Underground Testing

Per capita thyroid doses for the population of each county. Test series: Underground Era (1961-70).

Contrary to popular belief, many counties across the continental United States were exposed to iodine 131 and other radioactive isotopes during the era of underground testing.

You can see from this map that America’s Midwestern breadbasket was especially hard hit where the jet-stream collided with the gulf stream causing heavy rains. Some counties received doses equivalent to 30 times background radiation.

Iodine 131 was monitored the most; but it is also one of the shortest lived radioactive isotopes, with a half life of just 8 days. Other isotopes, such as strontium 90, also fell, rained or snowed out over America. Strontium 90 has a half life of 38 years; others are potent for centuries.