Abstract:
Food products and methods for synthesizing food products for reducing naturally occurring radioactive potassium isotope ( 40 K) in the human body requires separating the radioactive potassium isotope ( 40 K) from the non-radioactive isotopes (i.e.  39 K) in potassium. Various food products can then be prepared using the  39 K. These food products include manufactured products, such as sports drinks, baking soda, and dietary tablets, as well as altered liquid food products, such as orange juice and tomato juice.

Description:
FIELD OF THE INVENTION  
         [0001]    The present invention pertains generally to methods for reducing a person&#39;s exposure to radiation. More particularly, the present invention pertains to methods and products for reducing radioactive nuclides that are ingested or otherwise introduced into the human body. The present invention is particularly but not exclusively useful as a method for reducing radiation exposure from naturally occurring radioactive potassium isotopes ( 40 K) inside the body.  
         BACKGROUND OF THE INVENTION  
         [0002]    In our daily lives, we are each exposed to various types of naturally occurring ionizing radiation which is commonly referred to as background radiation. Naturally occurring background radiation comes from a number of sources that include terrestrial radiation, inhaled radionuclides, cosmic radiation and internal radionuclides. It happens, however, that some naturally occurring radioactive elements find their way into our bodies. Chief among these is the radionuclide potassium-40 ( 40 K).  
           [0003]    It is well known that potassium is an essential element for human physiology. In general, the body of an average adult contains about 250 grams of potassium and the daily dietary requirement is about 2 to 5 grams.  
           [0004]    Naturally occurring potassium, such as that which is ingested by humans with food products, consists of three separate isotopes:  39 K (93.1%),  40 K (0.0118%) and  41 K (6.88%). Of these, only the  40 K isotope is radioactive. Specifically, the radioactivity of  40 K involves β − -decay (89.4%) at 1.31 MeV, K-capture (10.6%) with γ at 1.46 MeV, and β + -decay (0.001%) at 1.5 MeV. The half-life of  40 K is 1.28×10 9  years. Fortunately, only a small fraction of all potassium (i.e. about 0.0118%) is in the form of the radioactive isotope of potassium ( 40 K).  
           [0005]    With the above in mind, the bodily inventory of 250 grams of naturally occurring potassium for the typical, average adult corresponds to approximately 4.5×10 20  nuclei of  40 K. The decay time constant of this  40 K is 5.8×10 16  seconds, and therefore the corresponding activity is 7.8×10 3  decays per second. This then corresponds to about 0.21 microcuries (one microcurie equals thirty-seven thousand disintegrations every second). Stated differently, and using another typical measurement, the radioactivity from  40 K that originates inside the body causes an exposure of about 0.47 millisieverts per year.  
           [0006]    Radioactive isotopes that are ingested or inhaled, and that therefore result in ionizing radiation emitted from inside the body, are not shielded and are the most damaging. On the other hand, radiation that originates outside the body may be stopped by clothing or by the skin if the energy level is not too high. Nevertheless, even when very high energy radiation originates outside the body, and penetrates the skin, it causes less ionization and less cell damage to vital organs than does comparable radiation which originates inside the body. All of the radiation exposure due to  40 K is, unfortunately, from ingested or internal radionuclides.  
           [0007]    For a rough approximation of the ionizations that are caused inside the body due to  40 K, it can be assumed that the  40 K decay is all due to β decay. Accordingly, for purposes of this approximation, β + -decay and γ radiation are ignored. With this in mind, the average electron energy for β-decay is 0.44 MeV, or about one-third of the decay energy. It is also assumed that the penetrating range of the electrons through body tissues is approximately equivalent to their penetration range in water. For electrons at 0.44 MeV the penetration range is 0.22 cm. The average energy required for ionization is 35 eV. Therefore, β-decay electrons at 0.44 MeV produce about 5.7×10 4  ion pairs per cm (i.e. 5.7×10 4  ionizations per cm).  
           [0008]    To approximate the extent that  40 K irradiation adversely affects human cells, the average size of a human cell is estimated to have an average dimension of approximately 30 microns. Therefore, using the penetration range approximated above (i.e. 0.22 cm), radiation may pass through as many as 73 cells. The number of the ionizations per cell is 170 (i.e. 5.7×10 4  ionizations/cm times 30×10 −4  cm/cell). The decay rate of 0.21 microcuries corresponds to 5.7×10 5  cells irradiated every second. Thus, if the volume of the human body is estimated at 0.06 m 3 , the total number of cells in the body is approximately 2.2×10 12 . Consequently, for this approximation, the time interval between successive ionizations of a cell is approximately 3.9×10 6  seconds. Stated differently, on average, each cell will be ionized once every 45 days.  
           [0009]    These ionizations of human cells can potentially lead to problems. As is well known, irradiation of cells causes damage that may eventually lead to cell mutations. If mutated cells do not die, but rather undergo cell division, their daughters may then contain the same mutations as the parent cells. For a worst case scenario wherein the cell division of mutant daughters leads to cancerous cells, a reduction of the internal irradiation rate would logically reduce the probability of the occurrence of cancer. Although the human body has evolved over the ages in an environment that includes potassium-40 and other potential carcinogens, it seems prudent to reduce the body&#39;s exposure to potentially cancerous matter.  
           [0010]    In light of the above, it is an object of the present invention to provide the capability to reduce radioactive isotope  40 K from the dietary intake of potassium. It is a further object of the present invention to provide a process and method for synthesizing a food product that is a source of nutrient potassium and that is largely free of ionizing radioactive  40 K. Another object of the present invention is to provide a process for removing  40 K from liquid food products that are a source of nutrient potassium. Still another object of the present invention is to provide a method to deplete naturally occurring  40 K in the human body that is simple to implement and that is cost effective.  
         SUMMARY OF THE PRFERRED EMBODIMENTS  
         [0011]    As stated above, the present invention is directed to food products and methods for synthesizing food products which can be ingested into the body. Specifically, the food products that pertain to the present invention contain nutrient potassium (K), but they are substantially free of the radioactive potassium isotope ( 40 K). This requires separating radioactive isotopes ( 40 K) from the non-radioactive isotopes ( 39 K,  41 K) that are in potassium (K). Since  41 K is non-radioactive and a very minor constituent of potassium, the object here is to recover a quantity of substantially pure non-radioactive isotope ( 39 K). Food products and tablets can then be prepared using the recovered quantity of non-radioactive isotope ( 39 K) to provide a source of nutrient potassium that is substantially free of the radioactive isotope  40 K.  
           [0012]    By ingesting the food products, or tablets, that are synthesized by the methods of the present invention, the body receives a source of nutrient potassium (K) which does not add to the body&#39;s inventory of radioactive potassium isotope ( 40 K). Thus, by supplementing the body&#39;s normal intake of potassium (K) with a potassium source having very low  40 K, or non-existent  40 K, the body is able to naturally deplete  40 K through the normal bodily processes. Examples of the food products that can be effective for this purpose include liquid products, sports drinks, mineral tablets and baking soda.  
           [0013]    An additional aspect of the present invention is directed to processes that involve liquid food products which have substantial quantities of natural nutrient potassium (K) such as orange juice or tomato juice. Specifically, as envisioned for the present invention, the radioactive potassium isotope ( 40 K) in these natural liquid food products may be removed by dialysis. Dialysis, however, will remove all potassium (K) from these liquid products. Thus, as envisioned for the present invention, a quantity of substantially pure non-radioactive potassium isotopes ( 39 K,  41 K) can then be added back into the product to prepare a product that is substantially free of radioactive potassium isotope ( 40 K).  
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0014]    The present invention is directed generally to ingestible products, and to methods for the preparation of these products. Specifically, the present invention is directed to products that, when ingested, will help supply a person&#39;s daily requirement for potassium. Importantly, the potassium that is in the products of the present invention is altered by isotope separation methods so as to be substantially free of the radioactive potassium isotope  40 K.  
         [0015]    From the table of exemplary products that is presented below, it can be seen that various foods and drinks are excellent sources for dietary potassium. Notably, dairy products, vegetables and fruits are examples of natural food items that are rich in natural dietary potassium. As discussed above, however, the natural potassium in these food items includes the radioactive potassium isotope  40 K. As also discussed above, for health reasons, it is desirable to reduce the amount of  40 K inside the body of an individual.  
                                                                         Food Item   Quantity (grams)   K Content (milligrams)                                        Beer   360   115           Coffee   180   124           Orange Juice   248   496           Avocado   173   1,097           Peanuts   145   1,018           Red Wine   102   113           Milk   244   370           Peach   87   171           White Bread   454   608           Beef   65   306           Tomato Juice   244   537           Spinach   55   307           Gatorade ®   240   30           Baking Powder   4.3 (1 tsp)   892           Mineral Tablet   1.2 (1 tab)   25                      
 
         [0016]    In general, it is basically impractical to remove the radioactive potassium isotope  40 K from many natural food items (e.g. avocados or peanuts). Accordingly, the present invention is not directly concerned with the direct alteration of such natural foods. Instead, the concern here is for the preparation of tablets and food products that can be synthesized using a potassium additive which is substantially devoid of the radioactive potassium isotope  40 K.  
         [0017]    For the synthesis or manufacture of products in accordance with the present invention, it is first necessary to prepare a potassium additive that is substantially free of the radioactive potassium isotope  40 K. This can be accomplished in any of several ways, all of which are known in the pertinent art. For example, it is known that plasma centrifuges, gas diffusion devices, laser procedures and chemical processes may be variously employed to separate isotopes from each other, such as to remove radioactive potassium isotopes  40 K directly from potassium. In any event, for the present invention it is desirable that the resultant potassium additive be essentially pure  39 K potassium.  
         [0018]    Because the potassium isotopes  40 K and  39 K are chemically equivalent, it happens that the absence of  40 K potassium in food products is unnoticeable. Stated differently, a food product containing only  39 K potassium will have the same basic taste and consistency characteristics as does naturally occurring potassium, before the  40 K isotope was removed. With this in mind, the use of the  39 K potassium in accordance with the present invention should be considered in two contexts. First, its use in the preparation of chemical compounds (e.g. baking soda), or tablets for use as dietary supplements. Second, its use as a replenishment for the natural potassium that has been removed from otherwise natural food items (e.g. orange juice).  
         [0019]    When  39 K potassium is to be used as a replenishment for natural food items (e.g. orange juice), it is first necessary to remove the natural potassium from the food item. As envisioned for the present invention, this can be done by conventional dialysis techniques. As is well known, dialysis results in the separation of colloids and crystalloids in solution by the differences of their rates of diffusion through a semipermeable membrane. Thus, dialysis removes all small ions such as salts or acids with small molecular weights.  39 K potassium, which has been prepared as disclosed above, can then be used to replenish the  40 K and other small molecular weight constituents that were removed from the solution. Orange juice, of course, is not the only example of a food item that can be altered to remove the radioactive isotope  40 K potassium. Other liquids and juices that are high in potassium, such as milk or tomato juice, can also be altered in this same manner. On the other hand, for manufactured drinks, such as sport drinks,  39 K potassium can be used directly as a constituent during manufacture.  
         [0020]    Regardless whether  39 K is used as a replenishment or as a constituent of manufacture, its use is beneficial in reducing the amount of  40 K potassium that is ingested by an individual. Specifically, in each instance, the portion of an individual&#39;s daily potassium intake that is supplied by products or food items containing pure  39 K potassium will reduce the individual&#39;s exposure to a proportional quantity of the radioactive isotope  40 K.  
         [0021]    While the particular Method For Reducing Radioactivity in the Human Body as herein shown and disclosed in detail is fully capable of obtaining the objects and providing the advantages herein before stated, it is to be understood that it is merely illustrative of the presently preferred embodiments of the invention and that no limitations are intended to the details of construction or design herein shown other than as described in the appended claims.