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Agency Response Letter GRAS Notice No. GRN 000096

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CFSAN/Office of Food Additive Safety

May 20, 2002

Robert G. Averill
The New Silk Road, Inc
Box 105
Montpelier, VT 05601

Re: GRAS Notice No. GRN 000096

Dear Mr. Averill:

The Food and Drug Administration (FDA) is responding to the notice, dated November 20, 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 January 3, 2002, and designated it as GRAS Notice No. GRN 000096.

The subject of the notice is silk fibroin protein food powder. The notice informs FDA of the view of The New Silk Road, Inc. (Silk Road) that silk fibroin protein food powder is GRAS for use in food as a protein source.

Section 409 of the Federal Food, Drug, and Cosmetic Act (the Act) provides that any substance that is added to food must undergo premarket review and approval by FDA, unless the use of the substance is GRAS. Under section 409, anyone may determine that the use of a substance is GRAS, and may market the substance for that use without informing the agency. However, it is the responsibility of anyone marketing a food product to ensure that use is safe and lawful. If FDA disagrees with the GRAS determination, FDA can take regulatory action to remove products that contains the substance from the market.

As discussed in the GRAS proposal, FDA has proposed to establish a voluntary notification procedure for independent GRAS determinations. This procedure provides an opportunity for a person who concludes that premarket approval is not required under section 409 to communicate that view to FDA, the federal agency that is responsible for implementing and enforcing section 409. A threshold question for a person who submits such a notice is whether the particular use of a substance satisfies the GRAS criteria, which are described in 21 CFR 170.30. As discussed in the GRAS proposal, FDA evaluates whether a GRAS notice provides a sufficient basis for a GRAS determination and whether information in the notice or otherwise available to FDA raises questions as to whether the use of the substance is GRAS. Proposed 21 CFR 170.36(c) describes in detail the information that FDA considers important in evaluating whether a notice provides a sufficient basis for a GRAS determination.

Your original notice consists of a brief letter, a list of purported health benefits, and a product flier. In addition, you submitted several amendments, received February 6, 2002, February 14, 2002, February 27, 2002, and March 7, 2002. These amendments contain additional claims of health benefits, product fliers, and an article obtained from an Internet site. Collectively, your original notice and amendments lack much of the information described in proposed 21 CFR 170.36. Accordingly, your notice, in its present form, does not provide a sufficient basis for a determination that the subject use of silk fibroin protein food powder is GRAS.

For your information, we are providing some examples of information necessary to establish safe conditions of use and to establish that such information is generally accepted by expert scientists; information that your notice lacks. To relate this to FDA’s previous discussion of what is needed for use to be GRAS, we are comparing your notice to FDA’s proposed rule for what is needed in a notice.

Under proposed 21 CFR 170.36(c)(1), your notice lacks:

  • Applicable conditions of use of silk fibroin protein food powder, including the foods in which silk fibroin protein food powder will be used and the levels of use in such food; and
  • A statement whether the basis for your GRAS determination is through scientific procedures or through experience based on common use in food. Although we believe that you intended your GRAS determination to be through scientific procedures, we cannot make assumptions about your basis for the GRAS determination.

Under proposed 21 CFR 170.36(c)(2), your notice lacks information regarding the identity of silk fibroin protein food powder, including:

  • The source of silk protein food powder, such as whether silk protein is isolated directly from insect cocoons or from textile scraps;
  • Genus and species of the source, if silk protein fibroin protein food powder derives from a natural biological source such as insect cocoons;
  • Information on potential toxicants and specifications for food-grade material; and
  • The method of manufacture of silk fibroin protein food powder.

Under proposed 21 CFR 170.36(c)(4), your notice lacks a detailed summary of the basis for your determination that the intended use of silk fibroin protein food powder is exempt from the premarket approval requirements of the Act because such use is GRAS. This summary should include:

  • A comprehensive discussion of, and citations to, generally available and accepted scientific data, information, methods, or principles that exposure (i.e., how much consumers will eat);
  • A comprehensive discussion of any reports of investigations or other information that may appear to be inconsistent with the GRAS determination; and
  • The basis for concluding, in light of the data and information described previously, that there is general recognition among experts qualified by scientific training and experience to evaluate the safety of substances added to food, that there is reasonable certainty that silk protein food powder is not harmful under the intended conditions of use.

In light of all these omissions, your notice does not provide a sufficient basis for a GRAS determination.

If you still believe you have a basis for establishing that use of this substance is safe and that its safety is generally recognized, we recommend that you review the agency’s discussion, in the GRAS proposal, of the scientific, legal, and regulatory underpinnings of the GRAS notification program. In particular, we recommend that you review the agency’s discussion of the differences between a food additive and a GRAS substance. As discussed in the GRAS proposal (62 FR 18940), a determination that a particular use of a substance is GRAS requires technical evidence of safety and a basis to conclude that this technical evidence of safety is generally known and accepted by qualified experts. In contrast, authorization of a particular use of a substance as a food additive requires technical evidence of safety and review and approval by FDA. For this reason, we also recommend that you review the information on the Office of Food Additive Safety’s home page regarding the food additive petition process ( If you have any further questions regarding the GRAS notification program, you may contact Dr. Kathleen McAveney Jones by telephone at (202)418-3097, by telefax at (202)418-3131, or through electronic mail sent to

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

Alan M. Rulis, Ph.D.
Office of Food Additive Safety
Center for Food Safety and Applied Nutrition

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