When must a shipper certify that hazardous materials were packaged according to regulations?

The correct answer highlights the specific scenario in which a shipper does not need to certify that hazardous materials were packaged in accordance with regulations. When a shipper is a private carrier transporting their own products, they are often exempt from certain certification requirements. This exemption is based on the understanding that the private carrier has direct control over the handling, packaging, and transportation of their own goods, thereby reducing potential risks associated with improper packaging since they are familiar with the materials being shipped and the associated regulations.

In other situations, such as when hazardous materials are being shipped to another business or when dealing with hazardous waste, the need for certification is more stringent. This is because the responsibility for ensuring compliance with safety standards and regulations typically falls upon the shipper in these cases, as they need to ensure the safety of all handling parties and the public during transportation.