The Russian scientists and firefighters who fought the Chernobyl fire reported a “metallic taste” in their mouth. That taste was from radioactive iodine. (It is well known that all iodine has a metallic taste.)
For example, Colonel Grebeniouk – who led the Russian troops in charge of controlling the situation – said:
There was a metallic taste in our mouths, an acidity. They say radiation has no taste. It was only later we realized it was the taste of radioactive iodine.
There is substantial evidence of ongoing nuclear chain reactions. Another piece of evidence – as pointed out by nuclear expert Arnie Gundersen – is that there are widespread anecdotal reports of people in Japan and the West Coast of the United States reporting a metallic taste in their mouths:
[vimeo http://www.vimeo.com/25002205 w=400&h=225]
Note 1: Iodine 131 decays to xenon 131, a non-radioactive form of xenon. Therefore, it is unlikely that a non-radioactive form of iodine would be in the air.
Note 2: There are, of course, other sources of “metallic tastes”.