INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY WORLD HEALTH ORGANIZATION TOXICOLOGICAL EVALUATION OF SOME FOOD COLOURS, ENZYMES, FLAVOUR ENHANCERS, THICKENING AGENTS, AND CERTAIN FOOD ADDITIVES WHO FOOD ADDITIVES SERIES 6 The evaluations contained in this publication were prepared by the Joint FAO/WHO Expert Committee on Food Additives which met in Rome, 4-13 June 19741 World Health Organization Geneva 1975 1 Eighteenth Report of the Joint FAO/WHO Expert Committee on Food Additives, Wld Hlth Org. techn. Rep. Ser., 1974, No. 557. FAO Nutrition Meetings Report Series, 1974, No. 54. DIOCTYL SODIUM SULFOSUCCINATE BIOLOGICAL DATA BIOCHEMICAL ASPECTS No data are available on the absorption and excretion mechanisms for this substance although surface-active agents are known to be absorbed through the skin and probably through mucous membranes (Smythe et al., 1941). Rat DSS labelled with 35S was administered orally in a single dose in an alcohol and water (1:1 V/V) solution to albino rats weighing 200 g. The animals were provided with food and water ad libitum. More than 85% of the administered DSS was excreted within 24-48 hours post dosing and essentially all within 96-120 hours. 25%-35% of the DSS was excreted in the urine 24-48 hours post dosing, then only trace amounts via this route. The faeces contained over 66% of the radio-label, indicating that the major route of elimination is the gastrointestinal tract. The tissues of rats 96-168 hour post dosing contained only trace amounts of radiolabel (American Cyanamid Co., 1969). In another study, two rats were administered orally a single dose of either 5 mg or 10 mg of DSS in water, and two rats a single dose of DSS, 10 mg by i.v. route. A fifth rat received a single oral dose of 5.8 mg of 2-ethyl-hexanol in 40% ethanol. 18.6% and 15.5% of the total dose was excreted in the urine and 0.9 and 8.7% in the faeces, in the first 24 hour post dosing period, in animals receiving the 5 or 10 mg oral dose. Animals receiving DSS i.v. excreted 12.3-15.5% in the urine in this period and none in the faeces. The 24-48 hour urine sample from the test animals did not contain detectable 2-ethyl-hexanol. Rats administered 2-ethyl-hexanol excreted 3.1% of the dose in urine and 3.9% in the faeces, in the first 24 hour post dosing (American Cyanamid Co., 1973). One adult male rat was administered 14C labelled DSS by gavage, at a dose level equivalent to 10 mg/kg bw. 64.1% of the administered radioactivity was excreted in the urine during the first 24 hours and approximately 1.0% during the 24-48 hour period. 37.4% and 0.9% of the administered radioactivity was excreted in the faeces during this period. DSS undergoes extensive metabolism in the rat since no unchanged DSS appeared to be present in the urine, and only a small amount was present in the faeces (American Cyanamid Co., 1973). Rabbit Two female rabbits were administered a single dose of 14C radio- labelled DSS (4 mg). One orally, one i.v. Each route of administration resulted in the excretion of over 90% of the radioactivity in the urine (87% and 69.7%, 0-24 hours after dosing, oral and i.v. respectively). Analyses of the 0-24 hour urine sample, indicated similar patterns of metabolites irrespective of the route of administration (American Cyanamid Co., 1973). Dog Two male beagle dogs were dosed with 4 mg/kg bw. 14C radio- labelled DSS, one orally, one i.v. Analyses of blood for 2-ethyl- hexanol compounds indicated that in the case of the i.v. injected dog the blood level of these compounds fell off rapidly during the first hour and was zero at eight hours. Oral administration of the DSS led to the appearance of small amounts of this compound in the blood after one hour, but the level was zero at eight hours. Each route of administration led to similar excretion patterns and metabolic profile. About 21% of the label was excreted in the urine in the first 24 hours, the bulk of the radiolabel being excreted in the faeces (about 70%) in the 24-48 hour post dosing (American Cyanamid Co., 1973). TOXICOLOGICAL STUDIES Special studies on reproduction DSS was fed in the diet to groups of 40 male and 40 female rats (Carworth Farms, CFE strain), for three successive generations at levels of 0, 0.5 or 1.0%. Pairs of rats were mated to produce two litters per generation with the exception of the F1b generation which was bred once to produce a single F2 generation. The F2 was bred twice to provide an F3a and F3b litter. The Fo generation was maintained on the test diet until three to four months of age before mating. For the first mating of the Fo generation and the F2 generation, the dams were continuously fed the test diets, and the pups weaned directly onto test diets. For the other three matings (F1b, F2 and F3a pups), DSS was removed from the diet of the dams before they were expected to cast their litters. After weaning, the pups were placed on test diets. Reproduction performance was evaluated in terms of Fertility Index, Gestation Index, Viability Index and Lactation Index. Litter size was reduced to 10 pups at day 5. Pups from all litters, including those which died before weaning, were examined for gross defects. Autopsies were performed on pups from the first mating of the F2 animals. Portions of all major organs from one female and male from each litter were examined histologically. Carcasses of the other pups were cleared and the skeletons stained and examined for defects. The first mating of the Fo generation and the F2 generation (dams continuously fed DSS and pups weaned to test diet), resulted in Fertility Indices and Gestation Indices that were high and comparable. The Viability Index was good, but slightly depressed for F3b pups. The Lactation Index depressed for both these matings (64, 46, 42 for F1a pups at 0, 0.5, 1.0 test diet respectively, and 71, 59, 53 for F3b pups for the respective diets). Also, for these groups, mean weight of the pups decreased with increasing concentration of DSS in the diet of dams. For the other three matings (F1b, F2, F3a pups), the viability and lactation indices, and the mean weight of pups from dams on test diets were less than those of control for the F1b pups, but similar to controls for the F2 and F3a pups. The lowering of survival rate and mean body weight of the F3b pups was attributed to impairment of nutrition, because of the taste of DSS secreted in the milk of the dams. Autopsy and skeletal studies of the pups, indicated no significant changes, with the exception of the occasional presence of an extra sternebra in the sternum between the fifth and sixth sternebra (1/29, 7/30, and 4/29 at 0, 0.5 and 1.0% test levels of DSS). This is considered to be a truly accessory sternebra, and not caused by parental exposure to DSS (American Cyanamid Co., 1970). Studies on the effect of DSS in the gut When tested on isolated rabbit jejunum in an organ bath, DSS had a distinct inhibitory effect on the pendular movements at a concentration of 0.7 mg/ml; at a concentration of 7 mg/ml these movements were virtually suppressed (Lundholm & Svedmyr, 1959). Studies on the laxative action of DSS In studies with normal rats, as well as those with a tendency to constipation induced by opium drugs, DSS potentiated the effect of laxatives containing anthraquinone derivatives (Lundholm & Svedmyr, 1959). Acute toxicity LD50 Animal (mg/kg bw) References Rat ca 1 800 p.o. Olsen et al., 1962 Mice ca 3 980 p.o. Lundholm & Svedmyr, 1959 Mouse 1 500 p.o. Schultz, 1941 Mice have been shown to tolerate 0.2 ml 5% solution s.c., although ulceration and necrosis developed at the injection site, or 0.5 ml of 0.2% DSS i.p. or 0.25 ml of 0.5% DSS i.v. which often produced severe haemolysis (Lorenz et al., 1940). Human patch tests using 1% DSS showed non-irritancy. Short-term studies Rat Groups of five male weanling rats were given diets containing 0, 2%, 4% and 8% DSS for 16 weeks. There was marked growth retardation at the 2% level without mortality but only one animal survived at 4% and all animals died within one week at the 8% level from severe gastrointestinal disturbances (Fitzhugh & Nelson, 1948). In another experiment groups of five male and five female rats were given 0, 0.19, 0.37, 0.55, 0.75 and 0.87 g/kg body weight of DSS in their diet for 24 weeks. No deaths occurred but there was some initial lag in body weight gain compared with controls. No significant haematological effects were noted. Histology of liver, spleen, kidney, pancreas, stomach and gut, bladder, gonads, heart, lung, brain and spinal cord showed nothing remarkable (Benaglia et al., 1943). In a further experiment groups of 12 male and 12 female weanling rats were treated with diets containing 0, 0.5%, 1.04% and 1.5% DSS for 26 weeks. There was no significant differences between tests and controls regarding body weight gain with the exception of female animals which showed some slight reduction at the 1.0% and 1.5% level during the third week. No adverse effects appeared in findings of haematology, urinalysis, food consumption, weight of spleen, liver, adrenal, kidney, gonads, as well as the histology of heart, lung, liver, spleen, kidney, adrenal, bladder, thyroid, pancreas, lymph nodes, gut, muscle, bone, marrow, gonads and thymus. Two controls and four test animals in the 1.5% group died, two of the latter from haemorrhagic gastroenteritis (Taylor, 1966). Rabbit Seven rabbits were given intragastrically 0.5 g DSS/kg bw daily for 24 weeks. Three animals died from severe diarrhoea and anorexia, two from unrelated causes and two survived without showing any pathological findings on gross and histological examination of liver, spleen, kidney, pancreas, gut, bladder, gonads, heart, lung, CNS (Benaglia et al., 1943). Monkey Three monkeys were given intragastrically 0.125 g DSS/kg bw daily for 24 weeks. Higher doses were not tolerated because of gastrointestinal irritation. No abnormal pathological findings were seen on gross and histological examination of liver, spleen, pancreas, kidney, gut, bladder, gonads, heart, lung, CNS (Benaglia et al., 1943). Dog Groups of three dogs received 0.1 or 0.25 mg DSS/kg bw in their food for 24 weeks. Higher doses caused gastrointestinal irritation. All dogs lost some weight but this was not considered due to the DSS. Gross and histopathology showed nothing abnormal in liver, spleen, pancreas, kidney, gut, bladder, gonads, heart, lung, CNS (Benaglia et al., 1943). Long-term studies Rat Groups of 12 male weanling rats were given 0, 0.25%, 0.5% and 1.0% DSS in their diet for two years. Body weight gain was slightly reduced in the 1% test group during the first three months and became more pronounced during the first year. No pathological changes were noted at gross examination and in the histology of lung, heart, liver, spleen, pancreas, stomach and gut, kidney, adrenal, testes, thyroid, parathyroid, lymph nodes, bone, muscle, marrow (Fitzhugh & Nelson, 1948). OBSERVATIONS IN MAN DSS has been used as a faecal softener in a large number of cases for many years since 1943 in infants, children and adults (Wilson & Dickinson, 1955). In chronic constipation it is used as a non-laxative softener but action does not become apparent for one to two days after taking it. Dosage employed is 10-20 mg daily for infants and children, 10-60 mg daily for adults, exceptionally 100 mg/day. Up to 300 mg can be taken without adverse effects (JAMA, 1956). Others have suggested 50 mg/day as optimum (Firing & short, 1956). Two male volunteers were each administered two 100 mg capsules of DSS. Peak serum values of 2-ethyl-hexanol compounds were observed two hours post dosing and these compounds were still present in the serum eight hours post dosing. Excretion of 2-ethylhexanol derivates in the urine of man only accounted for 2.5 to 5.5% of the administered dose, during the 48 hours post dosing. The urinary metabolites, as separated by counter-current distribution, did not resemble those from dog (American Cyanamid Co., 1973). Comments: Metabolism studies indicate that dioctyl sodium sulfosuccinate (DSS) is rapidly absorbed from the gastrointestinal tract and undergoes extensive metabolism. In man, as in the dog, the major route of excretion of the DSS metabolites is in the faeces, whereas in the rat and rabbit, a larger percentage of the metabolites appear to be excreted in the urine. However, the number of animals employed was small and the results quite variable. A multigeneration reproduction study in the rat indicates a no-effect level when the offspring are not exposed to dioctyl sodium sulfosuccinate or its metabolites through mother's milk. The long-term study in rats is inadequate as regards the number of animals used and only one sex was used. It has been used in man as faecal softener for many years. Because of the possibility that high dietary intakes may affect faecal consistency, uses should be carefully allocated. Recent findings with highly active surface agents suggest the possibility of adverse effects on the pulmonary circulation, particularly if rapidly absorbed into the systemic circulation. EVALUATION Level causing no toxicological effect Rat: 0.5% (= 5000 ppm) in the diet equivalent to 250 mg/kg bw. Estimate of acceptable daily intake for man 0-2.5 mg/kg bw* FURTHER WORK OR INFORMATION Required (by June 1978) Effects on neonatal animals particularly those exposed to dioctyl sodium sulfosuccinate through the milk. Adequate long-term study in a rodent species. Investigation of pulmonary circulatory effects including pulmonary hypertension. * Temporary. REFERENCES American Cyanamid Co. (1969) Unpublished data American Cyanamid Co. (1970) Report No. 70-239 Unpublished data American Cyanamid Co. (1973) P.R. vol. 18, 1220 Unpublished data AMA (1956) JAMA, 161, 63 Benaglia, A. E. et al. (1943) J. Ind. Hyg Tox., 25, 175 Firing & Short (1956) Anal. Chem., 28, 1827 Fitzhugh, O. G. & Nelson, A. A. (1948) J. American Pharm. Ass. Sci., 37, 29 Lorenz, E. et al. (1940) Nat. Cancer Inst., 1, 355 Lundholm, L. & Svedmyr, N. (1959) Acta Pharmacol. et Toxicol., 15, 373 Olson, K. J. et al. (1962) J. Soc. Geo. Chem., 13, 469 Schultz, F. H. jr (1941) (personal communication quoted in 5) Smyth, H. F. jr Seaton, J. & Fisher, L. (1941) J. Ind. Hyg. Tox., 23, 478 Taylor, R. E. (1966) Report from Harris Laboratory dated 1/2/66 Wilson, J. L. & Dickinson, D. G. (1955) JAMA, 158, 261 Yasuna, A.D. & Halpern, A. (1957) Amer. J. Gastroent., 28, 530
See Also: Toxicological Abbreviations DIOCTYL SODIUM SULFOSUCCINATE (JECFA Evaluation)