Most leasing companies have closed this loophole. Honda, for example, forced me to but mine out from a Honda dealership.

Dr noticed that goiters were prevalent in the Midwest from WW1 soldier fitness studies (I think), noticed that further from salt water you were, the more likely you were to have goiters. Figured it had to do with salt or saltwater seafood, eventually isolated it to iodine. Had experimented with dogs before moving on to people.

Edit: it has been a while since I heard the episode, basing it on my memory. My wife contends my memory is an unreliable narrator.

The first sentence covers it. Dr talked to a principal of a school nearby ( I think in Cleveland) to see if he could try it. They said “ hell no”. Then he talked to a principal in Akron ( I think) and they agreed. It was not an FDA regulated double blind study. He simply talked the principal into replacing salt with iodized salt.

From the revisionist history podcast, places near salt water tended to not be iodine insufficient, which is where the dr got the idea to add it to salt.

Dr talked a school principal into introducing iodized salt to schoolchildren, specifically girls. There were no rules or regulations about such things then. It was a huge success but would never happen in today’s society. Gladwell wishes/imagines being able to do this with vaccines, specifically Covid vaccines.