Unfortunately, at least one of those truths he's uncovered appears to be one founded in a fundamental misunderstanding of his subject. As has been documented again and again from a vast number of different and very trustworthy sources (I have personal experience working with The Guardian and they are about as benevolent and non-partisan as a news agency can be), it would appear Mr. Ash is horribly misguided. He repeatedly mentioned in both our classroom and during the Q&A that followed the that the official reasons the Japanese government has given for a greater number of children afflicted with thyroid cancer is The Screening Effect (by looking for something, you're more likely to find it), but ironically I can't help but wonder if it was Mr. Ash's desire for a gripping story to tell that led him into seeing these (what are, by all appearances) illusory correlations.
There was a moment in the final act of his documentary that tipped his hand a bit. It featured the unseen voice of Mr. Ash behind the camera sparring loudly with the assistant principal of a grade school in Fukushima, begging the man to explain how he could stand by while his children were being exposed to radiation. Rather than the assistant principal holding the austere scowl of an uncaring, money-grubbing businessman who felt no compunction over profiting on the lives of children or his eyes welling up with tears because of what his school was allowing yet was powerless to speak against... he simply stared at Mr. Ash in mild horror. A horror that anyone could think these children were at any risk at all. Mr. Ash wasn't allowed on the school grounds because he threatened to spread "the truth" as Ash claimed; rather he was disallowed because fear-mongering in front of small, easily frightened children is intolerable. And I have to stand in agreement with the assistant principal on this matter, as much as it pains me.