I have a mage discipline which focus on what is perceived as Vanishing. In reality they just teleport stuff by breaking chemical bonds and moving it. The limitation here is that the teleportation transports object's volume into the Wand/staff. Teleported volume can be calculated by taking tool's diameter and use it to calculate volume of sphere. Tool can absorb only volume equal to it's own volume. If the capacity is reached the tool is still working but the volume is transported into Vanisher's blood circulatory system (The magic is powered by blood - volume for volume)
I know body can process certain periodic elements and even utilize it. Like Calcium, Iron, Zinc. But I can imagine the mage would not want hit thermometer.
Two mages are fighting and one has full wand and miss his next shot. He hits water and now there are Hydrogen and Oxygen atoms from 5ml of water in his blood.
Would there be any consequence for body? What periodical elements might cause sickness or even lethal effect if appeared in blood.