CARBENDAZIM JMPR 1976
This pesticide was evaluated by the 1973 Joint Meeting
(FAO/WHO, 1974b). The data were not considered adequate for the
estimation of an acceptable daily intake for man and the following
studies were required.
(1) Long term studies to investigate chronic toxicity and
(2) Reproduction and teratogenicity studies.
(3) Metabolism and distribution studies in several species.
(4) Elucidation of the effect in the liver of female rats and
These studies have not been provided, and further evaluation
for the estimation of an acceptable daily intake was not possible.
Some further information on the occurrence and fate of
residues and on methods of analysis which has become available
since the 1973 Meeting is evaluated in this monograph addendum.
RESIDUES IN FOOD AND THEIR EVALUATION
RESIDUES RESULTING FROM SUPERVISED TRIALS
New residue data derived from supervised trials with fruits,
vegetables and individual industrial crops have been presented from
various sources. Most of the residues fall within the ranges
described in the earlier monograph (FAO/WHO, 1974b), and the data
therefore give further support to the guideline levels already
Special mention should be made of the data on carbendazim
applications to lettuce grown during the winter season in
greenhouses (Netherlands, 1976). The residue data presented in
Table 1 indicate that up to 2 months may be required before
carbendazim residues fall below 5 mg/kg when application is at the
rate of 4 kg/ha. This situation was dealt with in greater detail by
the 1975 Meeting in the evaluation of benomyl (FAO/WHO, 1976b) and
on the basis of the information then available the guideline level
of 5 mg/kg for benomyl, calculated as carbendazim, was recorded.
Unless carbendazim can be applied at lower dosage rates and
the usual trimming prior to marketing is effective in removing the
bulk of the residue, the level of 5 mg/kg would not be adequate to
cover residues resulting from the direct application of
carbendazim, even with a very long pre-harvest interval. The Meeting
considered that it could not record a limit high enough to cover
residues of the order indicated in Table 1. It was agreed that the
guideline level of 5 mg/kg recorded by the 1975 Meeting for benomyl
in lettuce and applying to total residues of benomyl, carbendazim and
2-aminobenzimidazole, expressed as carbendazim, should be retained.
New information on carbendazim residues in wheat (Netherlands,
1976) and peanuts (Snelson, 1976) are summarized in Table 2. This
supplements earlier data and confirms the previous guideline level
of 0.1 mg/kg (at or about limit of determination) for raw cereals.
Amendments, however should be made to include peanut hulls and hay
and wheat straw for animal feeding purposes.
FATE OF RESIDUES
In plants and soil
There is a continued interest in the behaviour of carbendazim
and other benzimidazole fungicides in general plant metabolism.
Rouchaud and co-workers (1974) confirmed the rapid uptake and
translocation of carbendazim following the application of either
carbendazim or benomyl) into the leaves of melon plants. Leroux &
Gredt (1975) from work with maize plants, suggest that carbendazim
is taken up in its non-ionic form, and they show that the maximum
absorption is at the base rather than the apex of the roots.
In the studies of Rouchaud et al. (1974) 7 metabolites were
identified from non-radioactive benomyl, namely: carbendazim,
2-aminobenzimidazole, benzimidazole, o-aminobenzonitrile, aniline
and B-glycosidic conjugates of carbendazim and of
The presence and rate of degradation of carbendazim in soils
were investigated by van Wambeke & van Assche (1976) in a well
designed 4-factor experiment to study the effects of soil
composition, microbiological activity, moisture content and
temperature. All of these greatly affect the degradation and their
influence is illustrated by the findings that only 0.1% of the
applied dosage of carbendazim was recovered after 126 days in a
humid. organic soil kept at 23°C, while about 60% was recovered
from a dry sandy soil, which was steam sterilized and kept at 10°C
for the same period.
Carbendazim is ionized by both acids and bases, and this
affects its behaviour in soils. Aharonson & Kafkafi (1975a) have
shown that acidity increases the absorption of carbendazim to soil
particles and thereby hinders leaching. These authors also confirm
the increased rate of degradation of carbendazim by increased
humidity of the soil.
TABLE 1. Carbendazim residues on greenhouse (winter) lettuce,
Treatment Dosage Time after Residues, mg/kg,
last application, mean (range)
days Exp. 1 Exp. 2
Spraying 4 kg/ha 11 - 31 (25-36)
20 - 19.5 (11-24)
27 - 10 (9-11.5)
32/34 17.9 (13-28) 6.5 (1.8-11.5)
41 8.2 (5-12) -
53 6.5 (4-8.5) -
62 0.9 (0.5-1.2) -
TABLE 2. Carbendazim residues in wheat and peanuts
Country Application Days after Residues, mg/kg
Crop Rate, treatment Straw/
kg/ha No. Kernels hay Hulls
Netherlands 0.15 2 52 <0.1 <0.1
3 50-51 <0.1-<0.1 <0.1-<0.1
0.24 1 48-120 <0.1-<0.1 <0.1-<0.1
3 50-51 <0.1-<0.1 <0.1-<0.1
0.3 2 15-54 <0.1 0.15
0.5 1 54 - <0.1
Australia 0.3 5 28 <0.1 2.0 <0.2
TABLE 3. Residues of carbendazim (including benomyl) in imported
Crop Number of samples containing .....mg/kg+)
0.1 0.1-0.5 0.6-2.0 2.1-5.0
Apples 101 18 6 2
Oranges 32 1 1
Strawberries 15 3 3
Total 213 samples
o) = February 1973 - July 1975
+) = Calculated as benomyl
Residues in food in commerce or at consumption
Earlier reports from Belgium and the Netherlands on market sample
surveys for benzimidazole fungicides have been described in a previous
monograph on benomyl (FAO/WHO, 1976b) they are of equal interest in
connection with carbendazim. A Further survey has now been reported
from Sweden, covering a total of 213 samples of imported fruit (Table
3). This survey gave broadly similar results, indicating that
quantifiable residues of carbendazim may be found in about 25% of
imported apples and strawberries at the time of marketing. Significant
residues were also found in two of 34 samples of oranges.
METHODS OF RESIDUE ANALYSIS
As in the case of other benzimidazole fungicides (FAO/WHO,
1976b), the greatest interest recently has been concerned with two
problems, namely the efficiency of extraction from crops and soils and
the selective determination of benzimidazole compounds, especially by
means of high speed or high-performance liquid chromatography. In
addition, a recent report on the gas-liquid chromatography of
carbendazim after trifluoroacetyl derivatization has been published
(Rouchaud and Decallonne, 1974).
Valuable reviews have been published on these subjects by Austin
et al. (1975), Baker & Hoodless (1974), Gorbach (1976), Watkins
(1976) and others.
For the final determination of carbendazim, UV-spectrophotometry
still seems to be the preferred method of measurement. This method
when combined with partition clean-up offers an adequate sensitivity
for most routine purposes (Gorbach, 1976). In the recently published
methods based on high speed liquid chromatography (Maeda & Tsuji,
1976) and gas liquid chromatography (Rouchaud & Decallonne, 1974) the
limit of detection is given as 0.02 mg/kg.
NATIONAL TOLERANCES REPORTED TO THE MEETING
Table 4 lists national tolerances reported to the Meeting. They
are additional to those reported previously with the exception of the
Netherlands tolerance "Grain (raw) 0.1 mg/kg" which replaces the
earlier provisional tolerance "Raw cereals 0.5 ppm".
TABLE 4. National tolerances reported to the Meeting
Country Crop mg/kg
Netherlands Citrus 3.5
Grain (raw) 0.1
New Zealand Fruits 5
This compound was evaluated by the 1973 Joint Meeting and
guideline levels for a number of commodities were recommended. Since
then new data have become available, partly in response to earlier
requests and partly as supplementary information which supports the
Data have been presented from supervised trials on carbendazim
treatments of greenhouse lettuce grown during the winter season. The
rate of decline of residues was so slow that even 50 days after
treatment the mean residue was above the guideline level of 5 mg/kg
previously recorded for benomyl but applying to total residues of
benomyl, carbendazim and 2-aminobenzimidazole. The Meeting considered
that it could not record a guideline level high enough to cover
residues resulting from such a use of carbendazim. In view of the
earlier evaluation of data on carbendazim and other benzimidazole
fungicides, it confirmed the guideline level of 5 mg/kg for benomyl.
On the basis of new information, recommendations can be made for
guideline levels in certain peanut products and in straw of wheat.
In the course of general studies on the fate of benzimidazole
fungicides, a rapid uptake and translocation of carbendazim residues
into plants has been confirmed. The behaviour and degradation of
carbendazim residues in soils has been further described.
In response to the request of the 1973 Meeting, information on
market sample surveys made in Belgium, the Netherlands and Sweden has
been presented to this and to the 1975 meeting. The data indicate that
residues of benzimidazole fungicides, presumably including
carbendazim, may be present in up to about 25% of a number of fruits.
vegetables and berries. Residues in positive samples were generally
low and only in occasional samples approached guideline levels.
Spectrophotometric, gas chromatographic and high-performance
liquid-chromatographic methods are now available for the determination
of carbendazim in various commodities. A full validation of methods
for regulatory purposes still seems to be lacking.
The following guideline levels, additional to those of 1973, are
Commodity Guideline level,
Peanut hull 0.2
Peanut hay, wheat straw 2
FURTHER WORK OR INFORMATION
Required (before an acceptable daily intake can be estimated and
maximum residue limits can be recommended)
1. Long-term studies to investigate chronic toxicity and
2. Reproduction and teratogenicity studies.
3. Metabolism and distribution studies in several animal species.
4. Elucidation of the effect on the liver in female rats and dogs.
5. Information on the nature and level of residues in meat, milk and
eggs after feeding animals on crops or feedstuffs treated with
1. Further studies to define the apparent "high-level" effects on
male reproductive organs.
2. Validation of methods of residue analysis for regulatory
Aagren, O. Residue data and other information on Benomyl and
1976 carbendazim submitted by the Swedish Codex
Secretariat. Letter no. 308/76 of July, 30.
Aharonson, N. & Kafkafi, U. Adsorption of Benzimidazole
1975a fungicides on montmorillonite and kaolinite clay
surfaces. J. agr. Fd Chem. 23, 434-437.
Aharonson, N. & Kafkafi, U. Adsorption, mobility and persistence of
1975b thiabendazole and methyl-2-benzimidazole-carbamate
in soils. J. agr. Fd Chem. 23, 720-724.
Austin, D.J., Briggs, G.G. & Lord, K.A. Problems in the assay
1975 of residues of carbendazim and its precursors.
Proc. 8th Brit. Insec. Fung. Conf., Brighton,
Baker, P.B. and Hoodless, R.A. Analytical methods for the detection
1974 and determination of residues of systemic
fungicides. Pestic. Sci., 5: 465-472.
FAO/WHO. 1973 Evaluations of some pesticide residues in Food.
1974 FAO/AGP/1973/M/9/1. WHO Pesticide Residues Series,
Gorbach, S. Review on the residue analysis of the systemic
1976 fungicides benomyl, carbendazim, thiophanate,
thiophanatemethyl and thiabendazole. Paper
presented to the International Union of Pure and
Applied Chemistry (IUPAC). 36 pages. Analytical
Laboratory, Hoechst, Germany.
Leroux, P. & Gredt, M. Absorption of methylbenzimidazole-
1975 2-yl-carbamate (carbendazim) by corn roots.
Pestic. Biochem. Physiol. 5, 507-514.
Maeda, M. & Tsuji, A. Determination of benomyl and 2
1976 (4-thiazolyl) benzimidazole in plant tissues by
high-performance liquid chromatography using
fluorometric detection. J. Chromat. 120, 449-455.
Netherlands. Carbendazim residue data submitted by the Nation
1976 al Codex Committee of the Netherlands.
Staatstoezicht op de Volksgezondheid, September
New Zealand. Information received from the National Codex
1976 Committee of New Zealand.
Rouchaud, J.P. & Decallonne, J.R. A gas chromatographic method
1974 for the analysis of MBC in plants and soil. J.
agr. Fd Chem. 22, 259.
Rouchaud, J.P., Decallonne, J.R. & Meyer, J.A. Metabolic Fate of
1974 methyl-2-benzimidazole carbamate in melon plants.
Phytopathology, 64, 1513-1517.
Snelson, J.T. Australian Residue data submitted through the
1976 National Codex Committee of Australia.
Van Wambeke, E. & van Assche, C. The importance of some factors
1976 involved with the persistence of carbendazim (MBC)
in soil. Report presented at the 28th
International Symposium on Crop Protection in
Gent, May 4, 1976.
Watkins, D.A.M. Benzimidazole Pesticides: Analysis and
1976 Transformations. Pestic. Sci. 7, 184-192.