WHO Pesticide Residues Series, No. 1
1971 EVALUATIONS OF SOME PESTICIDE RESIDUES IN FOOD
The evaluations contained in these monographs were prepared by the
Joint Meeting of the FAO Working Party of Experts on Pesticide
Residues and the WHO Expert Committee on Pesticide Residues that met
in Geneva from 22 to 29 November 1971.1
World Health Organization
1 Pesticide Residues in Food: Report of the 1971 Joint Meeting of
the FAO Working Party of Experts on Pesticide Residues and the WHO
Expert Committee on Pesticide Residues, Wld Hlth Org. techn. Rep.
Ser., No. 502; FAO Agricultural Studies, 1972, No. 88.
These monographs are also issued by the Food and Agriculture
Organization of the United Nations, Rome, as document AGP-1971/M/9/1.
FAO and WHO 1972
This pesticide was previously evaluated at the Joint Meeting in 1965
(FAO/WHO 1965c) and reviewed in 1967 (FAO/WHO 1968b). Very little new
information on this pesticide has appeared since 1967. It was
previously listed as ethylene dichloride.
Reference should be made to Appendix IV. It contains Section 3 of the
report on the 1971 meeting (FAO/WHO 1972a) where general principles
relating to residues of fumigants are discussed; also the Appendix
contains information on some commercially available mixtures of
RESIDUES IN FOOD AND THEIR EVALUATION
Post-harvest use on dry foodstuffs
1,2-dichloroethane has been widely used for many years, usually in
admixture with carbon tetrachloride as a fumigant for bulks of raw
cereals in bins or on floors. It is difficult to assess present world
usage but this is probably much less than formerly.
1,2-dichloroethane is physically sorbed by foods more strongly than
carbon tetrachloride but less markedly than 1,2-dibromoethane. There
is no available evidence of any reaction with the food constituents.
Studies with the isotopically labelled fumigant have not been made and
would probably be necessary to demonstrate any reaction, which, if
occurring, must be very small in amount.
The effect of processing to flour and broad has been studied by Wit et
al., (1969). There were some discrepancies between the results
reported by the different participating laboratories but the general
picture emerged that, starting with grain which had been aired for
several weeks after fumigation and which then contained 10 to 25 ppm
of 1,2-dichloroethane, the amounts found in white flour are usually
between 2 and 11 ppm and in bread were usually below 0.05 ppm.
Methods of residue analysis
Methods using gas-chromatography have now replaced earlier chemical
methods. Heuser and Scudamore (1968) obtained satisfactory extraction
of cereals and wheat flour by shaking at room temperature with a 5:1
by volume acetone and water mixture. Aliquots of the supernatant
liquid were injected into the gas-chromatograph and determined by a
flame ionization detector. This procedure was developed by Heuser and
Scudamore (1969) into a multi-residue scheme and it was found that a
B-ionization detector gave the highest response to 1,2-dichloroethane
giving a method which will determine 0.1 ppm.
National tolerances (as reported to meeting)
Australia, Canada and the United States of America all exempt ethylene
dichloride from the requirement of a tolerance on the grounds that no
hazard will remain when the food reaches the consumer.
1,2-dichloroethane has been extensively used as a post-harvest
fumigant for many years. It is usually applied in a mixture with
carbon tetrachloride, with small proportions of other fumigants
sometimes added. The main use is on bulks of raw cereals.
1,2-dichloroethane is physically sorted on these foods but there is no
evidence of any chemical breakdown or reaction. There is evidence of a
substantial reduction in the amount of residual fumigant when the
grain is milled and baked into bread. Analytical methods are available
which will determine 0,1 ppm of 1,2-dichloroethane.
There is a little direct information on the amounts of residual
1,2-dichloroethane appearing in commercial samples or in food reaching
the consumer. From the available information on the occurrence of
unchanged 1,2-dichloroethane in or on raw cereals or cereal products
after fumigation in accordance with good practice it appears that the
following amounts need not be exceeded and it is recommended that
these residue levels be used as guidelines:
In raw cereals at point of entry into a country
or when supplied for milling, provided that the
commodity is freely exposed to air for a period
of at least 24 hours after fumigation before
sampling 50 ppm
In milled cereal products which will be subjected
to baking or cooking 10 ppm
In bread and other cooked cereal products
(i.e. at or about the present limit of
determination) 0.1 ppm
Further work desirable
Additional data on residues of unchanged 1,2-dichloroethane occurring
in food in commercial practice.
Alumot, E. and Bieloria, R. (1969) Residues of fumigant mixture in
cereals fumigated and aired at two different temperatures. J. Agric.
Food Chem., 17: 869
Bieloria, B. and Alumot, E. (1966) Determination of residues of a
fumigant mixture in cereal grain by electron-capture
gas-chromatography. J. Agric. Food Chem., 14: 622
Conroy, M. W., Munsey, V. E. and Ramsey, L. L. (1957) Total volatile
organic halide determination of aggregate residue of carbon
tetrachloride, ethylene dichloride, and ethylene dibromide in
fumigated cereal products. 2. Ethanolamine-sodium reduction procedure.
J. Ass. Offic. Agr. Chem., 40: 185-189
Heuser, S. G. and Scudamore, K. A. (1968b) Determination of residual
acrylonitrile, carbon disulfide, carbon tetrachloride and ethylene
dichloride after fumigation. Chem. and Ind., 1154-1157
Heuser, S. G. and Scudamore, K. A. (1969) Determination of fumigant
residues in cereals and other foodstuffs: a multidetection scheme for
gas-chromatography of solvent extracts. J. Sci. Food Agric.,
Heuser, S. G. and Scudamore, K. A. (1970) Selective determination of
ionized bromide and organic bromides in foodstuffs by gas-liquid
chromatography with special reference to fumigant residues. Pesticide
Sci., 1: 244-249
Heuser, S. G., Goodship, G. and Duffin, P. (1968) Residues of ethylene
dibromide on samples of maize and prepared foods. Pest Infestation
Research, 1968. Agricultural Research Council, London
Lindgren, D. L., Gunther, F. A. and Vincent, L. E. (1962) Bromide
residues in wheat and milled wheat fractions fumigated with methyl
bromide. J. Econ. Entomol., 55: 773-776
Lynn, G. E. and Vorkes, F. A. (1957) Symposium: Residues in foods and
feeds resulting from fumigation of grains with the commoner liquid
formulations of carbon disulfide, carbon tetrachloride, ethylene
dichloride, and ethylene dibromide. J. Ass. Offic. Agr. Chem.,
McMahon, B. Malone. (1971) Analysis of commercially fumigated grains
for residues of organic fumigants. J. Ass. Offic. Chem., 54: 964-965
Malone, B. (1969) Analysis of grains for multiple residues of organic
fumigants. J. Ass. Offic. Analyt. Chem., 52: 800-805
Malone, B. (1970) Method for determining multiple residues of organic
fumigants in cereal grains. J. Ass. Offic. Analyt. Chem.,
Wit, S. L., Besemer, A. F. H., Das, H, A., Goedkoop, W., Loosjes, F.
E. and Meppelink, E. R. (1969) Results of an investigation on the
regression of three fumigants (carbon tetrachlorine, ethylene
dibromide and ethylene dichloride) in wheat during processing to
bread. Report No. 36/69