If we're imaging a world where corporations and governments would agree to this level of accountability, wouldn't it be eaiser to just make certain financial transactions into public records?
Currently we consider some things public records (registering a company y, the voting roll) and other things private (income and taxes, bank transactions). If there was the will to chnage things we could just make the financial records of all elected government officials and corporations with government contracts automatically publically accessible. This doesn't need block chain, a law could be passed deeming these "in the public interest" such that banks would have no grounds to refuse a request from journalists or any citizens to access them.
This would be a lot simpler and cheaper than block chain. But its unlikely to happen for the same reason that block chain won't be used for this either.
Talking about the ocean is odd, but there are towns in the UK (and most countries I'd assume?) where the natural level of fluoride is higher than the concentration they aim for when adding fluoride. I think that's a pretty good argument for it being safe - the people of Hartlepool have been drinking fluoride rich water for 13 centuries and don't have any noticeable issues compared to the rest OF County Durham.