditions towards the end of the Cretaceous. Furthermore, the record suggests multiple warming pulses during the LMWE. The results of this integrated approach are consistent with other latest Cretaceous temperature records, suggesting that the trend described here represents a global signal.status: publishe