TIP 17 - Response to Marine Chemical Incidents

The volume of chemicals transported by sea continues to increase year by year and, as a result, there is growing international awareness of the need for the development of safe and effective contingency arrangements for responding to chemical spills. However, the wide variety of chemicals, their varying physical properties and different behaviour once spilt and the potential for effects on human health and the marine environment mean that preparedness and response arrangements for chemical spills are far more complex than for oil spills. 

The term ‘chemical’ encompasses every substance known to man. However, not all chemicals transported by sea are considered hazardous but those that are have been termed ‘hazardous and noxious substances’ (HNS).

The OPRC–HNS Protocol1 defines HNS as “any substance other than oil that, 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 hazard associated with a particular chemical is dictated by its inherent properties and, as such, HNS may exhibit one or more of the following five properties: flammable, explosive, toxic, corrosive or reactive.

Another definition of HNS, but one that differs widely from that of the OPRC-HNS Protocol, is provided by the HNS Convention. Under that Convention, a substance is classed as HNS if it is included in one or more lists in the International Maritime Organization (IMO) Conventions and Codes listed in Table.

The Conventions and Codes listed are designed to ensure the safe transport of all types of chemicals. In addition to listing the different types of HNS, they also prescribe design and construction standards for the different ships involved in the transport of HNS, and regulations on the labelling, packing and stowage of chemicals. Radioactive and infectious substances are outside the scope of the HNS Convention and of this paper. 

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