Denatured salt has been treated with additives (such as ferric ferrocyanide or other approved agents) to render it unfit for human or animal consumption, typically to qualify for duty or tax exemptions applicable to non-food industrial salt. Importers must document the denaturing agent and concentration on the commercial invoice, as customs authorities may require proof of denaturant to apply the correct tariff treatment. Food-grade salt, by contrast, must meet FDA purity and additive standards.

Yes — sea water is explicitly included in this SITC heading alongside solid sodium chloride and brine. However, sea water imports for industrial use (such as mineral extraction or aquaculture) are uncommon given the cost of transport; the inclusion is primarily a classification convenience. Importers of concentrated brine or sea water should confirm the applicable HTS subheading with a licensed customs broker, as the form of the material affects classification.