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Sunday, January 27, 2013

Common Everyday Items That Are Radioactive

You are exposed to radioactivity every day, often from the foods you eat and the products you use. Here is a look at some common everyday products and foods that are radioactive. Some of these objects may pose a health risk, but most of them are a harmless part of your everyday environment. In almost all cases, you get more exposure to radiation if you take a ride in a plane. Still, it's good to know the sources of your exposure.
1. Brazil Nuts

Brazil nuts are probably the most radioactive food you can eat. They provide 5,600 pCi/kg (picocuries per kilogram) of potassium-40 and a whopping 1,000-7,000 pCi/kg of radium-226. Although the radium is not retained by the body for very long, the nuts are approximately 1,000 times more radioactive than other foods. It's interesting to note the radioactivity seems not to come from elevated amounts of radionuclides in the soil, but rather from the extensive root systems of the trees.
2. Beer

Michael Connors,
Beer is not particularly radioactive, but a beer does contain, on average, about 390 pCi/kg of the isotope potassium-40. All foods which contain potassium have some of this isotope, so you could sort of consider this a nutrient in beer. Of the items on this list, beer probably is the least radioactive, but I found it amusing to note that it is, in fact, slightly hot. So, if you were afraid of the Chernobyl energy drink from that movie "Hot Tub Time Machine," you might want reconsider. It could be good stuff.
3. Cat Litter

GK Hart/Vikki Hart, Getty Images
Cat litter is sufficiently radioactive that it can set off radiation alerts at international border checkpoints. Actually, it's not all cat litter you need to worry about -- only the stuff made from clay or bentonite. Radioactive isotopes naturally occur in clay at the rate of about 4 pCi/g for uranium isotopes, 3 pCi/g for thorium isotopes, and 8 pCi/g of potassium-40. A researcher at Oak Ridge Associate Universities once calculated American consumers buy 50,000 pounds of uranium and 120,000 pounds of thorium in the form of cat litter each and every year.

This does not pose much of a danger to cats or their humans. However, there has been a significant release of radionuclides in the form of pet waste from cats being treated for cancer with radioisotopes. Gives you something to think about, right?
4. Bananas

Bananas are naturally high in potassium. Potassium is a mix of isotopes, including the radioactive isotope potassium-40, so bananas are slightly radioactive. The average banana emits around 14 decays per second and contains about 450 mg of potassium. It's not something you need to worry about, unless you are hauling a bunch of bananas across an international border. Like kitty litter, bananas can trigger a radiation alert for authorities seeking nuclear material.

I don't want you thinking bananas and Brazil nuts are the only radioactive foods out there. Basically, any food that is high in potassium naturally contains potassium-40 and is slightly, but significantly radioactive. This includes potatoes (radioactive french fries), carrots, lima beans and red meat. Carrots, potatoes and lima beans also contain some radon-226. When you get right down to it, all food contains a small amount of radioactivity. You eat food, so you are slightly radioactive, too.
5. Smoke Detectors

Whitepaw, public domain
About 80% of standard smoke detectors contain a small amount of the radioactive isotope americium-241, which emits alpha particle and beta radiation. Americium-242 has a half-life of 432 years, so it's not going anywhere anytime soon. The isotope is enclosed in the smoke detector and poses no real risk to you unless you break apart your smoke detector and eat or inhale the radioactive source. A more significant concern is the disposal of smoke detectors, since the americium eventually accumulates in landfills or wherever discarded smoke detectors wind up.
6. Fluorescent Lights

Deglr6328, Creative Commons License
The lamp starters of some fluorescent lights contain a small cylindrical glass bulb containing less than 15 nanocuries of krypton-85, a beta and gamma emitter with a half-life of 10.4 years. The radioactive isotope is not a concern unless the bulb is broken. Even then, the toxicity of other chemicals typically outweighs any risk from radioactivity.
7. Gemstones

Gregory Phillips, Free Documentation License
Some gemstones, such as zircon, are naturally radioactive. Additionally, several gemstones may be irradiated with neutrons to enhance their color. Examples of gems that may be color-enhanced include beryl, tourmaline, and topaz. Some artificial diamonds are made from metal oxides. An example is yttrium oxide stabilized with radioactive thorium oxide. While most of the items on this list are of little to no concern where your exposure is concerned, some radiation-treated gemstones retain enough "shine" to be radiologically hot to the tune of 0.2 milliroentgens per hour. Plus, you may wear the gems close to your skin for an extended period of time.
8. Ceramics

Salvation Army, Creative Commons
You use ceramics every day. Even if you aren't using old radioactive stoneware (like brightly-colored Fiestaware), there's a good chance you have some ceramics that emit radioactivity.
For example, do you have a cap or veneer on your teeth? Some porcelein teeth have been artificially colored with uranium containing metal oxides make them whiter and more reflective. The dental work can expose your mouth to 1000 millirem per year per cap, which comes out to two and a half times the average whole body annual exposure from natural sources, plus a few medical x-rays.

Anything made of stone may be radioactive. For example, tiles and granite countertops are slightly radioactive. So is concrete. Concrete basements are especially high, since you get off-gassing of radon from the concrete and collection of the radioactive gas, which is heavier than air and can accumulate.

Other offenders include art glass, cloisonne enameled jewelry, and glazed pottery. Pottery and jewelry are of concern because acidic foods can dissolve small amounts of radioactive elements, so that you might ingest them. Wearing radioactive jewelry close to your skin is similar, where the acids in your skin dissolve the material, which may be absorbed or accidentally ingested.

9. Recycled Metal

Frank C. Müller, Creative Commons License
We all want to reduce our impact on the environment. Recycling is good, right? Of course it is, as long as you know what it is you're recycling. Scrap metal can get grouped together, which has led to some interesting (some would say horrifying) cases of radioactive metal getting incorporated into common household objects.

For example, back in 2008 a gamma-emitting cheese grater was found. Apparently scrap cobalt-60 found its way into the metal used to make the grates. Metal tables contaminated with cobalt-60 were found scattered across several states.
10. Glowing Items

Wiki Phantoms
You probably don't have an old radium-dial clock or watch, but there is a decent chance you have a tritium-lighted object. Tritium is a radioactive hydrogen isotope. Tritium is used to make glowing gun sights, compasses, watch faces, key ring fobs and self-powered lighting.

You may buy a new item, but it may include some vintage parts. Although radium-based paint may not be used anymore, parts from old pieces have been finding new life in jewelry. The problem here is that the protective face of the clock or whatever gets removed, allowing the radioactive paint to flake or peel off. This can result in accidental exposure.

Saturday, January 12, 2013

A circle drawn on a sphere (b) has a shorter circumference than one drawn on a flat sheet of paper (a), while a circle drawn on the surface of a saddle (c) has a longer cirumference, even though they all have the same radius.

From Brian Greens' Elegant Universe

Friday, January 4, 2013

Spatial Fabric around the Sun

Beautiful way to express how the earth is kept in its orbit by the Sun as it rolls along a 'valley' in the warped spatial fabric. This follows the "path of least resistance" in the distorted region around the sun. 

Also, this is another way to suggest how gravitational 'explosion' could me 'immediately' felt if something happened to the sun. Whereas it might take light to reach the Earth from Sun in about 8 minutes, Newton suggested the gravitational impact would be instantaneous!! Something travelling faster than light is still not allowed in Physics unless General Theory of Relativity is invoked.

From Brian Greene's The Elegant Universe