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!
Up there with CO32 as a pollutant. Not to mention the (literally!)deadly dihydrogen monoxide.