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.
TANNIN (FOOD GRADE)
Tannic acid was considered at the Tenth Meeting of the Joint FAO/WHO
Expert Committee on Food Additives but no ADI could be established
because of insufficient data (FAO/WHO, 1967). Those data and
additional ones which are summarized below have been reviewed in the
light of the use of tannins in food processing as a flocculant.
Biological data
Biochemical aspects
None available on food grade material.
Acute toxicity
Animal Route Material LD50 Reference
mg/kg
body weight
rat intragastric Aleppo tannin 1550 Food and Drug Res. Lab. (1964)
intragastric Tara tannin 3700 Food and Drug Res. Lab. (1964)
intragastric Chinese tannin 2800 Food and Drug Res. Lab. (1965)
intragastric Sicilian sumac 2650 Food and Drug Res. Lab. (1967)
tannin
intragastric Douglas fir 7500 Food and Drug Res Lab. (1967)
tannin
Aleppo tannin stimulated lachrymation and CNS depression. The tannins
generally appeared to produce motor depression and diarrhoea.
Short-term studies
Rat
Seven groups of 15 males and 15 females received daily either 0,
8, 80 or 800 mg/kg body weight of Aleppo tannin or tara tannin in
their diet for 12 weeks. Body weight, food intake and food utilization
showed no significant changes related to the substance. Liver and
kidney weights were similar for tests and controls. Gross and
histopathology showed only incidental abnormal findings unrelated to
the test substances (Food and Drug Res. Lab., 1964). Similar studies
at these same levels using Chinese tannin (Food and Drug Res. Lab.,
1965), Sicilian sumac tannin (Food and Drug Res. Lab., 1967) and
Douglas fir tannin (Food and Drug Res. Lab., 1967) produced comparable
findings.
Dog
Five groups of 4 males and 4 females received daily 0.0, 0.25,
0.234, 0.125 or 0.117% Peruvian tara tannin in their diets for 2
years. Chewing gum containing the tannin at a level of 0.5% was the
material actually incorporated into the diet, No ill effects were
noted at any level of tannin fed as judged by behaviour, food
consumption, haematology, organ function tests, organ weights and
gross and microscopic pathology (Rosner-Hixon Lab., 1965).
Long-term studies
Rat
Five groups of 50 males and 50 females received daily 0.0, 0.25,
0.234, 0.125, or 0.117% Peruvian tara tannin in their diets for 2
years. Chewing gum containing the tannin at a level of 0.5% was the
material actually incorporated into the diet. No ill effects were
noted at any level of tannin fed as judged by survival, growth, food
consumption, haematology, organ weights and gross and microscopic
pathology (Rosner-Rixon Lab., 1965).
Three-generation studies, 2 litters per generation, were carried
out in groups of 20 males and 20 females using Peruvian tara tannin at
feeding levels of 0.0 and 0.234% and at 0.0, 0.117 and 0.058%. Chewing
gum containing the tannin at a level of 0.5% was the material actually
incorporated into the diet. Pups of the group fed at the 0.234% level
were found to have significantly lower weights at weaning as compared
to the controls. This effect was not seen at the lower feeding levels,
nor were effects upon fertility, gestation, viability or lactation
indices seen at any feeding level (Rosner-Hixon Lab., 1969).
Comments
Almost all the early studies on commercial tannin from a variety
of sources have shown hepatotoxicity. Their relevance to the
assessment of food grade tannin is small because the presence of
commercial tannins is excluded by the specification for food grade
material. Some tannins occurring in natural foodstuffs, such as tea
and coffee, are not toxic.
Short-term studies are available on food grade tannins of
specified origin but only Peruvian tara has been tested in long-term
studies. While 2-year feeding studies in both dog and rat produced no
effects at levels up to 0.25%, reduced body-weights at weaning were
found for rat pups in a multigeneration study at a feeding level of
0.234%.
Evaluation
Level causing no toxicological effects in rats
1170 ppm (0.117%) in the diet, equivalent to approximately 60
mg/kg body-weight.
Acceptable daily intake for man
mg/kg body-weight
Temporary 0-0.6*
Temporary 0-0.3**
Further work required by June 1973
Further information on specifications is required.
Studies in a second species to demonstrate no increased toxicity
beyond that shown for Peruvian tara for tannin. derived from Turkish
Aleppo, Chinese tara and Sicilian sumac.
REFERENCES
Anon (1969) Lancet, ii, 34
FAO/WHO (1967) Wld Hlth Org. techn. Rep. Ser,373
Food and Drug Research Laboratories (1964, 1965, 1967) Unpublished
reports submitted to WHO
Rosner-Hixon Laboratories (1965) Unpublished report submitted to WHO
Rosner-Hixon Laboratories (1969) Unpublished reports submitted to WHO
* Derived from Peruvian tara.
** Turkish Aleppo, Chinese tara, Sicilian sumac.