A few considerations: any human cargo would be shipped with food and a means to keep it alive to its destination which is presumably several days away (Rotterdam?). That same human cargo can go several days without food as well and would likely be shipped with an ample supply of water. They're probably still alivd but approaching the end of their clock.

If people start to die in those containers they will stink. A lot. Those containers cannot be air tight or the human cargo would suffocate.