Science is Golden

by Karl Kruszelnicki

  Many computer games show radiation-contaminated areas as having a green glow.

  And even in the real world, hospital patients will laconically say that they’ve had so many X-rays that they glow in the dark. Indeed, the term ‘glow in the dark’ is a catch phrase for radioactivity.

  It’s not easy glowing green

  Say no to the glow

  Even though radiation is universally thought of as having a green glow, our bodies simply do not have sensors that can detect alpha particles, beta particles, or gamma rays. Radioactivity is invisible to us—it’s not green, or any other colour, it’s totally invisible.

  Radioactivity

  Although radioactivity has been around almost since the Big Bang, we only began to understand it in 1896. In that year, the French scientist Henri Becquerel discovered that uranium ores had the power to fog up photographic plates. The previously undiscovered radiation from the uranium was the fogging culprit.

  In general, radioactivity occurs in atoms that are unstable. The core or nucleus of an unstable atom loses some energy, usually by squirting it out as either particles or radiation. The particles can be either alpha particles or beta particles, while the radiation is gamma radiation. Different types of radiation cause differing degrees of damage to the cells in living tissue.

  Alpha particles can be stopped by a few centimetres of air, a sheet of paper, or even your skin. But if something that emits alpha particles bypasses the protective layer of your skin, gets inside your body and rests up against some cells, it can damage those cells. Beta particles have more penetrating power but can be stopped by only a thin sheet of aluminium. Gamma rays have the most penetrating power and can be stopped only by materials with greater density and/or thickness, such as concrete or lead.

  Sensing Radiation

  In general, we cannot sense radiation. But in conditions of extreme radiation, some of our other senses get overloaded and respond.

  A very powerful solar storm hit the old Soviet/Russian space station Mir (a beautiful word for ‘peace’) while a Russian cosmonaut, Sergei Avdeyev, was inside. He ‘felt’ the radiation even though he had retreated to the internal safe room, which was partially screened by all the mass around it. He later said: ‘I felt that the particles of radiation were walking through my eyes, floating through my brain, and maybe clashing with my nerves.’

  No Sensors for Radioactivity

  Now here is the core to busting the ‘Green Glow of Radioactivity’ myth. Our bodies simply do not have sensors that can detect alpha particles, beta particles or gamma rays. Radioactivity is invisible to us—it’s not green, or any other colour, it’s totally invisible.

  This makes working with radioactive materials potentially dangerous, and it is the reason why very specific Occupational Health and Safety regulations have been set up for workers in the industry. They have to wear special Radiation Exposure Detection badges, precisely because radioactivity is invisible.

  Glow-Boys or Jumpers

  In the nuclear industry, especially in the USA, the terms ‘glow-boy’ or ‘jumper’ refer to temporary workers. They are called ‘glow-boys’ because they supposedly ‘glow in the dark’, and ‘jumpers’ because they jump into a highly radioactive environment, do one short job and then get out again.

  In the 1970s, the glow-boy would carry out a high-risk repair or maintenance job in a very radioactive environment. Typically, these jobs consisted of cleaning up and removing radioactive waste, finding and repairing leaks, or doing emergency welding.

  In one short job, they would be exposed to about ten times more radiation than the average member of the public would be in a whole year. A ‘rem’ is roughly the dose of radiation that you would get from 40 chest X-rays. In a few minutes, the jumpers would be exposed to about 5–12 rem of radiation.

  Glow-boys were typically young men in their twenties. Unfortunately, they were not usually covered by either union protection or health insurance, and usually knew very little about the risks they were taking.

  The statistics are very sketchy, but by 1976, jumpers were getting 47% of all the radiation received by all workers in the US nuclear industry. Because the money was good, some jumpers were working at five nuclear power plants in the same calendar year.

  Chernobyl Glow-Boys

  Many members of the Kruszelnicki family came from Lviv, a town in Ukraine. Over the centuries, the borders have shifted, and this city has had many names (including Lvov, Lviv and Lamberg), and many owners (e.g. Poland, Russia and Ukraine).

  The family and I were wandering through a street market in Lviv one weekend, when I noticed a brightly coloured object. It was a medal with a scientifically correct depiction of how alpha particles, beta particles and gamma radiation would behave in an electrical field. My curiosity was piqued. The seller told me that this medal was given to the ‘liquidators’ of the nearby Chernobyl nuclear power plant.

  On 26 April 1986, at 1.23 am (lots of bad things happen when people are tired), Reactor Number Four at the Chernobyl nuclear power plant near Pripyat in Ukraine exploded. It blew the 2,000-tonne lid off the reactor.

  Inside the reactor building, the radiation levels were over 5 roentgen/sec—a lethal dose is 500 roentgen over five hours. The workers were receiving lethal doses within a few minutes—but didn’t know it, because human beings don’t have any sensors for radiation.

  Soldiers, firefighters and workers (officially called ‘liquidators’, and unofficially called ‘bio-robots’ by the military) were sent into the reactor to clean up radioactive rubble and to do whatever was necessary to stop the situation from getting worse. In the following three months, 237 people suffered acute radiation sickness, 31 of them dying. Two decades after the disaster, the vehicles used by the liquidators are still parked in Chernobyl—and are still giving off 10–30 roentgen/hr.

  I bought the brightly coloured medal in memory of those affected by the disaster.

  Green-Glowing Radiation

  But what about the green glow of the radium-painted wristwatches, night-time navigation instruments, pistol sights, external house numbers, internal light-switch panels in houses and even glowing eyes in toy dolls? Yes, from around 1913 to the 1960s, they did contain radium—and they did glow green.

  But the radium itself does not give off a green glow.

  Radium is extremely radioactive, being one million times more radioactive than uranium, weight for weight. There are approximately 25 isotopes, four of them existing in nature. The four natural isotopes have half-lives ranging from 3.6 days to 1,602 years.

  The radium used in products like wristwatches etc. was mixed with a chemical called a phosphor (made from zinc sulphide mixed with either silver or copper). The radium gave off alpha particles, which hit the atoms in the phosphor. The alpha particles forced the electrons in these atoms to jump to a higher energy level. When the electrons fell back down to their original energy level, they gave off a greenish glow—hence the myth about anything radioactive having a green glow. But it was actually the phosphor not the radium that gave these old products a green glow.

  Glowing Wristwatches

  You can still buy glow-in-the-dark wristwatches today. But they don’t have any radium in them.

  They contain tritium—an unstable isotope of hydrogen, with a half-life of 12.3 years. It gives off low-energy beta particles, which hit a phosphor, which then glows. These are safe, as long as you don’t break open the glass and try to eat or inhale the tritium. Tritium is also used in exit signs and on the sights of pistols and rifles.

  Radium Girls

  In the early part of the 20th century, there was the tragic case of the so-called Radium Girls.

  The US Radium Corporation made paints that glowed green in the dark, which they sold under the name ‘Undark’. The corporation also hired several hundred workers, all women, to paint highlights on about 250 watch dials each day. The women were paid about one-and-a-half cents per dial. They were encouraged to keep a fine point on their b
rushes by using their tongues or lips.

  Once inside the body, radium behaves like calcium and goes to the bones. The Radium Girls all suffered horrible diseases from the radiation and died terrible deaths, and even today, some of their graves are radioactive. Five of these poor working-class women subsequently mounted a court case against the corporation.

  As a result of the lengthy court case, safety standards for workers were vastly improved. The five Radium Girls each received US$10,000 in compensation.

  Cherenkov Radiation

  In some very uncommon cases, radioactive materials can also give off charged particles travelling at very high velocities. These particles can interact with the immediate environment to create a bluish glow. This environment can include the oxygen, nitrogen and water molecules in the air immediately around them, water in nuclear storage tanks, or water molecules that the radioactive materials absorb. This is called Cherenkov Radiation.

  But, in general, don’t think that you can recognise radioactivity by its green glow. That’s about as ‘see-through’ as Little Green Men.

  Sources of Light

  There are many ways that we can generate light, other than by burning carbon or heating thin metal wires.

  Chemiluminescence is used in so-called light sticks. A few chemicals combine to make a few other chemicals, and light is emitted. In a light stick, cyalume, water and a dye all combine to make a phenol, an activated dye, carbon dioxide and light.

  Bioluminescence is a specific variety of chemiluminescence that uses the enzyme ‘luciferase’. (Originally, Lucifer was God’s favourite – indeed, his name means ‘bringer of light’. But he displeased God and was cast out of Heaven into Hell.) This bioluminescence reaction is used by about 90% of the deep-sea life in the ocean to make light. This light is used for camouflage, attraction, repulsion and communication.

  Electroluminescence occurs when an electric field acts on certain semiconductors to give light. It has industrial uses, because of the long life of the components (50 years or more) and low power consumption.

  Mechanoluminescence occurs when mechanical energy somehow generates light. It has several varieties. One version, triboluminescence, was described back in 1620 by Francis Bacon. The mechanical energy forces electrical charges to separate and, eventually, make light. You can see this when you unpeel tape, open an envelope or crunch Life Savers lollies between your teeth in the dark.

  Photoluminescence happens on a very short time scale. It takes about 10 billionths of a second for a photon of energy to land, and then be re-emitted as a photon of light. There are a few different varieties of photoluminescence. In ‘phosphorescence’, the physics involves ‘forbidden’ energy states—this gives a time delay of several hours. This is the phenomenon used by ‘glow-in-the-dark’ materials that can be recharged by exposing them to light. Another variety is ‘fluorescence’, named after calcium fluoride (as in the mineral, fluorite), in which it was first noticed. In this case, high-energy photons of ultraviolet light are absorbed and lower energy photons of visible light are emitted.

  There are many other mechanisms by which light can be emitted, including radioluminescence, sonoluminescence and thermoluminescence.

  Reference

  Mackis, Roger M., ‘The great radium scandal’, Scientific American, August 1993, pp 94–99.

  A Glass Act

  If you enjoy reading Victorian novels, you’ll probably come across the phrase ‘ground glass’. Victorian authors had clever plots in which some of their fictional characters used this mysterious ‘ground glass’ to surreptitiously kill off unwanted relatives, in order to get their grubby little hands on the family fortune.

  The ‘ground glass kills you’ myth persists to this day. For example, overenthusiastic, anti-drug lobbyists claim that unscrupulous manufacturers of ecstasy cut the drug with ground glass to make it doubly dangerous. (But wouldn’t this immediately kill off their repeat business from returning customers?)

  As usual, you can’t believe everything you read and hear.

  Glass 101

  We have been making glass for over 3,500 years. The ancient Egyptians were making and exporting glass from their factories to their neighbours in Arabia, Mesopotamia, Syria, Cyprus and Crete around 1250 BC. Glass making was a complicated two-stage process. First, the raw materials were partially heated and then coloured and heated to a higher temperature to make round ingots that were exported to other workshops to be reworked into the final artefacts. At the time, the making of glass was a secret, guarded by the death penalty, and the glass itself was very precious and rare.

  Glass was still precious and rare about 500 years ago. Back then, it was believed that if you ground up some glass and fed it to an enemy, it would kill them. A few centuries later, the slave chronicles of pre–Civil War America refer to disgruntled black slaves who ‘poisoned masters and mistresses with arsenic, ground glass and “spiders beaten up in buttermilk”’.

  In Victorian novels, the victim after ingesting the ‘ground glass’, would die slowly and very painfully, thereby giving the murderer much satisfaction. This method of killing also had the supposed advantage of being unknown to the medical profession. It was, therefore, supposedly undetectable, leaving the investigators completely baffled.

  By the way, by ‘ground glass’ I don’t mean a sheet of glass that has been ground to be flat, with a slightly rough (matte) finish. (This kind of glass is used in the focusing screens of expensive still and movie cameras.) No, I’m talking about the kind of glass that you get if you smash it up into tiny pieces. And you then maliciously mix it into someone’s food.

  Medical Studies

  In 1642, the writer and physician, Sir Thomas Browne, described in his book, Pseudodoxia Epidemica, how he fed ground glass to dogs. He pointed out that at the time, it was commonly believed that ground glass added to the diet would kill. He explained how his test on the dogs had debunked the myth. (I guess he didn’t have to deal with a Grants Committee or an Ethics Committee.) He wrote: ‘That Glass is poison, according unto common conceit, I know not how to grant…from experience, as having given unto

  Dogs above a dram thereof {of ground glass}, subtilly (sic) powdered in Butter and Paste, without any visible disturbance.’

  It is possible to kill somebody with pieces of broken glass, but the circumstances have to be exceptional. In 1905, Dr F.J. Smith testified in court regarding the case of an infant who died this way. However, the infant had been force-fed ‘a quantity of roughly powdered glass, a considerable amount of which was found after death in the stomach, which was coated with a thick layer of tenacious mucus streaked with blood’.

  In 1916, Dr S.G. Shattock wrote a paper which examined the causes of appendicitis. He was especially interested in finding out whether swallowed items could cause appendicitis. He looked at iron filings, mine dust, steel fragments from grain-rolling mills, grape seeds, fragments of hair, sulphides of various metals including mercury and lead and, yes, broken or ground glass. He describes several experiments in which the feeding of ground glass had no ill effects—and he emphasised that ‘if it is attended with a fatal result, this must be rare’.

  Also in 1916, a poisoner in New York City testified that he had tried to use ground glass to kill people, but complained that it had proved useless.

  Since then, many people have written about this supposed peril. However, the nicest summary probably comes from Dr D.P. Lyle who, in 2004, wrote the enticingly entitled Forensics for Dummies. In another of his books, published in 2003, Murder and Mayhem: A Doctor Answers Medical and Forensic Questions for Mystery Writers, he addresses the ground glass conundrum. He writes that ‘very fine glass is unlikely to cause any lethal damage to the Gastro Intestinal tract…Even with coarser glass, the bleeding would probably not be massive or life-threatening, but slow and (would) lead to anaemia and fatigue.’

  Can you stomach this?

  An internal look at our digestive tract

  The gut is a very dynami
c organ, continually writhing around as it processes your food. It is also dynamic in itself—both the wall thickness of the gut and the internal diameter of the gut change all the time in a coordinated fashion. It both grinds your food very finely, as well as pushing it along the 8 metre-or-so length of the gut, before it finally emerges into your toilet bowl.

  True Now

  In the TV series Underbelly, about the gangland wars in Melbourne in the late 1990s and early 2000s, Jason Moran bites off a chunk from a drinking glass to show his opponents how tough he is. It did him no harm. (It was a bit of lead that got him in the end!)

  And what about all the magicians and performance artists who eat glass? They don’t die from it. But, of course, all stage performances could be subject to trickery.

  Which is why I was delighted to get an email from ‘George’. He described his own personal experience of eating glass. He had seen other people do it, so he figured it was safe, if he was careful. He wrote: ‘When I was young and therefore stupid enough, I had this party trick to amuse/amaze my friends. It was glass eating. And I am still alive. Strong young teeth are essential.

  ‘After the first bite, which was quite tricky and could easily make your lip bleed (because no sticking out points and therefore no good grip; after the first piece is broken off—no problem), the rest was quite easy. You just broke piece by piece, crush it with your teeth and swallow. Pieces as big as your last finger bone (2 cm long approx.) go down no problems. I never had cuts/bleeding inside the mouth, or the other end—from the perspective of my now mature age, I must say—surprisingly!