The Trump administration is seeking to roll back 2024 regulations that required a roughly 90% cut in emissions of ethylene oxide (EtO), a colourless, flammable gas used to sterilise some 20 billion medical devices annually and linked to leukaemia and other cancers. A Harvard legal analysis warns the move would not only leave approximately 2.3 million people — concentrated in low-income communities — exposed to the carcinogen, but would also permanently curtail the EPA's ability to strengthen protections when new science reveals a pollutant is more dangerous than previously understood; recent research shows EtO is around 60 times more carcinogenic than assessments used in the last regulatory review in 2006. Public health advocates say the stakes extend well beyond one chemical, describing the rollback as part of a broader administration strategy to limit oversight of toxic substances and effectively lock in a narrower reading of the Clean Air Act for future regulators.