Concentration of 232Th, 230Th and 228Th in various tissues of Japanese subjects

The concentration of 232Th, 230Th and 228Th in various human tissues of Japanese subjects obtained at autopsies are reported. The tissue samples were weighed, spiked with 234Th tracer and ashed by acid. The solution was dried on a hot-plate. Separation of thorium radionuclides was accomplished through cation-exchange resin chromatography and electrodeposition. The concentrations of thorium isotopes were measured by α-spectrometry. Thorium-232 and 230Th concentrations were found to be highest in lung, followed by bone. The maximum concentration of 228Th was in bone. The lowest concentrations of thorium isotopes were in muscle. (author)