food grade diatomaceous earth Is all unaltered diatomaceous earth (DE) food grade?

I am aware that all have not spent the money to have it certified and labeled as food grade, but I'm thinking that is just a way for the government to get more money and also have more control. All countries do not have an FDA, and therefore have no need to certify it, and have used it for thousands of years.

I just want to know the answer without somebody being afraid to say it is still food grade, labeled or not. I know the DE exposed to extreme heat is not safe and is for pool filters.
I very much doubt that all diatomaceous earth is food grade.  For some reasons why, consider the Wikipedia page for diatomaceous earth: "Kieselgur" was discovered when folks in the 1800s were trying to dig a well.  Since knowledge of hygiene was some decades away, it's not implausible that those people may have been trying to dig a well that happened to be near an outhouse.  I'd doubt that diatomaceous earth recovered from a site near an outhouse would be food grade.  

Also, Wikipedia lists "salt-water-derived" diatomaceous earth and specifically mentions that it is:


not suitable for human consumption
not effective as an insecticide
often calcined, which converts the safer amorphous silica present in most natural diatomaceous earths into a far more dangerous crystalline silica.  This can lead to silicosis if long-term exposure to airborne microparticles of crystalline silica occurs.


Thus, any diatomaceous earth that contains lots of salts or which has been calcined is unlikely to be food grade.