MALEIC HYDRAZIDE JMPR 1977
Arising out of the list of requirements published in the Report of the
1976 Joint Meeting (FAO/WHO, 1977a) some information on the stability
of residues of maleic hydrazide during the cooking of potatoes has
been referred to the Meeting. Data, on residues observed in tobacco
were also made available. The new information is reviewed below.
No new toxicological data have been provided. It was therefore
impossible to complete a evaluation or to establish an ADI for humans.
RESIDUES IN FOOD AND THEIR EVALUATION
RESIDUES RESULTING FROM SUPERVISED TRIALS
Information was available to the FAO Panel of Experts relating to
residues of maleic hydrazide Observed in tobacco and cigarettes in the
USA during the years 1961-75 Uniroyal chemical, 1977b). Data concerned
flue cured and Burley tobaccos, influence of harvest time, influence
of application rate, effect of curing, residues in stored tobacco, and
residues in tobacco products.
The data from supervised trials collected over 15 years from almost
100 locations clearly indicated extensive variability in observed
residue levels and a high probability of finding an occasional high
level in cured tobacco The average residue was 52 mg/kg in flue cured
and Burley tobaccos; however, the, data were strongly skewed towards
residues in the range 15-60 mg/kg. It would appear that as a guideline
level, 100 mg/kg would cover about 96% of all tobaccos examined; 95%
would be covered by 200 mg/kg but levels approaching 500 mg/kg were
The limited data available showed that neither air curing nor flue
curing appeared to alter the level of maleic hydrazide residues found
in freshly harvested tobacco leaves; it also appeared unlikely that
prolonged storage would lead to any notable reduction in residue
levels. Thus, the levels of maleic hydrazide found in freshly
harvested or recently cured tobacco leaves can serve as reliable
indicators of likely levels at all stages of trade in unblended leaf.
The effects of blending, however, are such that the variability of
residue level, as well as the levels themselves, are much reduced
during the manufacture of cigarettes, cigars, snuff etc. Examination
of 16 brands of cigarettes gave a range of residue levels from 22 to
52 mg/kg, with a mean value of 39 mg/kg. Residue levels observed in
limited samples of cigars, small cigars, smoking tobacco, chewing
tobacco and snuff were, in general, less than those found in
cigarettes; the highest level observed was 38 mg/kg, in smoking
tobacco. For such tobacco products a guideline level of 50 mg/kg
Tobacco samples from several countries were analysed by Nesemann,
Rabitz and Seehofer (1974). Tobaccos from the USA showed residues of
maleic hydrazide ranging from 35 to 94 mg/kg with an average of 65
mg/kg. Two 1969 samples from Italy contained 4 and 11 mg/kg,
respectively but other samples from that country and from Argentine,
Brazil, Bulgaria, China, Mexico, Philippines and Thailand contained
less than 2 mg/kg. Liu and Hoffmann (1973) determined maleic hydrazide
in tobacco smoke. They found that cigarettes containing about 30 µ of
maleic hydrazide each, yielded smoke containing an average of 1.2 µ g,
ie about 4% of the total originally present; hydrazine was not
detected in the smoke.
A full review of data concerning pesticide residues, including maleic
hydrazide, in tobacco and tobacco products was completed recently as
part of a study programme of the Directorate-General for Agriculture
of the Commission of the European Communities (Anonymous, 1976a,b,c).
A draft method for the determination of residues of maleic hydrazide
in tobacco and tobacco products is under discussion by the ISO
Committee TC 126. Consideration of this procedure has reached an
advanced stage and early publication is anticipated.
FATE OF RESIDUES
Commercially treated potatoes (3.4 kg a.i./ha) were sampled and
analysed for residues of maleic hydrazide (Uniroyal Chemical, 1977a).
The potatoes were divided into two parts longitudinally, one half
being analysed raw and the other after boiling in water, discarding
the liquor and mashing the cooked potato. Table 1 compares the residue
of maleic hydrazide found in the raw and cooked potatoes; no
significant difference in levels was observed.
TABLE 1. Residues of maleic hydrazide in potatoes before and after
Sample Treatment to harvest Maleic hydrazide found, mg/kg
interval (days) Raw cooked
A 65 10 10
B 50 22 20
Recovery of maleic hydrazide added at 20 mg/kg to untreated potatoes
was 95%. Samples were analysed by the method of Lane (1963).
These findings illustrate the inherent stability of residues of maleic
hydrazide to cooking processes. Additionally it has been observed that
crops containing maleic hydrazide can be boiled in strong caustic
solutions without loss of the residues or its hydrolysis. Under these
conditions the addition of zinc is necessary to act as a reducing
agent to liberate the hydrazine.
No data were available to the Panel concerning the effect on maleic
hydrazide residues of different methods of industrial processing in
the manufacture of various potato products; the requirement for this
information remains. Limited data from treated potatoes showed that
free hydrazine did not occur as a residue (Uniroyal Chemical, 1977a).
Residues of maleic hydrazide in harvested potatoes are not diminished
on cooking by boiling in water. No information was available regarding
other means of cooking or processing.
Tobacco treated with maleic hydrazide can contain up to a maximum of
500 mg/kg at harvest and thereafter, no loss occurring during curing
or storage; however, 90% of samples will be below 100 mg/kg. Blending
and manufacture of tobacco products, eg. cigarettes, cigars, snuff,
can reduce observed residues to below about 50 mg/kg. Generally, only
5-10% of the maleic hydrazide in tobacco transfers to the smoke.
The following guideline levels can be recorded for tobacco and tobacco
products. The guideline level for potatoes is confirmed at 50 mg/kg.
Guideline levels are for the sum of free and bound unchanged maleic
hydrazide and its B-D-glucoside.
Commodity Guideline level, mg/kg
Tobacco leaf 100
Tobacco products 50
FURTHER WORK OR INFORMATION
See Report of 1976 Meeting (FAO/WHO, 1977a, Annex 2). Data on the
effect of cooking on residues in potatoes and on the carry-over of
maleic hydrazide from raw into cured tobacco and into cigarette smoke
are no longer required. The other requirements remain.
Anonymous. (1976a) Pesticide residues in tobacco and tobacco products.
Volume 1. Information on Agriculture, No. 14. Comm. Europ. Commun.,
Anonymous. (1976b) Pesticide residues in tobacco and tobacco products.
Volume II. Information on Agriculture, No. 23. Comm. Europ. Commun.,
Anonymous, (1976c) Pesticide residues in tobacco and tobacco products.
Volume III. Information on Agriculture, No. 26. Comm. Europ. Commu.,
FAO/WHO (1977a) Pesticide residues in food. Report of the 1976 Joint
FAO/WHO Meeting. FAO Food and Nut. Ser., No. 9; FAO Plant Prod. and
Prot. Ser., No. 8; Wld. Hlth. Org. techn. Rep. Ser., No. 612.
FAO/WHO. (1977b) 1976 Evaluations of some pesticide residues in food.
Lane, J.R. (1963) Collaborative study of maleic hydrazide residue
analysis. J. Ass. Off. Agr. Chem 46(2): 261-268.
Liu, Y-Y. and Hoffmann, D. (1973) Quantitative chromatographic
determination of maleic hydrazide in cigarette smoke. Anal. Chem. 45:
Nesemann, E., Rabitz, H. and Seehofer, F. (1974) Methoden zur
quantitativen Bestimmug von Boiziden in Tabak. IV Eine Methoden zur
Bestimmug von Maleinsäure hydrazide. Beitr. Tabakforsch. 7: 240-243.
Uniroyal Chemical. (1977a) Persistence of maleic hydrazide in
Uniroyal Chemical. (1977b) Maleic hydrazide residues found in U.S.
tobacco. (Unpublished report and review).