# Isocyanates, flammable, toxic, n.o.s. or Isocyanate solutions, flammable, toxic, n.o.s. flashpoint less than 23° — Postal shipping restrictions by item category

For Isocyanates, flammable, toxic, n.o.s. or Isocyanate solutions, flammable, toxic, n.o.s. flashpoint less than 23°, carrier is USPS; restriction type is prohibited; scope is domestic mail (air and surface); conditions is Hazard class 3, UN2478, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited, recorded from its source on 2026-08-10.

- **Item category:** Isocyanates, flammable, toxic, n.o.s. or Isocyanate solutions, flammable, toxic, n.o.s. flashpoint less than 23° _(verified: appears in the quote below)_
- **Carrier:** USPS _(our reading, not quoted from the source)_
- **Restriction type:** prohibited _(our reading, not quoted from the source)_
- **Scope:** domestic mail (air and surface) _(our reading, not quoted from the source)_
- **Conditions:** Hazard class 3, UN2478, packing group II; domestic mail air: Prohibited; domestic mail surface: Prohibited _(verified: appears in the quote below)_

## What the source says

> Prohibited Isocyanates, flammable, toxic, n.o.s. or Isocyanate solutions, flammable, toxic, n.o.s. flashpoint less than 23° C 3 UN2478 II Prohibited Prohibited Isocyanates, toxic, flammable, n.o.s.

## Source

- https://pe.usps.com/cpim/ftp/pubs/pub52/pub52.pdf

Last verified: 2026-08-10. Review by: 2027-08-10.
Part of [Postal shipping restrictions by item category](https://referencesource.org/shipping-restrictions-by-class/).