Out of What Bodily Orifice Did They Pull This Figure?

The latest hysterical claim about radioactivity is that:

The U.S. federal drinking water standard for radioactive Iodine-131 is 3 picocuries per liter, but levels exceeding that by many times have been detected in rainwater sampled in California, Idaho, Minnesota, Ohio, Pennsylvania and Massachusetts.

As far as I can tell, the claim that the federal standard for drinking water is 3 pCi/liter came from a press release that may have been a typo. On the other hand, the radioactivity of bananas is 1000 times greater and the federal standard for tritium is 6000 times greater and the Japanese standard for I-131 is over 2000 times greater. I suspect the federal standard for drinking water (which I can't seem to find) is 3 nCi/liter [CITATION NEEDED].

Addendum: I've located the orifice:

EPA has set an average annual drinking water limit of 3 pCi/L for ¹³¹I so the public radiation dose will not exceed 4 millirem.

Three important things to remember: 1) The supposedly-intolerable levels of ¹³¹I are found in rainwater and will be diluted in drinking water. 2) The limit is for an average over a year. That will be much less than the peak amount when you recall that ¹³¹I has a half life of only 8 days. 3) It's still idiotic. To quote Charles Dickens:

‘If the law supposes that’, said Mr. Bumble, ‘the law is a ass—a idiot.’

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