[Federal Register Volume 61, Number 165 (Friday, August 23, 1996)]
[Rules and Regulations]
[Pages 43451-43454]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-21529]


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DEPARTMENT OF HEALTH AND HUMAN SERVICES
21 CFR Part 584

[Docket No. 95G-0039]


Food Substances Affirmed As Generally Recognized As Safe In Feed 
and Drinking Water of Animals; Hydrophobic Silica

AGENCY: Food and Drug Administration, HHS.

ACTION: Final rule.

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SUMMARY: The Food and Drug Administration (FDA) is amending its 
regulations for the listing of specific substances affirmed as 
generally recognized as safe (GRAS) in the feed and drinking water of 
animals and to provide that hydrophobic silica be affirmed as GRAS when 
used as an anticaking/free-flowing agent in vitamin preparations for 
animal feed. This action is in response to a petition filed by Degussa 
Corp.

EFFECTIVE DATE: August 23, 1996.

FOR FURTHER INFORMATION CONTACT: Sharon A. Benz, Center for Veterinary 
Medicine (HFV-226), Food and Drug Administration, 7500 Standish Pl., 
Rockville, MD 20855, 301-594-1729.

SUPPLEMENTARY INFORMATION:

I. Background

    In a notice published in the Federal Register of March 21, 1995 (60 
FR 14950), FDA announced that a GRAS affirmation petition for animal 
use (GRASP 2419) had been filed by Degussa Corp., c/o Counsel for 
Petitioner, Jerome H. Heckman, Keller and Heckman, 1001 G St. NW., 
suite 500 West, Washington, DC 20001. This petition proposes that part 
584 (21 CFR part 584) be amended to provide that hydrophobic silica, 
prepared by the hydrophobization of silicon dioxide with 
dichlorodimethylsilane, be affirmed as GRAS as an anticaking/free-
flowing agent in vitamin preparations for animal feed. FDA gave 
interested persons until June 5, 1995, to submit comments. FDA did not 
receive any comments in response to that notice.

II. Standards for GRAS Affirmation

    Under Sec. 570.30 (21 CFR 570.30), general recognition of safety of 
food ingredients may be based only on the views of experts qualified by 
scientific training and experience to evaluate the safety of food 
substances. The basis of such views may be either: (1) Scientific 
procedures, or (2) in the case of a substance used in food prior to 
January 1, 1958, through experience based on common use in food. 
General recognition of safety based upon scientific procedures requires 
the same quantity and quality of scientific evidence as is required to 
obtain approval of a food additive regulation for the ingredient and 
ordinarily is to be based upon published studies, which may be 
corroborated by unpublished studies and other data and information 
(Sec. 570.30(b)). General recognition of safety through experience 
based on common use of a substance in food prior to January 1, 1958, 
may be determined without the quantity or quality of scientific 
evidence required for approval of a food additive regulation; but 
ordinarily it is to be based upon generally available data and 
information concerning its pre-1958 history of use (Sec. 570.30(c)).
    The subject petition relies on scientific procedures evidence to 
support GRAS affirmation of hydrophobic silica in vitamin preparations 
for animal feed.

III. Safety Evaluation

A. Manufacturing Process

    According to the information in the petition, hydrophobic silica is 
manufactured from fumed amorphous silicon dioxide or precipitated 
silica by chemical reaction (methylation) of the

[[Page 43452]]

surface of the silicon dioxide particle with the methylating agent, 
dichlorodimethylsilane. The dichlorodimethylsilane is mixed with a 
slurry of silicon dioxide and reacts with most of the silanol groups (-
Si-OH) on the surface of the particle and converts them to methylsilyl 
groups (-Si-CH3). The methylation reaction occurs only at the 
surface of the silicon dioxide particle leaving 97 to 99 percent of the 
silicon dioxide intact. Thus, the particle of hydrophobic silica may be 
viewed as being composed of silicon dioxide with a surface of 
dimethylpolysiloxane ((CH3)2SiOSi(CH3)2).
    After further processing, the resulting hydrophobic silica 
generally contains 97 to 99 percent silicon dioxide. Fumed hydrophobic 
silicas generally contain greater than 99 percent silicon dioxide and 
precipitated hydrophobic silica contain greater than 97 percent silicon 
dioxide.
    Silicas used in the production of hydrophobic silica will be food-
grade and meet the requirements for purity as defined in the Food 
Chemical Codex, 3d edition, and the U.S. Pharmacopoeia and National 
Formulary XVII. The specifications for hydrophobic silica are those for 
silicon dioxide in the Food Chemical Codex, with the exception of a 
specification for not more than 50 parts per million (ppm) of 
dichlorodimethylsilane.

B. Uses of Hydrophobic Silica

    The proposed use of hydrophobic silica is as an anticaking/free-
flow agent in vitamin preparations for animal feed, as described in 21 
CFR 170.3(o)(1). Anticaking agents are processing aids used to impart 
noncaking, free-flowing properties to dry foods by decreasing adhesion 
forces between particles of materials to which they are added. 
Anticaking agents are commonly used in many foods, such as salt, 
spices, cereals, and sugars, and in complete animal feeds and feed 
ingredients in a manner similar to human foods.
    The methylation of the surface of the silicon dioxide particle only 
serves to render the particle surface of silicon dioxide hydrophobic. 
The increased hydrophobicity of the particle surface allows hydrophobic 
silica to act as anticaking and free-flow agents for hydrophobic 
substances, such as vitamin A preparations. The individual vitamin 
particles are coated with silica, which prevents caking and provides 
free-flow characteristics.
    Information supplied by the petitioner evidences that silicas and 
silicates have been used as direct food and feed ingredients for 
several decades. Silicon in the form of silicon dioxide is commonly 
used as an anticaking agent in various feed ingredients and complete 
feeds (21 CFR 573.940). Other silicates including silica aerogel (21 
CFR 582.1711); aluminum calcium silicate (21 CFR 582.2122); calcium 
silicate (21 CFR 582.2227); magnesium silicate (21 CFR 582.2437); 
sodium aluminosilicate (21 CFR 582.2727); hydrated sodium calcium 
aluminosilicate (21 CFR 582.2729); and tricalcium silicate (21 CFR 
582.2906) are recognized as GRAS as anticaking agents and have a 
history of use in the feed industry as such.
    The petition proposes that hydrophobic silica should not be used at 
levels greater than 5 percent in the vitamin preparation. This would 
result in no more than 1.5 ppm of hydrophobic silica in the finished 
feed. Other silicates are commonly used at levels 2 to 2.5 percent or 
2,000 ppm in finished feeds. The proposed use of hydrophobic silica is 
not expected to significantly contribute to the consumption of silicate 
by animals.

C. General Recognition of Safety of Silicates

    The petition provides information to support a determination that 
the use of hydrophobic silica is GRAS based upon the existence of an 
expert consensus that the components of hydrophobic silica have been 
shown to be safe based on scientific procedures and that the safety 
characteristics of the components can be extended to the product, 
hydrophobic silica. Foremost in the support of safety is published 
information indicating that similar silicate compounds are nontoxic at 
current levels used in food and feed, and that the inherent safety of 
silicon dioxide is not changed by making the surface portion 
hydrophobic because the toxicological profile is essentially the same 
as commonly used silicas.
    Both silicon dioxide and dimethylpolysiloxane have been widely used 
for years in the food, feed, pharmaceutical and dental industries. 
Information in the petition shows that the food safety of silicas has 
been evaluated by numerous scientific panels. These panels include the 
Select Committee on GRAS Substances of the Federation of the American 
Society for Experimental Biology (the Select Committee) that reviewed 
the use, exposure, and safety of silicas and silicates in 1979. This 
committee concluded that the absorption of ingested silicas is limited 
by its solubility in the contents of the alimentary canal and the 
absorbability of silicon dioxide appears to be slight. Further, the 
Select Committee concluded that silicon dioxide and various silicates 
occur abundantly in the earth's crust and are present in practically 
all natural waters, animals, and plants; they are part of the normal 
diet, and silicon compounds consumed as added food ingredients 
constitute only a minor proportion of the total dietary silicon intake 
(Ref. 1).
    The Select Committee also reviewed the properties, uses, and safety 
of methylpolysilicones for use as direct food ingredients in 1981, and 
it concluded that methylpolysilicones (also called 
dimethylpolysiloxane) used in food consist of high molecular weight 
compounds that are not absorbed to any appreciable extent from the 
gastrointestinal tract and have been demonstrated to be of low acute 
and chronic toxicity to animals and man. Moreover, the Select Committee 
also recognized the medical use of dimethylpolysiloxane as dimethicone 
and simethicone. Simethicone is widely used in over-the-counter drugs 
as an antiflatulence ingredient, and as such, is generally recognized 
as safe and effective (21 CFR 332.10) (Ref. 2).
    The Scientific Committee for Food of the Commission of European 
Committees, which reviewed the safety of silicates and silicon dioxides 
in 1991, concluded that available published data on orally administered 
silica and silicates, including amorphous silicon dioxide, substantiate 
the biological inertness of these compounds. It also concluded that 
silicates and silicones are sufficiently safe so that a restriction on 
their use is not required nor is the establishment of an acceptable 
daily intake (Ref. 3).
    The Food and Agriculture Organization/World Health Organization 
(FAO/WHO) Joint Expert Committee on Food Additives reached the same 
conclusion as the Scientific Committee for the European Communities and 
also determined that an acceptable daily intake was not necessary (Ref. 
4).

D. Corroborating Evidence of Safety of Hydrophobic Silica

    The petitioner also submitted relevant toxicological data that 
supports the safety of hydrophobic silica to man and animals. The 
submitted information is an article in the published literature 
entitled ``Characterization and Toxicological Behavior of Synthetic 
Amorphous Hydrophobic Silica'' (Ref. 5). The results reported from 
testing indicate that fumed or precipitated hydrophobic silica does not 
produce inflammation of the skin or mucous membranes, and acute and 
chronic oral tests yielded no adverse systemic effects. The submitted 
information

[[Page 43453]]

indicates that hydrophobic silica is nontoxic and the lack of toxicity 
is related to hydrophobic silica's nonabsorbability. The toxicological 
profile was essentially the same as similar GRAS silicates.

IV. Conclusion

    The agency has determined that the petition provides information to 
support a determination that the use of hydrophobic silica is GRAS 
based upon the existence of an expert consensus that the components of 
hydrophobic silica have been shown to be safe based on scientific 
procedures and that the safety characteristics of the components apply 
to the product, hydrophobic silica. Foremost in the support of safety 
is published information indicating that similar silicate compounds are 
safe at current levels used in food and feed and that the inherent 
safety of silicon dioxide is not changed when the particle surface is 
altered by methylation. Corroborating evidence has shown that the 
toxicological profile for hydrophobic silica is essentially the same as 
commonly used silicas. Therefore, the agency is affirming that 
hydrophobic silica when used as an anticaking/free-flowing agent in 
vitamin preparations for animal feed is GRAS when used in accordance 
with good manufacturing or feeding practices at levels not to exceed 5 
percent of the vitamin preparation.

V. Analysis of Impacts

    FDA has examined the impacts of the final rule under Executive 
Order 12866 and the Regulatory Flexibility Act (Pub. L. 96-354). 
Executive Order 12866 directs agencies to assess all costs and benefits 
of available regulatory alternatives and, when regulation is necessary, 
to select regulatory approaches that maximize net benefits (including 
potential economic, environmental, public health and safety, and other 
advantages; distributive impacts; and equity). The agency believes that 
this final rule is consistent with the regulatory philosophy and 
principles identified in the Executive Order. In addition, the final 
rule is not a significant regulatory action as defined by the Executive 
Order and so is not subject to review under the Executive Order.
    The Regulatory Flexibility Act requires agencies to analyze 
regulatory options that would minimize any significant impact on small 
entities. Because no current activity is prohibited by this final rule, 
the compliance cost to firms is zero. Because no increase in the health 
risks faced by consumers will result from this final rule, total costs 
are also zero. Potential benefits include wider use of this substance 
because of reduced uncertainty concerning its GRAS status, and any 
resources saved by eliminating the need to prepare further petitions to 
affirm the GRAS status of this substance for this use. The agency 
certifies that the final rule will not have a significant economic 
impact on a substantial number of small entities. Therefore, under the 
Regulatory Flexibility Act, no further analysis is required.

VI. Environmental Impact

    The agency has carefully considered the potential environmental 
effects of this action. FDA has concluded that the action will not have 
a significant impact on the human environment, and that an 
environmental impact statement is not required. The agency's finding of 
no significant impact and the evidence supporting that finding, 
contained in an environmental assessment, may be seen in the Dockets 
Management Branch (HFA-305), Food and Drug Administration, 12420 
Parklawn Dr., rm. 1-23, Rockville, MD 20857, between 9 a.m. and 4 p.m., 
Monday through Friday.

VII. Effective Date

    As this rule recognizes an exemption from the food additive 
definition in the Federal Food, Drug, and Cosmetic Act, and from the 
approval requirements applicable to food additives, no delay in 
effective date is required by the Administrative Procedure Act, 5 
U.S.C. 553(d). The rule will therefore be effective immediately (5 
U.S.C. 553(d)(1)).

VIII. References

    The following references have been placed on display in the Dockets 
Management Branch (address above) and may be seen by interested persons 
between 9 a.m. and 4 p.m., Monday through Friday.
    1. GRASP 2419, Appendix 11, ``Evaluation of the Health Aspects 
of Certain Silicates as Food Ingredients: Report of the Select 
Committee on GRAS Substances.''
    2. GRASP 2419, Appendix 12, ``Evaluation of the Health Aspects 
of Methylpolysilicones as Food Ingredients: Report of the Select 
Committee on GRAS Substances.''
    3. GRASP 2419, Appendix 10, ``Report on Silicates and Silicon 
Dioxide: The Scientific Committee for Food of the Commission of the 
European Communities.''
    4. GRASP 2419, Appendix 13, ``Evaluation Status of Silicon 
Dioxide (JECFA);'' ``FAO/WHO Food Additives Data System;'' ``FAO 
Food and Nutrition Paper,'' vol. 30/Rev. 1, 1985; ``Evaluations of 
the Joint FAO/WHO Expert Committee on Food Additives,'' 1956-1984.
    5. GRASP 2419, Appendix 6, ``Characterization and Toxicological 
Behavior of Synthetic Amorphous Hydrophobic Silica.''

List of Subjects in 21 CFR Part 584

    Animal feeds, Food additives.

    Therefore, under the Federal Food, Drug, and Cosmetic Act and under 
authority delegated to the Commissioner of Food and Drugs, 21 CFR part 
584 is amended as follows:

PART 584--FOOD SUBSTANCES AFFIRMED AS GENERALLY RECOGNIZED AS SAFE 
IN FEED AND DRINKING WATER OF ANIMALS

    1. The authority citation for 21 CFR part 584 continues to read as 
follows:

    Authority: Secs. 201, 402, 409, 701 of the Federal Food, Drug, 
and Cosmetic Act (21 U.S.C. 321, 342, 348, 371).

    2. New Sec. 584.700 is added to subpart B to read as follows:


Sec. 584.700  Hydrophobic silicas.

    (a) Product. Amorphous fumed hydrophobic silica or precipitated 
hydrophobic silica (CAS Reg. No. 68611-44-9, silane, dichlorodimethyl-, 
reaction products with silica).
    (b) Conditions of use. An anticaking/free-flow agent in vitamin 
preparations for animal feed.
    (c) Limitations. Not to exceed 5 percent in the vitamin 
preparation. It shall be used in accordance with good manufacturing or 
feeding practices. It must be of purity suitable for intended use, and 
it must comply with the following specifications:
    (i) Amorphous fumed hydrophobic silica: Not less than 99.0 percent 
silicon dioxide after ignition. Not more than 3 ppm arsenic. Not more 
than 0.003 percent heavy metals (as lead). Not more than 10 ppm lead. 
Not more than 2.5 percent loss on drying. Not more than 2 percent loss 
on ignition after drying. Not more than 1 percent insoluble substances. 
Not more than 50 parts per million dichlorodimethylsilane.
    (ii) Precipated hydrophobic silica: Not less than 94.0 percent 
silicon dioxide after ignition. Not more than 3 ppm arsenic. Not more 
than 0.003 percent heavy metals (as lead). Not more than 10 ppm lead. 
Not more than 7 percent loss on drying. Not more than 8.5 percent loss 
on
ignition after drying. Not more than 5 percent soluble ionizable salts 
(as sodium sulfate). Not more than 1 percent insoluble substances. Not 
more than 50 parts per million dichlorodimethylsilane.


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    Dated: August 18, 1996.
Stephen F. Sundlof,
Director, Center for Veterinary Medicine.
[FR Doc. 96-21529 Filed 8-22-96; 8:45 am]
BILLING CODE 4160-01-F