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U.S. Department of Health and Human Services

Database of Select Committee on GRAS Substances (SCOGS) Reviews

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Report No.:  23
Type of Conclusion:  2
ID Code:  9002-18-0
Year:  1973
CFR Section:  184.1115
SCOGS Opinion:  Agar-agar has relatively little effect when added to the diets of animals in amounts considerably greater than those present in the human diet. The observed increases in intestinal weight and length in animals appear to be related to the bulking and hydrocolloidal properties of the material, and these changes occur only at relatively high concentrations of agar-agar. Although no specific studies of the carcinogenicity or other long-term investigtions of agar-agar have been made, this material has a long history of use as a gelling agent and bulk component of experimental animal diets. Because 2 to 5 percent of this material has been used routinely in control diets in numerous studies witout reported significant effects, it is reasonable to conclude that even at these high levels, agar-agar produces no significant chronic effects. However, there is one report that agar-agar, fed at relatively high levels (400 to 1570 mg per kg per day), is lethal to many pregnant mice and rabbits but not to pregnant rats and hamsters fed at equivalent levels (650 to 1140 mg per kg per day). Significant numbers of material deaths occurred in pregnant mice and rabbits fed agar-agar at levels 110 fold greater (mice) and 30 fold greater (rabbits), than the maximum level estimated to be consumed by adults (13.2 mg per kg per day) in the daily diet, but no toxic effects were observed in pregnant mice and rabbits fed levels 25 fold greater (mice) and 9 fold greater (rabbits) than the estimated adult human intake level. With respect to these comparisons it should be emphasized that the Select Committee believes the intake estimate of 13.2 mg per kg per day (Table II) is overstated by a considerable margin, which could make the foregoing differences in each case even larger. It is noteworthy that similar toxic effects have been observed in identical tests on a number of other polysacchardies (gum arabic, sterculia gum, carob bean gum, guar gum, gum ghatti, gum tragacanth, carrageenan, propylene glycol alginate, and methyl cellulose) fed at very high levels. The relative sensitivity of the seveeral 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 harzard. Agar-agar is a product extracted from marine algae. The possibility exists that harmful concentrations of certain metals such as mercury, may be accumulated in the commercial product if algae are harvested from coastal waters contaminated with significant levels of such heavy metals (26). Current specifications for food grade agar-agar (4) place a limitation on the content of "heavy metals as lead." Because modern methods of analysis are capable of distinguishing between and measuring the amounts of the several metal elements, it would appear advisable to make the specifications for agar-agar more specific with respoect to allowable concentrations of potentially toxic heavy metals, such as mercury. The Select Committee has weighed the foregoing and concludes that: There is no evidence in the available information on agar-agar 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.