Extreme weather events, driven by changing climatic conditions, interact with our built environment by distributing-or redistributing-environmental risk and damaging physical infrastructure. We focus on the role of extreme weather events in the distribution of toxic substances within and between residential communities in the largest cities in the United States (US). We explore the impact of projected inland and coastal flooding on the redistribution of toxicity from known contaminated sites, and how patterns of toxic flow change the total population and social demographics of the population at risk from toxic materials. We use the Urban Adaptation Assessment and data on toxic site locations from the US government to evaluate risk of toxin dispersion from flooding in cities and down to the census tract level for the period 2021-2061. We demonstrate that future climate conditions significantly increase the risk of the dispersion of toxins from contaminated sites by 2041.