PTH and amyotrophic lateral sclerosis: Recent environmental studies in the Kozagawa focus in the southernmost part of the Kii Peninsula of Japan have revealed; 1) high levels of Mn and Al in the soils, 2) markedly low levels of Ca, Mg, and Zn in the drinking water, 3) lower Ca and Zn levels in serum and higher urinary levels of 8-hydroxy-2'-deoxyguanosine (8-OHdG, an oxidative stress maker of DNA), and 3) high Cu/Zn ratio (a marker of oxidative stress) and intact PTH in serum of the patients with ALS and also some residents (119, 120).