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
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).
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).
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).
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.,
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,
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.
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).
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).
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.,
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
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,
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 &
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).
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
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.
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.,
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,
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