I haven't thought about looking at the contents of a salt container because the assumption would be that it contained only salt, but after watching a video by AwareHouse Chef comparing different salt, I looked at the container in my kitchen. Apparently other ingredients are added mostly to stop the salt from clumping (you can resolve this by adding a few grains of rice to your salt shaker).
Yellow Prussiate of Soda contains hydrogen cyanide which is extremely poisonous.
I'll be more careful which salt I purchase in the future.
Another mention is Himalayan Sea Salt which comes from an ancient sea in Pakistan (there is no sea near the Himalayas)
As for the salt with all the added ingredients I will be using that as a weed killer.
