Category Archives: Food

Do Not Fear the Banana

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Zapperz has a short post on an article that appeared in the NY Times, chumming the waters of fear about radiation from granite countertops. I see that Chad has promised and delivered a bit of a rant, pointing out that popular media could and should do science. The problem is that they don’t — not in the living section, and sometimes not in the science section, and almost certainly not on the op-ed page.

But that’s not actually what piqued my interest here. It’s mediocre reporting, to be sure; the author makes sure to give “both sides” of the story, even though science boils down there being experimentally verified claims or not, so reporting knee-jerk reactions to the ticking of a geiger counter isn’t particularly responsible. But there was a snippet that reminded me of a conversation I was having last week.

Indeed, health physicists and radiation experts agree that most granite countertops emit radiation and radon at extremely low levels. They say these emissions are insignificant compared with so-called background radiation that is constantly raining down from outer space or seeping up from the earth’s crust, not to mention emanating from manmade sources like X-rays, luminous watches and smoke detectors.

And not to mention — because they don’t — people. That’s right: YOU are radioactive. An adult contains something like 140 g of potassium, of which about 16.5 mg will be K-40, which is radioactive with a 1.26 billion year half-life, yielding about 4400 decays per second. You also have C-14 in you, adding in another 3000 decays per second. The C-14 decay, and 89% of the K decays give betas, which will be deposited in your body. The other 11% of the K-40 decays have a 1.46 MeV gamma, and about half of them will be deposited in your body as well. This ends up being tens of millirem of dose per year.

The rest of the gammas escape, which means that you are a 6.5 nanoCurie gamma source. (Sleep with someone else 8 hours a night, all cuddled up? That’s around a millirem of dose each year. Not a cuddler? Here’s your excuse — your exposure decreases as you move away.) Do you use potassium in your water softener or as an alternative to table salt? What about bananas? That’s a 300 picoCurie source there, and you’re eating it. If you leave it alone, it’s only about 20 picoCuries of gamma.

The point here isn’t to make anyone afraid of bananas. You need potassium, and K-40 is along for the ride. But reporting like this gives no context, and paints a very simplistic “all radiation is bad” picture, when some dose is simply inescapable. It accentuates and panders to our inability to properly assess risk for unusual circumstances, especially with the mention of radon testing kits at the close of the article.

Fifth Law, Redux

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Survival of the Sudsiest, or George Will happens upon the fifth law of thermodynamics.

“The search for unpolluted drinking water is as old as civilization itself. As soon as there were mass human settlements, waterborne diseases like dysentery became a crucial population bottleneck. For much of human history, the solution to this chronic public-health issue was not purifying the water supply. The solution was to drink alcohol.”

Often the most pure fluid available was alcohol — in beer and, later, wine — which has antibacterial properties. Sure, alcohol has its hazards, but as Johnson breezily observes, “Dying of cirrhosis of the liver in your forties was better than dying of dysentery in your twenties.” Besides, alcohol, although it is a poison, and an addictive one, became, especially in beer, a driver of a species-strengthening selection process.

This fits right in with concepts from Jared Diamond’s Guns, Germs and Steel, in that civilization which didn’t develop the kind of population densities (i.e. towns) compelling people to drink alcohol did not see the genes for alcohol tolerance selected for (along with diseases that mutated and jumped from domesticated animals to humans in these regions with high densities)

Apparently I'm Doing it All Wrong

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The top ten home cooking mistakes.

Not so much mistakes as tips and hints. The author assumes you’re actually cooking, though.

MSG has a nasty reputation and can trigger a fatal reaction in a person allergic to it (a close friend of our maid of honor’s sister died of anaphylaxis after eating MSG), so it’s not for everyone

I’d say that would put a damper on the relationship.

But Why is it so Hot in the Okefenokee?

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Evaporative (Swamp) Coolers

I was discussing this with our resident mechanical systems guru just a few days ago — really hot, humid weather had some of the HVAC systems gasping, and if you can’t reject heat anymore, the system stops cooling (a basic bit of thermodynamics lost on some people). He was reminiscing about when he could use swamp coolers, in the southwest part of the US.

Evaporation works as a cooling mechanism, which is why we sweat when we get hot, because the molecules that go to the gas phase take more than their share of energy with them — somewhere around 2300 J/g, depending on the temperature. And the energy to change that one gram of water’s temperature by a single degree is 4.18 J, so if I have 100g of water and lose one gram to evaporation, the remaining water will cool by 5.5ºC! (Assuming, of course, no other heat transfer to warm it back up. But hey, we’re physicists. Our cows are spherical and inclined planes frictionless)

You can use this cool things off without ice — put the beverages in a canvas bag and hose it down and let evaporation do the work (the canvas holds on to the water, so it doesn’t just run off). It won’t make the beer frosty, but as long as the water can evaporate, it’ll cool it off some. (rule of thumb — if your cold beverage containers tend to “sweat,” then this probably isn’t going to work very well. But here’s another trick for you, from my navy days aboard the USS Disneyworld — to keep that pitcher cold, fill a tall glass or cup with ice and let it float in the pitcher. Cold but no dilution.)

Don't Wine About Your Carbon Footprint

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Calculating the carbon footprint of wine: my research findings

There’s a “green line” that runs down the middle of Ohio. For points to the West of that line, it is more carbon efficient to consume wine trucked from California. To the East of that line, it’s more efficient to consume the same sized bottle of wine from Bordeaux, which has had benefited from the efficiencies of container shipping, followed by a shorter truck trip. In the event that a carbon tax were ever imposed, it would thus have a decidedly un-nationalistic impact.

via Kottke