SETAC Globe - Environmental Quality Through Science
19 February 2015
Volume 16 Issue 2

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Report on an Advanced Course on Toxicologic Pathology of Fish

Stephen W. Feist, Cefas, and Helmut Segner, University of Bern

Recently, an advanced course on Toxicologic Pathology of Fish was held from 15-17 October 2014 at the Centre for Environment, Fisheries and Aquaculture Science (Cefas), Weymouth Laboratory, UK. The course, which was first held at the University of Berne in 2013, addressed the fact that while industry has an increasing need for trained toxicopathologists on non-rodent species, particularly fish, European universities currently offer almost no educational programs in ecotoxicologcial histopathology. The organizers’ main aim was to cover the principle aspects of fish toxicopathology for those entering or already engaged in assessment of toxicologic pathology of fish, with particular emphasis on practical assessment of histological slides. Additionally, in response to the primary feedback from the initial course, additional practical sessions were offered. Thanks to CEFIC-ECETOC for sponsoring the course and Leica for supplying several microscopes for the practical sessions.

It was also recognized that this course plays an important role in building a network of trained fish pathologists and providing mutual support and ongoing training to meet the international need for fish toxicopathologists. This need was strongly supported through the involvement of professors Jeff Wolf with the Experimental Pathology Laboratory, Virginia, USA, and Thomas Braunbeck from the University of Heidelberg, Germany, who both provided lectures and supported the practical sessions. Helmut Segner with the University of Bern, Switzerland, and Stephen Feist, Matthew Green and John Bignell with the Cefas Weymouth Laboratory, UK, provided additional presentations.

The course structure covered the following aspects:

Day 1

  • Registration, objectives and overview of the agenda
  • Introduction to toxicologic histopathology of fish: Target organs, examples of responses, differences from infectious disease (H. Segner, J. Wolf and S. Feist)
  • Principles of experimental design (J. Wolf)
  • Awareness and avoidance of artefacts in histotechnique (M. Green)

Toxicopathology of fishes in regulatory risk assessment

  • Fish histopathology in the regulatory environment (H. Segner)
  • Toxicopathology in early development of fish (T. Braunbeck)
  • Practical exercises – Normal histology, zebrafish, fathead minnow and medaka

Day 2

  • Misdiagnoses and missed diagnoses – The challenge in toxicologic pathology with fish, Pathology Working Group (J. Wolf)
  • Existing and emerging guidelines for toxpath in regulatory hazard assessment, including endocrine tissues (H. Segner and J. Wolf)

Toxicopathology of fishes in biomonitoring:

  • Toxpath in environmental monitoring and assessment (neoplastic changes and their relation to toxic exposure; classification of tumors, BEQUALM fish disease measurement and linkage of histopath to molecular tools and phenotypic anchoring) (S. Feist)
  • Freshwater monitoring (T. Braunbeck)
  • Practical session – case studies (microscope and presentation)
  • Practical session – BEQUALM ring test (J. Bignell)

Day 3

  • Practical session – Case studies (microscope and presentation)
  • Focus on liver histopathology – Biotoxins, neoplasia, pesticides, other
  • Overview of course, feedback and proposals for 2015
Workshop participants

A total of 16 participants from 10 different countries took part in the course with a wide range of expertise in fish pathology. The course organizers anticipated this and included presentations specifically tackling technical aspects of histology to be able to recognize artifact problems as well as confounding pathology associated with infectious disease. Emphasis was also given to the approaches required for toxicologic pathology regulatory assessment as well as those for monitoring the aquatic environment for the effects of contaminants. This included a specific presentation and practical test based on the internatial Biological Effects Quality Assurance in Monitoring Programme (BEQUALM) for fish disease with emphasis on liver lesions associated with contaminant exposure.

The course successfully featured a high levels of participant interaction. Feedback from most participants showed that more emphasis on practical examination of slides should be given in subsequent courses. The organizers will endeavor to meet this challenge and address other feedback to ensure the development of the course continues to meet the needs of the participants and regulators for availability of trained scientists able to undertake assessment of fish tissues for toxicological lesions. The next course is planned for October 2015 in Bern, Switzerland.

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