PROPYLENE GLYCOL ALGINATE First draft prepared by Dr G.J.A. Speijers and Mrs M.E. van Apeldoorn National Institute of Public Health and Environmental Protection Laboratory for Toxicology Bilthoven, The Netherlands 1. EXPLANATION Alginates are polyuronic acids which are major components of the cell walls of brown seaweed. Brown seaweeds have been used in food and feed for centuries but it is only since 1929 that alginates have been manufactured on an industrial scale. Alginates have valuable rheological properties which can be varied to a great extent by varying the degree of polymerisation of the polysaccharide or by changing the ionic environment. Thus alginates can provide solutions having a range of viscosities or gels of varying rigidities which may be used as texture modifiers in a wide range of food and industrial applications (Martin, 1986). Propylene glycol alginate is a reaction product of propylene oxide and alginic acid (Steiner & McNeely, 1951). This substance was evaluated at the thirteenth, fifteenth, and seventeenth meetings of the Committee (Annex 1, references 19, 26, and 32). At the seventeenth meeting an ADI for propylene glycol alginate of 0-25 mg/kg bw was allocated, based on a NOEL of 2 500 mg/kg bw/day in a long-term toxicity study in rats. At that meeting the Committee concluded that only the propylene glycol moiety is absorbed and metabolized, and that the alginate moiety is excreted unchanged in the faeces of rats and mice. Accordingly, the Committee decided that the contribution of propylene glycol alginate to total dietary propylene glycol intake from all sources should be included in the ADI for propylene glycol, which was allocated an ADI of 0-25 mg/kg bw (Annex 1, reference 32). Alginic acid and its ammonium, calcium, potassium, and sodium salts were evaluated by the Committee at its thirty-ninth meeting (Annex 1, reference 101) when a group ADI "not specified" was allocated. At its present meeting, the Committee evaluated new data from a 30-day study in rats, genotoxicity assays, a teratogenicity study in rabbits and a study in human volunteers. The previously published monographs have been expanded and are reproduced in their entirety below. 2. BIOLOGICAL DATA 2.1 Biochemical aspects 2.1.1 Absorption, distribution and excretion. In vitro hydrolysis studies with propylene glycol alginate in simulated gastric juice and simulated intestinal juice showed no hydrolysis in simulated gastric juice, while intestinal juice hydrolyzed 25% in 4 hours, 65% in 12 hours and 80% in 24 hours (McNeely & Shepherd, 1966). Five grams of propylene glycol alginate/kg bw (as a 10% aqueous solution), labeled with 14C in the alginate moiety, or 1 g of propylene glycol alginate/kg bw (as a 5% aqueous solution), labeled with 14C in the propylene glycol moiety, was administered as a single dose to mice (8/group) by gavage. Absorption, distribution and excretion of radioactivity were followed from 1 hour to 5 days after administration by whole body autoradiography. Some, but not all, of the label (labeled in the propylene glycol moiety) in a single dose of 1 g propylene glycol alginate/kg bw was absorbed. The unabsorbed portion was excreted in the faeces within 3 days while the absorbed radioactivity was distributed rapidly over the whole body, was concentrated in the liver and was completely removed from all tissues in 3-4 days. These findings are consistent with the fate of absorbed radioactivity from labeled free propylene glycol and its metabolites. Five days after administration of 5 g propylene glycol alginate (labeled in the alginate moiety)/kg bw traces of radioactivity were still noted in the rectum. It was concluded that released propylene glycol was absorbed and metabolized by the usual pathways (to acetate, lactate or glycogen) and had disappeared completely from the body after five days. The alginate moiety and the unhydrolyzed propylene glycol alginate were not absorbed from the gastrointestinal tract, but excreted in the faeces (Sharratt & Dearn, 1972). 2.1.2 Biotransformation No information available. 2.1.3 Effects on enzymes and other biochemical parameters No information available. 2.2 Toxicological studies 2.2.1 Acute toxicity studies The results of acute toxicity studies with propylene glycol alginate are summarized in Table 1. Table 1. Acute toxicity studies - propylene glycol alginate Animal Route LD50 Reference (mg/kg bw) mouse oral 7 800 FDRL, 1976 rat oral 7 200 FDRL, 1976 hamster oral 7 000 FDRL, 1976 rabbit oral 7 600 FDRL, 1976 2.2.1.1 Rats Groups of 60 rats were dosed with 5 g/kg bw propylene glycol alginate by gavage or were fed a diet containing 50 to 70% propylene glycol alginate for 24 hours. No adverse effects were observed. Autopsy 14 days after treatment did not reveal compound-related abnormalities (Woodard Res. Corp., 1972). Rats given 10 g propylene glycol alginate/kg bw orally as a suspension in corn oil showed a transient depression. No other effects were noted (Newell & Maxwell, 1972). 2.2.1.2 Rabbits Rabbits receiving an application of propylene glycol alginate as an aqueous paste on abraded skin or receiving an ocular application of dry powdered propylene glycol alginate did not reveal signs of irritation (Woodard Res. Corp., 1972). Rabbits injected intravenously, intraperitoneally, intramuscularly or subcutaneously with 6.2, 12.5 or 25 mg propylene glycol alginate/kg bw showed neither effects at the injection site nor any systemic effects (Steiner & McNeely, 1951). Rabbits injected subcutaneously or intramuscularly with up to 2 ml of a sterile aqueous 2% solution of propylene glycol alginate did not show gross or histological abnormalities at the injection site. Intraperitoneal and intravenous injections of similar amounts did not produce abnormal systemic effects (Ouer et al., 1935). 2.2.2 Short-term toxicity studies 2.2.2.1 Rats Two groups of 6 female rats received a diet containing 21.5% propylene glycol alginate and 21.5% glucose or a normal diet containing 21.5% glucose for 4 weeks. After 4 weeks of treatment 2 animals/group were killed and the remaining 4 animals/group received a normal diet for an additional 4 weeks. Thereafter the original control group received a diet containing 21.5% propylene glycol alginate and the original test group received a control diet for 2 weeks. The test group showed slight growth retardation but appearance and behaviour were normal. Faeces of the test group were slimy. Histopathogy of liver, kidneys and intestine of the 2 animals/group that were killed after the initial 4 weeks treatment time did not reveal abnormalities (MRCL, 1951). Fifteen male rats received 5% (w/w) propylene glycol alginate in the diet for 30 days. No diarrhoea was seen and bowel habit was normal. Urinalysis did not reveal abnormalities. All rats showed distension of the caecum, 5 rats showed distension of a portion of the ileum. Twelve rats showed distension of the colon to some degree, with soft contents. Soft ill-formed faecal pellets were seen in 10 rats. No further macroscopic changes were seen. Histopathology was not carried out (Anderson et al., 1991). 2.2.2.2 Guinea-pigs Four groups of 3 guinea-pigs received 0, 5, 10 or 15% propylene glycol alginate in their diet for 26 weeks. Body weight gain was reduced in test groups but mean food intake was similar to controls. Histopathology of various organs revealed no significant lesions (Nilson & Wagner, 1951). 2.2.2.3 Cats Eight experimental cats and one control cat were fed 0, 5, 10 or 15% propylene glycol alginate in a diet of dog food and canned salmon daily for 88-111 days. Test animals had difficulties in swallowing and eating because of the physical texture of the diet. The animals could not eat more than 100 g dog food and 30 g canned salmon/day and thus lost weight. At dietary levels of 10 and 15% the cats showed frequent soft stools. Macroscopy and microscopy did not reveal abnormalities (no details) (Nilson and Wagner, 1951). 2.2.2.4 Chickens 4 Groups of 13-day old chickens (number/group unknown) received 0, 5, 10 or 15% propylene glycol alginate in their diet for 3-7 weeks. At all dose levels growth rate was reduced due to difficulties with the diet. Histopathology showed slight transient tissue changes in controls as well as test animals (no details) (Nilson & Wagner, 1951). 2.2.2.5 Dogs Three groups of 3 male and 3 female Beagle dogs received a diet containing 0, 5 or 15% propylene glycol alginate for one year. Stool conditions were variable at the 15% dietary level. Weight gain and food consumption were normal. No effects on haematological (no details) parameters or serum urea nitrogen, serum alkaline phosphatase, blood glucose or urinalysis (no details) were seen. Organ weights (10) were comparable to controls. Histopathology (21 tissues) did not reveal compound-related changes (Woodard, 1959). 2.2.3 Long-term toxicity/carcinogenicity studies 2.2.3.1 Mice Four groups of 10 mice (bw 12-18 g) received 0, 5, 15 or 25% propylene glycol alginate in their diet for 12 months. At week 39 one control mouse and one mouse of the group fed 15% in their diet were killed. In the 25% group, increased mortality, a decreased maximum body weight, decreased food intake and increased water consumption were seen. At the 15% dose level a slightly decreased maximum body weight and a slightly decreased food intake were seen. The effects were probably due to increased water absorption of the diet which caused enough bulk to limit food intake (Nilson & Wagner, 1951). 2.2.3.2 Rats Four groups of 10 male and 10 female rats (age 4 weeks) received during their life span 0, 5, 15 or 25% propylene glycol alginate in their diet. At dose-levels of 15 and 25% in the diet lifespan was slightly reduced and decreased food consumption was seen. Death of rats in control as well as test groups was usually due to myocardial fibrosis, pneumonia and the multiplicity of cumulative processes associated with aging. There were no lesions attributed to toxaemia or to local irritative intestinal effects. The bulky diets caused loose and smeary faeces and weight gain was reduced, probably due to inanition. Organ weights were not determined. Histopathology of major tissues (liver, kidneys, spleen, heart, brain, lung, stomach, small intestines, large intestines, ovaries/testes) did not reveal abnormalities. A fifth group received 15% propylene glycol alginate in a different basal diet. This group showed an increased food and water consumption. Faeces were normal in this group. The group was killed after 37 weeks (Nilson & Wagner, 1951). Groups of 20 male and 20 female rats received 0% or 5% propylene glycol alginate in their diet for 2 years as the parent generation of a multigeneration study. Two male and two female rats/group were killed after one year for histopathology. After 2 years survival of this F0 generation was 67% for males and 78% for females in the control group and 56% for males and 58% for females in the test group. Survival time was 761 days. No difference from controls in general condition, general behaviour, skin, hair, eyes, mean body weight, or haematology (4 males and 4 females/group) was seen. Gross pathology and histopathology of 6 major organs did not reveal treatment-related effects (Morgan, 1959). 2.2.4 Reproduction studies 2.2.4.1 Rats Groups of 20 male and 20 female rats received 0 or 5% propylene glycol alginate in their diet. After 5-6 months some animals were mated to produce an F1 generation. 7 Males and 7 females were F1 controls and 10 males and 10 females the test group. The F1 generation was fed on similar diets and mated after 4 months to produce the F2 generation. The F2 generation consisted of 9 male and 10 female controls and 9 male and 10 female test animals and were also kept on similar diets. F0 generation survived 761 days, while F1 and F2 generation were killed after 202 and 212 days, respectively. No differences from controls were noted regarding mortality, general condition, mean body weight, fertility, gestation data, lactation and survival for the F1 and F2 generation. Haematology was performed in the F2 generation only and did not show abnormalities. Organ weights were not determined. Gross pathology and histopathology of 6 major organs did not show abnormalities (Morgan, 1959). 2.2.5 Special studies on genotoxicity The results of genotoxicity studies are summarized in Table 1. 2.2.6 Special studies on teratogenicity 2.2.6.1 Mice Groups of 22-32 pregnant albino CD-1 mice received daily from day 6 to 15 of gestation 0, 8, 36, 170 or 780 mg propylene glycol alginate/kg bw/dy by gavage as a suspension in corn oil. Up to 170 mg/kg bw/dy there was no effect on nidation or maternal or fetal survival. The number of abnormalities seen in either soft or skeletal tissues did not differ from the number occurring spontaneously in controls. At 780 mg/kg bw/dy maternal toxicity resulted in 7/32 deaths. Surviving dams and fetuses carried to term appeared normal in all respects (FDRL, 1972). 2.2.6.2 Rats Groups of 24 pregnant Wistar rats receved daily by gavage from day 6 to 15 of gestation 0, 7, 33, 155 or 720 mg propylene glycol alginate/kg bw/dy as a suspension in corn oil. On day 20 Caesarean section was carried out and dams and fetuses were examined for pathological and teratological effects. No compound-related effects were observed (FDRL, 1972). Table 1. Results of genotoxicity assays on propylene glycol alginate Test system Test object Dose-levels Results References Ames test Salmonella typhimurium up to 10 mg/plate neg1 Ishidate et al., 1984 (6 strains) Ames test Salmonella typhimurium 5% w/v negative2 SRI, 1972 (2 strains) Ames test Salmonella typhimurium up to 0.60% negative1 LBI, 1975 (3 strains) Mitotic recomb. Saccharomyces cerevisiae D-3 up to 1% w/v negative2 SRI, 1972 Mitotic recomb. Saccharomyces cerevisiae D4 2.5, 5.0 and 10% negative1 LBI, 1975 Host-mediated assay Salmonella typhimurium oral doses to mice negative SRI, 1972 TA 1530 and G46 i.p. in for 1-5 days up to mice 5 g/kg bw Host-mediated assay Sacharomyces cerevisiae oral doses to mice negative SRI, 1972 D-3 i.p. in mice for 1-5 days up to 5 g/kg bw Chromosomal aberration Chinese hamster fibroblasts up to 1.0 mg/ml negative2 Ishidate et al., assay (CHL cells) 1984; 1988 Chromosomal aberration human WI-38 cells up to 1.0 mg/ml negative2 SRI, 1972 assay Table 1 (contd) Test system Test object Dose-levels Results References Micronucleus assay rat bone-marrow once orally 0.03, negative SRI, 1972 2.5, or 5.0 g/kg bw or daily for 5 days 0.03, 2.5 or 5.0 g/kg bw Dominant-lethal assay rats once orally 0.03, 2.5, negative SRI, 1972 or 5.0 g/kg bw or daily for 5 days 0.03, 2.5 or 5.0 g/kg bw 1 Assay without and with metabolic activation. 2 Assay without metabolic activation. 2.2.6.3 Hamsters Groups of 20 to 23 pregnant golden hamsters received daily by gavage from day 6 to 10 of gestation 0, 7, 33, 150 or 700 mg propylene glycol alginate/kg bw/dy as a suspension in corn oil. On day 14 Caesarean section was carried out. There was no evidence of maternal toxicity or effect on reproduction. Examinations of fetuses did not reveal compound-related abnormalities (FDRL, 1974a). 2.2.6.4 Rabbits Groups of 10 to 15 pregnant rabbits received daily by gavage from day 6-18 of gestation 0, 8, 37, 173 or 800 mg propylene glycol alginate/kg bw/dy as a suspension in corn oil. On day 29 Caesarean section was carried out. No differences with respect to number of corpora lutea, implantation sites, resorption sites, number of live and dead fetuses or fetal weights were seen. Gross examination of the fetuses did not reveal external congenital abnormalities. Visceral and skeletal examination of fetuses from dosed does did not show any differences compared to control fetuses (FDRL, 1974b). 2.2.7 Special studies on bacteriology Two rats were fed control diet during 6 months, thereafter they received 5% polyethylene glycol alginate in their diet for 3 weeks followed by 2 weeks on control diet. Bacteriological examination of the intestinal flora showed lower counts of lactobacilli and aerobes but an increased count of coliforms compared to controls. The anaerobic counts were comparable with those of controls (Woodard, 1959). 2.3 Observations in humans Fifty individuals known to be allergic to numerous substances were tested intradermally with various dilutions of propylene glycol alginate. Fifty other individuals without an allergic history or family history of allergy were used as controls. 11 Individuals showed slight to moderate skin reactions (8 in test group, 3 in control group). When five of those showing the greatest reactions (all in test group) were fed propylene glycol alginate three showed mild allergic reactions which were duplicated in repeated tests. Three control individuals, who showed very slight skin reactions, did not react to oral administration of propylene glycol alginate (Ouer, 1949). Five healthy male volunteers received 175 mg propylene glycol alginate/kg bw/day orally for 7 days, followed by 200 mg/kg bw/dy for a further 16 days. The daily doses were consumed in three measured portions at intervals each day. The portions were prepared by adding the weighed aliquots of propylene glycol alginate with rapid stirring to 220 ml cold distilled water. The hydrocolloid was then allowed to hydrate for 24 h to a thick but fluid gel to which each volunteer added a pre-determined amount of orange juice prior to consumption. The treatment period was preceeded by a 7-day initial control period during which daily an amount of orange juice, equal to that to be used later, was consumed. During the treatment period enquiries were made with respect to apparent allergic responses. At day 3 of the initial control period, on the last day the of 23-day treatment period and on the last day of the 7-day recovery period the following parameters were examined; fasting blood glucose, plasma insulin, breath hydrogen concentrations, haematological parameters (Hb, Hct, MCV, MCH, MCHC, Er, Leu, Diff, platelets) and biochemical parameters (Na, Cl, K, CO2, urea, LDH [lactate dehydrogenase], ASAT, bilirubin, alk. phosphatase, phosphate, Ca, protein, albumin, creatinine, urate, lipids, cholesterol, HDL cholesterol and triglycerides). Routine urinalysis was carried out during the initial control week and during the third week of treatment. Five-day faecal collections were made during days 2-6 of the initial control period and during days 16-20 of the treatment period. Faecal transit time, wet wt., dry wt., water content, pH, occult blood, neutral sterols, fat, volatile fatty acids and bile acids in faeces were determined. No allergic reactions were observed. Propylene glycol alginate exerted no significant effects on faecal parameters (pH, water content, wet and dry wts.) Faecal transit time was constant in 3 volunteers, increased in one and decreased in one. Faecal total and individual volatile fatty acids and total and individual bile acids did not show changes. Faecal total neutral sterols and cholesterol decreased in each volunteer. Haematological, biochemical and urinary parameters did not show significant changes (Anderson et al., 1991). 3. COMMENTS An in vitro study showed partial hydrolysis of propylene glycol alginate in simulated intestinal juice (25% within 4 hours; 80% within 24 hours). Partial hydrolysis was also observed in an in vivo mouse study. Absorption, distribution, and excretion studies in mice showed that unhydrolysed propylene glycol alginate and the alginate moiety were not absorbed. Released propylene glycol was rapidly absorbed and metabolized to lactic and pyruvic acids. In various short- and long-term toxicity studies, 10% or higher propylene glycol alginate in the diet caused reduced growth accompanied by reduced food consumption and loose stools, the common effects in animals fed high doses of bulking agents. In a long-term toxicity study in mice (12 months) as well as in long-term toxicity studies in rats (> 2 years) the NOEL was 5%. There was no indication of a carcinogenic effect. Propylene glycol alginate did not induce gene mutations in bacteria or in yeast cells or chromosomal aberrations in mammalian cells in vitro or in vivo. In addition, in a 2-generation reproduction study in rats, 5% propylene glycol alginate in the diet did not cause any effects. Teratogenicity studies in rats, mice, hamsters and rabbits did not reveal any teratogenic activity of propylene glycol alginate at dose levels of up to 800 mg/kg bw/day. No adverse effects were observed in a recent 23-day study in five human volunteers in which the substance was given orally at a dose of 200 mg/kg bw/day. 4. EVALUATION The Committee noted that similar effects - reduced growth, and loose stool - have been observed in animal studies with other poorly absorbed compounds (including modified cellulose, polyalcohols, gums, modified starches and other alginates). The Committee reiterated that the ADI for propylene glycol alginate is limited only by the amount of propylene glycol that might be released. Propylene glycol alginate containes up to 36% propylene glycol. On the assumption that all of this amount is hydrolyzed, and taking into account the ADI of 0-25 mg/kg by for propylene glycol, the Committee allocated an ADI of 0-70 mg/kg bw (100/36 x 25) to propylene glycol alginate. The Committee was aware of new toxicological studies on propylene glycol, but as the compound was not on the agenda, the data were not reviewed. The Committee recommended that propylene glycol be reviewed at a future meeting. Because the ADI for propylene glycol alginate is based on the ADI for propylene glycol, the Committee also recommended that the former substance be reconsidered at the same meeting. 5. REFERENCES ANDERSON, D.M.W., BRYDON, W.G., EASTWOOD, M.A. & SEDGWICK, D.M. (1991) Dietary effects of propylene glycol alginate in humans. Fd. Add. Contam. 8 (3), 225-236 FDRL (1972) Food and Drug Research Laboratories Inc. Report on teratologic evaluation of PGA. PB-221 786. Submitted to WHO by Marinalg International, Paris, France. FDRL (1974a) Food and Drug Research Laboratories Inc. Report on teratologic evaluation of PGA in hamsters. PB-221 786. Submitted to WHO by Marinalg International, Paris, France FDRL (1974b) Food and Drug research Laboratories Inc. Report on teratologic evaluation of compound FDA 71-18. Propylene glycol alginate in rabbits. PB-267 196. Submitted to WHO by Marinalg International, Paris, France. FDRL (1976) Food and Drug Research Laboratories Inc. Paper No. 124, as summarized in RTECS. Submitted to WHO by Marinalg International, Paris, France. ISHIDATE, Jr., M., SOFUNI, K., YOSHIKAWA, K., HAYASHI, M., NOHMI, T., SAWADA, M. AND MATSUOKA, A. (1984) Primary mutagenicity screening of food additives currently used in Japan. Fd. Chem. Toxicol. 22 (8), 623-636 ISHIDATE, Jr., M., HARNOIS, M.C. AND SOFUNI, T. (1988) A comparative analysis of data on the clastogenicity of 951 chemical substances tested in mammalian cell cultures. Mutat. Res. 195, 151-213 LBI (1975) Litton Bionetics Incorporated Report PB-245 497 prepared for Food and Drug Administration. Mutagenic evaluation of Compound FDA 71-18 Propylene glycol alginate. Dated 30 June 1975. Submitted to WHO by Marinalg International, Paris, France MARTIN, G. (1986) Evaluation toxicologique et nutritionnelle des alginates: I. Définition, structure, fabrication, proprietés et applications. Sciences et Aliments 6, (no.4), 473-486 MCNEELY, W.H. & SHEPHERD, V.M. (1966) Report to Kelco Co. Labs. MORGAN, F.C.(1959) As cited in Woodard (1959) MRCL (1951) Medical Research Council Laboratories. Unpublished report. NEWELL, G.W. & MAXWELL, W.A. (1972) Unpublished Report from Stanford Research Institute, Menlo Park Co., submitted to DHEW/Public Health Service, U.S. FDA. NILSON, H.W. AND WAGNER, J.A. (1951) Feeding tests with some algin products. Proc. Soc. Exp. Biol. Med. 76, 630-635. OUER, R.A. et al. (1935) J. Biol. Chem. 5, 108 OUER, R.A. (1949) Sensitivity to Kelcoid. Preliminary study. Ann. Allergy 7, 681 SHARRATT, M. & DEARN, P. (1972) An autoradiographic study of propylene glycol alginate in the mouse. Food Cosm. Toxicol. 10, 35-40 SRI (1972) Stanford Research Institute Report PB-221 826 prepared for Food and Drug Administration. Study of mutagenic effects of propylene glycol alginate (71-18). Dated June 1972. Submitted to WHO by Marinalg International, Paris, France STEINER, A.B. & MCNEELY, W.H. (1951) Organic derivatives of alginic acid. Ind. Eng. Chem. 43, 2073 WOODARD, G. (1959) Unpublished Report. WOODARD RES. CORP. (1972) Unpublished Report on acute toxicity of PGA.
See Also: Toxicological Abbreviations Propylene glycol alginate (FAO Nutrition Meetings Report Series 46a) Propylene glycol alginate (WHO Food Additives Series 1) Propylene glycol alginate (WHO Food Additives Series 5) PROPYLENE GLYCOL ALGINATE (JECFA Evaluation)