What year does the grandfather clause exept shipments of government owned dangerous goods packaged?

The grandfather clause regarding the exemption of shipments of government-owned dangerous goods packaged is associated with regulations that were established under the Hazardous Materials Transportation Act. This clause typically applies to shipments made prior to the enactment of new regulations, which can vary depending on the specific regulation in question. For precise dates and details, it is essential to refer to the specific legislation or regulatory guidance in effect at the time of the exemption.