Chemical hazard assessments (CHAs) are a critical foundation for alternative assessments (AAs) and play an important role when making informed substitution decisions in the proactive design of products. In order to effectively substitute a safer alternative in the place of a chemical with high hazards, a practitioner must compare hazard endpoint data for the alternative and incumbent material in the form of comprehensive CHAs. This step in an AA can eliminate regrettable substitutions and lead to identification and promotion of safer chemicals, ultimately reducing the inherent hazard of chemicals in the supply chain. Hazard identification relies on identification of data on the target compounds as well as filling data gaps, which are increasingly being filled using new approach methodologies (NAMs). As corporate and state initiatives to identify and promote safer chemicals mature, we aim to highlight the current landscape of CHAs in AAs, existing challenges and successful implementation of informed substitution (such as in state programs, emerging certifications and industry collaborations). This session will highlight CHA best practices and emerging trends in the contribution of NAMs to robust chemical hazard profiles, as well as challenges encountered in conducting CHAs on mixtures and certain chemical classes that do not have discrete chemical structures (e.g., polymers and botanicals). In addition, approaches to account for variability in impurities and other chemical characteristics not captured in the generic hazard assessment of a specific chemical are also encouraged. Lastly, work describing how CHA’s have been successfully used in informed substitution efforts in proactive product design, and in support of alternative assessments driven by regulatory requirements are desired.