Magnetized materials is in IMDG Code under UN 2807, Class 9, MAGNETIZED MATERIAL.
For sea transport magnetized materials are not considered as hazardous as IMDG Code states “Not subject to the provisions of this Code but may be subject to provisions governing the transport of dangerous goods by other modes.”
For Air transport MAGNETIZED MATERIALS is hazardous as per the strength of magnetic field. If the flux is less than 0.002 gauss at 7 feet from the package containing magnetized material then not considered as hazardous and in any case the flux shall not be more than 0.00525 gauss at 15 feet from the package. There are packing and shipping paper requirements in IATA DGR.
Certain printer toner if number of cartridges exceeds certain value in a package may have flux density which may make the package as dangerous goods, magnetized material.
Even though not considered as hazardous by sea transport shipping lines may stow the containers carrying magnetized materials away from reefer containers or may not allow reefer containers for carrying it as it may effect and damage sensitive electrical, electronic and mechanical parts of refrigerating units.