Here’s a question someone posted to Hazmat101, a Yahoogroup on December 1, 2015:

To  compare notes.

1. Are marine pollutant placards required on a truck that contains non-bulk packages on its way to the port per 49 CFR? What if the truck has placards for Flammable packages?
2. Are marine pollutant placards required on a freight  container with non-bulk packages shipped by water from the continental  U.S. to Hawaii  under 49 CFR (not the IMDG code)? What if the freight containers has placards for Flammable packages?
3. Are marine pollutant placards required on a freight  container with non-bulk packages shipped by water under  the IMDG code? What if the freight container has placards for Flammable packages?

Citations appreciated.

Thanks in advance.

My reply that day (I must have been in the office!):

• Just a point of clarification, the Marine Pollutant marking is not a label nor a placard even if it is the size of one or the other.  It is a marking (49 CFR 172.322).
• The marine pollutant marking is not required on a vehicle that is transporting non-bulk packagings by highway since per 49 CFR 171.4 the hazardous material regulations do not apply to a Marine Pollutant transported by highway (or rail or air) in a non-bulk packaging.  It might be OK to display the Marine Pollutant marking on the vehicle even if it is not required, but I am not certain.  The presence of the Flammable Liquid placard does not impact display of the Marine Pollutant marking.
• A non-bulk packaging of a Marine Pollutant shipped by vessel is subject to the hazardous material regulations and therefore the non-bulk packaging and the freight container must bear the Marine Pollutant marking.  Marine Pollutant marking is not required on some non-bulk packagings of less than or equal to 5 L or 5 Kg (172.322(d)), however, a freight container of non-bulk packagings that do not have the Marine Pollutant marking due to 49 CFR 172.322(d) will still need to be marked with a placard-sized Marine Pollutant marking on all four sides (172.322(c)).The presence of the Flammable Liquid placard does not impact display of the Marine Pollutant marking.
• IMDG code requirements are the same as USDOT/PHMSA.  Non-bulk packaging of 5 liters or less or 5 Kg or less need not display the Marine Pollutant marking (5.2.1.6).  However, the freight container they are packed in must display the Marine Pollutant marking (5.3.2.3).  The presence of the Flammable Liquid placard does not impact display of the Marine Pollutant marking.