Complex sentence: Normal functioning of the kidney, brain, liver, heart, and numerous other systems can be affected by uranium exposure, because in addition to being weakly radioactive, uranium is a toxic metal, although less toxic than other heavy metals such as arsenic and mercury.
Split into simpler sentences: Normal functioning of the kidney, brain, liver, heart, and numerous other systems can be affected by uranium exposure, because in addition to being weakly radioactive, uranium is a toxic metal. DU is less toxic than other heavy metals such as arsenic and mercury.