I am an ecotoxicologist, and the issue of labelling and traceability is not my area of expertise. However, I can tell you that we feel somewhat the same way. The labelling of personal consumer products is important in order to be able to respond quickly in the event of a cargo spill. There is some tracking of those containers, but in order to prioritize a spill, there are several levels of response. Private sector companies, as well as provincial and federal agencies, must respond quickly to spills.
It comes back to the same idea that simple and clear labelling of the goods being transported is necessary. It's important to note that all cargo, regardless of the goods they carry, will have an impact on the environment if it's spilled and left in the water for a long period of time. That said, some materials are more toxic than others, so it's important to respond quickly to spills.