U. S. Food and Drug Administration
Center for Food Safety and Applied Nutrition
Office of Food Additive Safety
February 26, 2002

Timothy R. Smith
World Minerals, Inc.
2500 Miguelito Road
Lompoc, CA 93436

Re: GRAS Notice No. GRN 000087

Dear Mr. Smith:

The Food and Drug Administration (FDA) is responding to the notice, dated October 24, 2001, that you submitted in accordance with the agency’s proposed regulation, proposed 21 CFR 170.36 (62 FR 18938; April 17, 1997; Substances Generally Recognized as Safe (GRAS); the GRAS proposal). FDA received the notice on November 6, 2001, and designated it as GRAS Notice No. GRN 000087.

The subjects of the notice are composite filtration media. The filtration media are made from a range of ratios of diatomaceous earth and perlite. The notice informs FDA of the view of World Minerals, Inc. (World Minerals) that these composite filtration media are GRAS, through scientific procedures, for use as filter aids in food processing for a variety of liquid foods. The composite filtration media would be used at minimum levels necessary to accomplish the intended effect. The composite filtration media would typically be used at concentrations ranging from 0.5-5 percent (weight/volume) in a liquid foodstuff. The practical maximum concentration would be 25 percent (weight/volume).

World Minerals describes generally available information about diatomaceous earth, which currently is used as a filter aid in food processing.⁽¹⁾ World Minerals states that the diatomaceous earth used to manufacture its composite filtration media meets the specifications for diatomaceous earth in the Food Chemicals Codex (FCC, 4th Edition, 1996) and calls this starting material “FCC grade diatomaceous earth.” World Minerals states that FCC grade diatomaceous earth is a powder consisting of processed siliceous skeletons of diatoms obtained from sedimentary deposits. These siliceous skeletons are primarily composed of amorphous silica (i.e., silicon dioxide, SiO₂), with a typical composition of 88 percent (by weight) silicon dioxide. The remaining 12 percent contains various concentrations of aluminum, iron, sodium, potassium, and calcium, and low concentrations of other metallic elements.

World Minerals describes generally available information about perlite, which also is currently used as a filter aid in food processing.⁽²⁾ World Minerals states that the perlite used to manufacture its composite filtration media meets the specifications for perlite in FCC and calls this starting material “FCC grade perlite.” World Minerals states that FCC grade perlite is a thermally processed material that is manufactured from perlite ore, a hydrated natural glass of volcanic origin, typically composed of 72-75 percent (by weight) SiO₂, 12-14 percent Al₂O₃, 0.5-2 percent Fe₂O₃, 3-5 percent Na₂O, 4-5 percent K₂O, 0.4-1.5 percent CaO, and low concentrations of other metallic elements. The perlite ore is heated in air to a temperature of 870-1100 degrees Celsius, causing softening of the glass and vaporization of the water that is chemically bonded in the glass. This leads to expansion of the perlite ore particles, forming a frothy glass material known as expanded perlite. This expanded perlite (which is what World Minerals calls “FCC grade perlite”) has a bulk volume that is up to 20 times greater than the volume of the unexpanded ore. The expansion of the ore often causes the perlite particles to break, giving particles with intricate angular surfaces.

World Minerals describes the manufacturing process for composite filtration media. Various proportions of FCC grade diatomaceous earth, FCC grade perlite, and an alkali metal flux are used to make composite filtration media for different applications. The components are mixed, followed by heating (to 1300-1900 degrees Fahrenheit) in air in a rotary kiln for approximately 30 minutes. World Minerals states that the high temperature causes the perlite to soften and destroys any organic matter. The alkali metal flux also decomposes, and the sodium ions become relatively mobile in the expanded perlite, bonding the diatomaceous earth and expanded perlite. World Minerals provides recommended specifications for “food grade” composite filtration media with limits on the pH range (of the filtrate from an aqueous suspension) and on the levels of arsenic, lead, loss on drying, and loss on ignition. World Minerals states that the recommended specifications for levels of soluble arsenic and lead in its composite filtration media are similar to those listed in the FCC for diatomaceous earth and perlite.

World Minerals notes that element solubility from the composite is low and provides data from studies testing for element solubility using an aqueous ethanol extraction. World Minerals concludes that toxic or heavy elements are either absent or detected at such low concentrations that they are not of concern.⁽³⁾

Based on the information provided by World Minerals, as well as other information available to FDA, the agency has no questions at this time regarding the conclusion of World Minerals that composite filtration media are GRAS under the intended conditions of use. The agency has not, however, made its own determination regarding the GRAS status of the subject use of composite filtration media. As always, it is the continuing responsibility of World Minerals to ensure that food ingredients that the firm markets are safe, and are otherwise in compliance with all applicable legal and regulatory requirements.

In accordance with proposed 21 CFR 170.36(f), a copy of the text of this letter, as well as a copy of the information in your notice that conforms to the information in proposed 21 CFR 170.36(c)(1), is available for public review and copying on the homepage of the Office of Food Additive Safety (on the Internet at http://www.cfsan.fda.gov/~lrd/foodadd.html).

⁽¹⁾Several years ago, FDA contracted with the Life Sciences Research Office (LSRO) of the Federation of American Societies for Experimental Biology as part of its comprehensive review of GRAS and prior sanctioned food ingredients. To aid in that review, LSRO established the Select Committee on GRAS Substances (SCOGS). In a 1979 report, SCOGS concluded that there was no evidence in the available information on diatomaceous earth that demonstrated or suggested reasonable grounds to suspect a hazard to the public when used as a filter aid in food processing at levels that were then current or that might reasonably be expected in the future (SCOGS Report No. 61, Evaluation of the Health Aspects of Certain Silicates as Food Ingredients, 1979).

⁽²⁾Perlite was also reviewed by SCOGS. In a 1979 report, SCOGS concluded that there was no evidence in the available information on perlite that demonstrated or suggested reasonable grounds to suspect a hazard to the public when used as a filter aid in food processing at levels that were then current or that might reasonably be expected in the future (SCOGS Report No. 61, Evaluation of the Health Aspects of Certain Silicates as Food Ingredients, 1979).

⁽³⁾FDA expects that there will be virtually no exposure to composite filtration media from their use as filter aids, and exposure to elements extracted from the composites will be extremely low.

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