553. Zinc (WHO Food Additives Series 17)

ZINC

Explanation

Zinc was previously evaluated by the Joint FAO/WHO Expert
Committee on Food Additives for a provisional maximum acceptable daily
level in 1966 (see Annex I, Ref. 12). No toxicological monograph was
prepared.

Introduction

Zinc is an essential element in the nutrition of man, animals and
plants. It functions as an integral part of numerous enzymes. Two
classes of zinc enzymes have been identified: (1) the zinc-enzyme
complexes in which the binding between the enzyme and the ion is weak,
and there may be a low specificity for zinc in activating the enzyme;
and (2) zinc metalloenzymes in which the zinc is bonded firmly with a
definite stoichiometry. Because of its essentiality, zinc is present
in all plant and animal tissues. The total body zinc for a 70 kg
individual has been estimated to be 2.3 g. Protein foods are important
dietary sources of zinc. Oysters are the richest source of zinc (up to
1000 ppm (0.1%) zinc), with lesser amounts in other seafoods, muscle
meats and nuts (30-50 ppm (0.003-0.005%) range). Whole cereals may
contain 20-25 ppm (0.002-0.0025%) zinc, but most of this is lost
during milling procedures (e.g., flour may contain 3-9 ppm
(0.0003-0.0009%) zinc). Sugar, citrus fruits and non-leafy vegetables
are poor sources of zinc (about 1 ppm (0.0001%)). The average zinc
intake via the diet depends on protein sources. For an adult the
intake ranges from 14 to 20 mg/day. The recommended dietary allowance
(RDA) for adult men and women is 15 mg/day; however, the requirement
for zinc changes throughout life. In countries where whole cereals
form an important part of the diet, a higher requirement may be
needed, because phytate, a constitutent of the cereal, reduces the
bioavailability of the zinc (WHO, 1973).

BIOLOGICAL DATA

BIOCHEMICAL ASPECTS

Absorption, metabolism and excretion

Zinc, as contained in food and drink, is absorbed through the gut
mucosa which is the normal route of entry into the body. It is
absorbed at several sites in the gastrointestinal tract. The initial
site of absorption is the stomach and occurs within 15 minutes after
ingestion; however, the major site is the second portion of duodenum.
Absorption also occurs in other segments of both the small and large
intestine (Henkin & Aamodt, 1975; Methfessel & Spencer, 1973a,b).

The exact mechanism by which zinc is transported across the
gastrointestinal mucosa and serosa is not known. The formation of a
low molecular weight organic zinc chelate is thought to be the initial
event, possibly a tetrahedral quadradentate ligand formed from a small
organic molecule and the zinc, and it is this complex which is
absorbed from the gastrointestinal tract (Suso & Edwards, 1971a,b).
Studies on rats suggest that metallothionein, a low molecular weight
cytoplasmic metalloprotein, plays a key role in zinc haemostasis
(Richards & Cousins, 1976; Hall et al., 1979). It has been shown in
rats that there is a direct correlation between the dietary zinc
intake and the binding of zinc of intestinal mucosal metallothionein
(Hall et al., 1979). The absorption of zinc can be affected by many
substances. Both phytate and soy protein inhibit the formation of the
zinc-protein complex and as a result diminish the absorption of zinc
(Davis, 1972; O'Dell & Savage, 1960; Reinhold et al., 1973). Other
substances which adversely affect zinc absorption include cotton-seed,
peanut, safflower, calcium, phosphate, food and zinc itself (Davis,
1972; Heth et al., 1966; Nielsen et al., 1966a,b; Pecoud et al., 1975;
Schelling et al., 1973; Smith et al., 1962). The body burden of zinc
can be diminished either by reductions in the amount of zinc absorbed
as seen in several types of malabsorptive processes or by increases in
the removal of zinc from the body. The latter is evidenced by
increases in excretion seen in intrinsic kidney disease, reduced
plasma metal binding which is congenital in origin and inborn errors
of metabolism (Slavik et al., 1973a,b). The absorption of zinc has
been shown to be enhanced by the presence of histidine, cysteine,
methionine and ethylenediamine tetracetic acid. These are thought to
act by promoting the formation of the low molecular weight organic
zinc complex (Giroux, 1972; Nielsen, 1966a,b). The diminution of zinc
absorption can be species dependent, since in the rat a low protein
diet is associated with a reduction in zinc absorption, while the
reverse is the case with humans. Feeding studies with rats showed
that for absorbed zinc the faeces constitutes the major route of
elimination. Only minor amounts are eliminated in the urine.
Administration of large amounts of zinc did not result in elevated
tissue levels of zinc (Heller & Burke, 1927; Drinker et al., 1927a,b),
since increasing the level of zinc in the diet results in decreased
absorption.

In rats the absorption of zinc was measured following
administration of a single tracer dose of 0.5 µCi ⁶⁵Zn by gavage. The
net absorption of zinc varied from 0.7 to 1.8% in total groups of
animals receiving either 1.8 or 2.9 mg/zinc, respectively. In other
radiotracer studies with rats the addition of the zinc to the diet did
not affect stable zinc levels in the blood, heart, liver, kidney,
semitendinosus muscle, left tibia and small intestine, whereas the
faecal excretion of ⁶⁵Zn increased with the length of feeding time on
the zinc diet (Ansari et al., 1975).

Oral tracer studies with ⁶⁵Zn in mice have shown that although
liver, pancreas and kidney retain high levels of the radioisotope 96
hours after dosing the highest concentrations over longer periods of
time were found in bone tissues followed by liver and kidney (Ansari
et al., 1975).

Oral radiolabelled tracer studies in humans have shown the
presence of the isotope in the blood within 20 minutes of
administration, peak plasma levels within 2-4 hours and the recovery
of 50% of the total dose in the faeces within 15 days. The net
absorption in these various studies varied between 30% and 70%
(Richmond et al., 1962; Rosoff & Spencer, 1965; Spencer et al., 1965).

In humans the daily elimination of absorbed radiolabelled zinc as
in the order of 1% per day (Lombeck et al., 1975). The major route of
elimination was via the faeces which accounted for three-quarters of
the zinc eliminated with the remainder being removed by means of
the urine. In older adult males who were given a single dose of
radiolabelled zinc the majority of gastrointestinal absorption
occurred within 4 hours. By day 3, 66% of the isotope was found in the
faeces. After 21 days the following dietary retention of the
radiolabel was observed: 28% remained in the body, 2% was present in
the urine and 70% in the faeces (Richmond et al., 1962; Rosoff &
Spencer, 1965; Spencer et al., 1965). Studies on retention patterns of
intravenously administered ⁶⁵Zn, by normal human subjects, indicate
that there is a 2-component exponential pattern of retention. One a
rapid component which comprises 20% of the radiolabelled zinc with a
biological half-life of 8 days, and the other a slow component with a
biological half-life of 300-500 days (Aamodt et al., 1975; Richmond et
al., 1962; Henkin & Aamodt, 1975; Honstead & Brady, 1967).

TOXICOLOGICAL STUDIES

Special studies on carcinogenicity

Mouse

Mice exposed to drinking-water or mineral water containing levels
of zinc ranging from 10 to 20 ppm (0.001-0.002%) in 1 study and 0 to
200 ppm (0-0.02%) in another, developed tumours following 5 or more
months exposed to the zinc-containing water (DeSzilvay, 1964; Halme,
1961). However, the information provided in the publications relating
to these studies is inadequate for evaluation.

In another study mice were fed diets containing 50 000 ppm (5%)
zinc oleate, but after 3 months the level was reduced to 25 000 ppm
(2.5%) and after a further 3 months to 12 500 ppm (1.25%), because of
deaths due to anaemia. All surviving mice were killed at week 45. Mice

that died during the study or were killed at week 45 were autopsied
and lesions examined histologically. The incidence of tumours at all
sites showed no significant difference between test and control
animals (Walters & Roe, 1965).

Hamster

Random-bred Syrian hamsters, 2 months of age (N=49), were
injected directly into the testicles with 0.05 ml of a 4% solution of
zinc chloride. Treatment was daily for a period of 6 weeks. At either
week 17 or 18 the animals were sacrificed and the testes and pituitary
were removed for histological examination. Most of the testes
exhibited areas of coagulative necrosis surrounded by a zone of
pigmented and foamy macrophages and a variable amount of surviving
testes. In 2 animals sacrificed at 10 weeks, a small focus of
embryonal carcinoma adjacent to the area of necrosis was found in 1
testis. No metastases were noted in these animals, nor were any other
testicular neoplasms indicated in any of the other animals (Guthrie &
Guthrie, 1974).

Special studies on interactions with other metals

Dietary zinc has been shown to affect the metabolism of a number
of essential dietary elements, e.g., Cu and Fe, and also toxic
elements such as lead and cadmium (NRC, 1979). Excess dietary zinc in
the diet of pregnant rats adversely affects the zinc, copper, iron and
calcium status of the developing foetus (Cox et al., 1969).

Copper. Male Wistar rats were fed either a basal diet
containing 5 ppm (0.0005%) of copper and 80 ppm (0.008%) of zinc or
the basal diet plus 1.0% zinc carbonate for no longer than 15 days. To
ascertain whether zinc affected intestinal absorption of copper, all
of the animals were given orally or intraperitoneally copper alone or
copper and zinc in combination. The 1% zinc diet produced a reduction
in growth, haemoglobin concentration, ceruloplasmin activity and
copper concentration in liver, kidney and spleen with a concomitant
marked increase in the concentration of zinc in these tissues. The
administration of ⁶⁴CuCl₂ (35 µCi) by stomach tube in the zinc-fed
rats, followed by measurements of ⁶⁴Cu levels in blood showed that
zinc interfered with the absorption and utilization of copper (Ogiso
et al., 1974). In a study on the metabolism of zinc and copper in the
gastrointestinal tract of rats, it was shown that as the zinc content
of the stomach or duodenum increased, the copper content decreased.
Most of the zinc was present in the mucosal layer and was associated
with a low molecular weight protein (Ogiso et al., 1979). In another
study in which rats received diets containing adequate amounts of zinc
and copper, followed by a marked increase in dietary zinc, it was
shown that, while dietary zinc levels up to 450 ppm (0.045%) had a no
effect on intestinal absorption of copper, a level of 900 ppm (0.09%)

resulted in a 40% reduction in copper uptake. Increasing the level of
copper in the diet resulted in a marked decrease in zinc retention
(Hall et al., 1979).

Iron. In studies in which young rats were fed basal diets
containing 0.75% zinc carbonate, there was a reduction of iron storage
in the liver and spleen, while at the same time there was no reduction
in haemoglobin level. If a diet was used that was low in copper, the
zinc supplementation resulted in anaemia and lower levels of hepatic
copper in the test animals. The mechanism of depletion of iron stores
is not known, but it does not appear to be due to interference by zinc
with iron absorption from the diet, with cellular uptake of iron from
circulating transferrin, nor with capacity to store iron (O'Neil-
Cutting et al., 1981).

Selenium. Studies with pigs failed to show any interaction
between zinc and selenium (Van Vleet et al., 1981).

Cadmium. The effect of zinc on cadmium toxicity has been
discussed by Friberg et al. (1974). Many of the toxic effects
associated with administration of dietary cadmium, e.g., anaemia,
weight loss and also the acute toxic effects on the testes, could be
prevented by the simultaneous administration of zinc. However, dietary
zinc failed to prevent a decrease in the activity of liver enzymes
caused by cadmium (Friberg et al., 1974).

Lead. The influence of zinc on the biological effects of
orally ingested lead has been reviewed by Petering (1980). Lead
absorption in rats is markedly reduced when the level of zinc in the
diet is increased. In 1 study in rats, the Zn level was raised from 8
to 200 ppm (0.0008-0.02%). The absorption of lead as well as the blood
lead levels were reduced by about 60% (Cerklenski & Forbes, 1976). A
study of workers exposed to lead and zinc rather than lead alone
resulted in a reduced excretion of urinary 8-aminolevulinic acid and a
tendency to lower blood lead levels (Ditkiewicz et al., 1979; Meredith
& Moore, 1980).

Calcium. Interactions have been reported between dietary zinc
and calcium. In 1 study in which young rats were fed 0.75% zinc in the
diet (as zinc carbonate), there was a marked decrease in bone calcium
and phosphorus (Stewart & Magee, 1964). However, in another study with
rats, administration of high levels of calcium or calcium and
phosphorus in the diet increased the zinc requirement (Cabell & Earle,
1965). In a study with dogs, administration of zinc in the drinking-
water for 9 months increased the level of zinc in bone, but no changes
were noted in Haversian bone remodelling, blood chemistry and
circulating immunoactive parathyroid hormone levels (Anderson &
Danylchuk, 1979). Zinc deficiency also affects calcium metabolism
resulting in bone abnormalities in chicks and rat embryos (NRC, 1979).
However, it does not appear to affect collagen and mucopolysaccharide
formation (Philip & Kurup, 1978).

Effects on other biochemical parameters

Studies have been carried out with experimental animals to
determine the relationship between zinc levels in the diet and
zinc/copper antagonism and levels of serum cholesterol. In studies in
which animals were maintained on diets in which the zinc/copper ratio
was increased, either by decreasing copper levels at constant zinc
intakes or by increasing zinc at constant copper intake, it was first
suggested that this resulted in increased serum cholesterol levels
(Klevay, 1973). However, subsequent studies by Murthy et al. (1974)
showed that the effect was due to copper rather than zinc content of
the diet. Similar results were reported in a study with human subjects
(Freeland-Graves et al., 1980).

High levels of zinc in the diets of experimental animals result
in decreased cytochrome oxidase activity in the heart and liver, as
well as catalase in the liver. The effect is due to interference with
copper metabolism and is readily reversed by supplementation of the
diet with copper (NRC, 1979).

Diets deficient in zinc result in decreased activity of zinc-
dependent enzymes in the tissues, which is subsequently reflected in
changes in intermediary metabolism. However, interpretation of these
effects is complicated because the earliest effects of zinc deficiency
in the diet of experimental animals is decreased food intake, followed
by cessation of growth (NRC, 1979).

Special studies on mutagenicity

Zinc chloride did not show any mutagenic or DNA-damaging
capacity in a recombination-repair-deficient assay with strains of
B. subtilis H17 (Rec⁺, arg^-, try^-) and M45 (Rec^-, arg^-, try^-)
(Kanematsu et al., 1980).

Zinc sulfate produced no detectable aberrations of the bone
marrow metaphase chromosomes of rats when administered orally at
dosages of 2.75, 27.5 and 275 mg/kg bw (Litton Bionetics, 1973).

No significant aberrations in the anaphase chromosomes of human
embryonic lung cultures were noted when the cells were treated with
0.1, 1.0 and 10 µg/ml of zinc sulfate (Litton Bionetics, 1973).

In a dominant-lethal assay, 10 male rats were assigned to each of
5 groups. Three of the groups were given varying doses of zinc sulfate
(2.75, 27.5 and 275 mg/kg), while the other 2 comprised positive
(0.3 mg/kg triethylene melamine) or negative (saline) controls. The
test compound was administered via intubation on an acute (single
dose) or subacute (1 dose per day for 5 days) basis. Following
treatment, the males were sequentially mated to 2 females per week for
7 or 8 weeks. The results of this study did not detect any mutagenic
activity of zinc sulfate (Litton Bionetics, 1973).

Zinc sulfate produced no significant increases in mutation
frequencies, both in vitro and in vivo, in 2 histidine auxotrophs
of S. typhimurium (G-46 and TA-1530) and a diploid strain of
S. cerevisiae (D-3) in a host-mediated assay. A dose-related
increase in recombinant frequencies was noted in S. cerevisiae;
however, this was not considered significant, because the increase in
frequency was less than 4 times the negative control (Litton
Bionetics, 1973).

Zinc oxide and zinc stearate did not exhibit genetic activity in
a series of in vitro microbial assays with S. cerevisiae (D-4) and
S. typhimurium (TA-1535, TA-1537 and TA-1538), with and without
activation, although dose-related increases in mutation frequencies
were noted in mouse activation tests with strain TA-1537 (Litton
Bionetics, 1976, 1977).

Administration of ZnSO₄ to pregnant female rats on day 20 of
gestation resulted in the reduction of the incorporation of
³H-thymidine into the DNA of the liver and brain of the developing
foetus (Dreosti et al., 1981).

Special studies on reproduction

Groups of young rats were placed in cages and received either a
basal diet or the basal diet plus 0.25% or 0.5% of zinc dust, zinc
chloride, zinc oxide, zinc sulfate or zinc carbonate. After a period
of time the animals were mated and the offspring, after weaning, were
placed on identical dietary regimens. This was carried through for a
subsequent generation. No toxic effects were noted, with the animals
exhibiting normal growth, physical appearance and organ weight and
reproductive performance (Heller & Burke, 1927).

Special studies on teratogenicity

Mouse

Pregnant albino CD-1, outbred mice were dosed daily from day 6
through day 15 of gestation with zinc sulfate at levels equivalent to
0, 0.3, 1.4, 6.5 and 30 mg/kg bw. Body weights were recorded on days
0, 6, 11, 15 and 17 of gestation and all animals were observed daily
for appearance and behaviour. On day 17 all dams were subjected to
caesarean section and the numbers of implantation sites, resorption
sites, live and dead foetuses and pup body weights were recorded. All
foetuses were examined grossly, while one-third underwent soft-tissue
analysis and the remainder were examined for skeletal defects. Zinc
sulfate had no discernible effect on nidation or on maternal or foetal
survival or teratogenic effects (Food and Drug Research Laboratories,
1973a).

Hamster

Pregnant hamsters were dosed daily from day 6 through day 10 of
gestation with zinc sulfate at dose levels equivalent to 0.9, 4.1,
19.0 and 88 mg/kg bw. Body weights were recorded on days 0, 8, 10 and
14 of gestation. All animals were observed daily for appearance,
behaviour and food intake. On day 14 all animals were subjected to
caesarean section and the numbers of implantation and resorption
sites, live and dead foetuses and pup weights were recorded. All
foetuses were examined for external congenital defects, while one-
third underwent soft-tissue analysis and the remainder were examined
for skeletal defects. Zinc sulfate had no effect on implantation or
maternal or foetal survival. Analysis of soft and hard tissues did not
provide any evidence of compound-associated teratogenic effects (Food
and Drug Research Laboratories, 1973b).

Rat

Pregnant Wistar albino rats were dosed daily from day 6 through
day 15 of gestation with zinc sulfate at dose levels equivalent to
0.4, 2.0, 9.1 and 42.5 mg/kg bw. Body weights were recorded on days 0,
6, 11, 15 and 20 of gestation. All animals were observed daily for
appearance, behaviour and food consumption. On day 20 all dams were
subjected to caesarean section and the number of implantation sites,
resportion sites, live and dead foetuses and body weights of the live
pups were recorded. All foetuses were examined grossly for the
presence of external congenital abnormalities. One-third of the
foetuses underwent soft-tissue analysis, while the remaining two-
thirds were examined for skeletal defects. The administration of zinc
sulfate in this study had no clearly discernible effect on
implantation or on maternal or foetal survival. The number of
abnormalities seen in zinc-treated animals did not differ from the
number seen in negative controls (Food and Drug Research Laboratories,
1973c).

Foetal viability and development were examined on day 20 of
pregnancy in 4 adult hooded Wistar, female rats which received 20 mg
of zinc sulfate by gavage on day 6 through day 12 of gestation. Four
animals served as controls by receiving a similar volume of saline.
The number of foetuses were significantly reduced in the zinc-treated
dams, and no obvious malformations were seen in the pups which
survived to term (Dreosti et al., 1981).

Acute toxicity

LD₅₀
Compound Animal Route (mg/kg bw) Reference

Zinc sulfate Mouse Oral 611 Caujolle et al., 1964
Rat Oral 1 374 Caujolle et al., 1964

Zinc sulfate Rat Oral 750 Hahn & Schunk, 1955
.7H₂O

Zn (OAc)₂ Rat Oral 750 Hahn & Schunk, 1955
.7H₂O Rat Oral 2 460 Smyth et al., 1969

Zinc chloride Rat Oral 750 Hahn & Schunk, 1955
Rabbit Oral 750 Hahn & Schunk, 1955

Zinc sulfate Rat Oral 920 Litton Bionetics, 1973

Cat

Five cats were provided 50 g/kg bw of raw oysters which contained
900 ppm (0.09%) zinc. The intake of oysters varied between 18 and
50 g/kg bw, which resulted in zinc intakes of approximately 16-45 mg/kg
bw. No ill-effects were noted during a 24-hour observation period. Two
weeks later the experimental regimen was repeated with the same
result. Several months later an identical experiment was performed
with oysters containing 1970 ppm (0.197%) zinc with no indications of
ill-effects (Mannell, 1967).

Short-term studies

Rat

Zinc was administered either as a suspension of zinc oxide or as
solutions of zinc acetate, zinc citrate or zinc malate in daily doses
ranging from 0.5 to 34.4 mg of zinc for periods ranging from 35 to 53
weeks. Clinical and laboratory studies conducted during the course of
the study included observations on general health, body weight,
food and fluid intakes, urinalysis, haemoglobin and blood cell
determinations, gross and microscopic examination of tissues and
determinations of ingested zinc and of zinc content in urine, faeces,
tissues and organs. No evidence was obtained of significant clinical,
laboratory or gross and histological findings of damage resulting from
ingestion of the various forms of zinc (Drinker et al., 1927a).

Four groups of 25 Wistar rats each were maintained on diets that
provided 0, 60, 120 or 600 mg of zinc chloride/day. The 0, 60 and
120 mg/day dosages which were administered for 15 months produced no
adverse effects. The highest dose group which received zinc chloride
for 6 months showed a pronounced weight loss after 2 weeks on the test
diet. The first mortality was also noted at this time and 13 rats
died in the following 10 days. Six rats survived until 6 months.
Gastrointestinal erosion and renal congestion were noted at the
highest dose level (Wilkins, 1948).

Weanling male Sprague-Dawley rats were housed individually and
given free access to distilled and deionized water and were randomly
divided into 3 groups. The zinc content, provided as zinc carbonate,
of the diets used in these groups were 1.3, 50 and 550 ppm (0.00013,
0.005 and 0.055%). The animals on the 55 and 550 ppm (0.0055 and
0.055%) zinc diets received on each day an amount of diet equal to the
diet intake of the pair-mates on the 1.3 ppm (0.00013%) zinc diet.
After 4 weeks the animals were sacrificed and zinc levels in the
blood, heart, lung, spleen, liver and kidney determined. The animals
on the lowest zinc diet were considered to be on a zinc-deficient diet
and demonstrated anorexia by the fifth day of feeding. The food
efficiency ratio was lowest in the zinc-deficient diet as compared to
the other zinc diets. The rats on the higher zinc diets showed similar
weight gains and food efficiency ratios. These animals also exhibited
higher zinc content of the heart, kidney, liver and blood than those
on the zinc-deficient diet. Copper and magnesium content of the
tissues analysed showed no significant alterations. However, the iron
content of the kidney and liver was reduced in those animals on the 55
and 550 ppm (0.0055 and 0.055%) zinc diets (Kang et al., 1977).

Rabbit

One litter of newborn New Zealand white rabbits received
subcutaneous injections of 16 mg of zinc chloride between days 11 and
17 of postnatal life. Controls received subcutaneous injections of
hypertonic sodium chloride. The zinc-treated animals developed a
neurological syndrome characterized by decreased spontaneous activity,
mild ataxia, weakness of the hind legs and a diminished righting
reflex. These were associated with gliosis in the cerebral grey and
white matter and some pairing of astrocytic nuclei, but not with a
reduction in brain weight or lipid content or increase in cerebral
zinc levels. There was no evidence of neuronal loss, vascular damage
or changes in the cerebellum or spinal cord. These effects on the
central nervous system coincided with dilatation of the renal tubules,
granulation of the cytoplasm of the renal tubular epithelium and
elevated renal zinc levels (Prensky & Hillman, 1977).

Cat

Ten cats were fed canned salmon and milk once a day which was
mixed with one of the following dosages of zinc oxide for periods
ranging from 10 to 53 weeks: 33.8, 41.1, 44.0, 52.7, 64.4, 66.2,
121.4, 265.4, 340.4 and 420.2 mg/kg bw per day. No control animals
were used in the study. Urinalysis, haemoglobin determinations, blood
cell counts and autopsies revealed no toxic effects in 7 of the cats.
However, 3 of the animals did demonstrate fibrous changes in the
pancreas (Drinker et al., 1927a).

Dog

Three dogs (1 male and 2 females) were administered 1 of 3 doses
(36.1, 59.9 or 76.5 mg/kg bw) of zinc oxide on a daily basis for
varying durations (3, 15 or 19 weeks). No control animals were
included in the study. Urinalysis, haemoglobin determinations and
gross pathology did not show any compound-related effects (Drinker et
al., 1927a).

Pig

Groups of 6-9 weanling pigs were placed on diets which varied in
the amount of added zinc carbonate (0, 0.05, 0.10, 0.20, 0.40 or
0.80%) for 35-42 days. The addition of 0.1% zinc to the diet was
determined to be the maximum level tolerated. High levels were
associated with depressed weight gain and feed intake, arthritis,
gastritis, catarrhal enteritis, congestion of the mesentery,
haemorrhages in the axillary spaces, ventricles of the brain, lymph
nodes and spleen (Brink et al., 1959).

Long-term studies

Mouse

One hundred and fifty mice of the C3H strain were provided,
ad libitum, distilled water containing zinc sulfate at a
concentration of 500 ppm (0.05%). The control animals were provided
with distilled water. Control and compound-treated animals were
removed in groups of 5 every month. Plasma glucose and tissue zinc
were determined and a histological examination of tissues was carried
out. The last groups of mice were sacrificed at 14 months. The
histological examination revealed hypertrophy of the adrenal cortex
and pancreatic islets after 3 months as well as changes consistent
with hyperactivity of the pituitary. Zinc content of the liver, spleen
and skin, and plasma insulin and glucose concentrations were not
altered by the zinc treatment (Aughey et al., 1977).

Rat

Four groups of 8 Osborne Mendel weanling rats were maintained on
diets containing 0, 100, 500 and 1000 ppm (0, 0.01, 0.05 and 0.1%) of
zinc sulfate for 21 months. Blood counts were made in the first 3 and
last 5 months of the study. Bone marrow smears were made at the
termination of the study, at which time the animals were sacrificed
and autopsied. Microcytosis coupled with polychromasia and
hyperchromasia were noted at all dosage levels. However, these effects
did not persist despite the continuation of the zinc-containing diets.
The bone marrow of zinc-treated animals showed a myeloid-erythroid
ratio average of 1.16-1.35 as compared to a control value of 2.14.
While the kidneys of the male rats on 500 and 1000 ppm (0.05 and 0.1%)
were larger and more granular than those on 0 and 100 ppm (0 and
0.01%) levels, no other gross pathological lesions associated with
zinc administration were noted (Hagan et al., 1953).

Dog

Four Dalmatian puppies (10 weeks of age) received 200 mg/kg bw of
zinc sulfate daily for 7 weeks. At the end of this period of time, the
dosage was reduced to 100 mg/kg, because of persistent vomiting. This
dosage was further reduced to 50 mg/kg bw, because of a similar
problem, and continued until the end of the study 70 weeks later.
Hypochromic anaemia was observed in all 4 of the zinc-treated dogs.
Their bone marrows showed slight hyperplasia as compared to the
controls with no change in the myeloid-erythroid ratio (Hagan et al.,
1953).

OBSERVATIONS IN MAN

The Food and Nutrition Board of the United States (1980)
recommendations for dietary allowances for zinc are as follows:
infants 0-0.5 years, 2 mg, and 0.5-1.0 years, 5 mg; children 1-10
years, 10 mg; men and women 11-51+ years, 15 mg; pregnant women,
20 mg; and lactating women, 25 mg. Similar figures have been
recommended by WHO/FAO (WHO, 1973).

At this time, specific tests for zinc status in man, particularly
marginal zinc deficiencies, have not been established. Levels of zinc
in hair, urine and blood do not correlate well with zinc status.

Acute effects

Four hundred and fifty milligrams of zinc sulfate (in 200 ml
water) is an emetic dose for an adult. However, the metallic taste of
zinc solutions is detectable at 15 ppm (0.0015%) and is quite definite
at 40 ppm (0.004%). These levels are higher than those found in most
foods, but are not higher than those in some foods such as cooked meat
and oysters. Zinc bound to food components is not available in the

amounts analysed and would be expected to have less taste than ionic
zinc in water. In addition, the zinc may be slowly released on
digestion and would not cause the usual vomiting and gastrointestinal
irritation associated with high levels of zinc. In 1 study, 4 humans
were given oysters at a dose of 3 g/kg bw which contained 900 ppm
(0.09%) zinc. None of the individuals noticed any ill-effects. Several
months later the same experiment was performed with oysters containing
1970 ppm (0.197%) zinc. In this instance 1 of the 4 individuals
experienced nausea, severe cramps and diarrhoea (Mannell, 1967).

Two instances of mass food poisoning have been attributed to zinc
salts. In the first instance, between 300 and 350 people became ill.
The major symptom was severe diarrhoea with abdominal cramping. Other
symptoms included gross blood in their stools, tenesmus, occasional
nausea and vomiting and 9 cases of shock. It was also shown that when
the stools of these patients were examined excessive quantities of
zinc were found. The average duration of illness was 18-24 hours. In
the second episode approximately 50 individuals who consumed an
alcoholic punch became ill. The acute symptoms included hot taste and
dryness in the mouth, nausea, vomiting and diarrhoea. Subsequently,
the patients reported general discomfort, muscular pain and 1 instance
of double vision. The punch was analysed and found to contain 2200 ppm
(0.22%) zinc. The dosage per individual was estimated to be between
325 and 650 mg of zinc, which is equivalent to the emetic dosage range
(Brown et al., 1964).

Zinc toxicity has been reported in patients with impaired renal
function undergoing dialysis with water containing high levels of
zinc. The effects were reversed when zinc contamination of the water
which was derived from the use of a galvanized water tank was removed
(Petrie, 1977; Gallery et al., 1972).

Zinc deficiency

Zinc deficiency is associated with nutritional dwarfism which is
characterized by growth and sexual retardation. This syndrome, which
is common in the Middle East, is due to the diet of these individuals
that is high in phytate which binds zinc and therefore makes it
unavailable. A group of 19- and 20-year-old men and women who were
suffering from this syndrome were placed in 3 experimental dietary
groups for 6-12 months. One group received a well-balanced diet, the
second received the same diet plus 120 mg of zinc sulfate/day, while
the third group received the well-balanced diet alone for 6 months and
from then on the zinc supplementation of 120 mg/day. The 2 groups
which received the zinc supplementation demonstrated an alleviation of
the symptoms (Halsted et al., 1972).

Therapeutic use of zinc - wound healing

Chronic effects due to oral ingestion of zinc salts have not been
demonstrated. However, the use of zinc salts as an aid to wound
healing provides information on levels of orally administered zinc
that can be tolerated by man.

Fourteen patients suffering from decubitus ulcers were given
either 600 mg/day (divided into 3 doses) of zinc sulfate or a lactose
placebo for 4 months. Urinalysis, blood counts and serum clinical
chemistry conducted during the course of the study demonstrated no
evidence of toxicity (Brewer et al., 1967).

A group of patients with ulcers were divided into 2 groups of 52
individuals each. One group served as the control and received
660 mg/day of lactose, while the second group served as the test group
and received 660 mg of zinc sulfate/day for 10 weeks. The healing of
the ulcers was improved by the zinc treatment, while mild diarrhoea in
3 patients was the only toxic effect noted (Husain, 1969). Other
studies with patients who were treated with doses of zinc sulfate
which ranged from 440 to 660 mg/day for the treatment of bedsores or
leg sores also failed to demonstrate any untoward effects of the zinc
treatment (Carruthers, 1969; Cohen, 1969).

Thirty-four patients, 16 males and 18 females, suffering from
sickle cell anaemia were treated 3 times daily with either 220 mg of
lactose (placebo) or 220 mg of zinc sulfate for 6 months. It was
determined that the healing rate was improved 3-fold by the zinc
treatment, and that no symptoms of toxicity were associated with the
dosage used in this study (Serjeant et al., 1970).

Comments

Zinc is an essential element in the nutrition of man and animals
and has been identified as an integral part of numerous enzyme
systems.

The metabolism of zinc has been studied in experimental animals
and man. A number of dietary factors interfere with the absorption of
zinc, e.g., phytate, dietary factors and proteins. In addition,
administration of excess zinc results in decreased zinc retention.

Studies with experimental animals have shown that exposure to
high levels of dietary zinc can cause anaemia as well as decreased
levels of copper and iron absorption, and reduction in the activities
of several important enzymes in various tissues. These effects also
occur at lower levels of zinc exposure when the diet is deficient in
copper. It is not known if the results of these are applicable to
man. Zinc was not teratogenic and generally had no effect on the
reproductive performance of test animals. It was not mutagenic in a

number of bacterial and mammalian systems. The available long-term
studies are insufficient to assess carcinogenicity. The required daily
intake for adult humans is about 15 mg/day; however, the requirement
varies with age. In addition, where cereals constitute an important
part of the diet, a higher requirement may be needed. The average zinc
intake via the diet and for an adult ranges from 14 to 20 mg/day
(United States of America, United Kingdom) and is thus sufficient for
nutritional needs. Most reports of toxic effects of zinc in man relate
to acute effects, e.g., vomiting and diarrhoea, and are usually
associated with the ingestion of acid drinks that have been stored in
galvanized vessels. Certain foods such as oysters, which may contain
very high levels of zinc, do not produce an emetic response. No
information is available on toxic effects in man due to chronic
excessive intake of zinc. High doses of zinc have been used
therapeutically to promote healing of wounds. In clinical studies, up
to 600 mg of zinc sulfate has been administered daily, in divided
doses, for periods of several months without any reported adverse
effects, including effects on blood counts and serum biochemistry.

EVALUATION

There is a wide margin between nutritionally required amounts of
zinc and toxic levels. Clinical studies in which up to 600 mg of zinc
sulfate (equivalent to 200 mg elemental zinc) has been administered
daily in divided doses for a period of several months, provides a
basis for the evaluation.

Estimate for provisional maximum tolerable daily intake for man

0.3-1.0 mg/kg bw.

REFERENCES

Aamodt, R. et al. (1975) Studies on the metabolism of Zn=65 in man,
Fed. Proc., 34, 922

Anderson, C. & Danylchuk, K. (1979) The effect of chronic excess zinc
administration on the Haversian bone remodelling system and its
possible relationship to "Itai-Itai" disease, Environ. Res.,
20, 351-357

Ansari, M. et al. (1975) Effects of high but non-toxic dietary zinc on
zinc metabolism and adaptations in rats, Proc. Soc. exp. Biol.
Med., 150, 534-536

Aughey, E. et al. (1977) The effects of oral zinc supplementation in
the mouse, J. comp. Pathol., 87, 1-14

Brewer, R., Mihaldzie, N. & Dietz, A. (1967) The effect of oral zinc
sulfate on the healing of decubitus ulcers in spinal cord injured
patients, Proc. annu. clin. spinal Cord Inj. Conf., 16, 70-72

Brink, M. et al. (1959) Zinc toxicity in the weanling pig, J. anim.
Sci., 181, 836-842

Brown, M. et al. (1964) Food poisoning involving zinc contamination,
Arch. environ. Health, 8, 657-660

Carruthers, R. (1969) Oral zinc sulphate in leg ulcers, Lancet, 1,
1264

Cabell, C. & Earle, I. (1965) Additive effect of calcium and
phosphorus on utilization of dietary zinc, J. anim. Sci., 24,
800-804

Caujolle, F. et al. (1964) A comparison of the toxicities of zinc and
cadmium sulfates, C.R. Acad. Sci. Paris, 258, 375-377

Cerklenski, F. L. & Forbes, R. M. (1976) Influence of dietary zinc on
lead toxicity in the rat, J. Nutr., 106, 689-696

Cohen, C. (1969) Oral zinc sulphate in leg ulcers, Lancet, 1, 1213

Cox, D., Schlicker, S. & Chu, R. (1969) Excess dietary zinc for the
maternal rat, and zinc, iron, copper, calcium, and magnesium
content and enzyme activity in maternal and fetal tissue, J.
Nutr., 98, 459-466

Davis, G. (1972) Competition among mineral elements relating to
absorption by animals, Ann. N.Y. Acad. Sci., 199, 62-69

DeSzilvay, G. (1964) The carcinogenic influence of zinc in drinking
water, Minerva med., 55, 1504-1505

Ditkiewicz, B., Dutkiewicz, T. & Milkowska (1979) The effect of mixed
exposure to lead and zinc on ALA levels in urine, Int. Arch.
occup. environ. Health, 42, 341-348

Dreosti, I. et al. (1981) High plasma zinc levels following oral
dosing in rats and the incorporation of ³H thymidine into
deoxyribonucleic acid in rat fetuses, Res. Commun. chem.
Pathol. Pharmacol., 31, 503-513

Drinker, K., Thompson, P. & Marsh, M. (1927a) An investigation of the
effect of long-continued ingestion of zinc, in the form zinc
oxide, by cats and dogs together with observations upon the
excretion and storage of zinc, Am. J. Physiol., 80, 31-64

Drinker, K., Thompson, P. & Marsh, M. (1927b) An investigation of the
effect upon rats of long-continued ingestion of zinc compounds,
with special reference to the relation of zinc excretion to zinc
intake, Am. J. Physiol., 81, 284-306

Food and Drug Research Laboratories, Inc. (1973a) Final report -
teratologic evaluation of zinc sulfate in mice, 26 February

Food and Drug Research Laboratories, Inc. (1973b) Final report -
teratologic evaluation of zinc sulfate in hamsters, 26 February

Food and Drug Research Laboratories, Inc. (1973c) Final report -
teratologic evaluation of zinc sulfate in rats, 26 February

Food and Nutrition Board of United States (1980) Zinc. In: National
Research Council Committee on Dietary Allowances, ed.
Recommended Dietary Allowances, Washington, DC, National
Academy of Sciences, 144-147 pp.

Freeland-Graves, J. et al. (1980) Effect of dietary Zn/Cu ratios on
cholesterol and HDL-cholesterol levels in women, Nutr. Rep.
Int., 22, 285-293

Friberg, L. et al. (1974) Cadmium in the environment, Cleveland,
Ohio, CRC Press

Gallery, E., Blomfield, J. & Dixon, S. R. (1972) Acute zinc toxicity
in haemodialysis, Brit. med. J., 4, 331-333

Giroux, E. & Henkin, R. (1972) Competition for zinc among serum
albumin and amino acids, Biochim. Biophys Acta, 273, 64-72

Guthrie, J. & Guthrie, O. (1974) Embryonal carcinomas in Syrian
hamsters after intratesticular inoculation of zinc chloride
during seasonal testicular growth, Cancer Res., 34, 2612-2614

Hagan, E., Radomski, J. & Nelson, A. (1953) Blood and bone marrow
effects of feeding zinc sulfate to rats and dogs, J. Am. Pharm.
Assoc. Sci. Ed., 42, 700-702

Hahn, F. & Schunk, R. (1955) Investigations about acute zinc
intoxication, Nauyn-Schmiedebergs. Arch. exp. Pathol.
Pharmacol., 226, 424-434

Hall, A., Young, B. & Bremner, I. (1979) Intestinal metallothionein
and the mutual antagonism between copper and zinc in the rat,
J. inorg. Biochem., 11, 57-66

Halme, E. (1961) On the cancer-causing effect of Zn-containing
drinking-water, Vitalst.-Zivilisa, 6, 59-66

Halsted, J. et al. (1972) Zinc deficiency in man, Am. J. Med., 53
277-284

Heller, V. & Burke, A. (1927) Toxicity of zinc, J. biol. Chem., 74
85-93

Henkin, R. & Aamodt, R. (1975) Zinc absorption in acrodermatitis
enteropathica and in hypogeusia and hyposmia, Lancet, I,
1379-1380

Heth, D., Becker, W. & Haekstra, W. (1966) Effect of calcium,
phosphorus and zinc on zinc-65 absorption and turnover in rats
fed semipurified diets, J. Nutr., 88, 331-337

Honstead, J. & Brady, D. (1967) The uptake and retention of ³²P and
⁶⁵Zn from the consumption of Columbia River fish, Health
Phys., 13, 455-463

Husain, S. (1969) Oral zinc sulphate in leg ulcers, Lancet, II,
1069-1073

Kanematsu, N., Hara, M. & Kada, T. (1980) REC assay and mutagenicity
studies on metal compounds, Mutat. Res., 77, 109-116

Kang, H. et al. (1977) Zinc, iron, copper and magnesium concentrations
in tissues of rats fed various amounts of zinc, Clin. Chem.,
23, 1834-1837

Klevay, L. (1973) Hypercholesterolemia in rats produced by an increase
in the ratio to copper ingested, Am. J. clin. Nutr., 26,
1060-1068

Litton Bionetics (1973) Summary of mutagenicity screening studies,
host-mediated assay, cytogenetics, dominant lethal assay,
contract FDA 71-268 and 71-49, zinc sulfate

Litton Bionetics (1976) Mutagenic evaluation of zinc oxide, USP,
FDA 75-14

Litton Bionetics (1977) Mutagenicity evaluation of FDA 75-72 zinc
stearate USP 000557-05-1, FDA 75-72

Lombeck, I. et al. (1975) Absorption of zinc in acrodermatitis
enteropathria, Lancet, 1, 855

Mannell, W. (1967) Effect of oysters with high zinc content on cats
and man, BIBRA Info. Bull., 6, 432-433

Meredith, P. & Moore, M. (1980) The in vivo effects of zinc on
erythrocyte delta-aminolaevulinic acid dehydratase in man, Int.
Arch., occup. Environ. Health, 45, 163-168

Methfessel, A. & Spencer, H. (1973a) Zinc metabolism in the rat. I.
Intestinal absorption of zinc, J. appl. Physiol., 34, 58-62

Methfessel, A. & Spencer, H. (1973b) Zinc metabolism in the rat. II.
Secretion of zinc into intestine, J. appl. Physiol., 34,
63-67

Murthy, L., Klevay, L. & Petering, H. (1974) Interrelationships of
zinc and copper nutriture in the rat, J. Nutr., 104,
1458-1465

National Research Council (NRC) (1979) Zinc, Baltimore, University
Park Press, pp. 173-268

Nielsen, F., Sunde, M. & Hoekstra, W. (1966a) Effect of dietary amino
acid source on the zinc-deficiency syndrome in the chick, J.
Nutr., 89, 24-34

Nielsen, F., Sunde, M. & Hoekstra, W. (1966b) Effect of some dietary
synthetic and natural chelating agents on the zinc-deficiency
syndrome in the chick, J. Nutr., 84, 35-42

O'Dell, B. & Savage, J. (1960) Effect of phytic acid on zinc
availability, Proc. Soc. exp. Biol. Med., 103, 304-306

Ogiso, T. et al. (1974) Inhibitory effect of high dietary zinc on
copper absorption in rats, Chem. Pharm. Bull., 22, 55-60

Ogiso, T., Ogawa, N. & Muira, T. (1979) Inhibitory effect of high
dietary zinc on copper absorption in rats. II. Binding of copper
and zinc to cytosol proteins in the intestinal mucosa, Chem.
Pharm. Bull., 27, 515-521

O'Neil-Cutting, M., Bomford, A. & Munro, H. (1981) Effect of excess
dietary zinc on tissue storage of iron in rats, J. Nutr.,
III, 1969-1979

Pecoud, A., Donzel, P. & Schelling, J. (1975) Effect of foodstuffs on
the absorption of zinc sulfate, Clin. Pharm. exp. Therap.,
17, 469-474

Petering, H. C. (1980) The influence of dietary zinc and copper on the
biologic effects of orally ingested lead in the rat, Ann. N.Y.
Acad. Sci., 355, 298-308

Petrie, J. & Row, P. (1977) Dialysis anaemia caused by subacute zinc
toxicity, Lancet, 1, 1178-1180

Philip, B. & Kurup, P. A. (1978) Dietary zinc and levels on collagen,
elastin and carbohydrate components of glycoproteins of aorta,
skin and cartilage in rats, Indian J. exp. Biol., 16, 370-372

Prensky, A. & Hillman, L. (1977) Zinc and the developing nervous
system: toxic effects of zinc on the central nervous system of
the preweanling rabbit. In: Brain-fetal and infant, The Hague,
Nijhoff Medical Division, pp. 124-136

Reinhold, J. et al. (1973) Effects of purified phytate and phytate-
rich bread upon metabolism of zinc, calcium, phosphorus, and
nitrogen in man, Lancet, I, 283-288

Richards, M. & Cousins, R. (1976) Metallothionein and its relationship
to the metabolism of dietary zinc in rats, J. Nutr., 106,
1591-1599

Richmond, C. et al. (1962) Comparative metabolism of radionuclides in
mammals. I. Uptake and retention of orally administered Zn 65 by
four mammalian species, Health Phys., 8, 481-489

Rosoff, B. & Spencer, H. (1965) Tissue distribution of zinc-65 in
tumor tissue and normal tissue in man, Nature (Lond.), 207,
652-653

Schelling, J., Muller-Hess, S. & Thonney, F. (1973) Effect of food on
zinc absorption, Lancet, 2, 968-969

Serjeant, G., Galloway, R. & Gueri, M. (1970) Oral zinc sulphate in
sickle-cell ulcers, Lancet, II, 891-893

Slavik, M., Lovenberg, W. & Keiser, H. (1973a) Changes in serum and
urine amino acids in patients with progressive systemic sclerosis
treated with 6-azauridine triacetate, Biochem. Pharmacol.,
22, 1295-1300

Slavik, M. et al. (1973b) Alterations in metabolism of copper and zinc
after administration of 6-azauridine triacetate, Biochem.
Pharmacol., 22, 2349-2352

Smith, W., Plumlee, M. & Beeson, W. (1962) Effect of source of protein
on zinc requirement of the growing pig, J. anim. Sci., 21,
399-405

Smythe, H. et al. (1969) Range-finding toxicity data: List VII, Am.
ind. Hyg. Assoc. J., 30, 470-476

Spencer, H., Rosoff, B. & Feldstein (1965) Metabolism of zinc-65 in
man, Radiat. Res., 24, 432-445

Stewart, A. & Magee, A. (1964) Effect of zinc toxicity on calcium,
phosphorus and magnesium metabolism of young rats, J. Nutr.,
82, 282-295

Suso, F. & Edwards, H. (1971a) Ethylenediaminetetracetate acid and
⁶⁵Zn binding by intestinal digesta, intestinal mucosa and blood
plasma, Proc. Soc. exp. Biol. Med., 138, 157-162

Suso, F. & Edwards, H. (1971b) Binding capacity of intestinal mucosa
and blood plasma for zinc, Proc. Soc. exp. Biol. Med., 137,
306-309

Van Vleet, J., Boon, G. & Ferrans, V. (1981) Induction of lesions of
selenium-vitamin E deficiency in weanling swine fed silver,
cobalt, tellurium, zinc, cadmium and vanadium, Am. J. vet.
Res., 42, 789-799

Walters, M. & Roe, F. (1965) A study of the effect of zinc and tin
administered orally to mice over a prolonged period, Fd.
Cosmet. Toxicol., 3, 271-276

World Health Organization (1973) Trace elements in human nutrition,
WHO Tech. Rep. Ser., 532, 9-15

Wilkins, J. (1948) A note on the toxicity of zinc chloride, Vet.
Rec., 60, 81-84

ANNEX I

REPORTS AND OTHER DOCUMENTS RESULTING FROM PREVIOUS MEETINGS ON THE
JOINT FAO/WHO EXPERT COMMITTEE ON FOOD ADDITIVES

Documents marked with an asterisk may be obtained on request
from: Division of Environmental Health, World Health Organization,
1211 Geneva 27, Switzerland, or from Food Standards and Food Science
Service, Food and Agriculture Organization of the United Nations,
00100 Rome, Italy.

1. General principles governing the use of food additives (First
report of the Expert Committee). FAO Nutrition Meetings Report
Series, No. 15, 1957; WHO Technical Report Series, No. 129, 1957
(out of print).

2. Procedures for the testing of intentional food additives to
establish their safety for use (Second report of the Expert
Committee). FAO Nutrition Meetings Report Series, No. 17, 1958;
WHO Technical Report Series, No. 144, 1958 (out of print).

3. Specifications for identity and purity of food additives
(antimicrobial preservatives and antioxidants) (Third report of
the Expert Committee). These specifications were subsequently
revised and published as Specifications for identity and purity
of food additives, vol. I. Antimicrobial preservatives and
antioxidants, Rome, Food and Agriculture Organization of the
United Nations, 1962 (out of print).

4. Specifications for identity and purity of food additives (food
colours) (Fourth report of the Expert Committee). These
specifications were subsequently revised and published as
Specifications for identity and purity of food additives, vol.
II. Food colours, Rome, Food and Agriculture Organization of
the United Nations, 1963 (out of print).

5. Evaluation of the carcinogenic hazards of food additives (Fifth
report of the Expert Committee). FAO Nutrition Meetings Report
Series, No. 29, 1961; WHO Technical Report Series, No. 220, 1961
(out of print).

6. Evaluation of the toxicity of a number of antimicrobials and
antioxidants (Sixth report of the Expert Committee). FAO
Nutrition Meetings Report Series, No. 31, 1962; WHO Technical
Report Series, No. 228, 1962.

7. Specifications for the identity and purity of food additives
and their toxicological evaluation: emulsifiers, stabilizers,
bleaching and maturing agents (Seventh report of the Expert
Committee). FAO Nutrition Meetings Report Series, No. 25, 1964;
WHO Technical Report Series, No. 281, 1964 (out of print).

8. Specifications for the identity and purity of food additives
and their toxicological evaluation: food colours and some
anti-microbials and antioxidants (Eighth report of the Expert
Committee). FAO Nutrition Meetings Report Series, No. 38, 1965;
WHO Technical Report Series, No. 309, 1965 (out of print).

*9. Specifications for identity and purity and toxicological
evaluation of some antimicrobials and antioxidants. FAO
Nutrition Meetings Report Series, No. 38A, 1965; WHO/Food
Add/24.65.

*10. Specifications for identity and purity and toxicological
evaluation of food colours. FAO Nutrition Meetings Report
Series, No. 38B, 1966; WHO/Food Add/66.25.

11. Specifications for the identity and purity of food additives
and their toxicological evaluation: some antimicrobials,
antioxidants, emulsifiers, stabilizers, flour-treatment agents,
acids, and bases (Ninth report of the Expert Committee). FAO
Nutrition Meetings Report Series, No. 40, 1966; WHO Technical
Report Series, No. 339, 1966.

12. Specifications for the identity and purity of food additives
and their toxicological evaluation: some emulsifiers and
stabilizers and certain other substances (Tenth report of the
Expert Committee). FAO Nutrition Meetings Report Series, No. 43,
1967; WHO Technical Report Series, No. 373, 1967.

*13. Toxicological evaluation of some antimicrobials, antioxidants,
emulsifiers, stabilizers, flour-treatment agents, acids, and
bases. FAO Nutrition Meetings Report Series, No. 40A, B, C;
WHO/Food Add/67.29.

14. Specifications for the identity and purity of food additives
and their toxicological evaluation: some flavouring substances
and non-nutritive sweetening agents (Eleventh report of the
Expert Committee). FAO Nutrition Meetings Report Series, No. 44,
1968; WHO Technical Report Series, No. 383, 1968.

*15. Toxicological evaluation of some flavouring substances and
non-nutritive sweetening agents. FAO Nutrition Meetings Report
Series, No. 44A, 1968; WHO/Food Add/68.33.

*16. Specification and criteria for identity and purity of some
flavouring substances and non-nutritive sweetening agents. FAO
Nutrition Meetings Report Series, No. 44B, 1969; WHO/Food
Add/69.31.

17. Specifications for the identity and purity of food additives
and their toxicological evaluation: some antibiotics (Twelfth
report of the Expert Committee). FAO Nutrition Meetings Report
Series, No. 45, 1969; WHO Technical Report Series, No. 430, 1969.

*18. Specifications for the identity and purity of some antibiotics.
FAO Nutrition Meetings Report Series, No. 43A, 1969; WHO/Food
Add/69.34.

19. Specifications for the identity and purity of food additives
and their toxicological evaluation: some food colours,
emulsifiers, stabilizers, anticaking agents, and certain other
substances (Thirteenth report of the Expert Committee). FAO
Nutrition Meetings Report Series, No. 46, 1970; WHO Technical
Report Series, No. 445, 1970.

*20. Toxicological evaluation of some food colours emulsifiers,
stabilizers, anticaking agents, and certain other substances.
FAO Nutrition Meetings Report Series, No. 46A; WHO/Food
Add/70.36.

*21. Specifications for the identity and purity of some food
colours, emulsifiers, stabilizers, anticaking agents, and
certain other food additives. FAO Nutrition Meetings Report
Series, No. 46B; WHO/Food Add/70.37.

22. Evaluation of food additives: specifications for the identity
and purity of food additives and their toxicological
evaluation: some extraction solvents and certain other
substances; and a review of the technological efficacy of some
antimicrobial agents (Fourteenth report of the Expert
Committee). FAO Nutrition Meetings Report Series, No. 48, 1971;
WHO Technical Report Series, No. 462, 1971.

*23. Toxicological evaluation of some extraction solvents and
certain other substances. FAO Nutrition Meetings Report
Series, No. 48A, 1971; WHO/Food Add/70.39.

*24. Specifications for the identity and purity of some extraction
solvents and certain other substances. FAO Nutrition Meetings
Report Series, No. 48B, 1971; WHO/Food Add/70.40.

*25. A review of the technological efficacy of some antimicrobial
agents. FAO Nutrition Meetings Report Series, No. 48C, 1971;
WHO/Food Add/70.41.

26. Evaluation of food additives: some enzymes, modified starches,
and certain other substances: toxicological evaluations and
specifications and a review of the technological efficacy of
some antioxidants (Fifteenth report of the Expert Committee).
FAO Nutrition Meetings Report Series, No. 50, 1972; WHO Technical
Report Series, No. 488, 1972.

27. Toxicological evaluation of some enzymes, modified starches,
and certain other substances. FAO Nutrition Meetings Report
Series, No. 50A, 1972; WHO Food Additives Series, No. 1, 1972.

28. Specifications for the identity and purity of some enzymes and
certain other substances. FAO Nutrition Meetings Report Series,
No. 50B, 1972; WHO Food Additives Series, No. 2, 1972.

29. A review of the technological efficacy of some antioxidants and
synergists. FAO Nutrition Meetings Report Series, No. 50C,
1972; WHO Food Additives Series, No. 3, 1972.

30. Evaluation of certain food additives and the contaminants
mercury, lead, and cadmium (Sixteenth report of the Expert
Committee), FAO Nutrition Meetings Report Series, No. 51, 1972;
WHO Technical Report Series, No. 505, 1972, and corrigendum.

31. Evaluation of mercury, lead, cadmium, and the food additives
amaranth, diethylpyrocarbonate, and octyl gallate. FAO
Nutrition Meetings Report Series, No. 51A, 1972; WHO Food
Additives Series, No. 4, 1972.

32. Toxicological evaluation of certain food additives with a
review of general principles and of specifications (Seventeenth
report of the Expert Committee). FAO Nutrition Meetings Report
Series, No. 53, 1974; WHO Technical Report Series, No. 539, 1974,
and corrigendum.

33. Toxicological evaluation of certain food additives including
anticaking agents, antimicrobials, antioxidants, emulsifiers,
and thickening agents. FAO Nutrition Meetings Report Series,
No. 53A; WHO Food Additives Series, No. 5, 1974.

34. Evaluation of certain food additives (Eighteenth report of the
Expert Committee). FAO Nutrition Meetings Report Series, No. 54,
1974; WHO Technical Report Series, No. 557, 1974, and
corrigendum.

35. Toxicological evaluation of some food colours, enzymes, flavour
enhancers, thickening agents, and certain other food additives.
FAO Nutrition Meetings Report Series, No. 54A, 1975; WHO Food
Additives Series, No. 6, 1975.

36. Specifications for the identity and purity of some food
colours, flavour enhancers, thickening agents, and certain food
additives. FAO Nutrition Meetings Report Series, No. 54B, 1975;
WHO Food Additives Series, No. 7, 1975.

37. Evaluation of certain food additives: some food colours,
thickening agents, smoke condensates, and certain other
substances (Nineteenth report of the Expert Committee). FAO
Nutrition Meetings Report Series, No. 55, 1975; WHO Technical
Report Series, No. 576, 1975.

38. Toxicological evaluation of some food colours, thickening
agents, and certain other substances. FAO Nutrition Meetings
Report Series, No. 55A; WHO Food Additives Series, No. 8, 1975.

39. Specifications for the identity and purity of certain food
additives. FAO Nutrition Meetings Report Series, No. 55B, 1976;
WHO Food Additives Series, No. 9, 1976.

40. Evaluation of certain food additives (Twentieth report of the
Expert Committee). FAO Food and Nutrition Series, No. 1, 1976;
WHO Technical Report Series, No. 599, 1976.

41. Toxicological evaluation of certain food additives. FAO Food
and Nutrition Series, No. 1A, 1978; WHO Food Additives Series,
No. 10, 1978.

42. Specifications for the identity and purity of certain food
additives. FAO Food and Nutrition Series, No. 1B, 1977.

43. Evaluation of certain food additives (Twenty-first report of
the Joint FAO/WHO Expert Committee on Food Additives). WHO
Technical Report Series, No. 617, 1978.

44. Summary of toxicological data of certain food additives. WHO
Food Additives Series, No. 12, 1977.

45. Specifications for identity and purity of some food additives,
including antioxidants, food colours, thickeners, and others.
FAO Nutrition Meetings Report Series, No. 57, 1977.

46. Specifications for identity and purity of thickening agents,
anticaking agents, antimicrobials, antioxidants and
emulsifiers. FAO Food and Nutrition Paper, No. 4, 1978.

47. Guide to specifications - General notices, general methods,
identification tests, text solutions, and other reference
materials. FAO Food and Nutrition Paper, No. 5, 1978.

48. Evaluation of certain food additives (Twenty-second report of
the Joint FAO/WHO Expert Committee on Food Additives). WHO
Technical Report Series, No. 631, 1978.

49. Summary of toxicological data of certain food additives and
contaminants. WHO Food Additives Series, No. 13, 1978.

50. Specifications for the identity and purity of certain food
additives. FAO Food and Nutrition Paper, No. 7, 1978.

51. Evaluation of certain food additives (Twenty-third report of
the Joint FAO/WHO Expert Committee on Food Additives). WHO
Technical Report Series, No. 648, 1980.

52. Toxicological evaluation of certain food additives. WHO Food
Additives Series, No. 14, 1979.

53. Specifications for identity and purity of food colours,
flavouring agents, and other food additives. FAO Food and
Nutrition Paper, No. 12, 1979.

54. Evaluation of certain food additives (Twenty-fourth report of
the Joint FAO/WHO Expert Committee on Food Additives). WHO
Technical Report Series No. 653, 1980.

55. Toxicological evaluation of certain food additives. WHO Food
Additives Series, No. 15, 1981.

56. Specifications for identity and purity of food additives
(sweetening agents, emulsifying agents, and other food
additives). FAO Food and Nutrition Paper, No. 17, 1980.

57. Evaluation of certain food additives (Twenty-fifth report of
the Joint FAO/Expert Committee on Food Additives). WHO Technical
Report Series, No. 669, 1981.

58. Toxicological evaluation of certain food additives. WHO Food
Additives Series, No. 16, 1982.

59. Specifications for identity and purity of food additives
(carrier solvents, emulsifiers and stabilizers, enzyme
preparations, flavouring agents, food colours, sweetening
agents and other food additives). FAO Food and Nutrition
Paper, No. 19, 1981.

60. Evaluation of certain food additives and contaminants (Twenty-
sixth report of the Joint FAO/WHO Expert Committee on Food
Additives). WHO Technical Report Series, No. 683, 1982.

61. Specifications for identity and purity of food additives
buffering agents, salts, emulsifiers, thickening agents,
stabilizers, flavouring agents, food colours sweetening agents,
and miscellaneous food additives. FAO Food and Nutrition Paper,
No. 25, 1982.

ANNEX II
SURVEY OF PUBLICATIONS AND OTHER DOCUMENTS DIRECTLY RESULTING FROM ACTIVITIES OF THE JOINT
FAO/WHO EXPERT COMMITTEE ON FOOD ADDITIVES

Publications Year of
Meeting Year of Place of Topics dealt with or documents Identification publication
No. meeting meeting resulting codes^a or issue

1 1956 Rome General principles Report only NMRS 15 1957
governing the use TRS 126 1957
of food additives

2 1957 Geneva Procedures for the Report only NMRS 17 1958
testing of TRS 144 1958
intentional food
additives to
establish their
safety for use

3 1958 Rome Specifications for Mimeographed FAO 1959
identity and report
purity of Specifications FAO-Volume I 1962
antimicrobial
preservatives and
antioxidants

4 1959 Rome Specifications for Mimeographed FAO 1959
identity and report
purity of food Specifications FAO-Volume II 1963
colours

5 1960 Geneva Evaluation of the Report only NMRS 29 1961
carcinogenic TRS 220 1961
hazards of food
additives

^a NMRS = FAO Nutrition Meetings Report Series; TRS = WHO Technical Report Series.

Annex II (Con't)

Publications Year of
Meeting Year of Place of Topics dealt with or documents Identification publication
No. meeting meeting resulting codes^a or issue

6 1961 Geneva Antimicrobials and Report containing NMRS 31 1962
antioxidants also TRS 228 1962
(toxicology and toxicological
some monographs
specifications)

7 1963 Rome Emulsifiers, Report containing NMRS 35 1964
stabilizers, toxicological TRS 281 1964
bleaching and monographs and
maturing agents chemical
(toxicology and specifications
specifications)

8 1964 Geneva Food colours, Report NMRS 38 1965
antimicrobials and TRS 309 1965
antioxidants Specifications NMRS 38A 1965
(toxicology and for antimicrobials Food Add. 24.65 1965
specifications) and antioxidants
Specifications NMRS 38B 1966
and toxicology of Food Add. 24.65 1966
food colours
(containing also
materials from
4th to 10th
meetings)

^a NMRS = FAO Nutrition Meetings Report Series; TRS = WHO Technical Report Series;
Food Add. = WHO/Food Additives.

Annex II (Con't)

Publications Year of
Meeting Year of Place of Topics dealt with or documents Identification publication
No. meeting meeting resulting codes^a or issue

9 1965 Rome Antimicrobials, Report NMRS 40 1966
antioxidants, TRS 339 1966
emulsifiers, Toxicology NMRS 40A,B,C 1967
stabilizers, and some Food Add. 67.29 1967
flour-treating specifications
agents, acids and (containing also
bases materials from
10th meeting)

10 1966 Geneva Emulsifiers, Report only NMRS 43 1967 ,
stabilizers and (for monographs TRS 373 1967
certain other see meetings 8
substances and 9)

11 1967 Geneva Flavouring Report NMRS 44 1968
substances and TRS 383 1968
non-nutritive Toxicology NMRS 44A 1968
sweetening agents Food Add. 68.33 1967
Specifications NMRS 44B 1969
Food Add. 69.31 1969

12 1968 Geneva Antibiotics Report NMRS 45 1969
TRS 430 1969
Specifications NMRS 45A 1969
Food Add. 69.34 1969

^a NMRS = FAO Nutrition Meetings Report Series; TRS = WHO Technical Report Series;
Food Add. = WHO/Food Additives.

Annex II (Con't)

Publications Year of
Meeting Year of Place of Topics dealt with or documents Identification publication
No. meeting meeting resulting codes^a or issue

13 1969 Rome Food colours, Report NMRS 46 1970
emulsifiers, TRS 445 1970
stabilizers, Toxicology NMRS 46A 1970
anticaking agents, Food Add. 70.36 1970
certain other Specifications NMRS 46B 1970
substances Food Add. 70.37 1970

14 1970 Geneva Extraction Report NMRS 48 1971
solvents, TRS 462 1971
certain other Toxicology NMRS 48A 1971
substances, Food Add. 70.39 1971
technological Specifications NMRS 48B 1971
efficacy of Food Add. 70.40 1971
antimicrobial Efficacy NMRS 48C 1971
agents Food Add. 70.41 1971

15 1971 Rome Enzymes, modified Report NMRS 50 1972
starches, certain TRS 488 1972
other substances, Toxicology NMRS 50A 1972
technological FAS 1 1972
efficacy of Specifications NMRS 50B 1972
antioxidants FAS 2 1972
Efficacy NMRS 50C 1972
FAS 3 1972

^a NMRS = FAO Nutrition Meetings Report Series; TRS = WHO Technical Report Series;
Food Add. = WHO/Food Additives; FAS = WHO Food Additives Series.

Annex II (Con't)

Publications Year of
Meeting Year of Place of Topics dealt with or documents Identification publication
No. meeting meeting resulting codes^a or issue

16 1972 Geneva Contaminants: Report NMRS 51 1972
cadmium, lead, TRS 505 1972
mercury. Toxicology NMRS 51A 1972
Additives: FAS 4 1972
amaranth,
diethylpyrocarbonate
and octyl gallate

17 1973 Geneva Certain food Report NMRS 53 1974
additives. TRS 539 1974
Review of general Toxicology NMRS 53A 1974
principles FAS 5 1974
Specificationsb FNP 4 1978

18 1974 Rome Food colours, Report NMRS 54 1974
enzymes, flavours, TRS 557 1974
thickening agents, Toxicology NMRS 54A 1975
certain other food FAS 6 1975
additives Specifications NMRS 54B 1975
FAS 7 1975

^a NMRS = FAO Nutrition Meetings Report Series; TRS = WHO Technical Report Series;
FAS = WHO Food Additives Series; FNP = FAO Food and Nutrition Paper.

^b Published by FAO only.

Annex II (Con't)

Publications Year of
Meeting Year of Place of Topics dealt with or documents Identification publication
No. meeting meeting resulting codes^a or issue

19 1975 Geneva Food colours, Report NMRS 55 1975
thickening agents, TRS 576 1975
certain other Toxicology NMRS 55A 1975
substances FAS 8 1975
Specificationsb NMRS 55B 1976
FAS 9 1976

20 1976 Rome Certain food Report FNS 1 1976
additives, TRS 599 1976
antioxidants, Toxicologyc FAS 10 -
sweeteners, Specificationsb FNS 1B 1977
thickeners, FAS 11 1977
solvents and other
food additives

21 1977 Geneva Certain food Reportc TRS 617 1978
additives, Toxicologyc FAS 12 -
antioxidants, food Specificationsb NMRS 57 1977
colours and
thickeners

^a NMRS = FAO Nutrition Meetings Report Series; TRS = WHO Technical Report Series;
FAS = WHO Food Additives Series; FNS = FAO Food and Nutrition Series.

^b Published by FAO only.

^c Published by WHO only.

Annex II (Con't)

Publications Year of
Meeting Year of Place of Topics dealt with or documents Identification publication
No. meeting meeting resulting codes^a or issue

22 1978 Rome Certain food Reportb TRS 631 1978
additives and Toxicologyb FAS 13 1979
contaminants, Specificationsc FNP 7 1978
food colours,
miscellaneous food
additives,
asbestos, lead,
mercury, organic
tin, and organotin
compounds

23 1979 Geneva Food colours, Reportb TRS 648 1980
carrier solvents, Toxicologyb FAS 14 1980
extraction Specificationsc FNP 12 1979
solvents,
flavours,
inorganic salts
and salts of
organic acids

^a TRS = WHO Technical Report Series; FAS = WHO Food Additives Series; FNP = FAO Food and
Nutrition Paper.

^b Published by WHO only.

^c Published by FAO only.

Annex II (Con't)

Publications Year of
Meeting Year of Place of Topics dealt with or documents Identification publication
No. meeting meeting resulting codes^a or issue

24 1980 Rome Anticaking agents, Reportb TRS 653 1980
food Toxicologyb FAS 15 1981
antimicrobials, Specificationsc FNP 17
antioxidants,
emulsifiers,
flavours, food
colours,
sweeteners,
thickening agents,
miscellaneous food
additives

25 1981 Geneva Food colours, Reportb TRS 669 1981
flavours, Toxicologyb FAS 16 1982
sweeteners, Specificationsc FNP 19 1981
thickening agents,
extraction
solvents, carrier
solvents,
miscellaneous food
additives

^a TRS = WHO Technical Report Series; FAS = WHO Food Additives Series;
FNP = FAO Food and Nutrition Paper.

^b Published by WHO only.

^c Published by FAO only.

    See Also:
       Toxicological Abbreviations
       Zinc (EHC 221, 2001)
       ZINC (JECFA Evaluation)
       Zinc (UKPID)