What Is CDC in Shipping? Certain Dangerous Cargo Explained

What is CDC in shipping? It stands for Certain Dangerous Cargo, a United States regulatory category defined in 33 CFR 160.202. It is not a general term for hazardous goods. It is a specific, closed list of materials that, when carried in bulk above stated quantities, triggers extra advance notice, security zones, escort requirements and Captain of the Port controls on a vessel entering or moving within US waters.

If your vessel is carrying a CDC, the port call changes shape before you arrive. Notice periods lengthen, movements become scheduled rather than flexible, and the Coast Guard becomes an active participant in your transit rather than an inspecting authority you meet alongside.

What is on the CDC list

The regulation defines CDC by reference to hazard class and, for many materials, to a threshold quantity in bulk. The categories include:

• Division 1.1 and 1.2 explosives, as classified in the US hazardous materials regulations.
• Certain blasting agents and oxidizers carried in bulk above threshold quantities.
• Specified liquefied gases carried in bulk, including anhydrous ammonia, chlorine and other toxic or flammable gases.
• Specified bulk liquids and liquefied gas cargoes listed by name in the regulation.
• Certain bulk solids, including ammonium nitrate and ammonium nitrate based fertilizers above the stated quantity.

The Coast Guard publishes a Certain Dangerous Cargo job aid that resolves the regulation into a working list of several hundred materials with their proper shipping names, UN numbers and, where applicable, the quantity that makes them a CDC. That job aid is the practical reference, because the regulation itself is written by category rather than by product.

The quantity threshold is the trap

The most common misunderstanding is treating CDC as a property of the substance. For many entries it is a property of the substance and the amount. The same chemical may be an ordinary bulk cargo below a threshold and a CDC above it, and packaged quantities of a material are frequently outside the definition entirely while a bulk parcel of the same material is inside it.

That means the CDC determination has to be made against the actual manifest for the actual voyage, not against a standing list of what your ship usually carries. Chemical parcel tankers moving multiple grades are the vessels most likely to cross the line without anyone noticing at booking stage.

What it triggers on arrival

Vessels arriving in US ports already file an advance notice of arrival under 33 CFR part 160, generally 96 hours before arrival for vessels on a voyage of that length or more. Carrying a CDC adds to that baseline:

• Enhanced notice content. The notice must identify the certain dangerous cargo carried, and updates are required when the details change.
• Security zones. The Coast Guard establishes moving and fixed security zones around CDC vessels, and other traffic must keep clear of the stated distance. Several ports have standing published zones for CDC transits in their ship channels.
• Escorts and transit control. The Captain of the Port may require armed escort, tug escort, daylight-only transit, one-way traffic in the channel, or a specific transit window.
• Facility requirements. The receiving facility has its own obligations for handling and for security under the waterfront facility and maritime security regulations.

The operational consequence for the bridge and for commercial teams is that flexibility disappears. A CDC vessel that misses a transit slot may wait for the next scheduled window rather than proceed when a berth becomes free.

How CDC differs from the international dangerous goods framework

Internationally, dangerous cargoes are governed by the IMDG Code for packaged goods, the IBC Code for bulk chemicals and the IGC Code for liquefied gases, all supported by SOLAS chapters VI and VII. Those regimes are about safe carriage: packaging, segregation, stowage, tank design, ventilation and emergency response.

CDC sits on top of that and answers a different question. It is a security and consequence-management classification, introduced and expanded in the US after 2001, which selects the subset of cargoes whose release in a populated port would be catastrophic. A cargo can be fully compliant with the IMDG or IGC Code and still be a CDC, because compliance is not the issue. Potential consequence is.

Mariners should also note that CDC is a US term. Other jurisdictions have analogous concepts under different names, and a cargo that attracts escorts and security zones in a US port may be handled as routine hazardous cargo elsewhere.

Practical steps before a US call with hazardous bulk cargo

Check the UN number and the loaded quantity of every bulk parcel against 33 CFR 160.202 and the Coast Guard job aid, and do it at fixture rather than on passage. Confirm with the agent whether the receiving facility is authorized for the cargo. File the notice of arrival within the required period, with the CDC details complete, and update it if the cargo or the schedule changes.

Expect the Captain of the Port to impose conditions and build the resulting time into the voyage estimate.

Above all, keep the determination with someone who has the manifest. Agents usually flag CDC status, but the notice obligation sits with the vessel, and a late or incomplete notice is enforced against the ship.

The Maritime Safety section covers dangerous goods carriage under the IMDG and IGC Codes, and the Ports and Shipping section follows port state control and port entry requirements across the major trading regions.

The failures here are administrative, and they are expensive. The common mistake is screening cargo by trade name rather than by UN number and loaded quantity, so a part cargo that crosses a threshold is never reported. The second is a notice filed at fixture and never amended after a grade or schedule change. Both leave the ship arriving against a notice the Coast Guard treats as wrong.

What it costs is time and standing. A queried notice can push the transit window to the next tide or the next daylight period, and berth availability rarely waits. Where the receiving facility is not authorized for the cargo, the call is rejected outright. Civil penalties for a late or incomplete notice attach to the vessel, not to the agent who assumed someone else had filed it.

Sources and further reading

• 33 CFR 160 Subpart C: Notification of arrival, hazardous conditions and certain dangerous cargoes
• 33 CFR 160.202: Definitions
• USCG Certain Dangerous Cargo (CDC) job aid

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