Not to mention that the health effects are VERY easily treatable and apparently fully reversible.
Pretty much a non-issue if someone is given medical care when they get sick.
Use iodized salt. That fixes the problem.
People have been getting upset about perchlorates ever since the Greens started trying to eliminate 4th of July fireworks. They searched for health effects until they found a minor inhibition of iodine uptake.
Then, once people started researching it, they found perchlorates at very low levels in lots of places- it occurs naturally!