Hair as an indicator of the body content of polonium in humans: preliminary results from study of five male volunteers

The radionuclide 210Po is of importance from a radiation protection view and has properties that cause special problems when attempting to determine the body content in humans. Estimates have traditionally been made from either urine and/or fecal samples, which require a time-consuming radiochemical preparation before alpha spectrometric determination. In order to find a more simple and less labor intensive method hair has been used as a bioindicator and investigated in this study. The relationship between intake and excretion in hair has been estimated in five volunteers who ingested radioactive polonium (209Po as a bio-tracer for 210Po) in well determined quantities. Four of the volunteers were given 5-10 Bq 209Po in a single intake (acute intake) and one volunteer has ingested a daily intake of 58.7 mBq 209Po for a period of 180 d. Human hair was found to reflect the daily clearance of ingested polonium peaking at 0.001-0.01% d−1 of the ingested amount, thereafter decreasing mono-exponentially, corresponding to a biological half-time of 10-20 days. For the case of protracted intake a mono-exponential build-up was observed with a half-time of 40 ± 5 d. In addition, after cessation of intake, a short-term component (74%) with a biological half-time of 16 ± 4 d, and a long-term component (26%) with a half-time of 93 ± 53 d were observed. It is concluded that hair can be used to detect not only the amount of ingested polonium but also whether the intake was protracted or acute.