Parabens are added to deter mold growth, I believe.

I don't know if European products would use the USP designation, as USP means United States Pharmacopeia.
http://www.usp.org/about-usp/legal-r...ion/usp-us-law

As far as I know "food grade" does not mean a guarantee from all possible contamination. Purity levels, or water content have to conform to certain ranges that someone in the past has decided upon.

You can check out FDA.gov
but some foods are allowed rat hairs/feces in them even, but only in certain low levels. Reading what is in peanut butter for example is enough to make someone never want to eat it again!
http://www.cbsnews.com/news/11-total...-in-your-food/

Just remember we are breathing nano particles of pollution with each breath now. So the definitions are all relative IMO.

Beware of natural sources for various minerals. There have been contaminations with lead in dolomite (calcium source) and
Coral Calcium had heavy metals in it which were not discovered until well into the fad's success. Some Blue Green algae harvested naturally was found to have poisonous levels of fluoride in it, and one famous brand of glucosamine had too high of levels of manganese about 10 yrs ago.