Tobacco, radioactivity

Even higher organisms can be used for the production of labeled compounds. Plants, tobacco, or Canna indica for example, when grown in an exclusive atmosphere of radioactive carbon dioxide, [ 002], utilize the labeled precursor as the sole source of carbon for photosynthesis. After a suitable period of growth, almost every carbon atom in the plant is radioactive. Thus, plants can serve as an available source of C-labeled carbohydrates (9). 

Since cigarette tobacco already contains several micrograms of the TSNA, we determined the transfer rate of NNN into the smoke by spiking the tobacco column with NNN-2 - C. The smoke from such radiolabeled cigarettes is then analyzed by HPLC and the amount of unchanged NNN-2 - C is determined by liquid scintillation counting. Independent of the smoke pH, about 11% of the radioactive NNN is found in the mainstream smoke thus 41-46% of mainstream smoke NNN stems from the tobacco NNN and 54-59% are pyrosynthesized (11). 

Martell, E. A., Radioactivity of tobacco trichomes and insoluble cigarette smoke particles, Nature, 249 215-217 (1974). 

The observations made on effects of enviromnental agents on popnlations have been followed np in the laboratory. For example, if extracts of tobacco or coal tar are painted onto the skin of experimental animals, tnmors develop. Exposnre of experimental animals to X-rays or radioactive materials indnces tumor formation. 

Radon is another example of a very curious and toxic compound that many of us regularly inhale, hopefully in small amounts. For those regularly exposed to radon, there is an increased risk for lung cancer and, for those that smoke, radon exposure results in a three-fold increase in the incidence of lung cancer. In the United States it is estimated that indoor radon exposure causes between 7000 and 30,000 lung cancer-related deaths each year, second only to tobacco smoking. Radon-222 is a colorless and odorless radioactive gas that results from the decay of radium-226, which is widely distributed in the earth s crust. Radon decays with a half-life of 3.8 days into solid particles of polonium. It is actually the breakdown of... 

Burned tobacco contains some 4,800 distinct chemicals in either gas or particle phases. Many of the compounds in both phases are highly reactive, poisonous, and toxic. Harmful products include oxidants and poisons produced during burning, as well as radioactivity, heavy metals, and pesticides that may have accumulated within the tobacco leaf. Sixty-nine of these substances are known to cause cancer in humans and animals, and many others are known to be strong irritants. 

The compounds of the particle phase are collectively called tar, or total particulate matter (TPM). Tar is the oily residue left behind when moisture evaporates from burned tobacco. It contains thousands of compounds, including cancer-causing aromatic amines, nitro-samines, and polycyclic aromatic hydrocarbons that are present in both smoking and smokeless tobacco. Other harmful constituents include radioactive lead and polonium as well as arsenic, among others. 

No attempt is made here to review the basis of these recommendations, but some human studies with radioactive aerosols are described, with particular reference to those relevant to exposure to atmospheric pollutants, such as tobacco smoke and lead aerosols. 

The pulmonary system is the site of entry for numerous toxicants. Examples of toxic substances inhaled by human lungs include fly ash and ozone from polluted atmospheres, vapors of volatile chemicals used in the workplace, tobacco smoke, radioactive radon gas, and vapors from paints, varnishes, and synthetic materials used for building construction. 

Insects use camouflage coloration as a means of avoiding predation. The green color of the tobacco hornworm larvae, (Manduca sexta) can be separated into constituent blue and yellow components. The water soluble blue component is the biliprotein, insecticyanin. The yellow color is derived from lipoprotein bound carotenes. This lipoprotein, lipophorin, is the major lipid transport vehicle in insect hemolymph. In addition to transporting dietary lipid, lipophorin is also involved in the transport of lipophilic insecticides. Nearly all the recovered radioactivity in hemolymph from topically applied [14c] ddt is associated with lipophorin. Lipophorin of adult M. sexta is larger, less dense and is associated with small amounts of a third, adult specific, apoprotein. Alterations in adult lipophorin density, lipid content and apoprotein stoichiometry can be caused by injection of the decapeptide, adipokinetic hormone. 

Polonium was discovered in 1898 by Marie and Pierre Curie in their search for the sources of radioactivity in pitchblende. Polonium has 27 isotopes and is highly toxic and very radioactive. It has been suggested that the isotope 210Po, a natural contaminant of tobacco and an a-particle producer (see Section 21.1), might be at least partly responsible for the incidence of cancer in smokers. 

Fig. 12. HPLC-RC analysis of the metabolism of radiolabelled lAA conjugates by leaf discs from wild-type and RolB tobacco plants. After a 24 h metabolism period leaf discs were extracts with methanol and ca. 10 000 dpm aliquots were analysed by reverse phase HPLC-RC with column and flow rate, as in Fig. 6. Mobile phase 25 min, 10-60% gradient of methanol in 1% aqueous acetic acid. Detector radioactivity monitor operating in homogeneous mode [66,67]. Traces illustrate [ CJIAGluc metabolism by (A) wildBtype and (B) RolB leaf discs [ HJlAInos metabolism by (C) wildBtype and (D) RolB leaf discs [ C]IAAsp metabolism by (E) wildBtype and (F) RolB leaf discs [117],...

Smoking is an important indoor source of fine and coarse particles, with estimated increases of 25 to 45 pg m PM2.5 in homes with smokers (Wallace, 1996). Previously, Fishbein (1991) summarized concentration data for a range of metals, metalloids, and radioactive elements in cigarette tobacco, mainstream smoke, and side-stream smoke. Ligocki et al. (1995) estimated that indoor air metal concentrations in homes with smokers exceed those in homes without smokers by an average increment of 1.3 ng m for Cd, 0.18 ng m for As, and 21 pg m for Cr, consistent with other studies (e.g., Lioy etal., 1992 Lead-erer etal., 1994 Landsberger and Wu,... 

Many types of tobacco contain radioactive elements such as Ra and °Po at concentrations ranging from 0.1 to 0.47 pCi/g (1742, 2815, 3982, 3983). Phosphate fertilizers are the major source of these radioelements (3982, 3983) minor contributions come from airborne particles carrying °Pb and °Po. These particles are trapped by the trichomes on the undersides of the tobacco leaves (2467) and were first reported by Nystrom and Beilin (2815) in 1964. 

The presence of radioactivity, both a- and p-particles, in leaf and tobacco smoke has been reported in many publications. At earlier periods, the main concern was for P-activity found in cigars, cigarettes, and tobacco ash (113, 2657, 3367, 20A97). The a-emitting radioactive isotopes were suggested to be significant because of health concerns to smokers. The total a-activity in tobacco varies widely in green leaf, cured leaf tobacco, and tobacco smoke (2466, 3367, 3973). A very minor amount of °Po is transferred into the mainstream smoke (MSS). Twenty-four isotopes have been identified in tobacco smoke. The discovery of elements, isotopes, and ions in tobacco smoke has only been limited by the discovery and advancement of new analytical techniques. 

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