What material is NOT advisable for storage of explosive items?

Plastic bags are not advisable for the storage of explosive items due to their lack of adequate strength and durability to withstand the potentially hazardous conditions that accompany explosive materials. Unlike metal containers, which offer robust protection against puncture and provide grounded conductivity, or wooden crates that can provide sufficient structural integrity while being lightweight, plastic bags do not provide the necessary barriers or containment in case of a spontaneous reaction or leakage. Dunnage, typically used for packing and protecting cargo, may not pose the same risk as plastic but does not serve the primary function of secure storage for explosives. Given these factors, plastic bags are deemed unsuitable for safely storing explosive items.