Planet Tracker’s Toxic Footprints report revealed the investors behind petrochemical toxicity in the US Gulf states of Louisiana and Texas. When assessing the petrochemicals and plastics industry, toxic emissions are often either ignored or forgotten by the financial markets. This follow-up research paper reveals the known unknowns of toxic releases, those issues hidden from the public’s and investors’ view and which the Environmental Protection Agency (EPA) is not permitted to reveal. We also highlight how the data could be made more user-friendly. Financial institutions should demand transparency for toxic emissions so that they can conduct a thorough risk assessment of their investments.