PESTICIDE RESIDUES IN FOOD - 1983
Sponsored jointly by FAO and WHO
EVALUATIONS 1983
Data and recommendations of the joint meeting
of the FAO Panel of Experts on Pesticide Residues
in Food and the Environment and the
WHO Expert Group on Pesticide Residues
Geneva, 5 - 14 December 1983
Food and Agriculture Organization of the United Nations
Rome 1985
BUTOCARBOXIM
IDENTITY
Chemical Name
3 methylthio-O-[(methylamino)carbonyl] oxime-2-butanone (C.A.)
3-(methylthio)butanone O-methyl-carbamoyloxime (IUPAC)
Synonyms
Drawin 755(R), Afilene(R), Afort(R), CO 755, Wac 755
Structural Formula
O H
" '
O - C - N - CH3
/
H N
' "
CH3 - C - C - CH3
'
S
\
CH3
Other information on identity and properties
Empirical Formula C7H14N2O2S.
Molecular Weight 190.3
Appearance Almost colourless, viscous liquid, partly
crystallized.
Purity 95-97 percent for technical product.
Solubility Readily soluble in most organic solvents;
sparingly soluble in petrol and carbon
tetrachloride. Soluble up to 3.1 percent
in water.
Vapour pressure 8 × 10-5 Torr
Density 1.12 g/ml at 20°C
Melting point 34-37° (syn isomer)
Stability Decomposes above 80°C. Stable in neutral
solutions.
Isomers 85 percent syn isomer (formula I) and
15 percent anti isomer
Formulations Available formulations are emulsifiable
concentrates, 25 percent and 50 percent
active ingredient.
RESIDUES
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
Butocarboxim is a systemic insecticide, which is sprayed onto
plant foliage for the control of sucking insects such as aphids, the
citrus whitefly, leaf miners, etc. It also has a good secondary effect
on mites.
At present butocarboxim is commercially applied in the Federal
Republic of Germany, Luxembourg, Italy, Portugal, Spain, Israel, the
Netherlands and Taiwan province of China. Marketing is expected to
follow soon in the Soviet Union, Central America, France, Peru,
Morocco, Mexico, Turkey and Brazil. Approximately 350-400 tons
(1 ton = 0.09072 metric tonnes) of technical product are applied each
year in the first eight countries named, being allotted to the
following crops: citrus, 60-65 percent; cotton, 15-20 percent; stone
and pome fruit, 5-7 percent; vegetables, 2-4 percent; ornamentals,
2-4 percent.
After marketing is begun in the other countries, a total volume
of 500-600 tons of technical product is expected to be reached.
Preharvest Uses
The recommended application of butocarboxim under good
agricultural practice (GAP) is given in Table 1.
Other Uses
Butocarboxim is also applied to ornamentals in professional and
home gardens at 1 to 2 applications per season at the following rates:
foliar ca. 0.05-0.75 g/l; soil drench ca. 0.75-1 g/l; hydroponic ca.
0.5-0.75 g/l.
Table 1 Foliar Dosage Rates on Various Crops
Rate of use Applications/ Preharvest
Crop (kg a.i./ha/treatment) season interval
(No.) (days)
Citrus citron
lemon
orange 2.5 - 3.5 1-2 21
mandarin
grapefruit
Cotton 1 - 1.25 2-4
Pome fruit apple 1 - 1.5 1-2 14
pear
Stone fruit peach
plum 1 - 1.5 1-2 21
cherry
Vegetables bean 7
tomato 3
lettuce 21
cabbage 0.3 - 0.75 1-2 21
sweet pepper
eggplant
bamboo shoot
RESIDUES RESULTING FROM SUPERVISED TRIALS
Field and glasshouse trials have been conducted on relevant
crops, primarily in the Federal Republic of Germany, but also where
appropriate in the Netherlands, Spain, Italy, France and the United
States. Results are summarized in Table 2 (Wacker Chemie GmbH 1983).
Field trials on apples in Germany at treatment levels of 0,3 to
2 kg/ha gave residues (sum of butocarboxim and its metabolites)
ranging from 0.02 to 2.15 mg/kg at 14 days post-treatment. The value
of 2.15 appears anomalous compared to the bulk of the data in which a
high value of about 1.13 mg/kg is more prevalent. There were no data
available for pears or quinces.
Table 2 Residues of Butocarboxim and its Metabolites at Harvest
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
0 1 6-8 13-15 20-22 26-30
Apple 1973 1 × / 0.29 0.12 0.29 0.05 0.03 0.031 244
Germany, 2 kg/ha 0.26 0.14 0.51 0.62 0.16 0.172
Fed. Rep.
0.77 0.47 0.94 0.73 0.05 0.08 245
0.52 0.52 0.52 0.40 0.52 0.67
0.27 0.14 0.10 0.06 0.05 0.13 246
0.14 0.10 0.34 0.33 0.18 0.30
0.45 0.12 0.35 0.48 o.23 0.06 247
0.31 0.84 o.91 0.65 0.16 0.13
- 0.23 0.05 0.08 0.03 <0.03 253
- 0.35 0.04 0.39 0.37 0.39
2 × / 0.32 0.13 0.11 0.05 0.08 0.16 248
2 kg/ha 0.26 0.55 0.63 0.76 0.45 0.31
- 0.23 0.23 0.21 0.23 0.12 249
- 0.43 0.48 0.32 0.28 0.33
1974 2 × /
Germany, 0.3 kg/ha 1.47 - <0.1 <0.1 <0.1 <0.1 269
Fed. Rep. 10.14 - 1.1 2.15 0.1 N.D.
4 × / 0.19 - <0.05 <0.05 <0.05 <0.05 264
1 kg/ha 1.45 - 0.42 (0.50) (0.45) (0.45)3
0.20 - <0.05 <0.05 <0.053 268
0.71 - 0.37 0.31 0.16
0.47 - <0.05 <0.053 262
1.2 - 0.55 0.02
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
0 1 6-8 13-15 20-22 26-30
Cherry 1976 2 × / 0.88 - <0.07 <0.07 <0.07 287
Germany, 50 g/100 l 3.00 - 2.46 1.92 1.15
Fed. Rep. 0.72 - <0.07 <0.07 <0.07 288
5.64 - 4.90 4.77 3.23
1978 2 × /
Germany, 0.5 kg/ha <0.03 - <0.03 <0.03 <0.03 <0.03 296
Fed. Rep. <0.04 - 0.04 0.04 0.05 <0.04
2 × / 0.03 - - - <0.03 <0.03 297
0.75 kg/ha 1.9 - - - 1.7 2.4
Peach 1974 1 × /, - 0.42 0.24 0.21 0.19 0.191 282
Italy 75 g/100 l
Peach 1978 3 × / <0.03) - <0.03 <0.03) - <0.031 292
Germany, 1.5 kg/ha 2.8 - 2.6 1.9 - 1.92
Fed. Rep. 3 × /
1.5 kg/ha 4.5 - <0.03 <0.03 - <0.03 293
6.1 - 2.2 5.0 - 2.4
2 × / 9.5 - 0.4 0.1 - <0.03
1.5 kg/ha 5.0 - 5.0 5.4 - 2.8
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
0 11 20 28 36
Plum 1974 5 × / 0.18 - - <0.01 <0.01 <0.01 <0.01 272
Germany, 1 kg/ha 3.38 - - 2.47 2.65 2.34 1.82
Fed. Rep. 0.09 - - 0.05 <0.01 <0.01 <0.01 273
1.18 - - 1.40 1.90 2.44 2.18
0 8 16 24 29
Damson 7 × / 0.34 - <0.01 <0.01 <0.01 <0.01 274
1 kg//ha 5.21 - 2.47 2.18 1.93 1.36
0 14 21
1975 2 × / 0.76 - - 0.13 <0.05 289
Germany, 1 kg/ha 2.99 - - 2.60 2.24
Fed. Rep. 1.10 - - 0.12 <0.05 290
1.76 - - 2.40 2.67
28
Olive oil 1975 2 × / - - - - - <0.5
Italy 15 l/tree - - - - - <0.5
of 0.2%
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
0 1 6-8 13-15 20-22 26-30
Broad bean 1973 1 × / 0.41 0.05 0.02 N.D. N.D. 250
Germany, 0.5 kg/ha 0.31 0.37 0.10 0.07 0.07
Fed. Rep. 0.33 0.07 0.02 N.D. N.D. N.D. 251
0.71 0.68 0.91 0.31 0.28 0.11
1976 3 × / 0.11 - 0.07 0.06 - 0.04 295
Germany, 0.3 kg/ha 4.50 - 1.86 1.50 - 0.60
Fed. Rep.
Bush bean 1974 4 × / 0.67 - - 0.38 - 0.11 265
Germany 0.5 kg/ha 2.71 - - 1.93 - 0.62
Fed. Rep.
1974 4 × / 0.15 - - 0.17 - 0.13 266
Germany, 0.5 kg/ha 0.49 - - 1.15 - 0.21
Fed. Rep. 0.35 - - 0.35 - 0.10 267
0.94 - - 1.66 - 0.753
Cabbage 4 × / 0.12 - <0.05 <0.05 <0.05 <0.05 278
0.3 kg/ha 11.2 - 1.75 1.25 0.84 1.34
5 × / 0.19 - <0.05 <0.05 <0.05 <0.05 279
0.3 kg/ha 1.44 - 2.02 0.80 0.40 <0.05
37
0.24 - <0.05 <0.05 <0.05 <0.05 <0.05 280
26.8 - 1.57 1.32 0.88 1.00 0.27
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
1 3 5 10 24 44 49
Lettuce, 1973 1 × / 3.55 0.95 0.75 0.5 0.5 0.5 0.1 252
head Germany, 0.3 kg/ha 8.30 11.3 8.8 3.6 0.6 1.05 0.5
Fed. Rep.
0 1 6-8 13-15 20-22 26-30
1974 2 × / 1.47 - <0.1 <0.1 <0.1 <0.1
Germany, 0.3 kg/ha 10.70 - 1.10 2.15 0.1 N.D.
Fed. Rep.
0 1 6-8 16 20-22 26-30 47
1974 1 × / 2.70 - 2.00 <0.1 - - <0.1 270
Germany, 0.3 kg/ha 3.40 - 2.50 1.65 - - <0.1
Fed. Rep.
2 × / 2.50 - - <0.1 - <0.1 271
0.3 kg/ha 3.10 - - 1.20 - 0.04
9 15 19 21
Lettuce 1977 1 × / - - 0.50 <0.10 <0.10 <0.10 291
glasshouse Netherlands 75 g/100 l - - 5.00 3.30 2.20 1.90
10 15 18 21
13.5 - <0.10 <0.10 <0.10 <0.10
7.00 - 7.10 7.10 5.70 2.90
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
10 15 18 21
31.0 - 1.10 1.10 1.30 <0.10
6.40 - 8.10 9.10 7.30 9.00
Control ----------- <0.10 -------------------------------
1 14 21 93
Sugarbeet 1973 1 × / - 3.16 - 0.33 0.20 - 0.08 254
leaves Germany, 0.3 kg/ha - 10.89 - 3.67 2.08 - 0.30
Fed. Rep.
roots <0.03 <0.03 - <0.03 255
<0.03 <0.03 - <0.03
0 1 6-8 13-15 20-22 26-30
10
Radish 1973 1 × / - - 0.35 0.55 263
Germany, 3 kg/ha - - 0.98 1.13
Fed. Rep.
16 23
Tomatoes 1774 5 × / 0.40 - - 0.16 0.09 275
Germany, 0.5 kg/ha (0.65) - (0.35) 0.43
Fed. Rep.
0.17 - 0.11 0.05 <0.05 276
0.37 - 0.38 0.35 0.27
3 × / 0.14 - 0.14 0.09 0.09 <0.05 277
0.5 kg/ha 0.70 - 0.52 0.53 - 0.28
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
3 4
glasshouse 1977 1 × / - 0.10 0.10 291
Netherlands 75 g/100 l - 0.45 0.34
1 × /
35 g/100 l 0.10
0.14
9 16 23
Orange 1974 1 × / 0.91 - 0.39 0.36 0.32 283
Italy 75 g/100 l
0 1 9
peel 1975 1 × / - 1.04 0.08 286
Spain 75 mg/100 l - 1.36 0.45
pulp - - 0.07
- - 0.11
0 1 4 8 16 35 42 47
fruit 1978 3 × / 0.30 0.32 0.32 0.13 0.06 <0.02 <0.02 - 298
Spain 75 g/100 l 1.01 0.88 2.02 2.13 1.17 1.05 0.91 -
peel 1.00 0.80 0.87 0.40 0.21 <0.03 <0.03 -
3.50 2.42 3.16 2.50 2.80 1.87 1.87 -
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
0 1 4 8 16 35 42 47
pulp 0.07 0.16 0.09 <0.02 <0.02 <0.02 <0.02 -
0.17 0.38 1.56 1.12 0.63 0.65 0.43 -
fruit 0.49 0.23 0.13 0.08 0.03 <0.02 <0.02 - 299
0.43 0.31 0.38 0.45 0.47 0.54 0.40 -
peel 2.15 1.00 0.55 0.36 0.11 <0.03 <0.03 -
1.61 1.15 1.24 1.40 1.32 1.20 1.10 -
pulp <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 -
0.10 0.08 0.14 0.18 0.21 0.32 0.20 -
fruit 0.75 0.24 0.35 0.19 - 0.02 0.05 0.07 300
0.60 0.25 0.33 0.61 - 0.49 0.41 0.58
peel 3.04 0.76 1.00 0.54 - 0.05 0.11 0.22
2.46 0.90 1.00 1.57 - 1.07 0.99 1.24
pulp 0.03 <2.02 <0.02 <2.02 - <0.02 <0.02 <0.02
0.24 0.12 0.15 0.14 - 0.30 0.21 0.36
29
fruit 1978 1 × / 0.08 301
(unwashed) USA 75 g/100 l 0.28
peel 0.14
1.25
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
29
pulp <0.01
0.02
juice <0.01
<0.01
oil 0.05
0.06
press liquor 0.06
0.38
molasses 0.04
2.55
finisher 0.01
pulp 0.05
peel 0.04
frits 0.28
chopped <0.02
peel 0.15
dried 0.03
peel 0.71
fruit 1 × / 0.02
(unwashed) 150 g/100 l 0.79
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
29
peel 0.07
3.80
pulp 0.02
0.15
juice <0.01
<0.01
oil 0.07
0.08
press 0.01
liquor 0.71
molasses 0.07
6.79
finisher 0.01
pulp 0.10
peel 0.04
frits 1.04
chopped 0.04
peel 0.85
dried 0.03
peel 0.67
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
29
Grapefruit 1978 1 × /
USA 75 g/100 l
fruits 0.01 302
(unwashed) 0.18
peel 0.03
0.37
pulp <0.01
<0.11
juice <0.01
<0.01
Grapefruit
oil 0.09
0.18
press 0.01
liquor 0.08
molasses 0.04
0.17
finisher 0.05
pulp 0.03
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
29
peel 0.04
frits 0.29
chopped 0.02
peel 0.11
dried 0.05
peel 0.68
fruit 1 × / 0.01
(unwashed) 150 g/100 l 0.50
peel 0.02
1.80
pulp <0.01
0.03
juice <0.01
<0.01
oil 0.14
0.16
press 0.01
liquor 0.14
molasses 0.08
0.36
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
29
finisher <0.01
pulp 0.03
peel 0.08
frits 1.01
chopped 0.02
peel 0.54
dried 0.04
peel 0.91
0 1 4 8 12 22
Clementine 1981 1 × /, 1.47 0.66 0.04 0.06 <0.02 <0.02 303
fruit France 75 g/100 l 0.28 0.33 0.28 0.34 0.24 0.20
peel 5.27 2.36 0.06 0.20 0.05 <0.03
1.03 1.18 1.01 1.21 0.85 0.70
pulp 0.08 <0.02 0.03 <0.02 <0.02 <0.02
<0.02 <0.02 0.03 0.04 0.04 0.04
45 52 59 65
Hops, dry 1973 1 × / 0 0 0 0 257
Germany, (1 g/stem, 8.48 11.41 10.52 0
Fed. Rep. poured on)
Table 2 (con't)
Year and Applications (No.) After application (days) Report
Crop country and rate (a.i.) and Residues (mg/kg) No.
15 18 21 25
2 × / 0 2.49 4.53 0
4 kg/ha 15.0 16.8 4.10 7.90
8 12 15 19 23 28
Hops, dry 1973 3 × 1 4.30 1.94 0 0 0 0 259
Germany, 3.4 kg/ha 32.7 19.3 19.7 20.8 14.7 10.8
Fed. Rep.
58 64 70 76
1 × / 0 0 0 0 260
(1.5 g/stem, 5.53 2.33 0 0
poured on)
45 52 59 65
0 0 0 0
12.54 10.41 5.72 5.40
Source: Wacker Chemie, GmbH 1983.
1 Butacarboxim.
2 Metabolites - sulphoxide + sulphone.
3 Data unreadable; value obtained from disappearance curve.
() = Value uncertain.
Field trials in the Federal Republic of Germany and Italy on
cherries, peaches and plums (including damson) at treatment levels of
0.5 to 1.5 kg/ha gave residues (sum) ranging from 0.19 to 3.23 mg/kg
at 21 days post-treatment.
Field trials on broad beans and bush beans in the Federal
Republic of Germany at treatment levels of 0.3 to 0.5 kg/ha gave
residues (sum) ranging from 0.12 to 2.31 mg/kg at seven days post-
treatment.
A single field trial on olives in Italy at treatment rate of
15 1/tree of 0.2 percent dilution gave a residue of <0.05 mg/kg in
the oil at 28 days post-treatment.
Field trials on cabbage in the Federal Republic of Germany at a
treatment level of 0.3 kg/ha gave residues (sum) ranging from 0.45 to
0.93 mg/kg at 21 days post-treatment.
Field trials on head lettuce in the Federal Republic of Germany
at a treatment level of 0.3 kg/ha gave residues (sum) ranging from 0.1
to 1.65 mg/kg at 21 days post-treatment. Tests on glasshouse lettuce
in the Netherlands at 75 g a.i./100 1 water gave residues (sum)
ranging from 1.90 to 9.00 mg/kg at 21 days post-treatment. These
results are difficult to reconcile with the field data and the actual
treatment rates are uncertain.
A field trial on sugarbeets in the Federal Republic of Germany
with a single application of 0.3 kg/ha gave residues (sum) of
2.28 mg/kg in the leaves and <0.03 mg/kg in the roots at 21 days
post-treatment.
A field trial on radishes in the Federal Republic of Germany with
a single application of 3 kg/ha gave residues (sum) of 1.69 mg/kg at
14 days post-treatment.
Field trials on tomatoes in the Federal Republic of Germany
at a treatment rate of 0.5 kg/ha gave residues (sum) ranging from
0.35 to 0.66 mg/kg at 6 to 8 days post-treatment. A trial on
glasshouse tomatoes in the Netherlands, using applications of 35 g or
75 g a.i./100 1 water, gave residues at 3 days post-treatment of 0.14
and 0.45 mg/kg, respectively.
Field trials on oranges in Italy, Spain and the United States at
treatment rates of 4.5 to 9 kg/ha gave residues (sum) ranging from
about 0.5 to 1.12 in whole fruit, 1.2 to 3.87 in peel (fresh), 0.02 to
0.65 in pulp, <0.01 in juice, and 2.59 to 6.86 mg/kg in molasses at
29 to 35 days post-treatment. Similar tests on grapefruit in the
United States gave residues (sum) ranging from 0.51 to 0.19 in whole
fruit, 0.4 to 1.82 in peel (fresh), 0.03 to 0.11 in pulp, <0.01 in
juice and 0.21 to 0.44 mg/kg in molasses at 29 days post-treatment.
The fruit was not fully ripe at the time of processing and analysis.
A field trial on clementines in France with a single application
of 75 g a.i./100 1 water gave residues (sum) of 0.20 in whole fruit,
0.70 in peel and 0.04 mg/kg in pulp at 22 days post-treatment.
Trials on dry hops in the Federal Republic of Germany at
treatments of either 3.4 or 4 kg/ha or 1 to 1.5 g/stem poured on gave
the highly variable results shown in Table 2.
FATE OF RESIDUES
General
Chemical and physical properties of butacarboxim are similar to
those of other oximcarbamates, e.g. thiofanox and aldicarb. On and in
foliage in the field, butocarboxim oxidizes rapidly to the sulphone
via the sulphoxide. Simultaneously, the carbamate group is hydrolysed
to the corresponding oximes according to the general scheme shown in
Figure 1.
In plants
An experiment was conducted using French beans harvested 16 days
after treatment and containing residues of 0.35 mg/kg butocarboxim and
1.66 mg/kg water-soluble metabolites by analysis (Wacker Chemie, GmbH
1983b). Extracts were separated by thin-layer chromatography and
detected by spraying with an acetylcholinesterase reagent. The
presence of unchanged butocarboxim, its sulphoxide and sulphone
metabolites, and 2-demethylation derivatives were shown.
In soil
Soil samples taken in connection with the field trials on
sugarbeets (Wacker Chemie, GmbH 1973) had no detectable residues (sum)
above the limit of detection of 0.03 mg/kg. No detailed metabolic
studies of soil degradation are available; however, a report on the
migration properties of butocarboxim and butoxycarboxim (Wacker Chemie
GmbH 1978) indicated a half-like of 6 to 8 days for butocarboxim and
41 to 44 days for butoxycarboxim.
METHODS OF RESIDUE ANALYSIS
The bulk of the field trial data was obtained using the method of
Holden, et al. (1969) with suitable modifications as required. The
method is based on the separation of water soluble and toluene soluble
components after extraction. The oximcarbamate group in both portions
is saponified and the liberated methylamine converted to N-methyl-2,
4-dinitroaniline with 2,4-dinitrofluorobenzene. The N-methyl-2,
4-dinitroaniline is determined by gas chromatography utilizing an
electron capture detector. Average recoveries are about 72 percent for
parent compound and 59 percent for the sulphone and sulphoxide. The
limit of determination is usually about 0.04 mg/kg for most fruits and
vegetables.
An improved method of analysis was developed in 1976-77 based on
procedures described in "Pflanzenschutznachrichten Bayer 28/1976",
p. 388. After extraction with methanol, separation and clean up, the
toluene soluble portion (butocarboxim) is taken up in acetone and
determined directly by gas chromatography using a nitrogen-selective
thermionic detector. The metabolites in the aqueous phase are
transferred to chloroform, dried, taken up in methanol and subjected
to ester interchange with the aid of sodium hydroxide. The resulting
methyl-N-methyl carbamate is then determined by nitrogen-selective gas
chromatography. Recoveries averaged 81 percent for butocarboxim and 64
percent for the metabolites (sum). The sensitivity appears to be about
the same as for the older method. Because of its ease of use and
economy, the newer method is to be preferred for regulatory purposes.
NATIONAL MAXIMUM RESIDUE LIMITS REPORTED TO THE MEETING
National tolerances established in the Federal Republic of
Germany, representing the sum of butocarboxim, its sulphoxide and
sulphone, expressed as butocarboxim, are as follows:
Crop MRL (mg/kg) Preharvest interval (days)
Stone fruit 4 21
Pome fruit 3 14
Beans, fresh 3 7
Citrus fruit 2 21
Citrus pulp 1
Tomato 2 3
Lettuce 2 21
Cabbage 1 21
APPRAISAL
Butocarboxim is a systemic insecticide of the oximcarbamate
family, which is used primarily in foliar treatment for the control of
sucking insects, and secondarily for mite control on fruits,
vegetables and cotton, it is marketed as either a 25 percent or 50
percent a.i. emulsifiable concentrate, which is diluted to 0.1 - 0.15
percent with water for spray application. Recommended use rates range
from 0.3 to 3.5 kg/ha on most commodities, with post-treatment
intervals varying from 3 to 21 days. There are no post-harvest, animal
or soil treatment uses, but ornamental uses include soil drenching and
hydroponic incorporation.
Butocarboxim degrades rapidly in plants to form the sulphoxide
and, primarily, sulphone metabolites. Residues of the parent compound
rarely exceed the detectable limits beyond 14 days post-treatment.
Harvest residues at recommended post-treatment intervals can range
from 0.02 to 1.1 mg/kg for apples, 0.19 to 3.2 for stone fruits, 0.1
to 2.3 for beans, 0.1 to 1.7 for field-grown cabbage and lettuce, 2.3
for sugarbeet leaves, <0.03 for sugarbeet roots, 1.3-1.7 for
radishes, 0.4 to 0.7 for tomatoes and 0.2 to 1.1 for citrus (whole
fruit). The residue tends to locate mostly in the peel of citrus and
exceeds 2 mg/kg in fresh peel and 6.9 mg/kg in molasses. The results
of supervised trials on cotton (cottonseed and cottonseed oil
residues) were not available to the Meeting.
No data were available on metabolism in food animals or their
products and only limited information was available on plant and soil
metabolism. It is assumed that the metabolism of butacarboxim would be
similar to that of related compounds, such as aldicarb.
Although butocarboxim is currently registered for use in eight
countries, with eight more expected to follow soon, there was no
information on residues found in commerce and only national maximum
residue limits from the country of manufacture (Federal Republic of
Germany).
The original method of residue analysis, used in obtaining most
of the reviewed data, is based on extraction and separation of
residues into toluene (butocarboxim) and aqueous (metabolite)
fractions, followed by saponification of each fraction to liberate
methylamine. The methylamine is then converted to N-methyl-2,
4-dinitroaniline by treatment with 2,4-dinitrofluorobenzene. The
N-methyl derivative is then measured by gas chromatography with
electron capture detection. Limits of 0.02-0.04 mg/kg are usually
achieved for most fruits and vegetables.
A newer, simpler, and much preferred method was developed in
1976. In this procedure, the toluene and aqueous fractions are cleaned
up and the butocarboxim determined directly by gas chromatography with
a nitrogen-selective thermionic detector. The sulphoxide and sulphone
metabolites from the initial aqueous phase are subjected to ester
interchange in alkaline methanol to give methyl-N-methylcarbamate,
which is determined by gas chromatography using the nitrogen-selective
detector. Similar sensitivities are obtained. This method is
recommended for both research and regulatory use.
RECOMMENDATIONS
The Meeting concluded that the guideline levels listed below need
not be exceeded if good agricultural practice is followed. The levels
refer to the sum of butocarboxim and its sulphoxide and sulphone,
expressed as butocarboxim.
Commodity Guideline levels (mg/kg) Pre-harvest intervals
on which levels are
based (days)
beans 5 7
stone fruit 5 21
sugarbeet leaves 5 21
apples 2 14
citrus fruit 2 21
lettuce1 2 21
radish 2 7
cabbage 1 21
tomato 1 3
sugarbeet roots 0.1 21
1 Based on data from field-grown lettuce
FURTHER WORK OR INFORMATION
When available
Results of supervised trials in progress on residues in
cottonseed and cottonseed oil resulting from the foliar treatment of
cotton, in order to consider appropriate guideline levels.
Desirable
1. Data on residues in meat and milk resulting from the feeding of
cottonseed, cotton-seed oil or citrus by-products to animals.
2. Additional residue data from supervised trials on greenhouse
grown vegetables, particularly lettuce and tomatoes.
REFERENCES- RESIDUES
Holden, E.R., Jones, W.M. & Beroza, M. Determination of residues of
1969 methyl- and dimethyl-carbamate insecticides by gas
chromatography of their 2,4-dinitroaniline derivatives.
J. Agra Food Chem., 17: 56.
Wacker Chemie, GmbH. Report on soil analysis No. 256 (Unpublished)
1973
Wacker Chemie, GmbH. Reports on migration of butocarboxim and
1978 butoxycarboxim in soils. (Unpublished)
Wacker Chemie, GmbH. Reports of residue analyses No. 244-255, 257-283,
1983a 286-303. (Unpublished)
Wacker Chemie, GmbH. Results of tests for metabolites in treated
1983b French beans. (Unpublished)
See Also:
Toxicological Abbreviations