Salt sounds like such a pure product, but actually *most* brands available for sale in the grocery store cause issues for those with corn allergies, even those of medium sensitivity. The below statements apply to sea salt and table salt both:

• Packaging: Cardboard, especially recycled cardboard can contain corn fibers and may be dusted with corn starch to prevent it sticking together. Plastic may contain polymers from corn starch or may be dusted or oiled with corn products to prevent sticking.
• Ingredients: Iodized salt contains dextrose from corn to help the iodine stick to the salt crystals. Non-iodized salt often contains an anti-caking agent, which may not be directly from corn but often causes more sensitive corn allergics to react, probably due to cross contamination.
• Cross contamination: Companies that mine/extract/synthesize and package salt often produce a number of different products. Cargill is one example. Many of those products contain corny ingredients, and cross contamination is possible in the facilities.

The most sensitive folks with corn allergies actually have a very, very hard time with salt. In fact there is NO salt product out there that SOME corn allergic person hasn’t reacted to. Not one. You just have to pick some best bets based on who has reacted and how much their particular sensitivity matches yours, as people react differently to different derivatives.

What works for many people who cannot tolerate any pre-ground salt is to get a slab of himalayan salt intended for cooking, or large chunks of himalyan salt and rinse the outside under safe water for long enough to remove a layer from the exterior (presumably washing any contaminants down the drain with that layer), and then let it dry again and use a large blunt implement to whack the salt down into coarse chunks which you can load into a grinder. I use a large mortar and pestle designed for guacamole for this.   DO NOT STICK LARGE ROCKS OF SALT INTO YOUR BLENDER, not even if you have a Vitamix or Blendtec.  These are essentially rocks and will bust a hole through the side of your blender jar. If you get the rocks down to gravel sized that should be fine for the blender however.

Another technique I’ve been using lately is to use the chunks, rinse the outside, and then stick them in a jar full of water and shake it around to make a strong salt solution. This is much easier, but can be a bit difficult to measure how much salt to use. Full credit to Marci for this particular innovation.