Charcoal is described in the IMDG Code as "Black material originating from organic sources. Particularly includes carbon blacks, of animal or vegetable origin other non-activated carbon materials and charcoal produced from materials such as bone, & bamboo, coconut shell, jute and wood.”
Factors contributing to this risk include improper packaging, inadequate ventilation, and failure to adhere to International Maritime Organisation (IMO) regulation of Dangerous cargo as codified in the IMDG Code.
The Cargo Incident Notification System (CINS) in conjunction with the International Group of P&I Clubs and the TT Club has released comprehensive Guidelines for carriage of charcoal in containers. The Guidelines include a description of the risks involved in carriage of charcoal, the relevant provisions of the IMDG code, recommendations for container selection, requirements for packing, container stowage and segregation and documentation. A PDF version of the Guidance document is available here.