Magnesium hydroxide and magnesium peroxide fall under subheading 281610, while magnesium oxide is classified separately in heading 2825 (under metal oxides NESOI). The distinction turns on the specific compound: hydroxide (Mg(OH)₂) and peroxide (MgO₂) belong here, but the simple oxide (MgO) does not.

Barium compounds are industrial chemicals and do not trigger mandatory admissibility review by FSIS or APHIS, but importers should verify EPA Toxic Substances Control Act (TSCA) compliance and confirm the correct subheading between 281640 and neighboring headings, as classification can depend on the precise chemical form and purity.