FAO Nutrition Meetings
Report Series No. 40A,B,C
WHO/Food Add./67.29
TOXICOLOGICAL EVALUATION OF SOME
ANTIMICROBIALS, ANTIOXIDANTS, EMULSIFIERS,
STABILIZERS, FLOUR-TREATMENT AGENTS, ACIDS AND BASES
The content of this document is the result of the deliberations of the
Joint FAO/WHO Expert Committee on Food Additives which met at Rome,
13-20 December, 19651 Geneva, 11-18 October, 19662
1 Ninth Report of the Joint FAO/WHO Expert Committee on Food
Additives, FAO Nutrition Meetings Report Series, 1966 No. 40;
Wld Hlth Org. techn. Rep. Ser., 1966, 339
2 Tenth Report of the Joint FAO/WHO Expert Committee on Food
Additives, FAO Nutrition Meetings Report Series, 1967, in press;
Food and Agriculture Organization of the United Nations
World Health Organization
1967
POTASSIUM IODATE
Chemical name Potassium iodate
Empirical formula KIO3
Molecular weight 214.00
Definition Potassium iodate contains not less than
99 per cent. and not more than the
equivalent of 101 per cent. of KIO3
after drying.
Description Potassium iodate occurs as a white,
crystalline powder and may have a slight
odour.
Use As a rapid oxidizing agent used for
strengthening flour.
Biological Data
Biochemical aspects
It is presumed that the oxidizing effects of potassium iodate on
flour proteins are essentially similar to those caused by other
oxidizing agents; in addition, the formation or some halogenated
compounds might be expected. The main residue is iodide, but some
iodate may be present (London et al., 1965). In the rat the inhibiting
effect of iodine on the functional activity of the thyroid is
intensified by deficiency of dietary protein or by an excessive
proportion of vegetable protein or of vegetable and animal fat in the
diet (Shtenberg and Plotnikova, 1960).
Acute toxicity
Animal Route LD50 References
(mg/kg
body-weight)
POTASSIUM IODATE
Mouse (fasting) oral 531 ± 211 Webster et al.,
1957
Mouse (fed) oral 1 177 ± 61 Webster et al.,
1957
Mouse i.p. 136 ± 5 Webster et al.,
1957
Guinea-pig (fasting) oral <400 Webster, 1954
(continued)
Animal Route LD50 References
(mg/kg
body-weight)
POTASSIUM IODIDE
Mouse (fasting) oral 1 862 ± 100 Webster et al.,
1957
Mouse (fed) i.p. 2 068 ± 140 Webster et al.,
1957
Mouse i.p. 1 117 ± 30 Webster et al.,
1957
Daily intravenous injection of high doses (45 mg/kg) of potassium
iodate for up to 6 days in rabbits has produced retinopathy (Cucco,
1954).
Short-term studies
Mouse. Groups of 9 or 10 mice were given water to which has
been added 0, 0.05, 0.1, 0.25, 0.5 or 0.75 per cent. potassium iodate;
a group also received water containing potassium iodide equivalent to
a potassium iodate content of 0.84 per cent. Observation was continued
for 16 weeks. Reduction of water intake and weight gain was observed
in the groups receiving 0.5 per cent. and 0.75 per cent. potassium
iodate. Three mice on the highest level of intake of potassium iodate
died within the first week; the remainder survived for 16 weeks. No
changes were found grossly or microscopically, except at the 0.5 per
cent and 0.75 per cent. levels of intake. In these animals some
haemolysis had occurred, resulting in reduced haemoglobin levels and
haemosiderin deposits in the kidneys. Increased susceptibility to
iodate was not demonstrable (Webster et al., 1959).
Guinea-pig. Three groups of 6 male and 6 female guinea-pigs
received water containing 0, 0.05, 0.25 and 0.5 per cent. of potassium
iodate for 2 weeks. Except for reduced rate of weight gain and fluid
intake in the two highest intake groups, no other significant
abnormalities were observed (Webster et al., 1959).
Rabbit. Fourteen rabbits received daily amounts of sodium
iodate equivalent to 0.3099 mg/kg body-weight of potassium iodate for
4-14 months without ill effect (Murray, 1953).
Sheep. Groups of 2 male and 2 female lambs were fed on diets
containing 0, 50, 100 and 500 ppm of potassium iodate for 45 days
without demonstrable ill effect (Penick, 1955).
Fowl. Groups of 9 male and 10 female day-old chicks were fed a
basal diet containing 1.3 ppm of iodine with 1.2, 6, 30 and 150 ppm of
added potassium iodate for 10 weeks. Weight gain, efficiency of food
utilization, haemoglobin and methaemoglobin levels, blood cell counts
and mortality were unaffected (Brumbaugh et al., 1959).
Man. There is wide experience of therapeutic administration of
iodides and iodates to human subjects (Stacpoole, 1953).
Long-term studies
No data are available on animals.
Man. Iodized table salt at a level of 10 ppm has been used for
many years for prophylaxis against endemic goitre. No ill affects have
been reported. The intake of water with a high level of iodine (up to
50 µg/1) did not appear to have any significant deleterious effects on
general health, and provided some prophylaxis against thyroid
enlargement (Medical Research Council, 1948; WHO, 1958).
Comments
There is a paucity of information on the effect of iodates on the
nutritional value of flour and no long-term, studies appear to have
been carried out on iodate-treated flour or bread made from it.
Evaluation
Amounts of iodine of the order of a few micrograms per litre in
the drinking water have been shown to be prophylactic against thyroid
enlargement in children. Calculations show that the use of iodate as a
flour-maturing agent might well result in a daily intake of about 2000
µg, which exceeds considerably the normal daily requirement of iodine
(100-200 µg). It is undesirable for use as a food additive,
particularly in a staple food, since it has an important physiological
action.
REFERENCES
Brumbaugh, J. H., Mehring, A. L. jr & Titus, H. W. (1959) Poultry
Sci., 38
Cucco, G. (1954) Arm. ottal., 80, 102
London, W. T., Vought, R. L. & Brown F. A. (1965) New Eng. J. med.,
273, 381
Medical Research Council (1948) Memorandum No. 18, H.M.S.O., London
Murray, M. M. (1953) Bull. Wld Hlth Org., 9 211
Penick & Co. (1953) Unpublished Report from Univ. Pennsylvania
Stacpoole, H. H. (1953) Bull. Wld Hlth Org., 9, 283
Webster, S. H. (1954) Unpublished information
Webster, S. H., Rice, M. E., Highman, B. & von Oettingen, W. F. (1957)
J. Pharmacol. exp. Therap., 120, 171
Webster, J. H, Rice, M. E., Highman, B. & Stohlman, E. F. (1959)
Toxicol. appl. Pharmacol., 1, 87
WHO (1958) Bull. Wld Hlth Org., 18, No. 1-2
See Also:
Toxicological Abbreviations