This was done! It created terrible publicity incidents like the TSA forcing women to drink their own breast milk to prove it was safe. And not all liquids subject to this are things a person should swig even if they aren’t explosives. The extremely negative PR rightly stopped this practice.

People travel with liquids they don't intend to eat. Shampoo and all that.

There is also nothing that precludes explosives from being non-toxic. Presumably your demise is near if you are carrying explosives through security. What do you care about heavy metal poisoning at that point?