True concentration itself is free from such contaminants. It is a state in which the mind is gathered together and thus gains power and intensity. We might use the analogy of a lens. Parallel waves of sunlight falling on a piece of paper will do no more than warm the surface. But the same amount of light, when focused through a lens, falls on a single point and the paper bursts into flames.
Concentration is the lens.
It produces the burning intensity necessary to see into the deeper reaches of the mind. Mindfulness selects the object that the lens will focus on and looks through the lens to see what is there. Concentration should be regarded as a tool. Like any tool, it can be used for good or for ill. A sharp knife can be used to create a beautiful carving or to harm someone.