BHA (butylated hydroxyanisole) and BHT (butylated hydroxytoluene) are synthetic antioxidant preservatives. They stop fats and oils from going rancid, which is why they show up in cereals, chips, chewing gum, shortening, nut mixes, and packaged baked goods — anywhere a long shelf life matters. Both are FDA-classified as GRAS at the small levels used in food, and they've been in the food supply since the 1940s–50s.
The concern that keeps them on watch lists is BHA specifically. The US National Toxicology Program lists BHA as "reasonably anticipated to be a human carcinogen" based on animal studies where high doses produced tumors in the forestomach of rats. The FDA maintains that the amounts used in food are safe, and the human evidence is not conclusive — which is the gap between "listed as reasonably anticipated" and "banned." BHT has a weaker signal than BHA but is often discussed alongside it. Both face tighter restrictions in the EU and Japan than in the US.
For kids, BHA/BHT function as a "processing marker." They're most common in exactly the shelf-stable, kid-marketed foods parents already watch — sweetened cereals (BHT appears in the Lucky Charms ingredient list, for example), chips, and packaged snack cakes. The practical move isn't panic; it's that products relying on BHA/BHT tend to be ultra-processed, and the fresher/cleaner brands use natural antioxidants (vitamin E / mixed tocopherols, rosemary extract) instead.
How to spot it on a label: "BHA," "BHT," "butylated hydroxyanisole," "butylated hydroxytoluene," or phrases like "BHT added to preserve freshness" and "BHT (preservative)." Sometimes it's in the packaging rather than the food ("BHT added to the packaging material"). Brands that avoid them usually list "mixed tocopherols (vitamin E)" or "rosemary extract" as the preservative instead — a quick tell for a cleaner formulation.