Identify one key requirement for packaging dangerous goods.

The correct answer emphasizes that packaging must be strong enough to withstand normal transport conditions without leaking. This requirement is critical in ensuring the safety and integrity of dangerous goods during transportation. Proper packaging protects both the product and the environment by preventing leaks, spills, or contamination that could occur if the packaging fails. It also minimizes risks to handlers and the public, as it plays a vital role in preventing accidents and hazardous exposures.

The strength and integrity of the packaging are determined by factors such as the materials used and the design of the containers. Each type of dangerous good has specific packaging regulations outlining the requirements to ensure safety under various conditions encountered in transit.

The other options either do not adequately address essential safety concerns or include requirements that might not be universally applicable or necessary. For example, while reuse of packaging can be permitted under certain conditions, this does not guarantee that the reused packaging will still meet safety standards or be free of residues from previous contents. Similarly, labeling packaging with only the contents fails to provide critical information about the hazards and required handling precautions associated with those contents. Lastly, the notion that packaging must always be waterproof is too restrictive, as not all dangerous goods require waterproof packaging or even if water resistance is necessary could depend on the type of goods being transported.