This is the advice we have from DHL.
You can ship by road/sea disposable compressed gas cartridges under 50ml capacity provided a statement is presented on each shipment:
"Not restricted as per Special Provision 191 under ADR"

For air shipment:
SP A98 reads: Aerosols, gas cartridges and receptacles, small containing gas with a capacity not exceeding 50 ml, containing no constituents subject to these regulations other than a Division 2.2 gas, are not subject to these regulations unless there release could cause extreme annoyance or discomfort to the crew members so as to prevent the correct performance of duties.
The words " Not Restricted" and the Special Provision number (SP A98) Must be included in the description of the substance on the AWB as required by 8.2.6 of IATA Regulation.