Transition metals can serve as pro-oxidants.  For example, chronic manganism is a classic "pro-oxidant" disease.  Another disease associated with the chronic presence of a pro-oxidant transition-series metal is hemochromatosis,  associated with elevated iron levels.  Similarly, Wilsons disease is associated with elevated tissue levels of copper.  Such syndromes tend to be associated with  common symptomology.  Thus, all are occasional symptoms of (e.g) hemochromatosis,  another name for which is "bronze diabetes".   The pro-oxidant herbicide paraquat, Wilsons disease, and striatal iron have similarly been linked to human Parkinsonism.  Paraquat also produces Parkinsonian-like symptoms in rodents.