Sodium dithionite oxidizes and decomposes rapidly when exposed to moisture or air, generating heat and sulfur dioxide gas — a process that can lead to spontaneous combustion in bulk shipments. DOT classifies it as a flammable solid, requiring hermetically sealed, moisture-barrier packaging and careful stowage away from heat sources. Importers should specify packaging standards in purchase contracts and verify compliance before loading.

Dithionites (e.g., sodium dithionite) are inorganic salts of dithionous acid used primarily for bulk bleaching and reduction in textiles and paper. Sulfoxylates (e.g., sodium formaldehyde sulfoxylate/Rongalite) are organosulfur compounds offering greater stability in alkaline conditions, making them preferred for discharge printing pastes and specialty polymer applications. While both are reducing agents, they are not interchangeable and serve distinct process chemistries.