Cancerous lungs are shown in detail by combining a computed tomography scan yellow with a nanotechnology-based imaging technique blue to red, based on lesion density. Radioactive radon gas can create DNA damage that can lead to lung cancer, and historically there has been controversy regarding the level of risk this natural hazard represents.
But imaging and treatment of cancer also would not be possible without radiation. How can consumers balance these risks and benefits? There was more radon gas in the Watras house than was found in a typical uranium mine—nearly 20 times as much! Surprised, the radiation safety technicians checked the radon levels in the neighboring houses. The Watras house was located on the Reading Prong, a geological formation full of uranium deposits in the eastern United States.
Radon, a radioactive gas produced through the long decay chain of uranium into other isotopes, leaks from the ground in this area and then mixes with aboveground air. The fact that radon seeps from the ground over uranium- containing earth had been known since Some ground locations can have virtually no leakage, while a spot a few hundred feet away could have huge amounts of radon streaming out.
Just as water travels great distances along crevices in bedrock, subterranean radon travels along ground faults to emerge as a "spring" of gas. As it turns out, subterranean radon behaves like subterranean water. The Watras home was built right on top of a spring of radon gas. How many other houses built on radon springs were out there and, more importantly, how much danger did they pose to their residents? The Watras family had moved into their house in January of that year, so they had been exposed to the radon for less than a full year.
Nevertheless, doctors told them, based on risk estimates of the U. Environmental Protection Agency EPA , their brief exposure to radon made them seven times more likely to die of lung cancer within 10 years compared to a person without radon exposure. Their three young children might not make it to adulthood. Stanley and Diane Watras, with two of their children, pose outside of their home in Pennsylvania. Their house was found to contain unprecedentedly high levels of radon gas, naturally released from uranium deposits in the ground.
The Environmental Protection Agency subsequently used their home as a test laboratory to establish standard radon mitigation techniques for residences. The family moved out of the house immediately and tried to resume their normal lives. It had been firmly established since that breathing a lot of radon carries a substantial lung cancer risk. But after that, things get a little murky. Because another major cause of lung cancer poses a much bigger threat than radon, and this of course is cigarette smoking.
Cigarette smoke produces a statistical haze through which all radon data must be viewed. Expert panels have evaluated mountains of data on miners in an attempt to precisely determine the amount of lung cancer risk that could be attributed specifically to radon exposure, rather than to smoking, but their analytical efforts were hampered. This is not only because smoking was so prevalent among miners and nonminers alike, but also because smoking makes the lung cancer risk from radon worse—much worse.
It could be because radon and the chemicals in cigarette smoke damage DNA in somewhat different ways. For example, the ionizing radiation from radon tends to break DNA, whereas the highly reactive chemicals in cigarette smoke tend to attach themselves to the DNA and form what chemists call bulky adducts because they represent large chemical additions to the DNA structure.
Thus, having both types of DNA lesions at the same time might be much worse that having one type alone. Alternatively, smokers may be hypersensitive to radon because they have damaged their lungs to the point that their bronchi—the treelike tubes of air passageways—are no longer able to efficiently remove particles that are breathed in.
It might even be both, or perhaps neither. Nonetheless, smokers definitely are at higher risk of lung cancer caused by radon—six to eight times higher. In order to set limits to radiation dose, you need to be able to measure it. Uranium is often found associated with deposits of other rock, such as granite. The granite sample shown here is being measured with a radiation dose meter to determine its level of radioactivity, which could originate from other radioactive elements, such as thorium or potassium.
Natural stone in homes, such as granite countertops, are not usually a significant source of radiation. Radon is one of the few radiation hazards not typically measured in millisieverts mSv , the standard international unit for radiation dose equivalence.
Since most of the data comes from mine workers, the experts have chosen to calculate lung cancer risk from radon using a unit called the working level month WLM.
Although it has a technical and precise definition, for our purposes it can just be defined as the radon dose that a typical miner might receive from working in a typical radon-contaminated mine for one month.
Expressing radon dose in WLMs also has another practical advantage. It allows us to depict other radon exposures, such as living in a radon-contaminated home, in terms of the equivalent amount of mining work it would represent. The fitted line is drawn straight, rather than curved, because epidemiologists assume cancer risk is directly proportional to radiation dose at all dose levels, no matter how low those doses are.
Most scientists believe that there is a finite probability of contracting cancer from any exposure to a carcinogen, because there is no dose so low that DNA damage does not occur, and because DNA damage is the known precursor to cancer. Epidemiologists call this the linear no threshold LNT model of cancer risk assessment. Not all scientists favor linear models. Some strongly believe that the LNT approach to radiation protection has exaggerated the risk of cancer from low radiation doses, and their arguments have some merit.
In contrast, no credible scientists believe that the LNT model underestimates low-dose risk. Thus, the LNT model is generally considered the most conservative, affording the greatest degree of protection to the public.
Stated simply, working for one month in a typical uranium mine increases the odds of getting lung cancer by about 1 in 1, for a smoking miner, and 1 in 6, for a nonsmoking miner. Another way of expressing the risk of one month of work is as follows: For every 10, smoking miners that worked in a mine for one month, we would expect 10 of them to eventually contract cancer from their radon exposure.
Alternatively, if 10, nonsmoking miners worked for one month, we would expect fewer than two of them i. The geology of the state of Pennsylvania can be divided into physiographic provinces, as shown on this map. The geological formation called the Reading Prong, in the New England Province pink , is full of uranium deposits, and underlies the house belonging to the Watras family.
Their home happened to be located at a spot where radon gas emerged from the ground like a natural spring. All right you say, so much for the mines. What about my home? That means the concentration of radon in home air should be at or below 0. To go much lower than 0. Each time Mollie molded the brush, she ingested a little bit of the paint. She was one of the first to suffer agonizing pain in her limbs and jaw bone. Within 5 years of exposure, she died from radium poisoning at age 24 in Undark had two main ingredients: a fluorescent phosphor that glows a brilliant green when excited and radioactive Ra, which excites the phosphor.
Although it can be destructive, radioactivity can also be beneficial, especially when it comes to medical tests and certain medical treatments. Not only can radiation find tumors within the body, it can also destroy them or slow their growth.
Radiation also makes it possible to study matter, plants, and animals in an effort to understand the universe better. Read on to learn more about the history of misuses and transcendance of radioactivity to modern applications.
In , about a year after the discovery of X-rays, Henri Becquerel discovered that uranium spontaneously emits a penetrating radiation that can be registered on a photographic plate.
Although fluorescence and phosphorescence were known phenomena, they require an external energy source. Uranium was radiating all on its own. In , the three scientists shared the Nobel Prize in Physics for their discovery.
The Curies continued their study of radioactivity and in won a Nobel prize for the discovery of the elements radium and polonium and study of their compounds. Fascination with this newfound spontaneous radioactivity spread quickly, both inside the lab and commercially. Capitalizing on that popularity, manufacturers incorporated radioactive elements into products for their supposed cosmetic and healing properties and because they made things glow.
Some products included chocolate, glow-in-the dark toys and watches! Additionally, brightly colored uranium salts were incorporated into glass and dinner plates until the s, when sales of the radioactive dinnerware dropped. Radioactivity originates in atomic nuclei, which are held together by strong nuclear force.
Because strong force comes from the quarks that make up the nucleons protons and neutrons , more nucleons mean more strong force. But protons are positively charged, and so they repel each other. Adding more neutrons adds more strong force without adding charge.
Thus, heavy elements such as Au are stable despite having a large nucleus. Very large nuclei become unstable and decay into more stable species, releasing radiation as they do. Every element heavier than lead is inherently unstable—and radioactive—as are certain isotopes of lighter elements. Additionally, many other elements have at least one unstable isotope.
Nucleons also pair up, so even numbers are more stable than odd. This is why some light elements think 91 Tc or 3 H are also radioactive. Mollie had a toothache. The tooth was removed, but her gums never healed and the pain spread. She had more teeth removed, and painful ulcers arose in their place.
In May , her doctor reached into her mouth and, to his surprise, was able to lift out her loose, hole-filled jawbone. Mollie Maggia was the first dial painter to die from radium poisoning, though she was not the last. Some women had radium jaw, like Mollie. Others developed cancer and giant sarcomas of the bone. And some survived for years but lived with painful locking joints. The true danger of radium and other radioactive elements is that their nuclei emit one or more types of ionizing radiation when they decay see sidebar.
Health effects of ionising radiation Dose range Effects on human health including the unborn child Up to 10 mSv No direct evidence of human health effects 10 - mSv No early effects; increased incidence of certain cancers in exposed populations at higher doses - 10, mSv Radiation sickness risk of death ; increased incidence of certain cancers in exposed populations Above 10, mSv Fatal Source: ARPANSA.
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Radiation sickness risk of death ; increased incidence of certain cancers in exposed populations.
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