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.
This substance has been evaluated for acceptable daily intake by
the Joint FAO/WHO Expert Committee on Food Additives (see Annex 1,
Ref. No. 6) in 1961.
The previously published monograph has been revised and is
reproduced in its entirety below.
Very little, if any, guaiac resin is absorbed, much is passed out
in the faeces, and the remainder is destroyed in the colon (Johnson et
Animal Route (mg/kg bw)
Rat oral > 5 000 Lehman et al., 1951
Mouse oral > 2 000 Lehman et al., 1951
Mouse i.p. > 2 000 Lehman et al., 1951
Guinea-pig oral 1 120 Lehman et al., 1951
Six human subjects took a total of 10 doses 2 or 3 g at a time.
The only untoward sequel of ingesting these large quantities was the
passage of one or two loose stools in some instances (Johnson et al.,
Four groups of 10 rats received resin diets containing 10% lard
with 0%, 0.05%, 0.5% and 5% guaiac resin (0%, 0.005%, 0.05% and 0.5%
of the total diet). None of them showed any effect on growth rate
over a period of 41 weeks (Johnson et al., 1958).
Eight full-grown cats received a daily dose of 500 or 1000 mg of
guaiac resin for 34 to 117 weeks. Body weight, general behaviour,
appearance, red and white blood cell counts, and haemoglobin remained
normal. Two of the cats fed for 74 weeks showed no irritation of
intestinal mucosa; upon histological examination the lungs, kidney,
liver and spleen were found to be normal (Johnson et al., 1958).
Guaiac resin in doses of 500 or 1000 mg was administered to
11 fully grown dogs daily for 62 to 103 weeks. Body weight, general
behaviour, appearance, red and white blood cell counts, and
haemoglobin remained normal. Histological sections from three dogs
(fed 1000 mg guaiacum daily for 75 weeks) showed a normal intestinal
mucosa in each case, with no suggestion of irritation or injury. The
lungs, kidney, liver and spleen from these dogs were normal upon
microscopic examination (Johnson et al., 1958).
Forty rats were divided into four groups and fed diets containing
lard with 0%, 0.05%, 0.5% and 5% guaiac resin (0%, 0.005%, 0.05% and
0.5% of the total diet) for a lifetime study. The second and third
generation descendants (80 in number) of the original rats were
maintained throughout their lifetime on the same diet as their
parents. No differences were observed between the experimental groups
and the controls in regard to body weight, growth rate, life-span,
reproduction, or pathological examination (Johnson et al., 1958).
Groups of 10 rats each were maintained on diets containing 0% and
0.5% guaiac resin for a period of two years. No discernible difference
was observed between the two groups as determined by growth rate,
mortality, and pathological examination (Lehman et al., 1951).
OBSERVATIONS IN MAN
Eleven human subjects (four female and seven male) received 50 or
100 mg of guaiac resin daily for periods of 18 to 104 weeks. Red and
white blood cell counts, haemoglobin, kidney function, body weight,
number and consistency of stools, and general physical condition were
unchanged throughout the experimental period (Johnson et al., 1958).
The results reported provide a basis for estimating an acceptable
intake for man. These include studies in dogs, cats and human subjects
as well as biochemical studies on the action of guaiacun on the gut
and its fate in the organism.
Level causing no toxicological effect
Rat: 5000 ppm (0.5%) in the diet, equivalent to 250 mg/kg bw.
Estimate of acceptable daily intake for man
0-2.5 mg/kg bw.
Johnson, V. et al. (1938) Food Res., 3, 555
Lehman, A. J. et al. (1951) Advanc. Food Res., 3, 197