Determinations of silicon and phosphorus in rice planted on a district of high incidence of amyotrophic lateral sclerosis by neutron activation and X-ray fluorescence analyses

Silicon and phosphorus contents in polished and unpolished rice planted on a district of high incidence of amyotrophic lateral sclerosis (ALS) have been determined by neutron activation and X-ray fluorescence methods, and compared with those from control areas. In the neutron activation analysis, β-ray spectra of 32P produced by the 31P(n, γ)32P reaction on polished and unpolished rice were measured with a low background β-ray spectrometer. In the X-ray fluorescence analysis, characteristic X-ray were analyzed with a wavelength dispersive X-ray fluorescence spectrometer. Silicon contents in polished and unpolished rice from the ALS area are 42 μg.g-1 and 370 μg.g-1, respectively, and the corresponding phosphorus contents are 1210 μg.g-1, and 3370 μg.g-1, respectively. The data for ALS area are equal to those for the control area within atandard deviation. (author)