FAO Meeting Report No. PL/1965/10/1
WHO/Food Add./27.65
EVALUATION OF THE TOXICITY OF PESTICIDE RESIDUES IN FOOD
The content of this document is the result of the deliberations of the
Joint Meeting of the FAO Committee on Pesticides in Agriculture and
the WHO Expert Committee on Pesticide Residues, which met in Rome,
15-22 March 19651
Food and Agriculture Organization of the United Nations
World Health Organization
1965
1 Report of the second joint meeting of the FAO Committee on
Pesticides in Agriculture and the WHO Expert Committee on Pesticide
Residues, FAO Meeting Report No. PL/1965/10; WHO/Food Add./26.65
MANEB
Chemical name
Manganese ethylene-1,2-bisdithiocarbamate
Synonyms
Manzate, MEB, MnEBD
Empirical formula
C4H6N2S4Mn
Structural formula
BIOLOGICAL DATA
Biochemical aspects
No evidence.
Acute toxicity
Animal Route LD50 mg/kg References
body-weight
Rat Oral 7500 United Kingdom Ministry of Agriculture
Guinea-pig Oral 7500 United Kingdom Ministry of Agriculture
Short-term studies
Dog. Groups, each of 2 dogs, were fed maneb orally at the rate
of 2.0. 20, 75 and 200 mg/kg body-weight daily for one year. At the
two highest dose levels the animals showed marked and persistent
anorexia and weight loss and those given 200 mg/kg body-weight were
killed in extremis at 3-7 months. At 20 mg/kg body-weight similar
symptoms were observed, but were less severe. Toxic signs included
tremors, general malaise, weakness, gastro-intestinal disturbances,
depression of the reflexes in the hind limbs, posterior
incoordination, hypotonus, progressing at 200 mg/kg body-weight to
flaccid paraplegia. There was also evidence of impairment of kidney
function at 75 and 200 mg/kg body-weight. Microscopic examination
post-mortem revealed damage to the spinal cord, peripheral nerves and
muscles in those animals given 200 mg/kg body-weight, but no effect on
the thyroid gland (Clayton et al., 1957).
Long-term studies
Rat. Groups of rats, each of 25 males and 25 females, were fed
diets containing 25, 250, 1250 and 2500 ppm of maneb for 2 years. At
1250 ppm there was some depression of growth rate and at 2500 ppm
there was growth depression, impaired food consumption and increased
mortality rate. At the end of 2 years those animals receiving 1250 ppm
had an increased liver/body-weight ratio and those receiving 2500 ppm
showed, in addition, thyroid hyperplasia and nodular goitre (Clayton
et al., 1957).
Comments on the experimental studies reported
For maneb, as for most of the dithiocarbamates, short- and
long-term studies in animals have been reported, but for all of them
biochemical data are inadequate.
EVALUATION
The chemical nature of the residues of the dithiocarbamates in
or on the plant has not been ascertained. The compounds themselves
have effects on the thyroid, nervous system and blood in animals. In
the absence of information about their mode of action an acceptable
intake for man cannot be estimated.
Further work required
Determination and evaluation of toxicity of the residues
occurring in the plant. Extension of the long-term experiments,
including reproduction studies which should concern at least 2
species. Special attention should be given to neurological changes
goitrogenicity and occurrence of anaemia.
REFERENCES
Clayton, J. W., Hood, D. B., Barnes, J. R. & Borgmann, A. R. (1957)
Amer. industr. Hyg. Ass. Quart.
United Kingdom Ministry of Agriculture, Fisheries and Food
(Unpublished data)