The International Maritime Organization is the leader is setting conventions and codes that define Hazardous and Noxious Substances (HNS) and provides a framework for Canada's HNS Program.
The main policy is the International Convention on Liability and Compensation for Damage in Connection with the Carriage of Hazardous and Noxious Substances by Sea (HNS), 1996 (HNS Convention), which will, when it enters into force, provide compensation from damage resulting from the maritime transport of HNS. In 1996 the Canadian government signed the Convention and is it the process of ratification.
Under this Convention, HNS include:
The Convention also covers residues left by the previous carriage of HNS when carried as bulk cargo.
In addition to this Convention is the IMO Protocol on Preparedness, Response and Co-operation to pollution Incidents by Hazardous and Noxious Substances, 2000 (OPRC-HNS Protocol). According to this Protocol, hazardous noxious substances are defined as any substance other than oil which, if introduced into the marine environment is likely to create hazards to human health, to harm living resources and marine life, to damage amenities or to interfere with other legitimate uses of the sea.
The OPRC-HNS Protocol ensures that ships carrying hazardous and noxious liquid substances are covered by preparedness and response regimes similar to those already in existence for oil incidents.