ToxStrategies/21CT scientists are among the authors of a poster for the Annual Meeting of the American College of Toxicology, to be held virtually on November 10 through 19, 2021. The poster (by Amy Kimzey, Brian Welsh, and Marcie Wood) discusses the process of deriving exposure-based limits for impurities that might be encountered in pharmaceuticals for direct-to-brain administration and presents relevant case studies. The poster reviews three case studies—a salt, an alcohol, and an endogenous molecule—that exemplify the challenges of determining a limit for direct-to-brain administration routes. Dr. Kimzey will be available live on Monday, November 15 from 3:30 to 5:30 EST for a Q&A regarding their findings.