What it is
Synthetic antioxidants that keep industrial fats from going rancid over a long shelf life. Food that can't rot is food microbes don't even want.
Why your biology objects
They work by being more oxidizable than the fat they protect — sacrificial molecules. BHA is listed by the US National Toxicology Program as reasonably anticipated to be a human carcinogen on animal data; the dose debate continues, but vitamin E does the same job without the asterisk.