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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.

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    $\begingroup$ Is all water food grade? would you drink water out of a mountain stream? what about an unspecified large river? Or would you play it safe and dring water that's been certified as safe? It's the same thing. $\endgroup$ Commented Sep 8, 2015 at 8:35

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Is all unaltered diatomaceous earth (DE) food grade?

No, and that's because it's not regulated and in general trying to categorize "all" of something (regardless of source, and especially when unregulated) as "food grade" isn't possible. Here in the U.S., the Food and Drug Administration (FDA) has weighed in on the issue and determined that the components of diatomaceous earth are "generally regarded as safe (GRAS)" when used as a filter aid.

From the FDA's report entitled Select Committee on GRAS Substances (SCOGS) Opinion: Diatomaceous earth (filter aid):

Silicon dioxide and various silicates occur abundantly in the earth's crust, are present in practically all natural waters,animals, and plants, and are part of the normal human diet. The question of whether or not silicon is an essential human nutrient remains unresolved. Silicon compounds consumed as added food ingredients contribute only a minor proportion of the total dietary silicon intake. The estimated possible human intake of sodium aluminosilicate, the predominant silicate added to foods in this country, is approximately 0.3mg per kg body weight per day. Silicon compounds that are GRAS for use as direct food ingredient, except potassium and sodium silicates, are insoluble or very slightly soluble in water and appear to be biologically inert. The water-soluble silicates are also of low acute toxicity. The acute oral LD50 in rats of sodium aluminosilicate is >1g per kg. No significant tissue accumulation, pathology, or toxicity has been reported from the ingestion of those insoluble or very slightly soluble GRAS silicon compounds for which data are available. Of the five substances that were reported as added to foods in the NRC survey, biologic effects and safety data are available for all except sodium calcium aluminosilicate, and there is no reason to suspect that the toxicity of the latter would differ from those for which there are data. The results of two studies (1967-1970) in which various silicon compounds were fed to laboratory animals for 1 mo at a level of 0.8g per kg body weight (as silicon dioxide) and for 3 mo at levels of 6 to 30 mg per kg body weight suggests there may be a species-related susceptibility to renal damage from ingestion of sodium silicate, magnesium trisilicate, and finely ground quartz.

No substantiating reports of these effects have appeared. Magnesium trisilicate was recognized as safe for prolonged use in human ingestion in large amount as a component of antacid preparations by the Advisory Review Panel on Over-the-Counter Drugs, and the available evidence on the acute toxicity of sodium silicate indicates that it is low. Consumption data are lacking for aluminium calcium silicate and tricalcium silicate, two compounds that are listed as GRAS for use as anticaking agents. However, their use in keeping with good manufacturing practice and in currently regulated amounts would be of the same order of magnitude as the other GRAS silicates. In addition, the Select Committee has limited information on the amounts of talc that are currently used in foods. However a major food use of talc is in the coating of rice. Assuming package label statements are ignored and coated rice is not washed prior to cooking and no other losses occur, maximun per capita intake of talc from this source appears to be 0.5g per day. With respect to paper and cotton food- packaging products, the possibility is remote that biologically significant amounts of talc, diatomaceous earth, or sodium silicate migrate to food from packaging, materials containing these substances. Perlite, a naturally occuring polysilicate substance, has an oral LD50 in the rat of >10g per kg body weight. Estimates of the maximun quantities of minerals that might be extracted from perlite and diatomaceous earth used as filteraids in food processing indicates no hazard to public health. There are no food grade specifications for aluminum calcium silicate, sodium calcium aluminosilicate, and talc. Such specifications for the substances used in foods are desirable.

Specification for food grade talc should limit the content of asbestos fibers even though the potential hazard of ingested asbestos fibers even though the potential hazard of ingested asbestos is not clearly established. The Food and Drug Administration is sponsoring the development of an assay method for asbestos fibers. An upper limit for cadmium should be added to the specifications for food-grade perlite, and consideration should be given to the need for limitation of cadmium content of other silicates. In the light of all of the foregoing, the Select Committee concludes that: It is essential to establish food-grade specifications for aluminum calcium silicate, sodium calcium aluminosilicate, and talc, with provision for an upper limit of asbestos fibers in talc. There is no evidence in the available information on aluminum calcium silicate, calcium silicate, magnesium silicate, potassium silicate, sodium silicate, sodium aluminosilicate, sodium calcium aluminosilicate, tricalcium silicate, silica aerogel, and talc that demonstrates or suggests reasonable grounds to suspect a hazard to the public when they are used at levels that are now current or that might reasonably be expected in the future. There is no evidence in the available information on diatomaceous earth, silicon dioxides, sodium silicate, and talc that demonstrates or suggests reasonable grounds to suspect a hazard to the public when they are used as ingredients of paper and paperboard products used in food packaging in accordance with current practice. There is no evidence in the available information on sodium silicate and talc that demonstrates or suggests reasonable grounds to suspect a hazard to the public when they are used as ingredients of cotton and cotton fabrics used in dry food packaging in accordance with current practice. There is no evidence in the available information on diatomaceous earth and perlite that demonstrates or suggests reasonable ground to suspect a hazard to the public when they are used as filteraids in food processing at levels that are now current or that might reasonably be expected in the future.

*Complete reports containing details of the safety studies that formed the basis of the opinions and conclusions and are available from the National Technical Information Service (NTIS), 5285 Port Royal Road, Springfield, VA 22161 (703) 605-6000.

That said, "food grade" appears to apply to a mean particle size of less than or equal to 12 $\mu$m (Wikipedia), and only applies to diatomaceous earth labeled that way.

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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.

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