INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY
WORLD HEALTH ORGANIZATION
SUMMARY OF TOXICOLOGICAL DATA OF CERTAIN FOOD ADDITIVES
WHO FOOD ADDITIVES SERIES NO. 12
The data contained in this document were examined by the
Joint FAO/WHO Expert Committee on Food Additives*
Geneva, 18-27 April 1977
Food and Agriculture Organization of the United Nations
World Health Organization
* Twenty-first Report of the Joint FAO/WHO Expert Committee on Food
Additives, Geneva, 1977, WHO Technical Report Series No. 617
ADIPIC ACID
Explanation
This substance has been evaluated for acceptable daily intake by
the Joint FAO/WHO Expert Committee on Food Additives (see Annex I,
Ref. Nos. 11 and 13) in 1965.
The previous monograph has been expanded and is reproduced below.
EVALUATION FOR ACCEPTABLE DAILY INTAKE
BIOLOGICAL DATA
BIOCHEMICAL ASPECTS
Four young dogs were injected subcutaneously with 0.25 g adipic
acid (sodium salt), twice daily, for a period of five days. Urine was
collected during this period, and for three days following
administration of the test compound. Approximately 50% of the adipic
acid was recovered unchanged, from the urine (Flaschentrager, 1926).
Rats were administered orally 2.43 g adipic acid/day for two
successive days. Excretion of unchanged adipic acid in the urine,
reached a maximum on the second day of administration of the test
compound, and continued for three more days. Approximately 70% of the
dose was recovered unchanged in the urine (Enders, 1941).
Rats were fed 0.75 g adipic acid per day for a period of four
weeks. Three days after removal of adipic acid from the diet the rats
were sacrificed. No residues of adipic acid were detected in body
lipids or bound to body protein (Enders, 1941).
Rats which had been maintained for 20-25 weeks on diets
containing high levels of adipic acid (400 or 800 mg/day), and rats
which had not previously received dietary adipic acid, were
administered orally a total dose of 5.6 or 11.2 g of adipic acid, over
a period of 14 days. There was no significant difference in the amount
of unchanged adipic acid excreted in the urine of the test groups, nor
was there any indication of excretion of oxalic or succinic acid in
urine, above normal background levels (Lang and Bartsch, 1953).
Fasted rats were administered by gavage, 0.25 g of adipic acid.
After four hours the rats were sacrificed and liver glycogen
determined. No significant glycogen synthesis occurred (Stohr, 1939).
Fasted rats fed 250 mg 1-14C or 2-14C adipic acid. The carboxyl
group was oxidized more rapidly than the second carbon. About 70% of
the administered 14C was respired as CO2, during the 24 hour period
following administration of the test compound. Analysis of the urine
showed the presence of 14C labelled urea, glutamic acid, ß-ketoadipic
acid, citric acid and unchanged adipic acid. Tissues from sacrificed
rats contained little residual 14C. The 14C-glycogen was only
isolated from the liver, when conditions were used that favoured
glycogen formation. Adipic acid appears to be metabolized by
ß oxidation in the same manner as other fatty acids (Russoff et al.,
1960).
Administration of 50 g of adipic acid or its sodium salt to human
subjects, did not result in an increased excretion of urinary oxalic
acid (Kabelitz, 1943).
TOXICOLOGICAL STUDIES
Acute toxicity
LD50 References
Animal Route mg/kg body weight
Mice M p.o. 1 900 Horn et al. (1957)
Mice - i.v. 680 Horn et al. (1957)
Rat M i.p. 275 Horn et al. (1957)
Rat M p.o. 940 Litton Bioneties (1974)
Rat - p.o. 5 050 Younger Lab. (1975)
Short-term toxicity
Rat
Groups each of 17-20 female rats were maintained for four weeks
on diets containing adipic acid, at dose levels equivalent to 0, 10,
20 or 40 mg/kg for 28 days. No adverse effect on growth was noted
(Lang and Bartsch, 1953). Groups each of 18 male rats were maintained
for five weeks on test diets, containing adipie acid, at dose levels
equivalent to 0, 200, 400 or 800 mg/day. Growth was normal except in
the high dose group in which there was a decreased growth rate (Lang
and Bartsch, 1953).
In another study groups of rats were maintained for 35 weeks on
diets containing adipic acid so that daily dose was 0, 400 or 800 mg.
During the first three weeks of the study, the animals in the high
dose group, developed diarrhoea, and showed decreased growth rates.
However recovery occurred at the end of this period, and by the end of
the study, growth was similar in all groups. Pregnant females
maintained in the high dose group produced normal litters and were
able to suckle the offspring (Lang and Bartsch, 1953).
Long-term toxicity
Rat
Groups each of 30 rats (Carworth Farm strain, 20 male, 10 female)
were maintained on diets containing 0, 0.1, 1, 3, or 5% adipic acid,
for a period of two years. Weight gains were normal for the .1 and 1%
group, but significantly decreased for the 3 and 5% groups. Food
consumption was normal in all groups except in the 5% group, where
there was a consistent reduction in food intake. Survival of the test
and control group animals was similar. At autopsy there were no
significant differences in organ weight of test and control animals
(kidney, spleen and heart of females, and brain, thyroid, lungs,
heart, liver, spleen, kidneys, adrenals, and testis of males).
Microscopic examination of the thyroid, lungs, heart, liver, spleen,
kidneys, adrenals, stomach, small intestine, large intestine,
pancreas, bone marrow, testes or ovaries, and uterus, did not show any
compound related changes (Horn et al., 1957).
Special studies
Teratological studies
Mice
Groups of 20-24 mated female albino CD-1 mice were dosed with
adipic acid daily from day 6 through day 15 of gestation. The dose
levels used were 0, 2.6, 12.0, 56.0 and 263.0 mg/kg body weight. Body
weights were recorded on days 0, 6, 11, 15 and 17 of gestatton. On day
17 all dams were subjected to Caesarian section, and the numbers of
implantation sites, resorption sites and live and dead foetuses
recorded. The urogenital tract of each dam was examined. The body
weight of live pups was recorded. All foetuses were examined
externally, and one-third of each litter was examined for soft-tissue
abnormalities and the remaining two-thirds for skeletal abnormalities.
No compound related embryotoxic or teratogenic effects were observed
(Food and Drug Research Labs., Inc., 1973).
Rats
Groups of 20-24 mated female albino rats (Wistar derived stock)
were dosed daily with adipic acid at dose levels 0, 2.9, 13.0, 62.0
and 288 mg/kg body weight, from day 6 through day 15 of gestation.
Body weights were recorded on days 0, 6, 11, 15 and 20 of gestation.
On day 20 all dams were subjected to Caesarian section, and the
numbers of implantation sites, resorption sites and live and dead
foetuses recorded. The urogenital tract of each dam was examined. The
body weight of live pups was recorded. All females were examined
externally, and one-third of each litter was examined for soft-tissue
abnormalities and the remaining two-thirds for skeletal abnormalities.
No compound related embryotoxic or teratogenic effects were observed
(Food and Drug Research Labs., Inc., 1973).
Hamsters
Groups of 21-24 mated female golden hamsters were dosed daily
with adipic acid at dose levels of 0, 2.0, 9.5, 44.0 and 205 mg/kg
body weight from day 6 through 10 of gestation. Body weights were
recorded on days 0, 8, 10 and 14 of gestation. On day 14 all dams were
subjected to Caesarian section, and the number of implantation sites,
resorption sites and live and dead foetuses recorded. The urogenital
tract of each dam was examined. The body weight of live pups was
recorded. All foetuses were examined externally, and one-third of each
litter was examined for soft-tissue abnormalities and the remaining
two-thirds for skeletal abnormalities. No compound related embryotoxic
or teratogenic effects were observed (Food and Drug Research Labs.,
Inc., 1973).
Rabbits
Groups each of 10-14 mated female rabbits (Dutch-belted) were
dosed daily with adipic acid at dose levels 0, 2.5, 12.0, 54.0 and
250 mg/kg body weight, from day 6 through day 18 of pregnancy. Body
weights were recorded on days 0, 6, 12, 18 and 29 gestation. On day 29
all dams were subjected to Caesarian section and the numbers of
corpora lutea, implantation sites, resorption sites and live and dead
foetuses recorded. The urogenital tract of each dam was examined.
All foetuses were examined externally. The body weight of live
pups was recorded. All foetuses were maintained in an incubator for 24
hours, for the evaluation of neonatal survival. All surviving pups
were sacrificed, examined for visceral abnormalities, and then for
skeletal abnormalities. No compound related embryotoxic or teratogenic
effect were observed (Food and Drug Research Labs., Inc., 1974).
Mutagenicity studies
Host mediated assay
Acute study
Adipic acid was administered orally to male mice (ICR random-
bred) approximately 12 weeks old at three dose levels: 100, 2500 or
5000 mg/kg. Positive controls and negative vehicle controls were
included in the study. Salmonella TA-150, G-46 or Saccharamyces
D3 were injected i.p. 30 minutes after administration of the test
compound. Three hours after the injection, each animal was killed,
their peritoneal cavities were asceptically exposed and washed with 2
ml of sterile saline. As much fluid as possible was removed from the
cavity. The peritoneal washings were diluted and plated in accordance
with generally accepted procedures. The mutation frequency of bacteria
and the yeast mitotic recombinants (recombinant frequency), for each
of the samples was determined. There was no significant increase in
mutant frequencies at the dose levels tested with Salmonella TA-1530
and G-46. Tests with Sacchromyces D3 produced a dose-response
effect on recombinant frequency (Litton Bionetics, 1974).
Subacute study
Adipic acid was administered orally to male mice (ICR random-
bred) approximately 12 weeks old at three dose levels: 100, 2500 or
5000 mg/kg/day for five consecutive days. Thirty minutes after the
last dosing the animals were inoculated with the test organisms, and
treated in the same fashion as those in the acute study. There was no
significant increase in mutant frequencies with Salmonella TA-1530
and G-46, nor significant recombinant count increase with the
Saccharomyces.
In vitro study
Cultures of S. typhimurin (G-46 and TA-1530) were plated on
appropriate media and adipic acid added to the plate. Serial dilutions
of the cultures were made and the number of mutant colonies observed.
Cultures of strain D3 Saccharomyces cells were shaken with adipic
acid and plated, and the frequency of mutant colonies observed.
Positive controls and negative vehicle controls were included in the
study. There were no compound-related effects (Litton Bionetics,
1974).
In vivo cytogenetics
For the acute study, adipic acid was administered
intragastrically to groups each of 15 rats, at dose levels 0, 3.75,
37.5 or 375 mg/kg. For the subacute study the dose levels of adiplc
acid were 3.75, 37.5 or 375 mg/kg/day for five consecutive days.
Negative and positive controls were included in the study; chromosomal
abberations in the bone marrow cells of each group was evaluated. No
detectable significant abberation of the bone marrow metaphase
chromosomes was observed (Litton Bionetics, 1974).
In vitro cytogenetics
Human embryonic lung cultures (WI-38) were grown in the presence
of adipic acid (2, 20 or 200 mcg/ml) as well as positive and negative
control compounds. There was no significant abberatlon in the anaphase
chromosomes that could be attributed to the presence of the test
compound (Litton Bionetics, 1974).
Dominant lethal studies
Adipic acid was administered orally to groups each of 10 male
rats at dose levels of 3.75, 37.5, 375 mg/kg body weight (one dose per
the acute study) and in the subacute study 3.75, 37.5, 375 mg/kg body
weight (one dose/day for five days). A negative control group received
saline solution and a positive control group triethylene melamine
(i.p.) 0.3 mg/kg. The males were sequentially mated with two females
per week for eight weeks (seven weeks in the subacute study). The
females were sacrificed 14 days after mating, and the uterus examined
for corpora lutea early foetal deaths, late foetal deaths and total
implantations for uterine horn. In the acute study a significant
decrease in the average number of implantations at weeks 1 and 4, and
corpora lutea at weeks 4 and 7 was observed in the intermediate dose
level. Significant increases in pre-implantation losses were observed
at week 1 for both the low and intermediate dose. In the subacute
study only minor differences were observed between negative control
and experimental groups (Litton Bionetics, 1974).
REFERENCES
Enders, A. (1941) Arch. Exptl. Pathol. Pharmocol., 197, 706-709
Flaschentrager, B. (1926) Z. Physiol. Chem., 159, 297-308
Food and Drug Research Labs., Inc. (1973) Report FDA 71-50 (Adipic
Acid). Unpublished data submitted to USFDA
Food and Drug Research Labs., Inc. (1974) Report 71-20 (Adipic Acid).
Unpublished data submitted to USFDA
Horn, H. J., Holland, E.G. and Hazleton, L. W. (1957) J. Agr. Food
Chem., 5, 759-762
Kabelitz, G. (1943) Klinische Wochemschrift, 22, 439-441
Lang, K. and Bartsch, A. R. (1953) Biochemische Zeitschrift, 323,
462-468
Litton Bionetics (1974) LBI Project No. 2446. Unpublished data
submitted to USFDA
Russoff, I. I., Baldwin, R. R., Dominques, F. J., Monder, C., Ohan, W.
J. and Thiessen, R., jr (1960) Tox. and Appl. Pharmacol., 2,
316-330
Stohr, R. (1939) Klinische Wochenschrift, 17, 1663-1664
Younger Lab. (1975) Unpublished data submitted to Monsanto Company
See Also:
Toxicological Abbreviations
Adipic acid (ICSC)
Adipic acid (FAO Nutrition Meetings Report Series 40abc)
ADIPIC ACID (JECFA Evaluation)