There are two arsenic exposure endemic areas in Taiwan, one confined to the southwestern coast and the other to the northeastern coast. Blackfoot disease is an endemic peripheral vascular disease leading to gangrenous change of the foot and the lower extremity, which was found to be confined to the southwestern coast of Taiwan for approximately a century. A series of epidemiologic studies since mid-twentieth century suggest arsenic exposure from drinking artesian well water as a major cause of the disease. More recent studies carried out over the past decades confirmed the association between arsenic exposure and peripheral vascular disease in a dose-responsive pattern. Furthermore, the other clinical manifestations related to the cardiovascular system including diabetes mellitus, hypertension, ischemic heart disease, cerebral infarction and mortality from cardiovascular disease were also highly associated with arsenic exposure in the endemic areas. Studies also suggest the presence of subclinical arterial insufficiency and microcirculatory defects in seemingly normal subjects living in the blackfoot disease hyperendemic villages and that lower serum antioxidant levels of alpha- and beta-carotene are associated with a higher risk of arsenic-related ischemic heart disease. More recent studies suggest that the risk of peripheral vascular disease and hypertension is associated with the individual incapability to completely methylate inorganic arsenic.
