Big thanks Mrs. D for pointing me in the right direction. I wanted to find something I was comfortable with using regularly.

I then found this below:

http://www.epsomsaltcouncil.org/faq/

"Any package that has a "drug facts" box or that's labeled "USP" has been manufactured, tested and certified to meet stringent regulatory standards of the FDA and the United States Pharmacopeia, and is deemed safe and acceptable for human use. For human use, the Epsom Salt Council recommends only Epsom salt with the USP designation."


And also this:


http://www.floattanksolutions.com/ge...ow-epsom-salt/

"... there are only two distinct ‘grades’ of Epsom salt:
1. USP Grade – which stands for United States Pharmaceutical Grade, and is often also referred to as Food Grade. This is the most quality controlled Epsom Salt, expected by the manufacturer to be used in personal care products and food. Because of these uses, which require a more consistently pure salt, each batch of USP grade is tested and the quality of the salt is guaranteed.
2. Technical Grade – also known as Agricultural Grade or Industrial Grade, and is produced by manufacturers for use in these environments. The uses of Epsom salt on an industrial or mass-agricultural level do not require that the Epsom salt be as pure as USP grade salt. Because of this, manufacturers test these batches of salts less regularly, and there is a chance that certain batches contain impurities.
You could also say there is a third ‘grade’ of salt, which is Asian epsom salt. The only manufacturers of USP grade Epsom Salt are The PQ Corp (US based), Giles (US based), and K+S (Germany based). Salt from Asia (China and India, primarily) is almost always cheaper, however, it is more unregulated, and through personal experience we’ve found that heavy metals and impurities in the salt …

… Interestingly enough, despite there being two distinct grades of Epsom salt, there is very little different about the salt itself. Technical grade and USP grade are made in the same plants, on the same machines, from the same materials. The only difference between two is that USP grade has been certified by the FDA, whereas Technical grade has not.

… In all likelihood you would get the exact same salt, no matter which you ordered, as long as it’s from one of the three main manufacturers. However, because not every batch is tested, it’s also possible for extra heavy metals and other impurities to be present in technical grade salt, whereas purity is guaranteed with USP salt. … "