.the hazmat/dangerous goods danger is not always known where INDIVIDUAL non-aviation customers [shippers] send their "stuff."
In the past I have ordered substances, classed as HAZMAT by the shippers. I paid for surface shipping yet somewhere along the line somebody "did me a favour" and dispatched them by air.
I wasn't happy and complained to the shipper who seemed totally unconcerned. I then forwarded the info to the carrier who scknowledged receipt of the complaint but
AFAIK did nothing further.
I no longer use either supplier or shipper.