The element Technetium 99m Generator is also non-technically referred to as Moly Cow is a specific device that is used to extract the certain metastable isotope which is 99 Tc and this is actually extracted from as source of Molybdenum-99 which is in the process of decay. So the decay product of this Molybdeum-99 is the Technetium 99 and the generator is the middle man that provides laboratories with the element.
The usages of this element is quite varied, it can be used for nuclear and medicinal purposes and in lots of research laboratories as well. It is the short life of the technetium 99 that causes it to be instantly extracted from the generator that uses the Molybdenum to produce the technetium99.
Technetium is not exactly one of the chemical elements that naturally occur in the environment; so there is no real danger of encountering or handling Technetium elements by the layman. But usually Technetium elements are often used for industrial purposes and most commonly in research laboratories for nuclear studies.
It is in such places that the element needs to be handled with care and while keeping certain precautions and risks in mind. Whatever technetium component it might be, they are all highly toxic and should be treated and handled that way with care.