As health officials continue to investigate, the Food and Drug Administration (FDA) has urged consumers to avoid inhaling vitamin E acetate, a commonly used thickening agent in THC vape pens. The CDC has issued similar warnings against buying vape cartridges off the street and against modifying THC products with additives and diluents. Even seemingly legal solvents and additives have been called into question. Three major thicken agent makers, which were marketed as cheaper and “safer” alternatives to traditional cutting agents, have been subpoenaed by the New York State Department of Health after all three products were found to be made up of almost pure vitamin E acetate.