Japan - epidemiology, Cross-Sectional Studies, Humans, Middle Aged, Urinary Bladder, Overactive - epidemiology, Male, Urinary Bladder, Overactive - etiology, Case-Control Studies, Mercury Poisoning, Nervous System - complications, Urinary Bladder, Overactive - diagnostic imaging, Urination Disorders - diagnostic imaging, Urination Disorders - epidemiology, U...