FAO Nutrition Meetings
Report Series No. 48A
WHO/FOOD ADD/70.39
TOXICOLOGICAL EVALUATION OF SOME
EXTRACTION SOLVENTS AND CERTAIN
OTHER SUBSTANCES
The content of this document is the
result of the deliberations of the Joint
FAO/WHO Expert Committee on Food Additives
which met in Geneva, 24 June -2 July 19701
Food and Agriculture Organization of the United Nations
World Health Organization
1 Fourteenth report of the Joint FAO/WHO Expert Committee on Food
Additives, FAO Nutrition Meetings Report Series in press; Wld Hlth
Org. techn. Rep. Ser., in press.
ETHANOL
Biological Data
Biochemical aspects
Ethyl alcohol is rapidly and readily oxidized to CO2 and water.
The toxicity is diminished if substances which increase tissue
oxidation are given beforehand. The pathway is generally agreed to be
initial oxidation to acetaldehyde, conversion to acetyl co-enzyme A
and acetic acid, final combustion in kidney and liver to CO2 and
water (Browning, 1965). Lung tissue can also convert ethanol to CO2
(Masoro et al. 1953). The principal organ responsible for the
metabolism of ethanol is the liver - it employed two enzyme systems -
alcohol dehydrogenase and aldehyde dehydrogenase - both require NAD as
a cofactor (Westerfeld, 1961). Alcohol dehydrogenase activity has been
demonstrated in several other organs and tissues, including the
stomach and intestine (Spencer et al. 1964, Mistilis et al. 1969),
kidney (Buttner, 1965), lung (Moser et al. 1968), and brain (Raskin et
al. 1968), but their contribution to the overall metabolism of ethanol
is slight (Bartlett, 1949). Acetaldehyde dehydrogenase controls the
further oxidation of acetaldehyde to acetic acid (Camps, 1968). Using
C14 labelled alcohol it has been shown that rats exhale 75 per cent.
as CO2 in 5 hours and 90 per cent. in 10 hours. Two per cent. is
eliminated unchanged in the urine and expired air, while 0.5-2.0 per
cent. is conjugated and excreted in the urine as ethylglucuronide
(Bartlett & Barnett, 1949, Kamil et al. 1953).
Clearance of ethanol from blood depends on the blood levels
present. At low dosage it is proportional to the blood alcohol levels
when liver alcohol dehydrogenase is not fully saturated. As the
circulating blood ethanol level increases maximum metabolic conversion
is achieved. At still higher levels the resultant CNS depression
produced hypoventilation, hypothermia, and hypotension, with a
consequent decrease in alcohol metabolism (Lundquist & Wolthers,
1958). The rat metabolizes alcohol more slowly than the mouse and
faster than the dog (Aull et al. 1956). In dogs alcohol passes through
the kidneys by simple diffusion. During absorption from the G.I. tract
the concentration of ethyl alcohol was a little lower in peripheral
veins compared with arterial levels. 2-4% of total ingested alcohol
was eliminated by kidneys and 4% in the expired air (Treon, 1958).
Recent evidence suggests that man metabolises alcohol at a rate
depending upon the concentration present if catalase handles oxidation
but independent of concentration in the human body if alcohol
dehydrogenase handles oxidation. Tetraethylthiuram disulphide inhibits
acetaldehyde dehydrogenase and gives rise to toxic tissue accumulation
of acetaldehyde (Goodman & Gilman, 1967). Other possibilities are the
prevention of the oxidation of ethanol and the production of
disulphide metabolites. Any acetic acid formed joins the body acetate
pool (Treon, 1958). Etharel is distributed uniformly in body water
(Camps, 1968). Ethanol has a direct effect on liver cells in vitro,
decreases DPN and increases DPNH and therefore effects more acetate
incorporation into fatty acids (Lieber & Schmid, 1961). Acute ethanal
induced fatty liver differs from that induced by chronic small amounts
in that the latter responds to choline but not the former. Hence
hepatic fat may increase by (a) increased mobilization of fat from
depots, (b) increased fat synthesis and esterification in the liver
itself, (c) inducing a relative recline deficiency, all leading to the
picture of fatty infiltration and fibrosis (Klatskin, 1961). Decreased
fat oxidation in the liver may contribute to the fat accumulation
(Isselbacher & Greenberger, 1964). Ethanol produces a marked increase
in serum cholesterol in the dog, while in man a small but significant
increase occurs after large intakes. Hyperlipaemic subjects show
greater rise (Grande & Amatuzio, 1960). Ethanol has a moderate
short-lasting effect on adrenal medullary secretion producing a rise
in urinary adrenalin and noradrenalin output. This is probably due to
a sympathetic stimulation (Perman, 1961). Alcohol is not absorbed
through normal skin but can be absorbed through abraded areas (Camp,
1968).
Acute toxicity
Animal Route LD50 LD100 References
mg/kg mg/kg
body-weight body-weight
Frog s.c. - 7100-7900 Spector, 1956
Mouse oral 9488 - Spector, 1956
s.c. 8285 - Spector, 1956
s.c. - 4700 Browning, 1953
i.v. 1973 - Spector, 1956
inhalation - 29300 ppm Browning, 1965
Rat oral 13660 - Spector, 1956
i.p. 5000 - Spector, 1956
inhalation - 12700 ppm Browning, 1965
Guinea-pig i.p. 5560 - Spector, 1956
inhalation - 21900 ppm Browning, 1965
Rabbit oral 6300 - Spector, 1956
oral 9500 Spector, 1956
oral - 7890 Spector, 1956
oral - 9000-10000 Browning, 1953
i.p. - 3500 Browning, 1953
i.v. - 9400 Spector, 1956
Cat i.v. - 3945 Spector, 1956
Dog oral - 5500-6500 Spector, 1956
s.c. - 6000-8000 Spector, 1956
i.v. - 5365 Spector, 1956
Man oral - 6000-8000 von Oettingen,
1943
Dogs intoxicated by ingestion showed liver injury consisting of
cellular oedema at the periphery of lobules and increase in lipid
which regressed subsequently (MacNider, 1933). Inhalation of high
concentrations caused reversible fatty infiltration of the liver
(Weese, 1928).
Short-term studies
Mouse. Groups of 10 mice were fed for 5 weeks on a control diet
but drinking water was either normal water or 0.8 per cent., 4 per
cent. and 20 per cent. ethyl alcohol. Mortality increased with dose
but there was little effect on the mean weight of survivors (College
Pharmaceutical Society, (1962).
Groups of male and female mice were given ethyl alcohol (unknown
composition) i.p. for 6 months. No tumours were noted (Larson &
Heston, 1945).
Rat. Five female rats received orally 1 ml 40 per cent. aqueous
alcohol 3 times per week for 41 days. No tumours were observed
(Russell et al. 1941).
Nine groups of rats containing 5-25 animals received 20 per cent.
alcohol in their drinking water and additional cystine with or without
choline in their diet. Observation extended from 8 to 24 weeks. No
tumours were observed (Wanscher, 1953).
15 rats received 15 per cent. alcohol in water for up to 14
weeks. No tumours were observed (Baumann et al. 1942).
Groups of male rats received 15 per cent. alcohol in their
drinking water. After 177 days there were no tumours (Best et al.
1949).
24 rats were given 15 per cent. alcohol in their drinking water.
After 120 days there were no tumours (Klatskin et al. 1951).
In another experiment rats were given ethyl alcohol in their food
for 300 days without any pathological changes having been observed
(Nakahara & Mori, 1939).
Rabbit. 64 rabbits were given 20 per cent. alcohol in water by
stomach tube in quantities from 20-100 ml daily for 304 days. Thirteen
died of infection but no tumours were seen in the rest (Connor, 1940).
Dog. Twenty-three dogs received a 40 per cent. aqueous solution
at a rate of 10 ml/kg body-weight daily for 6 to 26 months without any
signs of tumour development (McNider & Donnelly, 1932).
Observations in man
Ethylalcohol acts principally on the brain whether ingested or
inhaled, first as an inhibitor of the higher functions and then as an
anaesthetic. The lethal dose for man is 8-10 ml per kg body-weight or
one quart of whisky or a blood level of 0.5% or more (Haag et al.
1951, von Oettingen, 1943). Death occurs from severe and probably
irreversible injury to CNS. Acute intoxication affects visual acuity,
fields of vision, eye co-ordination and distance judgement. The vapour
is slightly irritant to the eye and respiratory tract mucosa. Animals
as well as man develop tolerance. Inhalation concentrations up to 3500
ppm caused no irritation nor any subjective symptoms nor any rise in
blood alcohol levels (Treon, 1958). The TLV is 100 ppm (Amer, Conf.
Gov, Ind. Hyg., 1969). Moderate doses stimulate the appetite and food
absorption. Higher concentrations irritate the gastric mucosa (Jacobs,
1947). Ingestion of less than 0.5 g/kg does not affect the behaviour
of man, 0.5 - 2.0 g/kg cause some disturbance and doses above 2 g/kg
cause serious drunkenness (von Oettingen, 1943). Chronic ingestion
causes visual impairment and incoordination of voluntary muscles
(Browning, 1965). Chronic intake of alcohol amounting to over 160 g
pure alcohol per day for more than 10 years leads to hepatic cirrhosis
(Thaler, 1969). The preferential oxidation of ethanol in the liver
diverts NAD from other sites, leading to alteration of cellular
biochemistry and pathological damage despite enzyme inhibition of
alcohol dehydrogenase activity (Mistilis & Birchall, 1969). In man,
secondary nutritional inadequacies, along with electrolyte and mineral
imbalance may and do occur. The cardiotoxic effects could arise from
hypomagnesemia and hypozincemia. Ethanal is a diuretic and when it is
consumed with relatively large volumes of water magnesuria and
zincuria will result. If prolonged, cardiac damage, secondary to low
cardiac magnesium (Heggtveit et al. 1964) or zinc (Wendt of al. 1966)
can appear. 20% w/u i.p. ethanol produce a chemical peritonitis,
pancreatitis and peritoneal adhesions (Wiberg et al. 1969).
Long-term studies
Mouse. 16 mice received 0.1 ml of a 50 per cent. alcoholic solution
every two days rectally for 547 days. Two animals developed tumours of
which one was a sarcoma. In another experiment, 10 male and female
mice received 0.1 ml of a 50 per cent. alcoholic solution every two
days orally for 554 days. Two tumours of the back were observed
(Krebs, 1928).
Comments
Ethanol is a common component in the diet and it is not
appropriate to consider it in the same way as other extraction
solvents. As a solvent residue it will probably constitute no more
than 0.5% of any food.
Evaluation
The use of this solvent should be restricted to that determined
by good manufacturing practice. There is less urgency to ensure the
minimum amount of residues because of its dietary role, but residues
resulting from good manufacturing practice are unlikely to have any
significant toxicological effects.
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See Also:
Toxicological Abbreviations
ETHANOL (JECFA Evaluation)