Getting Real About Radiation Myths and Hazards
by Lewis Loflin
"Half-life" of a radioisotope is the time it takes for half of a sample of an element to undergo nuclear decay by throwing of either alpha particles (a helium 4 nucleus), a beta particle (high-speed negative electron), or gamma rays. The helium in the atmosphere is helium 4 or H4 which results from radioactive decay - you are breathing a type of nuclear waste product. This is also how we tell stellar helium (H3 2 protons, 1 neutron) versus terrestrial helium (H4 2 protons, 2 neutrons) apart.
Thus strontium 90 produced by nuclear blasts at Bikini Atoll in 1946 has a half-life of 28.8 years would have gone through 2.47 half-life cycles by 2017. Thus if we started with 1 pound of material in 1946 only 0.5 pounds would remain in 1975; by 2003 0.25 pound; by 2032 0.125 pounds would remain. At Bikini Atoll today the island and lagoon are filled with life.
Radioactivity levels or intensity depends on the half-life of the isotope. The half-life of U235 is 704 million years while the half-life of U238 is 4.468 billion years. So we have about half of the U238 the earth started with 4.5 billion years ago, but today less than 6 half-life cycles of the U235 we started with exists today. Not counting far more common radioactive potassium 40 the earth was far more radioactive in the past when life first appeared.
Shorter radioactive half-life means more intense radiation output - U235 emits higher radiation levels than does U238. The decay of uranium produces radium, which is highly radioactive, with a half-life of 1,600 years. The decay chain leading to lead produces radium, radon, polonium, etc. For your information bananas are radioactive due to the presence potassium-40.
Note: the rate of radioactive decay is not effected by temperature, chemistry, pressure, etc. Isotope ratios are the same they claim regardless of location, I dispute that. Carbon and oxygen isotope ratios are determined by temperature, the carbon cycle and biology, etc. that claim in general holds true for uranium, except for the rare instance in Africa.
Also note most isotopes are not radioactive.
See How Bacteria Created Natural Nuclear Fission. Dr. Lovelock claims when the earth first formed U235 was not 0.75%, but 33%.
Potassium-40 (K40) is a radioactive isotope of potassium which has a very long half-life of 1.251 billion years. It makes up 0.012% (120 ppm) of the total amount of potassium found in nature. The atmosphere which is 1% argon 40 is the "nuclear waste" byproduct of radioactive K40 decay.
K40 is the largest source of natural radioactivity in animals including humans. A 70 kg (154 lbs) human body contains about 140 grams of potassium, hence about 0.012% * 140 grams = 0.0168 grams of 40K; whose decay produces about 4,300 disintegrations (becquerel or Bq) per second continuously throughout the life of the body. Imagine that, 4,300 times per second your body is dosed with the radioactive bombardment of beta particles!
For example, the fear of radioactive iodine 129 is over-hyped. It decays with a half-life of 15.7 million years, with low-energy beta and gamma emissions, to xenon-129. Thus if one got 1 microgram of I129 as a child and lived to 100, most of it would go to the grave with them at 0.99999 micrograms and did nothing to harm anything. If it doesn't decay there's no radiation. One probably receives far more of a radiation dose from a banana a day.
Some isotopes have half-lives so short they are gone in seconds, others a few decades. That's why with a nuclear explosion being in a shelter even 48 hours allows many radioactive elements to decay to harmless by-products. When they tested an underwater nuclear explosion at Bikini Atoll in 1946 the area at first was showered with massive levels of radioactive sodium (half-life 15 hours), but in a week most of it decayed.
Opportunists selling radon test kits (and making millions) claim 20,000 cases of lung cancer are caused by radon every year but have ZERO empirical proof to back up that claim. How can they separate smoking from radon? They can't, but they did base this claim on a flawed model based on underground uranium miners. Miners are heavy smokers in general and are exposed to far more in a mine (rock dust, other heavy metals and radioactive elements) than anyone at home. It's hyped up again.
Bobby R. Scott of the Lovelace Respiratory Research Institute notes that there's evidence indoor radon my reduce lung cancer. To quote,
The linear-no-threshold (LNT) model is widely used for assessing the risk of cancer (including lung cancer) from low-level exposure to ionizing radiation and was initially adopted on the basis of high-dose data for mutation induction being misrepresented as an LNT function of radiation dose (Calabrese 2011). New low-dose data invalidate the LNT model...
What the "linear-no-threshold" means that the effect of low doses of radiation or a carcinogen is based on how lethal it is based on massive doses. For example water is 100% lethal at 1000 degrees for 100% of 1000 people exposed to it, so at 100 degrees or 1/10th is lethal to only 100 people. This is silly as almost every food, plant, or insect has carcinogens that are harmless to us. Life has evolved to ignore low-level radiation, etc. that fills the environment.
The effect of radiation varies by type and exposure and a unit known as a sievert measures biological effect. Let's look at some units for radiation.
1 sievert (Sv) = 1000 milli=sieverts (mSv) = 1 million micro-sieverts (uSv).
For X-rays and gamma rays 1 rad = 1 rem = 10mSv.
For neutron radiation 1 rad = 5 to 20 rem (depends on energy level) = 50-200 mSv.
For alpha particle (helium nucleus) 1 rad = 20 rem = 200 mSv.
1 sievert = 100 rem
1 becquerel (Bq) = 1 count per second (cps)
1 curie = 37,000,000,000 becquerel = 37 Gigabecquerels (GBq)
While alpha particles and neutrons can do the most damage they are easy to shield against. Gamma and X-rays are far more penetrating and require heavy protective shielding. During a nuclear air detonation over the 'Ghost Fleet" at Bikini Atoll in 1946 little fallout was produced and little physical damage was done to the target ships, but the massive burst of gamma rays killed test animals on ships a half-mile away even through 10-20 inches of steel. This is the idea behind neutron bombs that produce little blast or fallout but kill by a massive dose of gamma rays.
Note that neutron radiation can make steel, etc. radioactive.
Jacquelyn Yanch of the MIT's Dept. of Nuclear Science and Engineering whose specialty is nuclear radiation effect on biology says normal background radiation in the U.S. averages 2.6mSv, but in parts of China, etc are ten times that. 500 mSv begins to show symptoms of radiation poisoning, while those exposed to fallout at Hiroshima received 'whole body" doses of 4500mSv suffered a 50% death rate.
As for low level doses there's no real evidence of ill health effects. Dr. Yanch notes lower levels of exposure over a longer period is better than a massive dose all at once. She also says "the real equivalence may be closer to one-tenth that of a rapid dose."
The "Environmental Protection Agency's action level of 4 pico-curies/L of air or approximately 150 Bq per cubic meter. Compare that to the 4300 Bq of potassium 40 you are hit with every second. 1 curie = 37,000,000,000 becquerel.
So as a general rule - short half-life, more intense radiation for a shorter period. long half-life, the opposite. This also comes down to chemistry and types of radiation. Cobalt-60 emits intense gamma rays that are very penetrating. Cesium-137 and Strontium-90 can act like potassium and calcium in the food chain. But very small amounts regardless of hype are harmless.
FYI: casualties at Fukushima - 0; Casualties at Chernobyl - less than 60. Most areas around both are safe to live in. In fact, the region around Chernobyl is filled with animals including rare horses, bears, wolves, and deer.
"There was no Fukushima nuclear Disaster." Dr. Kelvin Kemm CEO Nuclear Africa.
Try to get hysterical anti-nuclear activists and Luddites to quantify their claims and how they derived them will bring stares of contempt. Selected Radioisotopes and their Half-Lives:
Iodine-129 - 15.7 million years
Carbon-14 - 5,760 yrs.
Polonium-210 - 138.4 days
Polonium-214 - 1.64 x 10^4 days
Polonium-215 - 0.0018 sec.
Polonium-216 - 0.16 sec.
Cesium-137 - 30 yrs.
Chlorine-36 - 3.1 x 10^5 yrs.
Cobalt-60 - 5.26 yrs. Strontium-90 - 28.8 years
Krypton-85 is a radioisotope of krypton that has a half-life of about 10.75 years Atomic number 36. It's a colorless, odorless, inert gas produced by nuclear fission.
1) Bobby R. Scott, Lovelace Respiratory Research Institute, 2425 Ridgecrest Drive SE, Albuquerque, NM 87108 USA; Phone: 505-348-9470, Fax: 505-348-8567; Email: bscott@LRRI.org
On the web: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3315166/
2) Explained: rad, rem, sievert, becquerels A Guide terminology about radiation exposure. by David L. Chandler MIT News March 28, 2011.
Download Explained: rad, rem, sievert, becquerels A Guide terminology about radiation exposure. PDF archive.
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