Isotope labelled (±)-Propylene Oxide (P835241), which is a carcinogenic substance to rats and potentially humans (1). (±)-Propylene oxide also has the ability to self-polymerize at room temperature in the presence of powdered potassium hydroxide (2). (±)-Propylene oxide is used in industry for fumigation in the food industry, inducing the formation of persistent toxic chlorohydrins. Drinking water contaminant candidate list 3 (CCL 3) compound as per United States Environmental Protection Agency (EPA), environmental, and food contaminants.