1. Perhaps Mr. Nana brought them there, planning to use them for some domestic purposes or his children rolled them there.
2. The drums were sent from Italy to Nigeria because it is easier dumping chemical in Nigeria than in Italy. Secondly, because, perhaps, the factory owners were not allowed to dump them there in Italy.
3. It was money.
4. They are referred to as "the mountain of death" because they are piled on top of each other very high- like a mountain. They are a sure and definite source of causing death.