Tuesday, April 12, 2011
Don't Drink The Water?
There was a story in a number of media outlets today about high levels of radioactive isotopes of Iodine in Philadelphia drinking water detected last week - amounts as high as 2.2 pCi/L (picoCuries per liter of water). The EPA's limit is 3.0 pCi/L Obviously, the first thing that comes to mind is the Fukishima nuclear disaster in Japan, which has just been upgraded to a level of severity on par with Chernobyl.
In a number of the articles I have read, experts are saying that the amount of radiation measured in Philly's water is not a big deal, and somebody is always quoted as saying the opposite "for balance." With trust in government at quite a low in the last 40 years, skepticism is natural, but with a lot of my friends wondering if the water is safe (myself included), I think it's a good idea to break down some of what we know and figure out what this means for public health.
Disclaimer - I am not a chemist, physicist or public health expert, merely a guy with an ecology degree and a blog, so I welcome anybody to correct any errors I may make or add to my comments.
First off - there are several kinds of radiation measures, a number of which you have probably heard on the news. These measures can tell you the radioactivity of a substance, the amount of dosage a human has absorbed or several other things. The Curie (Ci) is a non-metric measurement of radioactivity. Although I strongly prefer metric units, the Philly Water Dept measured in Ci, so let's talk in Curies to make life simple.
Second - all objects continuously emit electromagnetic radiaton, even human beings. This is how we're able to date archaeological objects - by measuring the decay of radioactive isotopes of carbon in formerly living objects.
Third - the water measurement was in pCi/L, picoCuries per liter of water. The prefix "pico" denotes a 1 in a Trillion multiplier (1/1,000,000,000,000 or 1x10-12)). This is important because there are lots of radioactive objects and substances that would be useful as points of comparison. Many every-day radioactive objects have levels of radiation measured on different orders of magnitude: nano (1/1,000,000,000), micro (or milliCuries per weight or volume. At the risk of being insulting, this is worth explaining a bit. This chart gives a little rundown - keep in mind that these prefixes denote immense changes in magnitude of ONE THOUSAND. A centimeter is less than an inch, a meter is a few feet, a kilometer is a few blocks, a megameter is twice the width of Pennsylvania.
Now based some figures from various health departments and universities (links provided), here are the equivalents in water volume from the Queen's Lane facility:
1 Coffee = 12.27 nCi/lb
One pound of coffee has the same radioactive content as 5335 Liters of Philadelphia water.
Animals, plants = 6 pCi/g
One gram of any living animal or plant has the same radioactive content as 2.6 Liters of Philadelphia water. That means that a one pound steak has approximately the same amount of radiation as 73.8 Liters of Philadelphia water.
Beer (dry weight) = 390 pCi/kg
One kg of the solids left by dehydrating beer (which is probably equivalent to about 10 kg of beer by wet weight, not sure of the volume because I don't know beer's density) has the same radioactive content as 170 Liters of Philadelphia drinking water.
So I guess these levels of radioactivity in Philly water are not really that high, and the EPA standards seem awfully strict. Apparently, in August there were elevated levels of radioactivity in Philly's reservoirs but this went more or less without comment. I would be interested to see how much radioactive Iodine from Fukishima is being deposited in the Delaware watershed relative to elsewhere. I don't know how high the radioactive particles ride in the air across the Pacific, because my expectation would be that much of the radioactivity will condense over the western mountain ranges and fall as rain in the West or Midwest before it reaches here.
Anyways, I hope this was helpful, I'm gonna go get a drink.