Residue Reviews / Ruckstands-Berichte: Residues of Pesticides and Other Foreign Chemicals in Foods and Feeds / Ruckstande von Pesticiden und Anderen Fremdstoffen in Nahrungs- und Futtermitteln

160 Pages·1963·5.78 MB·English

by  Francis A. Gunther (eds.), A. L. Taylor (auth.)

RESIDUE REVIEWS
RESIDUES OF PESTICIDES AND OTHER
FOREIGN CHEMICALS IN FOODS AND FEEDS
ROCKSTANDS-BERICHTE
ROCKSTANDE VON PESTICIDEN UND ANDEREN
FREMDSTOFFEN IN NAHRUNGS- UND FUTTERMITTELN
EDITED BY
FRANCIS A. GUNTHER
RIVERSIDE
ADVISORY BOARD
MARIA E. ALESSANDRINI, ROMA • J. W. COOK, WASHINGTON
S. DALGAARD-MIKKELSEN, K0 BENHAVN
SIMONE DORMAL VAN DEN BRUEL, BRUXELLES • C. L. DUNN, WILMINGTON
C. G. DURBIN, WASHINGTON· R. W. FOGLEMAN, PALO ALTO
J. C. GAGE, WELWYN • T. H. HARRIS, WASHINGTON
L. W. HAZLETON, FALLS CHURCH' G. HECHT, WUPPERTAL-ELBERFELD
H. HURTIG, OTTAWA· O. R. KUMMER, BONN· G. K. KOHN, RICHMOND
H. F. LINSKENS, NIJMEGEN • H. MARTIN, BASEL' N. N. MELNIKOV, MOSCOW
R. MESTRES, MONTPELUER . B. L. OSER, NEW YORK CITY
S. W. SOUCI, MONCHEN . R. TRUHAUT, PARIS' S. L. WIT, UTRECHT
VOLUME 2
SPRINGER-VERLAG
BERLIN GOTTINGEN' HEIDELBERG
1963
ISBN-13: 978-1-4615-8376-9 e-ISBN-13: 978-1-4615-8374-5
DO!: 10.1007/978-1-4615-8374-5
All rights, especially that of translation into foreign languages, reserved. It is aIso forbidden to
reproduce this book, either whole or in part, by photomethanical means (photostat, microfilm
and/or microcard) or by other procedure without written permission from Springer-Verlag.
© by Springer-Verlag OHG
Berlin' Gottingen • Heidelberg 1963
Softcover reprint of the hardcover 1s t edition 1963
Library of Congress Catalog Card Number 62-18595
Preface
Residues of pesticides and other "foreign" chemicals in foodstuffs are
of concern to everyone everywhere; they are essential to food production
and manufacture, yet without surveillance and intelligent control some of
those that persist could at times conceivably endanger the public health.
The object of "Residue Reviews" is to provide concise, critical reviews
of timely advances, philosophy, and significant areas of accomplished or
needed endeavor in the total field of residues of these chemicals in foods,
in feeds, and in transformed food products. These reviews are either general
or specific, but properly they may lie in the domains of analytical
chemistry and its methodology, biochemistry, human and animal medicine,
legislation, pharmacology, physiology, regulation, and toxicology; certain
affairs in the realm of food technology that are concerned specifically with
pesticide and other food-additive problems are also appropriate subject
matter. The justification for the preparation of any review for this book-
series is that it deals with some aspect of the many real problems arising
from the presence of residues of foreign chemicals in foodstuffs.
The scope of "Residue Reviews" is international. It encompasses those
matters, in any country, which are involved in allowing pesticide and other
plant-protecting chemicals to be used safely in producing, storing, and
shipping crops. Added plant or animal pest-control chemicals or their
metabolites that may persist into meat and other edible animal products
(milk and milk products, eggs, etc.) are also residues and are within this
scope. The so-called food additives (substances deliberately added to foods
for flavor, odor, appearance, etc., as well as those inadvertently added
during manufacture, packaging, distribution, storage, etc.) are also con-
sidered suitable review material.
Manuscripts are contributed by invitation, and may be in English,
French, or German. Suggestions for reports on specific subjects will always
be welcomed, but preliminary communication with the editor is recom-
mended before volunteered reviews are submitted in manuscript form.
F.A.G.
Department of Entomology
University of California
Riverside, California
April 20, 1962
Table of Contents
Nematocide residues in plants.
By Dr. A. L. TAYLOR .
The determination of organophosphate pesticides and their residues
by paper chromatography.
By M.E.GETz. 9
La determination de residus d'insecticides et de fongicides par la
methode polarographique.
Par Professeur P. H. MARTENS et P. NANGNIOT 26
Absorption, translocation, exudation, and metabolism of plant growth-
regulating substances in relation to residues.
By Dr. ]. W. MITCHELL and P. ]. LINDER. 51
Parathion residues on leafy crops.
By Dr. C. H. VAN MIDDELEM . 77
The utilization of infrared and ultraviolet spectrophotometric proce-
dures for assay of pesticide residues.
By R. C. BLINN and Professor F. A. GUNTHER 99
Subject index 153
Nematocide residues in plants
By
A. L. TAYLOR ':.
Contents
I. Introduction . . . . . .
II. Chemicals used as nematocides 2
1. Bromine compounds 2
2. Chlorine compounds 3
3. Dithiocarbamate . 4
4. Phosphorothioates 4
5. Isothiocyanate 5
III. Conclusion 5
Summary .. . 5
Resume .. . 6
Zusammenfassung 7
References 8
I. Introduction
Although one nematocidal chemical was in use before 1900, widespread
use of chemicals for the control of plant-parasitic nematodes in soil is a
development of the past 16 years. The most popular and useful of these
are volatile materials popularly known as "soil fumigants". These are
usually applied by placement 15 or 20 cm. beneath the soil surface in lines
about 30 cm. apart. This application method is known as "area treatment".
A popular alternative method is placement of the nematocide beneath the
planting rows only, leaving the intervals between rows untreated. This is
known as "row treatment". The fumigants diffuse from the application
points through the upper 45 to 60 cm. of the soil. Other soil nematocides
are applied in water solution or emulsion or are in granular form to be
mixed with the soil. All are more or less toxic to plants and are usually
applied to the soil several days or weeks before planting; a few are suf-
ficiently non-toxic to certain kinds of plants so that they can be applied
at planting time or even around the roots of growing plants. In any case,
there is ample opportunity for crop plants growing in soil treated with
nematocides to take up the undecomposed nematocides or the products of
their decomposition.
~. Nematologist, Crops Research Division, Agricultural Research Service,
U.S. Department of Agriculture, Beltsville, Maryland.
Residue Reviews, Vol. 2
2 A. L. TAYLOR
II. Chemicals used as nematocides
1. Bromine compounds. The nematocide probably used on more acres
than any other is ethylene dibromide (1,2-dibromoethane or EDB). For
area application the minimum application rate is 54 lb. per acre (60.6 kg.
per ha.) 1. If this diffuses through the upper 15 inches of soil the concen-
tration in the soil is about 10 parts per million by weight. For some
purposes such as nursery or flower crops, three to four times as much might
be used. Apparently EDB decomposes in soil, and most of the bromine
remains in the soil. This can readily be absorbed by plants.
BROWN et al. (1958) grew tobacco and tomato plants on various kinds
of soil which had been fumigated with EDB. Plants grown on loamy sand
contained over four times as much bromine as plants on the same soils
without EDB. Drying of the soil after fumigation affected the results very
little, which was interpreted as indicating that the bromine was present in
inorganic form. Tomato plants in these experiments accumulated as much as
1430 p.p.m. of bromine and tobacco plants as much as 2280 p.p.m. by green
weight. CALL and HAGUE (1957) found that the amount of bromine sorbed
by soil was closely related to the surface area of the soil particles, organic
matter, moisture and clay content. Soil treated with ethylene dibromide
may be toxic to certain kinds of crop plants, notably onions.
Peanut hay from experimental plots treated with 301bs. of EDB per
acre (33.6 kg. per ha.) of ethylene dibromide in Virginia accumulated an
average of 314 p.p.m. of bromine (dry-weight basis), while hay from
adjacent untreated control plots contained 43 p.p.m. When this hay was
fed to dairy cattle the average bromine content of the milk was 32 p.p.m.
compared with 9 p.p.m. for cows fed hay from the control plots (YOUNG
et al. 1955).
Two additional nematocides containing bromine are in widespread use.
One of these, 1,2-dibromo-3-chloropropane (DBCP), is used in the same
manner as ethylene dibromide for field crops, application rates ranging
from 17.3 lbs. per acre (19.4 kg. per ha.) to five or six times this amount.
Numerous experiments have shown that a residue highly toxic to
certain kinds of plants remains in the soil for several weeks or months
after application of DBCP. Onions are so very sensitive to DBCP that it is
possible to use germinating onion seed to detect the presence of as little as
2.5 p.p.m. of this material in soil (RINKOV et at. 1960, O'BANNON 1958).
On the other hand, DBCP can be applied around the roots of other kinds
of plants with no appreciable damage. The exact nature of the DBCP
residue has not been reported. CASTRO and SCHMITT (1962), using a neutron-
activation method developed by V. P. GUINN and J. POTTER of the Shell
Development Corporation, were able to demonstrate the presence of 2.7 to
5.0 p.p.m. of bromine in oranges from trees growing in soil treated with
69.2Ibs. of DBCP per acre eight months earlier. The same method indicated
that oranges from adjacent untreated plots contained less than 0.03 p.p.m.
of bromine.
1 All application rates in this paper are actual. amoun.ts of the technical
grade of the chemical as sold to the user unless otherwtse specified.
Nematocide residues 3
The other nematocide containing bromine is methyl bromide (mono-
bromomethane). This is generally used in seedbeds, nurseries, and green-
houses as a combination control for nematodes, weed seeds, bacteria, fungi,
and soil insects. The application rate is 436 to 8721bs. per acre (488 to
976 kg. per ha.) of a mixture containing 2 percent chloropicrin as a warn-
ing agent or formulated with xylene or other solvents.
Soil treated with methyl bromide undoubtedly has a residue toxic to
onions and various other kinds of plants, but its exact nature has not been
reported. Like the DBCP residue, this residue is not toxic to many other kinds
of plants. In fact, with most kinds of plants, growth after methyl bromide
treatment is very good because of the elimination of plant parasites.
A number of "tolerances" for bromine residues in plants grown in soil
treated with various nematocides have been established by the Food and
Drug Administration of the Department of Health, Education and Welfare
of the United States Government 1. Among these are: asparagus, 10 p.p.pm.
lima beans, 5 p.p.m.; snap beans, 10 p.p.m.; broccoli, 75 p.p.m.; carrots,
75 p.p.m.; cauliflower, 10 p.p.m.; maize (grain), 50 p.p.m.; sweet corn,
50 p.p.m.; cucumbers, 30 p.p.m.; eggplant, 50 p.p.m.; lettuce, 30 p.p.m.;
melons, 75 p.p.m.; parsnips, 75 p.p.m.; peppers, 30 p.p.m.; sweet potatoes,
50 p.p.m.; white potatoes, 75 p.p.m.; squash, 50 p.p.m.; and tomatoes,
50 p.p.m.
2. Chlorine compounds. Another class of nematocides has 1,3-di-
chloropropene-1 as the most active ingredient, either in the technical form
or mixed with about 50 percent of 1,2-dichloropropane and related C3
compounds. These are widely used on soil to be planted to various crops,
notably tobacco, pineapple, and vegetables. The minimum application rate
for area treatments is 200 lbs. of the 50 percent mixture pf'r acre (224 kg.
per ha.) that is, about 40 p.p.m. by weight of the soil. Several times this
amount might be used for some crops. According to SHAW (1948), dichloro-
pro penes and related compounds decompose in the soil and form hydro-
chloric acid. Because of the presence of buffers in the soil, there is no
appreciable effect on soil pH. The soil remains toxic to plants for some
days after application, so a waiting period of two weeks before planting
is usually recommended for minimum applications, with more in proportion
for large amounts.
With the possible exception of chlorine, residues from dichloropropene
nematocides have been reported in plants only when amounts four or five
times greater than needed for good control of nematodes were used. In
these cases, flavor tainting has been reported.
Dichloropropene nematocides are approved for pre-planting use on soil
to be planted to a wide variety of crops on the assumption that no residue
will result if they are properly used (USDA Summary).
1 The "wlerances" discussed here and eIsewhere in this paper are the amounts
of pesticide or its decomposition products which can remain as a residue in or on
food without risk of injury to the consumer. The tolerance is specific for the
pesticide and the crop and is set by regulation. Established tolerances are periodi-
cally summarized in the United States Department of Agriculture Summary of
Registered Agricultural Pesticide Chemical Uses, herca:fter referred to as USDA
Summary (see References section).
1*
4 A. L. TAYLOR
Technical chloropicrin (trichloronitromethane) is used as a nematocide,
particularly in greenhouses and on seedbeds, as well as in strawberry fields.
Application is by injection into the soil at rates ranging from 200 to 1021 lb.
per acre (224 to 1144 kg. per ha.), the higher rates being used when control of
soil bacteria, fungi, and weed seeds is desirable. Chloropicrin is highly
toxic to plants, but this effect disappears after a waiting period of 7 to
14 days under ordinary conditions. According to STARK (1948), chloro-
picrin is adsorbed by soil in amounts directly correlated with the clay
content, but very little is adsorbed on organic matter. Only a small amount
of information is available on the occurrence in plants of residues from
chloropicrin applied to the soil. According to the USDA Summary it can
be used for all crops on a non-residue basis with maximum applications of
1021 lb. per acre and a 7- to 14-day waiting period before planting.
3. Dithiocarbamate. SMDC (sodium N-methyl dithiocarbamate di-
hydrate) is applied to soil at a maximum rate of 490 lb. per acre (549 kg.
per ha.), injected in field soil at a maximum rate of 1901bs. per acre
(213 kg. per ha.). or applied with water at a maximum rate of 3161b. per
acre (354 kg. per ha.).
According to the manufacturer, SMDC decomposes in the soil releasing
a gas highly toxic to plants, fungi, nematodes, and soil insects, killing
these during the first day or two after application. In cool soil (below
15° C.) a waiting period of 30 days between treatment and planting is
recommended. At higher temperatures, no residue toxic to plants is left
after seven to ten days. SMDC is registered for use on all crops on a non-
residue basis, the implication being that there will be no detectable residue
in plants when it is used according to directions (USDA Summary).
4. Phosphorothioates. The most widely used nematocide having no
fumigant action is "V-C 13" (O-2,4-dichlorophenyl O,O-diethylphosphoro-
thioate). This is reported to have long residual action, implying excellent
stability in the soil. The maximum application rate is 112.5 lb. per acre
(126 kg. per ha.) for soil to be planted to corn, cucumbers, peppers, squash,
or strawberries, with a 14-day period between treating and planting. For
application immediately before planting, 15.5 lb. per acre (17.4 kg. per ha.)
is used for soil to be planted to beans, muskmelons, peppers, rhubarb, or
tomatoes. At these rates, no harmful residue will be found in edible
portions of plants grown in the soil (USDA Summary).
According to BOYD (1959), who analyzed strawberries and a variety of
vegetables for residues of V-C 13 by measuring cholinesterase inhibition,
the largest residues were found in root crops, much smaller ones in leaves,
and only insignificant amounts in true fruits.
One of the newer nematocides which has undergone extensive testing is
zinophos (O,O-diethyl 0-2-pyrazinyl phosphorothioate). This is applied
at the rate of 2 to 8 lb. per acre (2.24 to 8.96 kg. per ha.) for control of
nematodes and certain soil arthropods, application being by working or
washing into the soil. Apparently it has good stability in the soil, though
it decomposes in strongly alkaline solution (pH 11.0). At this time, it has
peen approved only for experimental control of sting nematodes on peanuts
Nematocide residues 5
at rates up to 41b. per acre (4.48 kg. per ha.). Probably it will also be used
as a control for nematodes in and around the roots of living nursery
plants.
5. Isothiocyanate. Methyl isothiocyanate is the active ingredient of
one of the newer nematocides. It is formulated with either an inert solvent
or dichloropropenes. Maximum application rates are 95 lb. per acre (106 kg.
per ha.) for light soil and 114 lb. per acre (128 kg. per ha.) for heavy soil
for control of nematodes, fungi, weeds, and soil insects. A waiting period
of 32 days between treating and planting is required for the light appli-
cation and 39 days for the heavy application. No information on the
decomposition products is available, but according to the USDA Summary,
no residues will be found in food crops if methyl isothiocyanate is used
as specified.
DMTT (3,4-dimethyltetrahydro-1,3,5,2H-thiadiazine-2-thione) is used
for the control of nematodes, weeds, and fungi in seedbeds, at application
rates up to 3481bs. per acre (390 kg. per ha.). According to TORGENSON
et at. (1957), DMTT hydrolyzes soon after it is applied. The decomposition
products identified were methyl isothiocyanate, formaldehyde, hydrogen
sulfide, and monomethylamine, but it is probable that these degrade further.
With a waiting period of three weeks between application of the chemical
and planting (or longer if the soil is very wet or the temperature below
15° C.) no residue will be found in food crops grown on treated soil
(USDA Summary).
III. Conclusion
It is evident that the published information on the reactions of nemato-
cidal chemicals in soils and plants is meager and incomplete, but apparently
sufficient unpublished information on residues in food plants to justify
registration under Federal Insecticide, Fungicide and Rodenticide Act and
the Miller Amendment to the Federal Food, Drug and Cosmetic Act is
available.
Summary
Nematocides are chemicals used for the control of nematodes, princi-
pally plant-parasitic and other nematodes in soil. Nematocides in common
use are mostly volatile materials acting as fumigants, but several nemato-
cides are not fumigants. Fumigants are applied by injection into the soil
and other nematocides by drenching or by mechanical mixing with the soil.
In all cases there is a possibility of residues being taken up by plants
growing in the soil.
Bromine compounds used as nematocides include 1,2-dibromoethane,
1,2-dibromo-3-chloropropane, and monobromomethane. These decompose in
the soil leaving residues containing bromine which are toxic to certain kinds
of plants such as onions and can be taken up by many kinds of plants. The
United States Food and Drug Administration has established tolerances
6 A. L. TAYLOR
ranging up to 75 parts per million of bromine in edible portions of plants
grown in soil treated with these nematocides.
Chlorine compounds include 1,3-dichloropropene-1, dichloropropanes,
and trichloronitromethane, which leave residues containing chlorine in the
soil, but nothing detectable in edible portions of plants under the ordinary
conditions of use.
Sodium N-methyl dithiocarbamate dihydrate decomposes in the soil
and releases a gas toxic to nematodes and other soil pests, but no residue
has been reported in plants.
Nematocides without fumigant action are 0-2,4-dichlorophenyl 0,0-
diethyl-phosphorothioate and O,O-diethyl 0-2-pyrazinyl phosphorothioate.
These form residues capable of inhibiting cholinesterase, but only insig-
nificant amounts have been detected in edible portions of crop plants.
Methyl isothiocyanate, the active ingredient in one of the newer nema-
tocides, is released as a decomposition product of another one (3,4-dimethyl-
tetrahydro-1,3,5,2H-thiadiazine-2-thione). No residues from these have been
reported in edible portions of plants.
Published information on the reactions of nematocides is meager and
incomplete, though there is apparently sufficient unpublished information
to justify registration under the laws regulating pesticides in the United
States.
Resume""
Les nematocides sont des produits chimiques utilises pour la lutte contre
les nematodes, principalement 1es nematodes du sol, qu'ils soient parasites
des plantes ou non. Les nematocides d'usage courant sont, pour la plupart,
des composes volatils qui agissent comme fumigants, mais tous ne Ie sont
pas. Les fumigants sont appliques par injection dans Ie sol, les autres
produits par arrosage abondant ou melange mecanique avec Ie sol.
Les composes bromes utilises comme nematocides comprennent Ie 1,2-
dibromerhane, Ie 1,2-dibromo-3-chloropropane et Ie monobromethane. Ces
produits se decomposent dans Ie sol en abandonnant des residus bromes qui
sont toxiques pour certaines especes telles que les oignons et absorbes par de
nombreuses plantes. La "Food and Drug Administration" des Etats-Unis
a etabli des tolerances allant jusqu'a 75 parts par million de brome dans les
parties comestibles des pI antes qui croissent dans les sols traites par ces
nematocides.
Les composes chlores comprenant Ie 1,3-dichloropropene-1, les dichloro-
propanes et Ie trichloronitromethane abandonnent des residus chlores dans
Ie sol, mais, dans les conditions habituelles d'utilisation, ceux-ci ne passent
pas en doses decelables dans les parties comestibles des plantes.
Le N-methyl dithiocarbamate sodique dihydrate se decompose dans Ie
sol en donn ant naissance a un gaz toxique pour les nematodes et autres
parasites du sol, mais aucun residu n'a ete releve dans les plantes.
Les nematocides qui n'exercent pas d'action fumigante sont Ie 0-2,4-
dichlorophenyl O,O-diethyl-phosphorothioate et Ie O,O-diethyl 0-2-pyra-
~. Traduit par S. DORMAL VAN DEN BRUEL.