Is it possible to poison someone's food on a daily basis in order to give them cancer?
The thing here is that i'm worried someone at my workplace might be poisoning other people's water (each employee has his own packs of water bottles at their desks, also, this person seems to have some mental issues). It is possible to put chemicals in a bottle with no water leaking via a syringe. So my fear is that this bad person (this person IS bad., believe me) may have poisoned, in a daily basis for 3 or 4 weeks, our water.
So the question is, could this person poison the bottles to make others get cancer? Or another highly dangerous disease?