Evaluation of certain food additives.
This book is the outcome of a Joint Meeting of the WHO Core Assessment Group and FAP panel of experts on food additives at Geneva during June 8-17, 2004. The committee plays a vital role in the improvement of food safety on a global basis, and deliberates with a primary objective of recommending acceptable daily intakes (ADIs) and to prepare specifications for the identity and purity of food additives.
The contents are presented as follows: Introduction and General considerations followed by technical data on two classes of food additives viz., Flavouring agents, and Specific food additives other than flavouring agents. This is a toxicological monograph which describes the food additive in question, summarizes the toxicological data, and provides evaluation based on likely total human intake for each of these specific food additives, and recommends the ADIs. The first part deals with food additives such as benzyol peroxide, [alpha]-cyclodextrin, hexose oxidase, lutein, hydroxy ethylidine-1, 1-diphosphonic acide (HEDP), steviol glycosides, D-tagatose, xylanses from Bacillus subtilis, and zeaxanthin.
Most of the benzyol peroxide used in food processing is converted to benzoic acid, the committee considered the acceptability of small quantities of benzoic acid residues added to the diet. Further, the committee restated its conclusion from the previous meeting and opined that a maximum concentration of 100 mg/kg body weight (bw) of benzyol peroxide does not pose a safety concern. With regard to [alpha]-cyclodextrin, the short-term studies (28 and 90 days) showed low oral toxicity in both rats and dogs. At 20 per cent dietary dosages which correspond to 49.3 mg/kg bw/day in mice, 20 g/kg bw/day in rats and 5.9-7.5 g/kg bw/day in rabbits, [alpha]- cyclodextrin failed to induce any embryotoxicity and was non-teratogenic. The intended usage levels of cyclodextrin range from a maximum of 10 g/kg in non-alcoholic beverages to a maximum of 100 g/kg in bakery products. While toxicological data on hexose oxidase from Chondrus crispus expressed in Hansenula polymorphia and lutein from Tagetes erecta L. were evaluated, no ADIs were specified for these food additives. The committee has examined the safety aspects of antimicrobial solutions which are prepared from acetic acid and octanoic acid together with hydrogen peroxide using HEDP as a sequestrant or stabilizer and strongly opined that they would not pose a safety concem. In any case, HEDP does not pose a safety concern at the levels of residue which are expected to remain on food at the time of consumption.
The toxicological data on steviol glycosides which are natural constituents of the plant Stevia rebaudiana Bertoni, were also examined comprehensively. Following oral administration, steviol glycosides are poorly absorbed in both experimental animals and humans. Following review of the new data on the metabolism of stevioside in humans and its possible genotoxicity in vivo, the committee concluded that it was not genotoxic. While evidences showed beneficial pharmacological effects of stevioside in hypertensive or type 2 diabetes mellitus patients, the committee felt that no conclusive evidence was available to prove that such effects would also occur at lower levels of dietary exposure. Toxicological data available on D-tagatose, xyalnase from B. subtilis, and xyalnase from B. subtilis containing a modified xyalanse gene were also evaluated, although no ADIs were specified. In the category of specific food additives data on zeaxanthin, a naturally occurring xanthophyll pigment has also been evaluated. The oral [LD.sub.50] values for zeaxanthin were found to exceed 4000 mg/kg bw in rats and 8000 mg/kg in mice. No treatment related effects were reported in a 90 day study in rats at doses up to 1000 mg/kg bw per day. There was no treatment--related effects on a wide range of toxicological end points in monkeys administered zeaxanthin by gavage at 0.2-20 mg/kg bw per day in a 52 wk study. Based on non-genotoxic nature of the additive and negative results in developmental study, the committee felt no need for generation of data on carcinogenicity.
The second part is a small section which is dedicated to revision of specifications on aluminium powder, iron oxides and titanium oxides; aluminium lakes of colouring matters, hydroxypropyl/hydroxypropylmethyl cellulose, magnesium sulphate, polyvinyl alcohol and metal levels and arsenic specifications. For most of the compounds the existing specification were revised except for magnesium sulphate.
The third part deals with eight groups of flavouring agents such as pyridine, pyrrole and qunoline derivatives; aliphatic and alicyclic hydrocarbons; aliphatic, linear, unsaturated aldehydes, acids and related alcohols, acetals and related esters; monocyclic and bicyclic secondary alcohols, ketones and related esters; amino acid and related substances; tetrahydrofuran and furanone derivateives and Phenyl substituted aliphatic alcohols and related aldehydes and esters. While the committee recommended that none of the flavouring agents in this group would present safety concerns at estimated current intakes, new specifications and monograph were prepared for all of them.
The fourth part deals with safety aspects related to glycyrrhizinic acid, and its monoammonium salt as a natural constituent of liquorice and its use as a flavouring subastance in various food products. The absorption, distribution, biotransformation and excretion of glycyrrhizinic acid and monoammonium salt have been presented both in experimental animals and humans. Both glycyrrhizinic acid, and its hydrolysis product have been shown to be largely confined to the plasma, bound to serum albumin and are not taken up in tissues to significant extent. The oral [LD.sub.50] values of glycyrrhizinic acid and its various salts in mice, guineapigs and dogs are reported to be in the range of 308-12,700 mg/kg bw. Short-term toxicity studies have shown effects in mice and rats which are related to mineralocorticosteroid excess. Long-term studies (96 wk) in mice have shown no dose-related increase in the incidence of tumours up to 229 mg/kg bw per day in males. Further, the exposure to glycyrrhizinic acid through consumption of liquorice confectionery was also assessed and the estimated intakes were in the range of 5-50 mg/day with a maximum of 100-300 mg/day. The committee suggested that an intake of 100 mg/day would be unlikely to cause any adverse effect in the majority of adults. However, there exists a sensitive subset of the population who appears to show signs of pseudohyperaldosteronism at lower exposures than those which produce effects in the general population.
This report series has four important annexures at the end. In Annex 1 the committees enlists the various reports and other documents resulting from previous meetings of the Joint FAO/WHO Expert Committee on Food Additives. This section has listed 172 such documents. This is followed by Annex 2 which lists the acceptable daily intakes and other toxicological information and information on specification of various food additives dealt in this meeting. In Annex 3 specific details on further information required or desired by the committee have been listed. This has special reference to magnesium sulphate, steviol glycosides, and zeaxanthin-rich extrct from Tagetes erecta L. In Annex 4, summary of the safety evaluation of secondary components of flavouring agents with minimum assay values of less than 95 per cent have been provided.
In conclusion, this is an excellent reference book and presents a complete insight on the toxicological data of specific food additives, their intended usage pattern and possible human exposure, and provides a complete bibliography. It is a well documented report which should come handy to all toxicologists, scientists involved in regulatory agencies and a good guide to those who are engaged in basic research on specific food additives. Further, it is a welcome addition to food scientists and libraries of research institutions dealing with issues on contemporary food additives.
Department of Biochemistry & Nutrition
Central Food Technological Research Institute
Mysore 570020, India
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|Publication:||Indian Journal of Medical Research|
|Article Type:||Book review|
|Date:||Jun 1, 2007|
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