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Given the vital role of thyroid hormones (THs) in vertebrate development, it is essential to identify chemicals that interfere with the TH system. Whereas, among nonmammalian laboratory animals, fish are the most frequently utilized test species in endocrine disruptor research, for example, in guidelines for the detection of effects on the sex hormone system, there is no test guideline (TG) using fish as models for thyroid‐related effects; rather, amphibians are used. Therefore, the objective of the present project was to integrate thyroid‐related endpoints for fish into a test protocol combining OECD TGs 229 (Fish Short‐Term Reproduction Assay) and 234 (Fish Sexual Development Test). The resulting integrated Fish Endocrine Disruption Test (iFEDT) was designed as a comprehensive approach to covering sexual differentiation, early development, and reproduction and to identifying disruption not only of the sexual and/or reproductive system but also the TH system. Two 85‐day exposure tests were performed using different well‐studied endocrine disruptors: 6‐propyl‐2‐thiouracil (PTU) and 17α‐ethinylestradiol (EE2). Whereas the companion Part A of this study presents the findings on effects by PTU and EE2 on endpoints established in existing TGs, the present Part B discusses effects on novel thyroid‐related endpoints such as TH levels, thyroid follicle histopathology, and eye development. 6‐Propyl‐2‐thiouracil induced a massive proliferation of thyroid follicles in any life stage, and histopathological changes in the eyes proved to be highly sensitive for TH system disruption especially in younger life stages. For measurement of THs, further methodological development is required. 17‐α‐Ethinylestradiol demonstrated not only the well‐known disruption of the hypothalamic–pituitary–gonadal axis, but also induced effects on thyroid follicles in adult zebrafish (Danio rerio) exposed to higher EE2 concentrations, suggesting crosstalk between endocrine axes. The novel iFEDT has thus proven capable of simultaneously capturing endocrine disruption of both the steroid and thyroid endocrine systems. Integr Environ Assess Manag 2024;20:830–845. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: Zebrafish were exposed to 6‐propyl‐2‐thiouracil (PTU) or 17α‐ethinylestradiol (EE2) in an experiment that merged OECD test guidelines (TGs) 229 and 234, the integrated fish endocrine disruptor test (iFEDT).PTU and EE2 had strong effects on established endocrine‐related endpoints in zebrafish adults and their offspring, but also on thyroid‐related endpoints.PTU induced a massive proliferation of thyroid follicles in any life stage, and histopathological changes in the eyes, whereas EE2 caused only slight histopathological changes in thyroid follicles.Merging of TGs 229 and 234 proved feasible, and the iFEDT provides a promising tool for assessment of thyroid hormone system disruption in zebrafish. [ABSTRACT FROM AUTHOR]

There has been increasing interest in endocrine‐disrupting chemicals (EDCs) among scientists and public authorities over the last 30 years, notably because of their wide use and the increasing evidence of detrimental effects on humans and the environment. However, test systems for the detection of potential EDCs as well as testing strategies still require optimization. Thus, the aim of the present project was the development of an integrated test protocol that merges the existing OECD test guidelines (TGs) 229 (fish short‐term reproduction assay) and 234 (fish sexual development test) and implements thyroid‐related endpoints for fish. The integrated fish endocrine disruptor test (iFEDT) represents a comprehensive approach for fish testing, which covers reproduction, early development, and sexual differentiation, and will thus allow the identification of multiple endocrine‐disruptive effects in fish. Using zebrafish (Danio rerio) as a model organism, two exposure tests were performed with well‐studied EDCs: 6‐propyl‐2‐thiouracil (PTU), an inhibitor of thyroid hormone synthesis, and 17α‐ethinylestradiol (EE2), an estrogen receptor agonist. In part A of this article, the effects of PTU and EE2 on established endpoints of the two existing TGs are reported, whereas part B focuses on the novel thyroid‐related endpoints. Results of part A document that, as expected, both PTU and EE2 had strong effects on various endocrine‐related endpoints in zebrafish and their offspring. Merging of TGs 229 and 234 proved feasible, and all established biomarkers and endpoints were responsive as expected, including reproductive and morphometric changes (PTU and EE2), vitellogenin levels, sex ratio, gonad maturation, and histopathology (only for EE2) of different life stages. A validation of the iFEDT with other well‐known EDCs will allow verification of the sensitivity and usability and confirm its capacity to improve the existing testing strategy for EDCs in fish. Integr Environ Assess Manag 2024;20:817–829. © 2023 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC). Key Points: Zebrafish were exposed to 6‐propyl‐2‐thiouracil (PTU) or 17α‐ethinylestradiol (EE2) in an experiment that merged OECD test guidelines 229 and 234, the integrated fish endocrine disruptor test (iFEDT).PTU and EE2 had strong effects on various endocrine‐related endpoints in zebrafish adults and their offspring.All established biomarkers and endpoints were responsive as expected, including reproductive and morphometric changes (PTU and EE2), vitellogenin levels, sex ratio, gonad maturation, and histopathology (only for EE2) of different life stages.Merging of test guidelines 229 and 234 proved feasible, and the iFEDT provides a promising tool for assessment of endocrine disruption in zebrafish. [ABSTRACT FROM AUTHOR]

Welds of ultra‐high strength steels and their post‐weld treatment for increasing the fatigue strength Whenever even higher‐strength steels were developed, there were doubts about their cost‐effectiveness and usability. However, the development from S355 to S460 and finally to S700 has shown that this innovation paid off in a very short time. In terms of sustainability, the use of ultra‐high strength steel up to S960 can save resources, make connections more efficient and extend the service life of bridges. These aspects can be realised through the use of ultra‐high strength steel, and the extension of the scope from S700 to S960 in prEN 1993‐1‐12 forms a basis for this. At the same time, further investigations are required, such as the adaptation of the design rules for welding and for the use of post‐weld treatment to increase the fatigue strength. This paper presents results from two current AiF FOSTA projects. As part of the research project "Effective design concepts for mixed connections in steel structures", this paper presents extensive investigations on butt and fillet welded joints of ultra‐high strength steels S960. As part of the research project "FAT‐classification of HFMI‐treated ultra‐high strength structural steels considering geometric manufacturing imperfections in steel construction", this paper presents results and a proposal for extending the DASt guideline 026 and the new Annex F in prEN 1993‐1‐9 to ultra‐high strength steels up to S960 for the constructional detail transverse stiffener. [ABSTRACT FROM AUTHOR]

Early vertebrate development is partially regulated by thyroid hormones (THs). Environmental pollutants that interact with the TH system (TH system-disrupting chemicals [THSDCs]) can have massively disrupting effects on this essential phase. Eye development of fish is directly regulated by THs and can, therefore, be used as a thyroid-related endpoint in endocrine disruptor testing. To evaluate the effects of THSDC-induced eye malformations during early development, zebrafish (Danio rerio) embryos were exposed for 5 days postfertilization (dpf) to either propylthiouracil, a TH synthesis inhibitor, or tetrabromobisphenol A, which interacts with TH receptors. Subsequently, one half of the embryos were exposed further to the THSDCs until 8 dpf, while the other half of the embryos were raised in clean water for 3 days to check for reversibility of effects. Continued THSDC exposure altered eye size and pigmentation and induced changes in the cellular structure of the retina. This correlated with morphological alterations of thyroid follicles as revealed by use of a transgenic zebrafish line. Interestingly, effects were partly reversible after a recovery period as short as 3 days. Results are consistent with changes in TH levels measured in different tissues of the embryos, for example, in the eyes. The results show that eye development in zebrafish embryos is very sensitive to THSDC treatment but able to recover quickly from early exposure by effective repair mechanisms. Environ Toxicol Chem 2023;42:1276-1292. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC., (© 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.)