Cellulose is a major constituent of many foods of plant origin. As such it is a significant portion of the diet, but is neither degraded nor absorbed. Cellulose derivatives considered in this report are virtually unabsorbed and little or no degradation of absorbed and little or no degradation of absorbable products occurs in the human digestive tract. In man, consumption of large amounts appears to have no effect other than providing dietary bulk, reducing the nutritive value of such foodstuffs and possibly exerting a laxative effect. However, the existence of certain data and the different categorization of cellulose and the several cellulose derivatives on the GRAS list suggest that the Select Committee should render a separate opinion on each substance considered in this report.
A. CELLULOSE, MICROCRYSTALLINE CELLULOSE
Although pure cellulose and regenerated cellulose, including microcrystalline cellulose are not on the GRAS list, there is nothing in the available information to suggest that such forms of cellulose have significantly different biological properties that distinguish these forms of cellulose from those currently considered as GRAS or from naturally occurring cellulose. In view of the foregoing, the Select Committee concludes that: There is no evidence in the available information on pure and regenerated cellulose, including microcrystalline cellulose, 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 future.
B. METHYL CELLULOSE
In humans, virtually 100 percent of orally ingested methyl cellulose can be recovered in the feces withihn four days, indicating that absorption does not occur. However, in pregnant mice, very high doses of methyl cellulose, while not teratogenic, cause a significant increase in maternal mortality and retardation of fetal maturation. Such increased maternal and fetal toxicity does not occur at a dose of methyl cellulose which is 26-fold (or more) greater than that estimated to be the average daily adult dietary intake. It is noteworthy in this regard that similar toxic effects have been observed in identical tests performed by the same investigators on a large number of other polysaccharides fed at very high doses. The relative sensitivity of the several animal species to these effects varies, depending on the particular polysaccharide tested, but in all cases very large doses are required. Until these effects have been adequately explained, it appears to be inappropriate to conclude that unrestricted use of such substances in food would be without hazard. In the light of the foregoing, the Select Committee concludes that: There is no evidence in the available information on methyl cellulose that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when it is used at levels that are now current and in the manner now practiced. However, it is not possible to determine, without additional data, whether a significant increase in consumption would constitute a dietary hazard.
C. CARBOXYMETHYL CELLULOSE
Carboxymethyl cellulose is converted spontaneously to a salt in alkaline solution, and it is probable that the distinction between carboxymethyl cellulose and its salts is artificial. However, carboxymethyl cellulose is liested as GRAS as a substance migrating to food from cotton or cotton fabrice used in dry foods packaging, while its sodium salt is listed as GRAS as a miscellaneous or general purpose food additive. In view of the separate listing of carboxymethyl cellulose, the Select Committee concludes that: There is no evidence in the available information on carboxymethyl cellulose that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when it is used in dry food packaing materials originating from cotton or cotton fabrics as now practed or as it might reasonably be expected to be used for such purposes in future.
D. SODIUM CARBOXYMETHYL CELLULOSE
Despite the probable lack of distinction between sodium carboxy methyl cellulose and its parent compound, carboxymethyl cellulose, only the sodium carboxymethyl cellulose is GRAS as a miscellaneous and general purpose food additive. As such, there are no data that suggest it reacts differently than pure and regenerated cellulose or carboxymethyl cellulose. In view of the foregoing the Select Committee concludes that: There is no evidence in the available information on sodium carboxymethyl cellulose that demonstrtes, or suggests reasonable grounds to suspect, a hazard to the public when it is used at levels that are now current or that might reasonably be expected in future.
E. HYDROXYPROPYLMETHYL CELLULOSE
Hydroxypropylmethyl cellulose is not listed as GRAS. It is a food additive used as a thickening agent, stabilizer and emulsifier. Hydroxypropylmethyl cellulose is sinthesized from methyl cellulose by the action of alkali and propylene oxide. There are no data available to suggest that hydroxypropylmethyl cellulose possesses adverse health effects; however, teratology studies dimilar to those conducted with mehtyl cellulose are not available for its hydroxypropyl derivative. Therefore, it is suggested that, in due course, appropriate studies should be conducted with hydroxypropylmethyl cellulose. The Select Committee has weighed the foregoing and concludes that: There is no evidence in the available information on hydroxypropylmethyl cellulose that demonstrates, or suggested reasonable grounds to suspect, a hazard to the public when it is used at levels that are now current and in the manner now practiced (21 CFR 121.1021)
F. ETHYL CELLULOSE AND CELLULOSE ACETATE
There is a paucity of data concerning possible adverse health effects of ethyl cellulose and cellulose acetate. both are included in the GRAS list as substances migrating to food from paper or paperboard products used in food packaging. According to the NRC survey (6), very small amounts of ethyl cellulose also appear to be used in hard candy and chewing gum. In the GRAS context, the quantity of ethyl cellulose or cellulose acetate migrating to foods from packaging would be orders of magnitude below the levels of cellulose and cellulose derivaties now known to occur in foods. In the light of the foregoing, the Select Committee concludes that: There is no evidence in the available information on ethyl cellulose and cellulose acetate that demonstrates, or suggests reasonable grounds to suspect, a hazard to the public when they are used in food packaging materials as now practiced or as they might be expeccted to be used for such purposes in future.