The transport of hazardous waste is supervised by international transport regulations, which specify certain requirements for the movement of hazardous waste across state boundaries.

The world of hazardous waste classifications is a complicated one - not all harmful waste is classified as hazardous for shipping purposes, but some harmless wastes are classified as hazardous for shipping, for example, paper is green-listed waste and as it is not harmful or poisonous, but if it is to be shipped across a sea or ocean it would be classified as a 4.1 hazard due to its high flammability danger. However, nickel oxide, which is amber-listed due to its carcinogenic properties, is not classified as hazardous for shipping requirements and zinc oxide is green-listed, but is classified as hazard 9 (miscellaneous dangerous goods) for shipping purposes.