Risk assessment in the 21st century: Roadmap and matrix

Michelle R. Embry, Ammie N. Bachman, David R. Bell, Alan R. Boobis, Samuel M. Cohen, Michael Dellarco, Ian C. Dewhurst, Nancy G. Doerrer, Ronald N. Hines, Angelo Moretto, Timothy P. Pastoor, Richard D. Phillips, J. Craig Rowlands, Jennifer Y. Tanir, Douglas C. Wolf, John E. Doe

Research output: Contribution to journalReview articlepeer-review

96 Scopus citations


The RISK21 integrated evaluation strategy is a problem formulation-based exposure-driven risk assessment roadmap that takes advantage of existing information to graphically represent the intersection of exposure and toxicity data on a highly visual matrix. This paper describes in detail the process for using the roadmap and matrix. The purpose of this methodology is to optimize the use of prior information and testing resources (animals, time, facilities, and personnel) to efficiently and transparently reach a risk and/or safety determination. Based on the particular problem, exposure and toxicity data should have sufficient precision to make such a decision. Estimates of exposure and toxicity, bounded by variability and/or uncertainty, are plotted on the X- and Y-axes of the RISK21 matrix, respectively. The resulting intersection is a highly visual representation of estimated risk. Decisions can then be made to increase precision in the exposure or toxicity estimates or declare that the available information is sufficient. RISK21 represents a step forward in the goal to introduce new methodologies into 21st century risk assessment. Indeed, because of its transparent and visual process, RISK21 has the potential to widen the scope of risk communication beyond those with technical expertise.

Original languageEnglish (US)
Pages (from-to)6-16
Number of pages11
JournalCritical reviews in toxicology
Issue numberSUPPL.3
StatePublished - Aug 2014


  • Exposure
  • Framework
  • Hazard
  • Problem formulation
  • Risk
  • Risk assessment
  • Risk policy
  • Tiered

ASJC Scopus subject areas

  • Toxicology


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