Trade-remedy exposure varies by origin and changes over time. Importers should check the current CBP and USTR databases for any antidumping, countervailing duty, or Section 301 orders applicable to the specific country of origin before entry.

Mixed concentrates are classified according to the metal that gives the material its essential character, typically the predominant metal by value. A concentrate where lead predominates would generally fall under 2607, while one where zinc predominates would fall under the zinc ores heading. A CBP binding ruling is recommended for concentrates where the split is close.