Regulatory oversight varies by chemical type: the EPA administers TSCA (Toxic Substances Control Act) requirements for industrial chemicals; FDA oversees pharmaceutical and food-contact chemicals; USDA APHIS and EPA jointly regulate pesticides and agricultural chemicals. Many chemical imports also require EPA TSCA certification at entry, even for products not subject to specific restrictions.

Unlike NAICS codes, which group products by production process, HTS classification for chemicals is driven by chemical composition, molecular structure, and functional group. A single NAICS 325 subsector may span dozens of HTS chapters (Chapters 28–38 primarily), so importers must classify each distinct chemical substance individually rather than relying on the NAICS grouping.