Industrial ecology has revolutionized our understanding of material stocks and flows in our economy and society. For this important discipline to have even deeper impact, we must understand the inherent nature of these materials in terms of human health and the environment. This paper focuses on methods to design synthetic chemicals to reduce their intrinsic ability to cause adverse consequence to the biosphere. Advances in the fields of computational chemistry and molecular toxicology in recent decades allow the development of predictive models that inform the design of molecules with reduced potential to be toxic to humans or the environment. The approach presented herein builds on the important work in quantitative structure-activity relationships by linking toxicological and chemical mechanistic insights to the identification of critical physical-chemical properties needed to be modified. This in silico approach yields design guidelines using boundary values for physiochemical properties. Acute aquatic toxicity serves as a model endpoint in this study. Defining value ranges for properties related to bioavailability and reactivity eliminates 99% of the chemicals in the highest concern for acute aquatic toxicity category. This approach and its future implementations are expected to yield very powerful tools for life cycle assessment practitioners and molecular designers that allow rapid assessment of multiple environmental and human health endpoints and inform modifications to minimize hazard.green chemistry | safer chemicals | rational design | toxicity prediction I ndustrial ecology and green chemistry are two rigorous scientific disciplines with global scientific communities that empower sustainability science. Sustainability science is the science, technology, and innovation in support of sustainable development-meeting human needs and reducing hunger and poverty while maintaining the life support systems of the planet (1, 2). With a systems view, industrial ecology investigates material and energy flows of coupled human-natural systems and has made significant strides in assessing the impacts of these flows on the environment and human health (3-8). The need for more sustainable products and processes has triggered (further) development of a large number of environmental assessment tools (9), including substance flow analysis (10), chemical/product risk assessment (11), life cycle assessment (LCA) (12-14), and a variety of screening tools (15-19). The knowledge generated by these investigations and assessments provides key information about the chemicals, materials and processes with the most significant adverse impacts throughout the life cycle. We need to understand the inherent nature of these materials to not only quantify their impact on human health and the environment but also to facilitate the design of a more sustainable materials basis of our society. Analogous to the industrial ecology assessment tools, several National Academies of Science reports have identified the need for new green chemist...