Answer to Question #8521 Submitted to "Ask the Experts"

Information on radioactivity in tobacco products was recently reported in a book by the National Council on Radiation Protection and Measurements (NCRP), Ionizing Radiation Exposure of the Population of the United States, Report No. 160, 3 March 2009.

Chapter 5 of this book addresses consumer products and activities. Tobacco products are discussed on pages 156-162. Many factors will affect the radiation dose that may result from smoking cigarettes. The first has to do with the quantity of radioactive elements in the tobacco, especially polonium-210 and lead-210. These two radionuclides may be collected from airborne deposition on tobacco leaves or taken up from the ground through the root system. The amount of these nuclides inhaled also depends on the amount transferred from the tobacco to the smoke or absorbed on filters. The amount retained in the lungs depends on the particle size and other factors. 

Khater (2004) determined that about 50 percent of the polonium-210 inhaled is retained in the smoker's lungs and a one-pack smoker would inhale about 120 millibecquerel (mBq) or 3.2 picocuries (pCi) each of polonium-210 and lead-210. 

Desideri et al. (2007) estimated that 20 cigarettes would result in an inhalation of 80 +/- 30 mBq each of polonium-210 and lead-210. 

From these data 100 mBq per pack of cigarettes is a reasonable estimate for intake of each radionuclide, polonium-210 and lead 210. When these radionuclides are inhaled they may be deposited on lung tissues (bronchial epithelium) especially in the areas of branching or bifurcation of airways in the lower lung. Emission of alpha particle radiation from polonium-210 can cause damage to growing cells near the surface of lung tissues. Depending on solubility of the radionuclides, they may also be carried to other organs including the kidney, liver, bone marrow, and spleen. 

To determine the total effective dose (to all parts of the body), one has to consider the direct deposition of alpha particle energy in lung tissues and the dose to various organs that may result from polonium-210 and lead-210 absorbed in the blood stream and carried to other parts of the body. Report 160 (Table 5.6) gives an average annual effective dose as 18 microsieverts (uSv) or 1.8 millirem (mrem) for one cigarette per day. At one pack of 20 cigarettes a day, the annual effective dose would be 360 microsieverts (36 mrem). On this basis a single pack of 20 cigarettes would result in an effective dose of 1 microsievert or 0.1 mrem. For comparison, 36 mrem per year for a pack-a-day smoker gives an effective dose similar to what everyone receives on the average from outer space at 33 mrem/yr or from the ground at 21 mrem/yr (Table 2.1). 

Ray Johnson, MS, PE, FHPS, CHP
(author of the section on tobacco products in NCRP Report 160).

Orhan H Suleiman, MS, PhD

References
National Council on Radiation Protection and Measurements. Ionizing radiation exposure of the population of the United States. Bethesda, MD: NCRP; NCRP Report No. 160; 2009.

Desideri  D, Meli MA, Feduci L, Roselli C. 210 Po and 210 Pb inhalation by cigarette smoking in Italy. Health Physics 92(1); 2007.

Khater AEM. Polonium-210 budget in cigarettes. J Environ Radioact 71(1):33-41; 2004.