Megacity Bugout?

I have a son who is 1 year old and will be 2  in May.   When I was around his age, one place I got to visit was Tokyo.   My parents took me there on a trip from Manila, where they were living (and where I was born).   I can't say I remember being an infant in Tokyo, but I can say I've been there.

Tokyo is the #1 Largest "Megacity" in the world with a population (34.2 million people) equal to California's in one huge metropolitan area that includes Yokohama.    Officially there are 8.6 million within the city limits (the green oval you see in the LANDSAT image above is the Emperor's Palace)  Yesterday, the Japanese health ministry announced that Tokyo's drinking water was too radioactive for infants to drink.

Ei Yoshida, head of water purification for the Tokyo water department, said at a televised news conference that Iodine 131 had been detected in water samples at a level of 210 becquerels per liter, about a quart. The recommended limit for infants is 100 becquerels per liter. For adults, the recommended limit is 300 becquerels. 

With about 9 million people affected, (including those in a few nearby "towns" of 100,000+ people each) stores sold out of bottled water in an hour of panic buying.  This news left me to ponder:

-- While infants were cautioned not to drink tap water eg. in formula, pregnant mothers were not so restricted, even though experts cited in the NYTimes article above said that pregnant mother are at high risk, that they absorb Iodine and pass it through the placenta to their fetuses.

-- At first I was hopeful that this announcement might encourage somewhat more reliance on breastfeeding over using formula.   However, it dawned on me that there are mixed messages to these mothers as to whether they can consume the tap water or not.   We know that our fellow mammals, cows, when making milk, do concentrate and pass along radioactive Iodine they've taken in from the environment (this was a big problem at Chernobyl when humans drank that milk).  So I see no reason to assume that human brestmilk is not similar.    I find it discouraging that the NYTimes article about nutritional needs of infants doesn't even contain the word "breast" !!

-- A 50% increase in the I-131  levels in the water would cause the safe limit to (300 Bq/liter) to be exceeded for all adults.  (NOTE: Late breaking stories are now reporting a decline in radiation in the drinking water--let's hope this is permanent and real, not just a response to there now being no alternative since bottled water is sold out!).  Even at the current level (200 Bq/liter) is it really  OK for 9 million people to be getting 2/3 of the unsafe dose?  Suppose, at this level, that an adult can be 99.9% sure they won't get thyroid cancer.  Well 99.9% safe means 0.1% unsafe.   So in Tokyo's population, that would mean 9,000 cancer cases.   I just made those numbers up, so don't use them.  But the point is that for a population that big you need a much higher margin of safety.  Tokyo is big enough to beat 1 in a million odds.

"What's the worst case scenario?"  This question is often asked.   To me the worst case would be if the a big new radioactive release, (eg of Plutonium in the MOX fuel at reactor 3) coincided with a wind shift that puts Tokyo/Yokohama in the line of fire.  Winds have supposedly carried the fallout over the ocean up till now  (though this doesn't explain how it got into Tokyo's water?).  But weather forecasts are now calling for a change in wind direction, within days turning  Tokyo's millions into potential downwinders.   Imagine what would ensue if 1.) all people with children or 2.) everybody decided they should get out of "Dodge".    Japan has extensive earthquake/emergency plans, but how do you evacuate a population the size of California's ???   Has anyone  considered this (worst case) possibility?  Here's google.com's answer:

ps.  This post is dedicated to my parents: my father who lived in Yokohama, and my mother who decided to marry my father after visiting Tokyo.  I am grateful to them for their decisions  which have affected my life and for their continued  inspiration and support.