Milk data revision explanation?

Submitted by Anonymous on Thu, 2011-04-14 09:38

Could you please explain in a bit further detail the revision of the milk data? In particular:

  1. How the calculation was done for the revised data and how this resulted in an increase?
  2. Could you confirm which revised date's data corresponds to the original data date? For example the 4/4/11 on both are for the same sample?
  3. If yes, does this means 0.70 Bq/L was revised to 1.40 Bq/L with the error going from +-0.27 to +-0.54)? If so, then please explain how you calculated the jump in error? It does not appear to be uniform across the dates.

thanks

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I think the revised numbers

Submitted by moon1234 (not verified) on Thu, 2011-04-14 13:10.

I think the revised numbers for I-131 are pretty easy to understand. They corrected for the 8 day half life that I-131 has. This way they will be comparing the radiaiton numbers AT THE TIME THE MILK WAS BOTTLED vs. the time at which the testing occured.

If there was an 4-8 day (or longer) lag between the time that the milk was bottled and the time that the milk was sampled the amount of I-131 will be significantly reduced compared to the time when it was bottled.

In order to see a trend, either up or down, in the amount of radiation in milk the point at which the numbers refer to (when it was bottled) needs to be the SAME for all samples. Otherwise no comparison can be made.

This is a good catch by UC Berkley team.

What is interesting is that we are seeing I-131 and Cs-137 numbers INCREASING in milk over time and not decreasing. This would mean to me that MORE I-131 and Cs-137 is still arriving from Fukushima or some other source.

It would be interesting to have grass and milk testing on the SAME dates and to then see if there is a correlation between higher grass numbers and higher milk numbers. Then to see how LONG it takes from detecting higher radiation in grass to the amount in milk. If there is then a reduction in radiation in grass how long it will take to see a noticeable reduction in milk.

Essentially this would give us an idea of biological half life. The would probably be easiest to do with Cs-137 since I-131 has such a short half life. This would then give us a time frame to avoid milk consumption when higher levels are detected in Grass.

I would assume biological half life for CS-137 will be longer than I-131 just due to half life.