Keith Morris-Schaeffer

Keith Morris-Schaffer, Ph.D.

Senior Scientist
Chemical Regulation & Food Safety

Dr. Morris-Schaffer is a toxicologist that specializes in the evaluation of chemical exposures and their impacts on human health. His experience includes human health risk assessments for a variety of chemicals and agents, such as agrochemicals, metals, extractable and leachable substances, and dermal sensitizers. He has conducted toxicology evaluations of conventional pesticides, and biopesticides, including assisting clients with regulatory strategies for scientific waiver rationales, addressing data gaps, and coordinating product toxicology testing. He has working familiarity with human health data registration for the California Department of Pesticide Regulation, United States Environmental Protection Agency, and the European Union.

His project work also involves risk assessment reports for stewardship programs that support consumer product safety. He has experience with gathering and interpreting technical data and information for exposure assessments under California Proposition 65 and developing tools to maintain sustainable Proposition 65 compliance programs. Dr Morris-Schaffer has conducted chemical and product reviews as well as coordinated product testing for consumer products to support compliance assessments. He is familiar with deriving estimated Safe Harbor Levels, both MADLs and NSRLs, using established regulatory guidance and precedent.

Dr. Morris-Schaffer also specializes in evaluating dermal sensitization risk from organic and/or metal residuals that can potentially leach from consumer products. He has leveraged product composition and leaching data, read-across analyses, and established regulatory approaches to provide quantitative and qualitative sensitization risk assessments for clients.

Prior to joining Exponent in 2019, Dr. Morris-Schaffer successfully defended his doctorate in toxicology at the University of Rochester. His research project experience includes neuro- and pulmonary toxicology assessments of developmental exposure to common air pollutant constituents (e.g. diesel, elemental carbon). His primary thesis work investigated the developmental toxicity of traffic-derived ultrafine particles inhalation following neonatal hyperoxia exposure. He has expertise and familiarity in nanotoxicology, risk assessment, and inhalation dosimetry including Multiple-Path Particle Dosimetry (MPPD). He received his M.S. in Toxicology at the University of Rochester in 2016 where he was trained in biochemistry, toxicology, epigenetics, epidemiology, biostatistics, pharmacology and physiology.


  • Ph.D., Toxicology, University of Rochester, 2019
  • M.S., Toxicology, University of Rochester, 2016
  • B.A., Psychology, SUNY Geneseo, 2014


Edwards CM, Small D, Bell T, David-Drori J, Hansen C, Morris-Schaffer K, Canale C, Ng J, Markowski VP. Early postnatal decabromodiphenyl ether exposure reduces thyroid hormone and astrocyte density in the juvenile mouse dentate gyrus. Physiology & Behavior. 2020. 216:112798.

Jew, K., Herr, D., Wong, C., Kennell, A., Morris-Schaffer, K., Oberdörster, G., O’Banion, K., Cory-Slechta, D.A., and Elder, A. Selective memory and behavioral alterations after ambient ultrafine particulate matter exposure in aged 3xTgAD Alzheimer’s disease mice. Particle & Fibre Toxicology 2020 16:45

Morris-Schaffer K, Merrill AK, Jew K, Wong C, Conrad K, Harvey K, Marvin E, Sobolewski M, Oberdörster G, Elder A, Cory-Slechta DA: Effects of neonatal inhalation exposure to ultrafine carbon particles on pathology and behavioral outcomes in C57BL/6J mice. Particle & Fibre Toxicology 2019. 16:10.

Morris-Schaffer K, Merrill A, Wong C, Jew K, Sobolewski M, Cory-Slechta D: Limited developmental neurotoxicity from neonatal inhalation exposure to diesel exhaust particles in C57BL/6 mice. Particle & Fibre Toxicology 2019, 16:1.

Morris-Schaffer K, Sobolewski M, Welle K, Conrad K, Yee M, O'Reilly MA, Cory-Slechta DA: Cognitive flexibility deficits in male mice exposed to neonatal hyperoxia followed by concentrated ambient ultrafine particles. Neurotoxicol Teratol 2018, 70:51-59.

Sobolewski, M, Anderson, T, Conrad, K, Marvin, E, Klocke, C, Morris-Schaffer, K, Cory-Slechta, DA. Developmental Exposures to Ultrafine Particle Air Pollution Reduces Early Testosterone Levels and Adult Male Social Novelty Preference: Risk for Children’s Sex-Biased Neurobehavioral Disorders. NeuroToxicology 2018, 68:203-211

Morris-Schaffer K, Sobolewski M, Allen JL, Marvin E, Yee M, Arora M, O’Reilly MA, Cory-Slechta DA: Effect of neonatal hyperoxia followed by concentrated ambient ultrafine particle exposure on cumulative learning in C57Bl/6J mice. NeuroToxicology 2018, 67:234-244.

Allen JL, Oberdorster G, Morris-Schaffer K, Wong C, Klocke C, Sobolewski M, Conrad K, Mayer-Proschel M, Cory-Slechta DA: Developmental neurotoxicity of inhaled ambient ultrafine particle air pollution: Parallels with neuropathological and behavioral features of autism and other neurodevelopmental disorders. NeuroToxicology 2017, 59:140-154.

Allen, J. L., Klocke, C., Morris-Schaffer, K, Conrad, K., Sobolewski, M., Cory-Slechta, DA: Cognitive Effects of Air Pollution Exposures and Potential Mechanistic Underpinnings. Current environmental health reports 2017, 4(2): 180-191.

Sobolewski, M., Allen, J. L., Morris-Schaffer, K, Klocke, C., Conrad, K., & Cory-Slechta, DA: A novel, ecologically relevant, highly preferred, and non-invasive means of oral substance administration for rodents. Neurotoxicol Teratol 2016, 56: 75-80.


Morris-Schaffer, K, Merrill, A, Sobolewski, M, and Cory-Slechta, DA. Effects of Neonatal Inhalation Exposure to Ultrafine Carbon Particles and Diesel Particulate on Pathology and Behavioral Outcomes in C57Bl/6J. Poster Presentation. Genetic and Environmental Toxicology Association, Sacramento, CA, 2019.

Morris-Schaffer, K. Limited Developmental Neurotoxicity from Neonatal Exposure to Ultrafine Carbon Particles or Diesel Particulate Matter. Poster presentation, Society of Toxicology, Baltimore, MD, 2019.

Morris-Schaffer, K. Limited Developmental Neurotoxicity from Neonatal Exposure to Ultrafine Carbon Particles or Diesel Particulate Matter. Oral presentation, Northeast Regional Chapter of Society of Toxicology, Shrewsbury, MA, 2018.

Morris-Schaffer, K, Sobolewski, M, and Cory-Slechta, DA Neonatal hyperoxia followed by concentrated ambient ultrafine particle exposure leads to cumulative learning deficits in C57Bl/6J mice. Poster presentation, Society of Toxicology, San Antonio, TX, 2018.

Morris-Schaffer, K, Allen, JL, Sobolewski, M, and Cory-Slechta, DA Neurotoxicological consequences of developmental exposure to hyperoxia and air pollution: concurrent risk factors of premature birth. Poster presentation. Society of Toxicology, Baltimore, MD, 2017.

Morris-Schaffer, K, Allen, JL, Wong, C, Oberdorster, G, and Cory-Slechta, DA. Poster Presentation. Neonatal ultrafine particulate matter inhalation exposure adversely impacts white matter development. Society of Toxicology, New Orleans, LA, 2016.

Professional Affiliations

Genetic and Environmental Toxicology Association of Northern California (GETA) - Board 2020-present
Member 2019-present

National Society of Toxicology (SOT) - 2019-present Associate Member, 2018-2019

Graduate Student Leadership Council Communications Chair, 2014-2019 Student Member

Additional Information

Peer Reviewer

Inhalation Toxicology



News & Events