The ingredient is diacetyl. I don't know what the exposure to it is that is necessary to show this link, but they talk about industrial exposure.<p>It also says that diacetyl is an ingredient in beer and wine. Just wanted to correct this: Diacetyl is a by-product of certain types of yeast fermenting. If the beer or wine is given a solid diacetyl rest, the yeast will often clean up most of that. It's especially prominent in ales (top-fermented beer). If you taste a buttery, oily taste at the backend of a beer, it's probably diacetyl.