A Hard Rain

It's been a few days since my last blog.  There's a lot to report from
Japan, but I'm going to focus on what's happening here in the US.  The
main news here in the San Francisco Bay Area is the results from
U.C. Berkeley's Nuclear Engineering Lab.  I strongly recommend their
site and its FAQ:

http://www.nuc.berkeley.edu/UCBAirSampling 

http://www.nuc.berkeley.edu/node/2044#lowdoserisk 

First, I should clear up some mis-reporting that occurred: So far
there have been no detections of hazardous levels of radiation in Bay
Area drinking water (as one might have interpreted when reading
certain recent headlines.) ...and drinking water has been tested.  So
tap water is safe at present, and this lab is continuing to test tap
water and I assume they will let us know ASAP if there is any
increase/risk from drinking tap water.

However, it is now clear that on March 17 and afterward radioactive
rain fell in the SF Bay Area.  From that date forward, detectable
levels of I-131 and Cesium have been discovered in rainwater samples
collected from the roof of Etchevary Hall in Berkeley (trivia: I used
to live on the same street, 1 block away from this building.  trivia2:
this building used to house a nuclear reactor!)  The highest recorded
reading for I-131 is 20 Bq/L recorded on 3/23.  (This reading means
that if you drank 1 full liter of that rainwater, then every second
there would be 20 radioactive decays in your body; every hour there
would be 72,000 decays) On other days, the readings were much lower,
(around 5 Bq/L) but still I-131 was detectable.

What to think about this?  The EPA limit for drinking water is 0.111
Bq/L, so the peak rainwater reading is 181 times over the limit.  More
relevantly, the average value is about 5 Bq/L, which is still about 6
times over the limit.  Here are some reasons why this figure is not an
automatic sign of serious danger:

1. you didn't drink that rain water, you've been drinking tap water
which is fine.
2. the EPA calculated that limit assuming the person would be exposed
to this level of radiation for a whole year.  So you'd need to drink 
that rain water for a couple of months  to exceed the EPA annual
max. dose.
3. *IF* the release of radioactive Iodine stops, then the I-131 
present in our environment now will be about 90% gone a month from now.
(due to the 8 day half life)

Here are some reasons to be concerned.

1. That rain fell on everything around here: roofs, gardens, farms,
streams.  Thus it can and will get into the food supply.  (UC Berkeley is
testing the food supply and has not found dangerous levels...yet)

2. If other isotopes, like Cs-137 are present, they will not decay
away quickly.  (30 year half life).  The tables on the site above
suggest that signficantly less Cs-137 is present than I-131.
However I didn't see a quote for the EPA limit on Cs-137

3. We don't know how long this will go on.  If the situation in Japan
continues to deteriorate, then we may well be getting "fresh" rains of
newly made I-131.  In this case the 1 year exposure time defined by
the EPA may come into play.  This is why it is important to look for
signs of continuing out-of-control nuclear reactions at the reactors in
Japan.

Note: the Berkeley site lists (in parentheses) numbers relating to
dosage of one airplane flight from SF to DC.  I don't put much value
in these numbers since they compare internal doses (eg. from food or
water) with external doses, eg. from air flights or X-ray machines.
However they do serve to remind us that we live in an environment has a
small level of radioactivity.  We always have & always will.

This site has an animation of an atmospheric model showing how the air
gets from there to here.

My Thoughts: Food is extremely safe now. We don't know how long this
will go on.  (Today's reports of increased risks of new Hydrogen
explosions at Fukushima Daiichi suggest no end in sight.)  As the
father of an infant, it seems prudent to me to stock up on any foods
that we can make last right now while they are still safe.  The
radioactivity in our food may go up, but will not go down.  I expect
it will never exceed the "unsafe" levels.  However these levels may
not be created w/ infants in mind.

My understanding is that there is no genuinely "safe" level of
radiation.  Every decay contains the possibility of causing damage to
our cells and our genes in particular, however small.  Since we live
with background radiation every day, we need not be concerned about
new radiation sources at the background level.  Its when our level of
exposure exceeds background that we need to start to consider taking
action.  Consider this question:

Assuming you drive every day, what is the safe level of not wearing
your seat belt?  No belt once per week (1/7) is certainly safer than
no belt ever.  Is neglecting a seat belt once per month a safe level?
After all, the odds of something happening are 1/30 times the odds of
getting in a crash in the first place.  A much safer approach would be
to ignore your seat belt only one day per year, every year.  This is
365 times safer than never wearing a belt.  Is that safe enough for
you or not?

My answer is: if you can take some precaution w/o causing additional
risk/harm, why no do it? This is why I just bought large quantities of
yogurt, (high Iodine, high Calcium which is chemically similar to
Strontium), strawberries (high Iodine) and seaweed (high Iodine)
bananas (Potassium, similar to Cesium).  I'm using these healthy foods
to make items (some frozen) to feed to my son over the coming weeks
and months.  These foods have elements we all need anyway, so there's
no downside, and the upside is the peace of mind of knowing that I've
taken a step to reduce the overall risks.

Oh, where have you been, my blue-eyed son? 
And where have you been, my darling young one? 
I've stumbled on the side of twelve misty mountains,
I've walked and I've crawled on six crooked highways,
I've stepped in the middle of seven sad forests,
I've been out in front of a dozen dead oceans,
I've been ten thousand miles in the mouth of a graveyard,
And it's a hard, and it's a hard, it's a hard, and it's a hard,
And it's a hard rain's a-gonna fall.
                      -Bob Dylan, A Hard Rain's a-gonna Fall