# Sodium cyanide, solution · USPS · III — Mailing and air-carriage restrictions by item category For Sodium cyanide, solution · USPS · III, item category is Sodium cyanide, solution; carrier is USPS; dot packing group is III; restriction type is restricted; scope is domestic mail: surface only (air prohibited), recorded from its source on 2026-08-29. - **Item category:** Sodium cyanide, solution _(verified: appears in the quote below)_ - **Carrier:** USPS _(our reading, not quoted from the source)_ - **DOT packing group:** III _(verified: appears in the quote below)_ - **Restriction type:** restricted _(our reading, not quoted from the source)_ - **Scope:** domestic mail: surface only (air prohibited) _(our reading, not quoted from the source)_ - **Conditions:** Hazard class 6.1, UN3414, packing group III; domestic mail air: Prohibited; domestic mail surface: 6A ## What the source says > Sodium cyanide, solution 6.1 UN3414 III Prohibited 6A ## Source - https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf Last verified: 2026-08-29. Review by: 2027-08-29. Part of [Mailing and air-carriage restrictions by item category](https://referencesource.org/shipping-restrictions-by-class/).