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
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.
CALCIUM, POTASSIUM, SODIUM FERROCYANIDE
These compounds were evaluated for acceptable daily intake by the
Joint FAO/WHO Expert Committee on Food Additives (see Annex 1, Ref.
No. 20) in 1969.
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.
Because of the strong chemical bond between iron and the cyanide
groups these salts have a low toxicity. Dogs injected i.v. with sodium
ferrocyanide (0.5 g/kg bw), excreted the salt without renal damage
demonstrated by high urea clearance, absence of gross or microscopic
haematuria. Repeated clearance several weeks after injection was found
to be entirely normal without chronic haematuria, albuminuria or
cylindruria. Sodium ferrocyanide, inulin and creatinine show the same
excretory behaviour in respect to plasma clearance. In the dog,
ferrocyanide is probably excreted entirely by glomerular filtration
(Van Slyke et al., 1935; Berliner et al., 1950; Chinard, 1955). I.v.
infusion of ferrocyanide and creatinine (20 mg%) into dogs gave an
average clearance ratio of 0.966 ± 0.41. Ferrocyanide clearance ratios
showed no relationship to plasma ferrocyanide concentration (Berliner
et al., 1950). "Instantaneous" injection into renal artery of dogs of
combinations of inulin, creatinine and sodium ferrocyanide showed that
there was no displacement of one glomerular substance with respect to
another in spite of very rapid changes in serum concentration
Rabbits injected i.v. with either sodium or calcium ferrocyanide
(0.25 g/kg bw), showed similar rates of excretion of ferrocyanide in
the urine. In another experiment rabbits were injected i.v. with
either sodium, calcium or magnesium ferrocyanide and histochemical
studies made on the kidneys to determine ferrocyanide distribution.
Ferrocyanide appeared to be eliminated via the glomeruli. There was no
evidence of tubular excretion. Some storage of ferrocyanide occurred
in the proximal convoluted tubule cells after the urine was free of
demonstrable ferrocyanide (Gersh & Stieglitz, 1934).
Female dogs 10 to 20 kg were injected i.v. with 1000 mg of
ferrocyanide. 94 to 98% of the administered ferrocyanide was
recovered in the urine in 24 hours. Ferrocyanide could not be detected
in red blood cells, gastric juice or faeces (Kleeman et al., 1955).
Rats dosed orally with 200 mg/kg potassium ferrocyanide excreted
about 47% unchanged in the faeces and 3% in the urine. Faecal and
urinary excretion of ferrocyanide and thiocyanate was at a maximum
from day 1 to day 3 after dosing, and thereafter declined to a low
level (Gage, 1950).
Animal Route (mg/kg bw)
Rat Oral 1600-3200 Fasset, 1958
Groups of 10 male and 10 female rats were maintained for 13 weeks
on diets containing 0, 0.05, 0.5 and 5.0% sodium ferrocyanide. Growth
rate and food consumption was normal except at the 5% level, where
there was slight depression. Haematocrit and haemoglobin values were
depressed at the 5% level. Kidney weight of both males and females at
the 5% level and females at the 0.5% level was increased as were male
adrenal and female pituitary gland weights in the 5% group. The
kidneys of rats at the 0.5% level showed a minimal degree of tubular
damage. The effect was more marked at the 5% level, in addition
granular and calcified deposits were observed (Oser, 1959).
Groups each of eight young beagle dogs (four male, four female)
received food containing 0, 10, 100 or 1000 ppm (0%, 0.001%, 0.01% or
0.1%) of sodium ferrocyanide. Diets were offered 1 h/day, 6 days/week.
The average intake of sodium ferrocyanide was approximately 0.26, 2.6
and 26 mg/kg bw per day. Body weight and food consumption of control
and test animals were similar. Haematologic, biochemical tests, and
urine analysis of test and control animals were similar and within
normal limits. There were no marked differences in absolute and
relative organ weight of test and control animal. Histological studies
of organs and tissues indicated chronic inflammation of the liver and
kidney of one test animal in the 0.1% group. No effect on kidney
histology was noted in any other test animal (Morgareidge, 1970).
No data are available.
OBSERVATIONS IN MAN
Glomerular function was studied in 115 humans, 45 healthy,
70 patients with glomerulonephritis, hypertension and amyloidosis.
10 ml 5% sodium ferrocyanide was nontoxic in adults and 0.0077 g/kg
tolerated in infants. 25% was excreted in 80 minutes and the remainder
in the next 90 minutes by glomerular filtration. Patients had slower
rates of excretion (Forero & Koch, 1942).
Following i.v. injections of sodium ferrocyanide in amounts
ranging from 0.55 to 6.2 g into humans ferrocyanide and urea clearance
rates were found to be essentially similar suggesting that
ferrocyanide was excreted like urea with about 40% reabsorption.
Subjects receiving excessive doses of ferrocyanide (5X recommended)
developed a marked albuminuria accompanied by numerous granular casts,
white cells, epithetical cells and rare red blood cells. Symptoms
disappeared within two weeks. There was no change in urea clearance
during this period (Miller & Winkler, 1936). 0.1% sodium ferrocyanide
was administered by i.v. infusion to six infants, nine days to 14
months of age. The comparative rate of glomerular filtration of inulin
and sodium ferrocyanide suggested tubular reabsorption of the latter
substance in infants. There was no evidence of urinary disturbance in
infants given sodium ferrocyanide (Calcagno et al,, 1951).
A group of nine human subjects, which included patients with
liver and kidney damage were injected (i.v.) with 30 to 50 mg of
Fe59-labelled ferrocyanide. In the normal subject an average of 80%
(68 to 87%) of the administered radioactivity was recovered in 24 to
48 hours. There was no significant radioactivity detected in pooled
faeces, saliva or gastric juice. In normal subjects the half time
value (T 1/2) was 135 minutes. The rate of disappearance was slower in
patients with renal damage. There was some evidence of in vivo
binding of ferrocyanide to plasma albumin. In dogs the T 1/2 of
labelled ferrocyanide was 40 to 50 minutes. No significant
radioactivity was found in the pooled faeces, saliva or gastric juices
of dogs (Kleeman & Epstein, 1956).
Human studies have demonstrated that i.v. injected ferrocyanide
is excreted by glomerular filtration. Tubular reabsorption occurs in
man but not in dogs. High levels were nephrotoxic in the single short-
term study available but no renal function tests were performed.
The material is unstable in acid solution.
Level causing no toxicological effect
Rat: 500 ppm (0.05%) in the diet equivalent to 25 mg/kg bw.
Estimate of acceptable daily intake for man
0-0.025 mg/kg bw.*
FURTHER WORK OR INFORMATION
Required by June 1974.
Metabolic studies in man. If these reveal any untoward effects, a
long-term study in one species will be required.
Berliner, W. R., Kennedy, T. J. & Hilton, J. G. (1950) Amer. J.
Physiol., 160, 325-329
Calcagno, P. L., Husson, G. S. & Rubin, M. I. (1951) Proc. Soc. exp.
Biol. & Med., 77, 309-311
Chinard, F. P. (1955) Amer. J. Physiol., 180, 617-619
Fassett, D. W. (1958) In: Patty, F. A., Industrial hygiene and
toxicology, New York, John Wiley & Sons, Vol. II, p. 2036
Forero, A. & Koch, M. M. (1942) Rev. de med. y alimentacion, 5, 34-46
Gage, J. C. (1950) Unpublished report submitted by I.C.I. Ltd.,
Industrial Hygiene Research Laboratories
Gersh, I. & Stieglitz, E. J. (1934) Anatomical Record, 58, 349-364
Kleeman, C. R. & Epstein, F. H. (1956) Proc. Soc. exp. Biol. & Med.,
Kleeman, C. R. et al. (1955) Amer. J. Physiol., 182, 548-552
Miller, B. F. & Winkler, A. (1936) J. clin. Invest., 15, 489-492
Morgareidge, K. (1970) Unpublished report by Food and Drug Research
Lab. Inc., submitted by International Salt Co. Inc. to WHO
Oser, B. L. (1959) Unpublished report by Food and Drug Research Lab.
Inc., submitted by International Salt. Co. Inc.
Van Slyke, D. D., Hiller, A. & Miller, B. F. (1935) Amer. J. Physiol.,