The first reply to a dangerous goods enquiry is always a question rather than a rate, and it frustrates people who expected a price. It is not obstruction. Almost nothing about a hazardous shipment (the mode, the packing, the vessel, the cost, whether it can travel at all) can be determined until the substance is identified precisely, and 'chemicals' or 'batteries' does not identify anything.
The five questions
1. What is the UN number?
A four-digit identifier assigned to the substance or article. Everything downstream follows from it: the proper shipping name, the hazard class, the packing requirements, the segregation rules and the mode restrictions. It appears on the safety data sheet, and without it nothing can be quoted.
2. What is the packing group?
Roman numerals I, II or III, describing the degree of danger within the class: high, medium or low. It determines the packaging standard required and, in some cases, the quantity limits that apply per package and per conveyance.
3. Do you have a current safety data sheet?
Carriers and ground handlers check the classification on the declaration against the one on the data sheet, and a mismatch stops the shipment at acceptance. The sheet has to be current: a superseded version with an outdated classification is a rejection waiting to happen at the worst possible moment.
4. What is the net quantity per package?
Quantity thresholds change which rules apply. Limited and excepted quantity provisions reduce the requirements substantially for small amounts, and exceeding a threshold moves the same substance into a far more demanding regime, sometimes into one that particular services will not accept at all.
5. Which mode, and is that mode actually available?
This is the question people find most surprising, and it is the most important one.
The rules are not the same by mode
| Mode | Framework | Practical consequence |
|---|---|---|
| Sea | IMDG Code | Segregation and stowage rules govern what may travel alongside what |
| Air | IATA Dangerous Goods Regulations | The most restrictive regime; some substances are forbidden outright |
| Road (Europe) | ADR | Driver certification, vehicle marking and tunnel restrictions apply |
| Rail (Europe) | RID | Broadly aligned with ADR, with its own consignment requirements |
Where responsibility sits
Classification, packing, marking, labelling and the dangerous goods declaration are the shipper's legal obligations. A forwarder arranges the carriage, checks that the documentation is consistent and complete, and will refuse a consignment that is not. It cannot classify a substance on the shipper's behalf, because only the shipper knows what is actually in the package.
This matters because an undeclared or misdeclared dangerous good is treated as an offence rather than an administrative error, and the consequences run to carrier claims, regulatory penalties and, in the serious cases, criminal liability. The mis-declaration of hazardous cargo has been implicated in fires aboard container vessels, which is why acceptance checks are as unforgiving as they are.
Plan for a longer lead time
- Vessel and aircraft acceptance is not automatic: some services will not take particular classes, and finding the ones that will takes time.
- Segregation requirements can affect where a container is stowed and therefore which sailing can take it.
- Packaging to a UN specification may need to be sourced rather than assumed.
- Documentation is checked more than once, and any inconsistency restarts the process.
None of this makes hazardous cargo difficult to move. It makes it difficult to start moving quickly, which is a different problem with a straightforward solution: begin the conversation earlier than you would for general cargo, and begin it with the safety data sheet attached.
Published 15 July 2026.
