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Your Environment. Your Health.

Clustering and Classification Workshop

Applications to Investigate Adverse Effects of Chemicals on Human Health and Environment workshop
October 3-4, 2022 • 8:30 a.m. – 3:00 p.m. EDT (tentative)

illustration of atoms and DNA

Main Purpose

This 2-day virtual workshop is part of the NIEHS/DNTP scientific outreach activities to discuss Clustering and Classification Methods (and related cheminformatic tools as part of New Approach Methodologies (NAM)s) and their applications to facilitate toxicology research and provide information for risk assessment. The workshop will introduce the concept of similarity and the different classification and clustering approaches as well as their uses for scientific toxicity research and risk assessment. The invited speakers and expert discussants will help to identify best practices and guidelines for the application of these approaches. Participation from attendees to round table discussions will be encouraged.

This workshop is supported by the DNTP/NIEHS Consumer Products and Therapeutics Program, which has a goal of developing and applying define approaches to infer hazard across specific structural and functional substance classes.

Workshop Goals

  • Increase communication and collaboration from different sectors: government, academia and industry (US & international)
  • To educate and correct misconceptions and develop new ideas/concepts (best practices & innovation)
  • To introduce the different classification and clustering approaches and their uses for scientific toxicity research and risk assessment
  • To involve both NAM developers and users (regulators, researchers) to increase benefit and exchange

Discussion Topics

  • Chemical similarity: supervised vs unsupervised similarity (clustering)
  • Classic read-across (analogues) and endpoint specific classification/clustering-based approaches (surrogates)
  • How to develop and how to apply the clustering and classification approaches
  • “Relativity” of chemicals similarity: supervised vs unsupervised similarity (clustering)
  • Applications and examples


Registration opens August 22, 2022.

Draft Agenda



Session 1 (morning): Chemicals and Similarity: Structures and Bioactivity

  • This session will provide an introduction covering chemical structures and the concept of similarity from a structural, biological, phenotypic, and mechanistic perspective, including how similarity matters and depends on the context and goal in research and regulatory assessment. It will also include a discussion on the concept of activity cliffs and cases where subtle differences in structural characteristics can lead to orders of magnitude differences in biological activity.

  • Round Table Discussion

Session 2 (afternoon): Supervised and Unsupervised Approaches

  • This session will define and redefine terms ranging from molecular descriptors, fingerprints, tox alerts, machine learning, read-across, QSAR, univariate/multivariate analysis, classification, clustering, etc. and give an introduction to the general theory of supervised and unsupervised learning approaches, covering the concept of analogues and surrogates and how to select the right ones depending on the goal and context.

  • Round Table Discussion



Session 3 (morning): How and When to Apply the Different Approaches

  • This session will provide an overview of the different possible applications of supervised and unsupervised clustering and classification approaches and how to apply them, separately or in combination, and interpret results. This session will be important to for a discussion on best practices.

  • Round Table Discussion

Session 4 (afternoon): Applications and Examples

  • The last session will provide examples of applications of different approaches for research and regulatory assessment uses.

  • Round Table Discussion


For questions about the workshop content, please contact Kamel Mansouri at 984-287-3187 or Vicki L. Sutherland at 984-287-3193. For logistical questions, please contact Kerri Voelker at 919-794-4710.

American Disabilities Act Accommodations Requests

Individuals with disabilities who need accommodation to participate in this event should contact Kerri Voelker at 919-794-4710. TTY users should contact the Federal TTY Relay Service at 1-800-877-8339. Requests should be made at least 5 business days in advance of the workshop.

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