Thorium excretion in feces by mineral sands workers

An attempt has been made to correlate the thorium excreted in the feces of two male workers in the monazite section of a mineral sands dry separation plant over a ten-day period with personal air sampling measurements. The air-borne radioactivity was measured on a daily basis using a total (inspirable) dust filter, an integrating personal dosimeter, and a personal cascade impactor. The thorium content of the feces was measured using inductively coupled plasma mass spectrometry. The results suggest that thorium fecal analyses are able to detect acute and chronic exposures to the inhalation of thorium bearing dusts and to confirm the amount of inhaled thorium predicted from air sampling programs and metabolic models.