Marine Pollutants – Compliance and Exemptions – IMDG CODE 38-16

Harmful substances when transported in packaged form needs to follow provisions of annex III of MARPOL and may have certain exemptions from said annex. Annex III of the International Convention for the Prevention of Pollution from Ships, 1973, as modified by the Protocol of 1978 (MARPOL), deals with the prevention of pollution by harmful substances carried by sea in packaged form.

What are harmful substances?

“Harmful substances” are those substances which are identified as marine pollutants in the International Maritime Dangerous Goods Code (IMDG Code) or which meet the criteria in the Appendix of to annex III of MARPOL.

How does IMDG Code identify a substance as marine pollutant?

IMDG Code identifies marine pollutants with a symbol “P” in column 4 of dangerous goods list in chapter 3.2. Additionally, certain marine pollutants are identified only in the alphabetical index of IMDG Code. These are those marine pollutants which has not been assigned to an N.O.S. or generic entry.  

If an entry is not identified as marine pollutant in column 4 of dangerous goods list in IMDG Code and the substance is not identified as marine pollutant in the alphabetical index however the properties of the substance meet the criteria of appendix of Annex III of MARPOL then it has to be transported as marine pollutant.

Appendix of annex III of MARPOL is in accordance with classification of environmentally hazardous substance in Globally Harmonized System of Classification and Labelling of Chemicals (GHS).

What are the compliance requirements for Marine Pollutants?

All dangerous goods and marine pollutants must only be transported in authorized Packagings, Intermediate Bulk Containers (IBCS) and Tanks with quantity limitations as stipulated by IMDG Code through Packing, IBC and Tank Instructions and must be marked, labelled placarded and documented as per the relevant provisions of IMDG Code.


Every package, IBC and container and tank carrying marine pollutant must be marked with the environmentally hazardous substance mark as shown below.

This mark must be a square set at 45 Deg angle, that is diamond shape. The symbol fish and tree must always be black in a background of white or any suitable contrasting color. The line forming this diamond shape must be 2 mm and the size must be 100 x 100 mm.

Size of Marine Pollutant mark:

On packages and IBCs size must be 100 x 100 mm when these packages and IBCs are loaded into a container all four sides of the container must be marked with 250 x 250 mm marine pollutant marks. When solid or liquid marine pollutants are loaded in a tank container the mark must be 250 x 250 mm size.

Durability of Marine Pollutant Mark:

Durability of marine pollutant mark must be such that it is still identifiable on packages and containers/tanks surviving at least three months’ immersion in the sea.

Max quantity per package for marine pollutants:

Packing and IBC instructions in column 8 and 10 of IMDG Code restricts type of packages/IBCs and quantity thereof. When we transport a marine pollutant in tank containers it is little tricky to decide what is the maximum degree of filling. Degree of filling in a tank container is determined according to the hazard involved during transport which takes into consideration of the coefficient of expansion of liquid.

If an entry in dangerous goods list of chapter 3.2 which is not identified as a marine pollutant in column 4 and is assigned with degree of filling as TP1 and the actual cargo is a marine pollutant then shipper must use the formula as per TP2 for calculating degree of filling. Refer section of IMDG Code.

Stowage on board ships:

On cargo ships stowage categories, A, B & E is on or under deck and categories C & d is on deck only. However, if a marine pollutant having stowage category A, B or E is being loaded, even though allowed on or under deck, preferably the container must be loaded under deck and for categories C & D which permits only on deck stowage preference shall be given to stowage on well-protected decks or to stowage inboard in sheltered areas of exposed decks.


For any substance which is a marine pollutant the dangerous goods declaration must indicate same by words “MARINE POLLUTANT” which may be supplemented with term ENVIRONMENTALLY HAZARDOUS.


As per section of IMDG Code Marine pollutants packaged in single or combination packagings containing a net quantity per single or inner packaging of 5 L or less for liquids or having a net mass per single or inner packaging of 5 kg or less for solids are not subject to any other provisions of IMDG Code relevant to marine pollutants provided the packagings meet the general provisions as mentioned in sections, and to of IMDG Code.

According to this exemption a cargo which has no other properties of another hazard class but only a marine pollutant which as solid is transported under UN No. 3077 ENVIRONMENTALLY HAZARDOUS SUBSTANCE, SOLID, N.O.S. or as liquid is transported under UN 3082 HAZARDOUS SUBSTANCE, LIQUID, N.O.S., when packed 5 kg or 5 liters less than per pack need not be marked, labelled placarded or documented or stowed as MARINE POLLUTANT.



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