ABSTRACT
The naturally occurring radionuclides of (235)U, (238)U and (232)Th and their daughter products are a potential major source of anthropogenic radiation to tobacco smokers. Often overlooked is the presence of (40)K in tobacco and its implication to radiation dose accumulation in the human body. In this study, these three radiation sources have been determined in four typical US cigarettes using neutron activation analysis (NAA). The NAA reactions of (238)U(n,γ)(239)U, (232)Th(n,γ)(233)Th and (41)K(n,γ)(42)K were used to determine (235)U, (238)U and (232)Th and (40)K, respectively. The activity of (238)U can easily be determined by epithermal NAA of the (238)U(n,γ)(239)U reaction, and the activity of (235, 234)U can easily be deduced. Using isotopic ratios, the activity due to (40)K was found by the determined concentrations of (41)K (also by epithermal neutrons) in the bulk material. Each gram of total potassium yields 30 Bq of (40)K. The annual effective dose for smokers using 20 cigarettes per day was calculate to be 14.6, 137 and 9 µSv y(-1) for (238,235,) (234)U, (232)Th and (40)K, respectively. These values are significantly lower that the dose received from (210)Po except for (232)Th.
Subject(s)
Nicotiana/chemistry , Potassium Radioisotopes/analysis , Radiation Exposure/analysis , Smoking/metabolism , Thorium/analysis , Uranium/analysis , Absorption, Radiation/physiology , Adult , Female , Humans , Male , Potassium Radioisotopes/pharmacokinetics , Radiometry/methods , Risk Assessment/methods , Thorium/pharmacokinetics , Uranium/pharmacokineticsABSTRACT
Naturally Occurring Radioactive Material (NORM) or Technology Enhanced Naturally Occurring Radioactive Material (TENORM) can be a potential health risk. It is now well known that the underlying geology in many parts of Texas has given rise to levels of (226)Ra and (228)Ra that often exceed the limits set by the US Environmental Protection Agency. A detailed literature search was undertaken to assess the levels of (226)Ra and (228)Ra in all of the Texas counties. Several statistical evaluations of the data were performed. The Hickory aquifer in the Llano Uplift region of Texas has consistently had the highest number of (226)Ra and (228)Ra concentrations above the legal limit. As well many of the affected rural communities may not have the financial resources to rectify the problem.
