The study comparison is flawed.

The 2001 study only accounts for nodules 5mm or greater. You can see this if you click thru to the research abstract at [link to docs.google.com (secure)] that is referenced by ENEnews, the source that Business Insider uses.

The 2012 study accounts for all nodule sizes, both over and under 5mm. Also, in the intervening decade, ultrasound detection has become more accurate as equipment resolution increased. So the 2001 study cannot be compared on the same playing field as the 2012 study since many nodules may have been missed in 2001.

While I'm not saying that there hasn't been an increase in thyroid cysts in Japanese children, just a cursory glance at the cited sources shows that comparing 0.8% to 36% in the case of these two studies is like comparing apples and oranges.