Toxicological evaluation of some food additives including anticaking agents, antimicrobials, antioxidants, emulsifiers and thickening agents WHO FOOD ADDITIVES SERIES NO. 5 The evaluations contained in this publication were prepared by the Joint FAO/WHO Expert Committee on Food Additives which met in Geneva, 25 June - 4 July 19731 World Health Organization Geneva 1974 1 Seventeenth Report of the Joint FAO/WHO Expert Committee on Food Additives, Wld Hlth Org. techn. Rep. Ser., 1974, No. 539; FAO Nutrition Meetings Report Series, 1974, No. 53. POLYGLYCEROL ESTERS OF FATTY ACIDS Explanation These substances have been evaluated for acceptable daily intake by the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1, Ref. No. 13) in 1966. Since the previous evaluation, additional data have become available and are summarized and discussed in the following monograph. The previously published monograph has been expanded and is reproduced in its entirety below. BIOLOGICAL DATA BIOCHEMICAL ASPECTS The polyglycerol esters of fatty acids include a large group of closely related compounds of complex composition. However, the individual components are found as normal constituents of the human diet, i.e. glycerol, glycerol mono-, di- and tri-fatty acid esters and individual fatty acids, with the exceptions of the artificially produced polymers of glycerol, polymers of certain fatty acids and the actual separate esters between these polymers. These latter compounds represent the toxicologically important constituents. In vitro experiments on lipase digestion of polyglycerol esters showed a slower rate of digestion than that of olive oil and the ester did not affect the lipase digestion of olive oil (Unilever Research Laboratory, 1966). Digestibility or caloric utilization have been used to demonstrate metabolic conversion; 16 male and female rats were fed a diet containing 1% ground-nut oil and 9% polyglycerol ester or 10% groundnut oil (as control) for six and 12 weeks. Polyglycerol ester as an energy source was almost equivalent to ground-nut oil, as measured by growth rate. Digestibility was calculated as 92%. In another experiment rats were kept on a restricted food intake (18 calories/day) for 17 days. After realimentation With 9% polyglycerol ester and 1% ground-nut oil, no adverse effect was noted on the animals' ability to gain weight. Rats fed polyglycerol ester for 54 days as 9% of the diet showed no difference in composition of carcass fat, liver fat, liver free fatty acids and liver phosphorus when compared with groups fed 1% or 10% ground-nut oil in the diet. Liver vitamin A levels were unaffected. A polyglycerol ester was shown to be absorbed by intestinal lymphatics, and chylomicron counts showed normal lipaemia. Suspensions in water were more slowly absorbed and reduced the rate of gastric emptying compared with ground-nut oil. The serum cholesterol level of rats was unaffected by the presence of 10% polyglycerol ester in a 42% fat diet (Unilever Research Laboratory, 1966). Hydrolysis of the tri- and polyglycerol esters in vitro with fresh pancreatic juice plus bile showed that 89 to 98% of oleate esters were hydrolyzed. Eicosanoate compounds were hydrolyzed at a much slower rate than the oleate esters. The metabolic fate of polyglycerol esters in rat has been studied using fatty acid 14C-labelled (oleic acid and eicosanoic acid), tri- and polyglycerol esters. More than 90% of the 14C label of the triglycerol and approximately 40% of the polyglycerol was absorbed. Hydrolysis occurred mainly before absorption. 66 to 70% of the radioactivity from the oleic acid and 55% from the eicosanoic-labelled compounds appeared as respiratory CO2 during the test period (51 hours); most of the remaining activity being incorporated into the carcass. Rats fed polyglycerol esters labelled with 14C in the tri- or poly-glycerol moiety excreted the unchanged polymerized glycerol, primarily in the urine with less than 7% of the 14C label appearing in respiratory CO2 and the carcass (Michael & Coots, 1971). Weanling rats were fed each day a restricted 5 g basic diet supplemented with either 0, 0.5 or 1 g lard or 1 g polyglycerol ester of various molecular weights prepared from cotton-seed or peanut oil. After three weeks, the rats were placed on unrestricted diets containing polyglycerol or lard of 8% for a period of eight weeks. Weight gain of rats fed the polyglycerol ester was the same as those fed lard. Autopsy and histopathological examination of liver, kidneys and ileum showed no compound-related effects. No appreciable residues of polyglycerol esters were detected in the epididymal fat (Babayan et al., 1965). TOXICOLOGICAL STUDIES Acute toxicity Rat Rats given single doses of 7, 14 and 29 g/kg bw of a polyglycerol ester by intubation showed no signs of any toxic effect. Repeated dosing with 10 g/kg bw daily over five days caused no deaths. Rats, injected i.p. with 1, 3 and 7 g/kg bw, showed no adverse effects; single doses of 10 g/kg bw caused some peritoneal reaction but no deaths (Unilever Research Laboratory, 1966). Rabbit Rabbits dosed orally with 10-29 g/kg bw showed no toxic effects. Short-term studies Rat Thirteen rats maintained on 9% polyglycerol ester and 1% ground- nut oil for 17 weeks showed normal kidney function (Unilever Research Laboratory, 1966). Rats kept 22 weeks on 9% PGE + 1% ground-nut oil showed no difference in weights of liver, kidney, adrenal, spleen and testes when compared with controls on 10% ground-nut oil. Gross autopsy and histological examination of liver revealed no abnormalities (Unilever Research Laboratory, 1966). Groups each of 100 rats equally divided by sex were maintained on diets containing 0, 2.5, 5.0 or 10.0% of polyglycerol ester (deca-glycerol deca-oleate) for 90 days. There were no adverse effects on survival, growth, organ weights, body weight ratios and hematologic parameters. Urinary nitrogen values for female rats in the 10% group was significantly higher than controls at weeks three and nine of the study. Autopsy and microscopic examination of tissues did not show any compound-related effects. The percentage of dietary fatty acids absorbed, as measured by faecal fatty acids decreased as the level of polyglycerol ester increased in the diet (King et al., 1971). Rats were fed polyglycerol ester with a high melting point for eight months. No residues were detected in depot fat, or in fat of muscle, liver, kidney or spleen. When the esters were injected subcutaneously or intravenously, polyglycerol esters were detected in fatty deposits near the site of injection (Ostertag & Wurziger, 1965). Eight rats were maintained on a nutritionally adequate biscuit diet containing 15% of polyglycerol ester of fatty acids (Palsgaard No. 1016) for five weeks. No abnormalities attributable to the additive were apparent at autopsy and on histological examinations, the findings being as in a control group fed 15% of a vegetable oil in the diet (Briski, 1970). Long-term studies Mouse Groups of 25 male and 25 female mice were fed for 80 weeks on either polyglycerol ester or ground-nut oil at 5% in their diet. No adverse effect on body weight, food consumption, peripheral blood picture and survival rate were noted. Carcass fat of the test group showed no polyglycerol residues. The levels of free fatty acids, unsaponifiable material, fatty acid composition of carcass fat and organ weights were the same in test and control groups, except for the liver and kidney weights of female mice which were significantly higher. Microscopic examination of all major organs showed nothing remarkable (Unilever Research Laboratory, 1966). Rat A test group of 22 rats, with a control group of 28, were kept on a diet containing 1.5% of polyglycerol ester for three generations and maintained for over one year without significant variation in fertility and reproductive performance. Gross and histological examination of the third generation revealed no consistent abnormality related to the test substance (Unilever Research Laboratory, 1966).' In another experiment 28 male and 28 female rats were fed 5% polyglycerol ester or ground-nut oil in their diet for two years. No adverse effects on body weight, food consumption, peripheral blood picture, and survival rate were noted. Liver function tests and renal function tests at 59 and 104 weeks were comparable between groups. The carcass fat contained no polyglycerol and the levels of free fatty acid, unsaponifiable residue and fatty acid composition of carcass fat were no different from controls. Organ weights, tumour incidence and tumour distribution were similar in control and test groups. Complete histological examination of major organs showed nothing remarkable (Unilever Research Laboratory, 1966). Mice were maintained on a diet containing 1% of a polyglycerol ester emulsifier for a period of 15.5 months. There were no significant differences between growth rate and longevity of test and control animals, nor was there any indication of carcinogenic activity (Bickel et al., 1964). OBSERVATIONS IN MAN Thirty-seven volunteers, aged 19 to 24, were fed 2-20 g polyglycerol ester per day for three weeks in their diet. No abnormalities were detected in plasma proteins, serum amino-acids, thymol turbidity, serum bilirubin, total and free serum cholesterol, serum alkaline phosphatase, SGOT, SGPT, cholinesterase, cholesterol esterase, 24 hour urine volume, urinary creatinine, urea output, total and split faecal fat or total faecal nitrogen (Unilever Research Laboratory, 1966). Comments: The toxicological assessment of this group of diverse but related substances is based on an evaluation of satisfactory evidence for one member and assumes that alterations in the fatty acid distribution or polyglycerol content of individual members have no toxicological bearing and only affect the physical and emulsifying properties of each ester. The metabolic studies point to hydrolysis of these polyglycerol esters in the gastrointestinal tract and the utilization and digestibility studies justify the assumption that the fatty acid moiety is metabolized in the normal manner. Analytical studies have produced no evidence of cumulation of the polyglycerol moiety in body tissues. Human studies showed no adverse effects. It is desirable to have properly conducted biochemical studies on other members of this group, that do not conform to the specifications detailed above, particularly those containing short-chain fatty acids. EVALUATION Level causing no toxicological effect Rat: 50 000 ppm (5%) in the diet equivalent to 2500 mg/kg bw. Estimate of acceptable daily intake for man 0.25 mg/kg bw.* FURTHER WORK OR INFORMATION Desirable: Properly conducted biochemical studies on other members of this group that do not conform to the specifications already established, particularly those containing short-chain fatty acids. REFERENCES Babayan, V. K., Kaunitz, H. & Slanets, C. A. (1965) J. Amer. Oil Chem. Soc., 41, 434 Bickel, J., Therkelsen, A. J. & Stenderup, A. (1964) Arzneimittel Forsch., 14, 238 Briski, B. (1970) Unpublished report, Institute of Public Health of Croatia, Yugoslavia King, W. R., Michael, W. R. & Coots, R. H. (1971) Tox. Appl. Pharm., 20, 327 Michael, W. R. & Coots, R. H. (1971) Tox. Appl. Pharm., 20, 334 Ostertag, H. & Wurziger, J. (1965) Arzneimittel-Forsch., 15, 869 Unilever Research Laboratory (1966) Unpublished report * As polyglycerol esters of palmitic acid.
See Also: Toxicological Abbreviations Polyglycerol esters of fatty acids (FAO Nutrition Meetings Report Series 40abc) POLYGLYCEROL ESTERS OF FATTY ACIDS (JECFA Evaluation)