PESTICIDE RESIDUES IN FOOD - 1984
Sponsored jointly by FAO and WHO
EVALUATIONS 1984
The monographs
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
Rome, 24 September - 3 October 1984
Food and Agriculture Organization of the United Nations
Rome 1985
AMITRAZ
Explanation
Amitraz was reviewed by the 1980 JMPR. 1/ A temporary ADI of
0.0005 mg/kg was estimated and a number of temporary MRLs proposed.
Additional residue data on whole olives from supervised trials were
required by 1984 and additional residue data on citrus fruit and
further trials on hops, eggplant and onions were considered desirable.
The present meeting was informed that the use of amitraz on
olives has not been developed commercially. Residues data on pears and
citrus were made available, as well as new information on plant
metabolism.
RESIDUES IN FOOD AND THEIR EVALUATION
USE PATTERN
Amitraz is registered in a number of territories for the control
of various mite species of citrus (Panonychus citri, Tetranychus
spp., Phyllocoptruta oleivora). Cultural practices and agronomic
needs differ among these territories. For example, higher rates of
amitraz are required to control infestations of Tetranychus spp.
than for other mite species. Similarly, application volumes vary
depending on local practice and the number and size of trees. Thus,
approved uses are often expressed differently in the different
territories. These have been standardized in terms of maximum spray
concentration and an approximate equivalent rate of amitraz per
hectare in Table 1.
The use of amitraz has been approved recently in the Netherlands
on strawberries for the control of spider mite at 38 g/100 1 up to
flowering and after the last picking (1981), and on eggplant,
peppers and tomatoes in glasshouses for the control of spider mite at
76 g/l 1000m2 by swingfog or pulsfog only, with a three-day interval
between last application and harvesting (1981/82). Its use on pig,
cattle and sheep has been approved since 1980.
1/ See Annex 2 for FAO and WHO documentation
TABLE 1. Registration Status of the Use of Amitraz on Citrus
Approved application rates
Withholding
period Spray concentration Approximate
Territory (days) (%a.i.) g a.i./ha
Cyprus 14 0.04 600
Ecuador 14 0.12 500
Iran NA 0.02 400
Italy 14 0.04 400
Japan 14 0.02 1 200
Malaysia 7 0.04 400
Morocco 28 0.01 1 200
Republic of Korea NA 0.02 900
Spain 7 0.04 400
Taiwan province of China 14 0.02 400
Turkey 28 0.04 400
RESIDUES RESULTING FROM SUPERVISED TRIALS
Apples and Tomatoes
Apple and tomato samples from amitraz trials were analysed for
amitraz and its metabolite BTS 27 271. An analytical procedure was
used that involved the conversion of amitraz to BTS 27 271 and the
assay of the total BTS 27 271 residue. The maximum residue of BTS
27 271 in apples 28 days after a single spray application of amitraz
was found to be 0.24 mg/kg. In tomatoes, three days after a single
spray application of amitraz, the maximum residue of BTS 27 271 was
found to be 0.46 mg/kg (Table 2).
Citrus
Residues on citrus grown in the United States have been
determined by the "total residue" method, in which all residues
containing the 2,4-dimethyl-analine moiety are measured and the
residue expressed as amitraz equivalent. (The residue method
recommended by JMPR/Codex determines the sum of amitraz and its
metabolite N-(2,4-dimethylphenyl)-N'-methylformamidine (BTS 27 271).
Residue values determined by the "total amitraz" method may be
converted to equivalent values determined as BTS 27 271 by dividing by
a factor of 1.8.)
Grapefruit
Following one to three applications of amitraz at up to
24 oz/acre (1 lb/acre = 1.12 kg/ha), mean residues in grapefruit over
a period of 1 to 14 days ranged from <0.05-1.04 mg/kg, with an
over-all mean of 0.49 mg/kg (Table 3).
Lemon
Following one or two applications of amitraz at a rate of
24 oz/acre, mean residues in lemons over a period of 1 to 12 days
ranged from 0.44 to 1.23 mg/kg in lemons, with an over-all mean of
0.81 mg/kg (Table 4).
Lime
Following one to three applications of amitraz at up to
5 oz/acre, mean residues in limes over a period of 1 to 14 days
ranged from 0.16 to 2.11 mg/kg, with an over-all mean of 0.84 mg/kg
(Table 5).
Tangerine and Tangelo
Following a single application of 24 oz/acre of amitraz to
tangerines, mean residue levels over a period of 1 to 12 days were
0.79 to 1.49 mg/kg, with an over-all mean of 1.16 mg/kg. For tangelo,
following one or two applications, the equivalent residue levels were
0.73 to 1.85 mg/kg and 0.86 mg/kg, respectively (Table 6).
TABLE 2. Amitraz Residues in Tomatoes from Supervised Trials, The Netherlands
Application
Year No. Rate Formulation Residues1 Reference
(kg a.i./ha) (mg/kg)
1974 1 1.14 40 0.40 (0.29-0.46) Goodall &
Somerville, 1974
1974 1 1.14 40 0.27 (0.17-0.36) Greve &
Hogendoorn, 1975
1979 1 76 g a.i./ pulsfog 0.11 (0.08-0.17) Netherlands,
1 000 m2 1979
1980 1 80 g a.i./ pulsfog 0.15 (0.10-0.21) )
(glass- 1000 m2 ) van Adrichem &
house) ) Vogelezang,
) 1981
1980 1 81 g a.i./ swingfog 0.05 (0.02-0.07) )
(glass- 1 000 m2 )
house) )
1 Measured three days after application; determined and expressed as
N-2,4-dimethylphenyl-M-methylformamidine.
TABLE 3. Amitraz Residues in Grapefruit from Supervised Trials, United States
Application
Rate No. Spray volume Interval Residues (mg/kg) Reference
(oz a.i./ (gal/acre) (days) Range Mean
acre)
4.5 300 1 0.17 - 0.19 0.18 Ford, 1981b
8 0.10 - 0.15 0.13
15 0.11 - 0.12 0.11
29 0.07 - 0.08 0.08
43 0.06 - 0.07 0.07
9 300 1 0.33 - 0.38 0.36 Ford, 1981b
8 0.18 - 0.27 0.23
15 0.15 - 0.18 0.17
29 0.12 - 0.16 0.14
43 0.09 - 0.13 0.11
24 1 800 7 0.18 - 0.37 0.28 Upjohn &
7.5 100 1 0.32 Boots,
7 0.18 1974 - 1981
14 <0.05
15 100 1 0.61
7 0.43
14 <0.05
24 3 1 0.82 - 1.27 1.04 Ford, 1981d
7 0.71 - 1.09 0.98
14 0.84 - 1.02 0.92
Note: 1 lb/acre = 1.12 kg/ha; 1 U.S. gal/acre = 9.36 l/ha
TABLE 4. Amitraz Residues in Lemons from Supervised Trials, United States
Application
Rate No. Spray volume Interval Residues (mg/kg) Reference
(oz a.i./ (gal/acre) (days) Range Mean
acre)
48 1 200 1 1.86 - 1.93 1.90 Ford, 1981a
7 1.17 - 1.37 1.26
14 1.11 - 1.15 1.13
28 0.73 - 0.79 0.76
56 0.38 - 0.41 0.40
112 0.12 - 0.20 0.17
24 180 1 1.14 - 1.24 1.19 Ford 1981d
7 0.99 - 0.99 0.99
24 2 180 1 1.19 - 1.26 1.23
7 0.66 - 0.93 0.80
24 2 40 1 0.57 - 1.04 0.81
12 0.34 - 0.70 0.52
24 2 500 1 0.68 - 0.81 0.73
24 2 1 200 1 0.59 - 0.64 0.62
7 0.40 - 0.47 0.44
TABLE 5. Amitraz Residues in Limes from Supervised Trials, United States
Application
Rate No. Spray volume Interval Residues (mg/kg) Reference
(oz a.i./ (gal/acre) (days) Range Mean
acre)
7.5 250 86 <0.05 Ford, 1981c
15 86 <0.05
24 40 1 2.07 - 2.15 2.11
7 1.18 - 2.17 1.68
7.5 100 1 0.41
7 0.27
14 0.16
15 1 0.64
7 0.28
14 0.23
24 3 40 1 1.37 - 2.07 1.72
12 0.60 - 1.11 0.86
TABLE 6. Amitraz Residues in Tangerines and Tangelos from Supervised Trials, United States
Application
Rate No. Spray volume Interval Residues (mg/kg) Reference
(oz a.i./ (gal/acre) (days) Range Mean
acre)
TANGERINE
24 40 1 0.86 - 2.11 1.49 Upjohn &
12 0.63 - 0.85 0.74 Boots,
1981b
TANGELO
24 500 97 0.26 - 0.38 0.32 Upjohn &
24 40 1 1.13 - 2.57 1.85 Boots,
12 0.73 - 0.97 0.85 1981a
24 2 500 1 0.65 - 1.07 0.86
14 0.72 - 0.73 0.73
Orange
The application rate of 24 oz/acre is that approved under an
experimental use permit in the United States and for which a temporary
tolerance of 2 mg/kg has been established. At this rate, the range of
residue values in oranges over a period of 1 to 7 days following a
single application was 0.18 to 1.25 mg/kg, with an overall mean of
0.48 mg/kg. Following two applications, the equivalent values were
0.32 to 1.01 mg/kg and 0.59 mg/kg. Following three applications, the
range of mean values over a period of 1 to 21 days was 0.26 to
2.20 mg/kg, with an overall mean of 0.188 mg/kg (Table 7).
Residues of amitraz in oranges, grown in the United States,
treated at higher rates (i.e. 40 oz/acre or 2.8 kg/ha) were within the
range of expected values, as were those crops treated at lower rates
(Table 8).
The analytical method used to determine residues in or on oranges
grown in Japan measured amitraz and its metabolite BTS 27 271
separately. Studies undertaken in Japan are summarized in Tables 9 and
10. In the former, the data indicate that the majority of the residues
are in the peel, with residues being predominantly present as the
metabolite BTS 27 271. The second study (Table 10) confirms the low
residues (generally less than 0.01 mg/kg of the parent compound
following a preharvest interval of 15 days.)
Two studies were conducted in China in 1982 and 1983 to determine
the persistence and residue distribution of amitraz in oranges. The
first study determined the residues of amitraz from trials conducted
on oranges grown in Guangdong. In 1983 this study was repeated in
Guangdong and Guangxi. The method of analysis used to measure residues
was the same as that used in the United States, which determines
amitraz and its metabolites containing the 2,4-dimethylaniline moiety.
These studies are unpublished but are summarized in Tables 11 and 12.
These data confirm the general levels of amitraz residues found in
other studies and their distribution within the fruit.
The residues of 2,4-dimethylaniline (BTS 24 868) in two samples
of commercially grown oranges were determined using an analytical
method that had been initially developed for BTS 24 868 residues in
pears. Peel and flesh were analysed separately. The recoveries of BTS
24 868 from control oranges ('Valencia' and 'Maroc Late'), fortified
at either 0.1 or 0.05 mg/kg, gave an over-all mean and standard
deviation of 82.4 ± 15.7 percent. Mean BTS 24 868 residues in the peel
of control oranges fortified with 0.25 mg/kg of either amitraz, BTS
27 271 or BTS 27 919 were found to range from 0.012 to 0.026 mg/kg
(equivalent to 4.8 to 10.3 percent artefactual conversion of the
parent compounds to BTS 24 868). Residues of BTS 24 868 in the flesh
of oranges from the two commercial orchards analysed were below the
limit of detection (0.003 mg/kg), as were the total amitraz-derived
residues (limit of detection 0.025 mg/kg). Residues of BTS 24 868 in
the peel of these oranges were 0.022 mg/kg (Grower 1) and 0.040 mg/kg
TABLE 7. Amitraz Residues in Oranges from Supervised Trials, United States
Application1
Rate No. Spray volume Interval Residues (mg/kg) Reference
(oz a.i./ (gal/acre) (days) Range Mean
acre)
1 1 900 1 0.11 - 0.50 0.26 Upjohn &
7 0.12 - 0.46 0.25 Boots
1 1 300 1 0.24 - 0.25 0.25 1974-1981
7 0.17 - 0.24 0.21
1 100 1 1.00 - 1.49 1.25
7 0.86 - 1.19 1.03
1 100 1 0.62 - 0.79 0.71
7 0.44 - 0.61 0.53
1 180 1 0.24 - 0.71 0.48
7 0.14 - 0.22 0.18
1 1 800 7 0.26 - 0.37 0.31
1 1 800 1 0.31 - 0.36 0.34
2 100 1 0.58 - 0.88 0.73 Upjohn &
7 0.39 - 0.71 0.55 Boots,
2 1 300 1 0.30 - 0.35 0.33 1974-1981
7 0.32 - 0.32 0.32
2 100 1 0.63 - 1.38 1.01
10 0.47 - 0.76 0.62
2 180 1 0.60 - 0.71 0.66
7 0.40 - 0.53 0.47
3 1 1.85 - 2.42 2.20 Ford, 1981c
7 1.13 - 1.54 1.46
14 0.98 - 1.23 1.07
21 0.68 - 1.54 1.11
Table 7 (continued)
Application1
Rate No. Spray volume Interval Residues (mg/kg) Reference
(oz a.i./ (gal/acre) (days) Range Mean
acre)
3 1 0.47 - 0.59 0.52
7 0.28 - 0.42 0.35
14 0.38 - 0.42 0.40
21 0.19 - 0.33 0.26
3 1 0.57 - 1.37 0.88
7 0.52 - 1.32 0.82
21 0.69 - 1.45 1.14
3 1 0.60 - 0.80 0.73
7 0.37 - 0.74 0.55
1 Rate of application was 24 oz a.i./acre in all trials
TABLE 8. Amitraz Residues in Oranqes from Supervised Trials, United States
Application
Rate Spray volume Interval Residues (mg/kg) Reference
(oz a.i./ (gal/acre) (days) Range Mean
acre)
19.8 1 000 1 0.99 - 1.09 1.06 Ford, 1980
7 0.69 - 0.92 0.79
14 0.55 - 0.65 0.59
27 0.38 - 0.46 0.42
49 0.16 - 0.28 0.23
119 0.10 - 0.14 0.11
141 0.09 - 0.09 0.09
40 1 000 1 0.62 - 0.69 0.65 Ford, 1981a
7 0.42 - 0.49 0.46
14 0.34 - 0.48 0.40
28 0.31 - 0.36 0.34
58 0.27 - 0.34 0.31
40 1 000 1 1.67 - 1.94 1.79 Ford, 1981a
7 1.16 - 1.35 1.25
14 0.83 - 0.95 0.89
28 0.48 - 0.54 0.52
56 0.20 - 0.22 0.21
40 1 000 1 0.58 - 0.66 0.63 Ford, 1981a
8 0.46 - 0.59 0.53
15 0.49 - 0.52 0.51
31 0.51 - 0.55 0.52
57 0.41 - 0.49 0.45
TABLE 8. (continued)
Application
Rate Spray volume Interval Residues (mg/kg) Reference
(oz a.i./ (gal/acre) (days) Range Mean
acre)
19.8 1 000 1 0.64 - 0.85 0.73 Ford, 1980
8 0.50 - 0.53 0.51
14 0.43 - 0.48 0.46
28 0.26 - 0.31 0.29
56 0.15 - 0.16 0.15
112 0.06 - 0.08 0.07
147 0.05 - 0.05 0.05
4.5 300 1 0.19 - 0.27 0.25 Ford, 1981b
8 0.10 - 0.15 0.13
15 0.12 - 0.14 0.13
29 0.09 - 0.12 0.10
43 0.08 - 0.12 0.10
9 300 1 0.39 - 0.45 0.41 Ford, 1981b
8 0.23 - 0.34 0.28
15 0.23 - 0.28 0.26
29 0.13 - 0.16 0.14
43 0.14 - 0.16 0.15
TABLE 9. Amitraz and BTS 27 271 Residues in Oranqes from Supervised Trials, Japan1
Residue (mg/kg) 2 Reference
Interval Compound
(days) analysed Peel Pulp Whole fruit
20 Amitraz 0.01 <0.007 <0.01 Takano,
BTS 27 271 0.77 0.176 0.35 1974
30 Amitraz 0.01 <0.007 <0.01
BTS 27 271 0.46 0.116 0.19
40 Amitraz - - -
BTS 27 271 0.26 0.098 0.13
50 Amitraz - - -
BTS 27 271 0.08 0.073 0.07
1 Spray concentration 0.02% amitraz.
2 Residues of amitraz and BTS 27 271 analysed separately.
TABLE 10. Amitraz Residues in Oranges from Supervised Trials, Japan
Spray Part No. of Interval Residue
volume1 analysed applications (days) (mg/kg)2 Reference
(1/ha) Lab.A Lab. B
8 000 Flesh 0 - <0.01 <0.01 Nissan &
2 15 <0.01 <0.01 Boots,
2 30 <0.01 <0.01 1972
3 7 <0.01 <0.01
3 15 <0.01 <0.01
3 30 <0.01 <0.01
Peel 0 - <0.01 <0.01
2 15 <0.01 0.01
2 30 <0.01 0.01
3 7 0.09 0.10
3 15 0.10 0.07
3 30 0.02 0.02
6 000 Flesh 0 - <0.01 <0.01
2 15 <0.01 <0.01
2 30 <0.01 <0.01
3 7 <0.01 <0.01
3 15 <0.01 <0.01
3 30 <0.01 <0.01
Peel 0 - <0.01 <0.01
2 15 <0.01 <0.01
2 30 <0.01 <0.01
3 7 0.08 0.08
3 15 <0.01 <0.01
3 30 <0.01 <0.01
1 Spray concentration 0.01% amitraz.
2 Residue determined as amitraz alone.
TABLE 11. Amitraz Residues in Oranges from Supervised Trials, China1
Residues (mg/kg)
Interval
Applications Days Peel Pulp Whole fruit
Range Mean Range Mean Range Mean
1 0 0.98-1.13 1.04 0.026-0.046 0.034 0.44-0.51 0,47
20 0.50-0.60 0.56 0.015-0.063 0.059 0.21-0.25 0.23
40 0.31-0.55 0.42 0.068-0.083 0.074 0.15-0.27 0.20
2 0 1.25-1.94 1.66 0.08-0.10 0.09 0.58-0.63 0.61
7 1.12-1.27 1.20 0.09-0.13 0.11 0.38-0.44 0.41
14 0.83-0.95 0.89 0.09-0.13 0.11 0.28-0.32 0.30
2 20 0.74-0.82 0.77 0.09-0.17 0.12 0.24-0.32 0.28
25 0.68-0.73 0.71 0.13-0.16 0.15 0.27-0.29 0.28
30 0.63-0.69 0.66 0.13-0.13 0.13 0.24-0.24 0.24
35 0.57-0.73 0.65 0.10-0.15 0.13 0.22-0.27 0.25
40 0.73-0.82 0.77 0.13-0.16 0.15 0.28-0.30 0.29
1 Spray concentration 0.01% amitraz; application rate 2 600 l/ha; residues determined by
"total residue" method.
TABLE 12. Amitraz Residues in Oranges from Supervised Trials, China1
Residues (mg/kg)
Interval
Applications Days Peel Pulp Whole fruit
Range Mean Range Mean Range Mean
1 0 1.83-1.91 1.88 0.004-0.008 0.006 0.72-0.83 0.77
20 0.55-0.62 0.58 0.06-0.11 0.09 0.24-0.29 0.27
40 0.26-0.43 0.33 0.05-0.08 0.07 0.13-0.19 0.16
2 0 1.47-1.56 1.51 0.06-0.10 0.08 0.53-0.54 0.54
20 0.46-0.50 0.48 0.13-0.14 0.13 0.23-0.31 0.26
40 0.36-0.38 0.37 0.10-0.14 0.12 0.18-0.20 0.19
1 0 1.11-1.13 1.12 0.014-0.016 0.015 0.49-0.54 0.51
20 0.57-0.59 0.58 0.08-0.12 0.10 0.27-0.29 0.28
40 0.36-0.53 0.46 0.06-0.09 0.08 0.16-0.24 0.20
2 0 1.29-1.95 1.61 0.08-0.09 0.09 0.24-0.70 0.50
20 0.35-0.36 0.36 0.09~0.13 0.11 0.17-0.19 0.18
40 0.25-0.32 0.28 0.07-0.08 0.07 0.12-0.15 0.13
1 Spray concentration 0.01% amitraz; application rate 3 000 l/ha; residues determined by
"total residue" method.
(Grower 2) with the corresponding total amitraz-derived residues being
0.14 and 0.35 mg/kg. Expressed as a percentage of the total
amitraz-derived residue, the BTS 24 868 residues ranged from 15.6 to
18.3 percent. This is outside the range of artefactual conversion of
the known metabolites to BTS 24 868 and, therefore, indicates that
approximately 50 percent of the BTS 24 868 residues in peel are "true"
residues. However, when calculated on a whole fruit basis by combining
the results from peel and flesh, a maximum value of less than
0.01 mg/kg BTS 24 868 was obtained (McGibbon, 1984b).
Pear
A method has been developed for the analysis of
2,4-dimethylaniline residues (BTS 24 868) in pears. The recoveries of
BTS 24 868 from control pears ('Williams','Bon Chretian' and
'Conference'), fortified at either 0.1 or 0.05 mg/kg, gave an over-all
mean and standard deviation of 74.3 ± 12.4 percent. Mean BTS 24 868
residues in control pears fortified with 0.5 mg/kg of either amitraz,
BTS 27 271 or BTS 27 919 were found to range from 0.006 to 0.018 mg/kg
(equivalent to 1.5 to 4.3 percent conversion of the parent compounds
to BTS 24 868). The mean residues of BTS 24 868 in commercially-grown
pears treated with amitraz under normal field practice ranged from
0.002 to 0.005 mg/kg, with a minimum detectable level estimated at
0.001 mg/kg. The level of total amitraz-derived residues in the
treated pears was found to be in the range 0.10 - 0.20 mg/kg. The
ratio of BTS 24 868 residues in the treated fruit to the total
amitraz-derived residue was calculated as 1.2 to 3.9 percent. This is
within the range of artefactual conversion of coexisting amitraz and
its metabolites. It follows, therefore, that there is no evidence to
suggest that specific BTS 24 868 residues exist in the treated pears
(McGibbon, 1984a).
Citrus and Processed By-products
Studies have been conducted on the distribution of amitraz
residues in citrus and on the effects of processing. In 'Valencia' and
'Navel' oranges, approximately 80 percent of the residue present at
harvest was in or on the peel. Residues were more evenly distributed
in 'Hamlin' oranges, primarily because of their thinner peel. In
grapefruit, approximately 90 percent of the residue occured in the
peel. These studies are summarized in Table 13.
In processing studies dry citrus pulp from processed oranges
contained residues some four to seven times higher than in fresh
fruit. Residues in citrus molasses were approximately 50 percent lower
than those in dry pulp. The remaining fractions contained levels at or
below those detected in fresh fruit.
TABLE 13. Amitraz Residues in Citrus Peel and Flesh from Supervised Trials
Amitraz (mg/kg)
Fruit Application Days
variety rate after Peel Whole Peel Edible Flesh Reference
(% a.i.) application (%) fruit flesh (%)
Valencia 0.03 58 27.4 0.31 0.92 0.06 15 Ford, 1981a
orange
Navel 0.03 112 29.4 0.08 0.20 0.04 32 Ford, 1981a
orange
Navel 0.03 x 2 57 32.2 0.45 1.35 0.05 7 Ford, 1981a
orange
Hamlin 0.015 145 20.8 0.057 0.11 0.038 53 Ford, 1980
orange 0.015 + oil 145 22.2 0.096 0.20 0.067 55
0.015 145 20.2 0.045 0.10 0.031 53
0.015 + oil 145 20.2 0.051 0.10 0.030 47
Grapefruit 0.01 1 31.3 0.19 0.62 0.005 1.7 Ford, 1980
8 28.1 0.14 0.44 0.007 3.9
15 25.8 0.11 0.44 0.011 6.7
29 26.0 0.07 0.24 0.010 10.6
43 27.9 0.07 0.27 0.015 12.6
0.02 1 37.0 0.37 0.88 0.002 0.4
8 28.9 0.27 0.65 0.008 2.9
15 27.7 0.15 0.53 0.012 5.6
29 30.2 0.16 0.37 0.018 9.4
43 28.8 0.12 0.35 0.015 9.6
FATE OF RESIDUES
In Plants
Previous studies (FAO/WHO, 1981b) have shown that
amitraz degrades rapidly to yield predominantly BTS 27 271
[N-(2,4-dimethylphenyl)-N'-methylformamidine] and smaller amounts of
BTS 27 919 (2,4-dimethylformanilide).
Pears
Radiolabelled amitraz was applied to commercially grown pears
(var. 'Conference') at two sites in the United Kingdom (Levington and
Nottingham). An E.C. formulation was used at a spray concentration of
0.06 percent a.i. (i.e. identical to that used in the United States).
Samples of fruit were analysed at maturity 29 days (Levington) and 61
days (Nottingham) after treatment. At harvest, 48.2 percent of the
applied radioactivity remained in the fruit, of which BTS 27 271
(14.0 percent) and BTS 27 919 (5.3 percent) were the main metabolites
characterized. Amitraz accounted for less than 1 percent, with BTS
24 868 and BTS 28 037 (N,N'-bis-dimethylphenylformamidine) each
comprising a further 1.2 percent, although in the case of BTS 24 868
the amount detected may well be artefactual. Uncharacterized polar
compounds accounted for 34.8 percent, while the remainder of the
radioactivity (41.0 percent was fibre-bound (McGibbon & Kelly, 1984b).
Lemons
Amitraz was applied to the fruit of lemon trees (cv. 'Four
Seasons') maintained under glass. An E.C. formulation was used at a
spray concentration of 0.06 percent a.i. Samples of fruit were
harvested at maturity 32 days after treatment. At harvest, 89.5
percent of the applied radioactivity remained in or on the fruit, of
which 72.5 percent was found in the peel. BTS 27 271 (27.2 percent)
and BTS 27 919 (9.0 percent) were the main metabolites characterized.
Unchanged amitraz comprised 12.4 percent, while BTS 28 037 and BTS
24 868 accounted for 2.2 and 2.8 percent, respectively, of the total
radioactivity recovered, with the possibility that BTS 24 868 was
produced as an artefact. Uncharacterized polar compounds accounted for
25.1 percent while the remainder of the radioactivity (13.2 percent)
was fibre-bound. (McGibbon & Kelly, 1984a).
These new data confirm the previous findings that amitraz is
metabolized within a relatively short time. The major metabolites
remaining at harvest are BTS 27 271 and BTS 27 919. The presence of
any significant residues of BTS 24 868 is not indicated by either the
metabolism studies or the investigations aimed at specific analysis
for residues of the metabolite. A diagrammatic representation of the
metabolism of amitraz in plants is given in Figure 1.
NATIONAL MAXIMUM RESIDUE LIMITS
The following MRLs from the Netherlands were reported to the
meeting:
Pome fruit 0.5 mg/kg
Strawberries 0.05 mg/kg
Bell peppers 0.2 mg/kg
Eggplant 0.2 mg/kg
Tomatoes 0.2 mg/kg
Milk 0.05 mg/kg
Meat 0.05 mg/kg
Other food 0 (0.05) mg/kg
Limits include and are expressed as
N-2,4-dimethylphenyl-N-methylformamidine.
APPRAISAL
The meeting examined new residues data on citrus fruit and noted
that with a 14-day interval between last application and harvest,
most residue levels were less than the temporary MRL for oranges of
0.5 mg/kg (for amitraz plus N-2,4-dimethylphenyl-N'-
methylformamidine), even at the relatively high rates of use in the
trials in the United States (and approved under an experimental use
permit). The meeting confirmed its previous estimate.
Although the maximum residues in some citrus samples were about
2 mg/kg, it is not known if the high rates used will be recognized as
good agricultural practice and the meeting, therefore, decided not to
include these in its evaluation.
REFERENCES
Ford, J.J. Persistence of amitraz on Florida-grown Hamelin oranges.
1980 Report RI 34-017-06 (R 82) submitted by FBC to FAO.
(Unpublished)
Ford, J.J. Persistence of the acaricide amitraz on California Citrus -
1981a Part II. Report RESID/82/15 (R 133) submitted by FBC to FAO.
(Unpublished)
Ford, J.J. Additional residue studies of the acaricide amitraz on
1981b Florida-grown citrus. Report RESID/83/43 (R 135) submitted
by FBC to FAO. (Unpublished)
Ford, J.J. Residue decline on mature Hamlin oranges treated with three
1981c applications of Mitac EC. Report US/R-7 (R 151) submitted by
FBC to FAO. (Unpublished)
Goodall, E. & Sommmerville, L. Estimation of combined residues of BTS
1974 27 419 1974 and BTS 27 271 on Dutch apple and tomato crops.
Report No. Ax 74028 submitted by Aseptafabriek BV to FAO.
(Unpublished)
Greve, P.A. & Hogendoorn, E.A. Residuen van BTS 27 271 in appel en
1975 tomaat. RIV Report nr. 17/75 Tox-Rob. (Unpublished)
McGibbon, A.S. Residues of 2,4-dimethylaniline (BTS 24 868) in
1984a field-grown pears. Report METAB/84/3 (R 179) submitted by
FBC to FAO. (Unpublished)
McGibbon, A.S. Residues of 2,4-dimethylaniline (BTS 24 868) in
1984b field-grown oranges. Report METAB/84/5 (R 180) submitted by
FBC to FAO. (Unpublished)
McGibbon, A.S. & Kelly, I.D. The metabolism of 14C-amitraz in lemons
1984a under glasshouse conditions (an interim report). Report
METAB/84/6 submitted by FBC to FAO. (Unpublished)
McGibbon, A.S. & Kelly, I.D. The metabolism of 14C-amitraz in pears
1984b (an interim report). Report METAB/84/4 submitted by FBC to
FAO. (Unpublished)
Netherlands. Residuproef Asepta Tetranyx of tomaat. Proef nr. 79-167
1979 submitted by Aseptafabriek BY to FAO. (Unpublished)
Nissan & Boots. JA-119 (BTS 27 419) Residues analysis - citrus. Report
1972 (R 162) submitted by Nissan & Boots to FAO. (Unpublished)
Takano, J. BTS 27 419 residue analysis on citrus and pears and apples
1974 in Japan. Report 1974 (R 99) submitted by Nissan & Boots to
FAO. (Unpublished)
Upjohn & Boots. Residue determinations for U-36,059 (amitraz) and
1974 - metabolites in oranges, USA. Report (R 157) submitted by
1981 Upjohn & Boots to FAO. 1981 (Unpublished)
Upjohn & Boots. Residue determinations for U-36,059 (amitraz) and
1981a metabolites in tangelos, USA. Report (R 158) submitted by
Upjohn & Boots to FAO. (Unpublished)
Upjohn & Boots. Residue determinations for U-36,059 (amitraz) and
1981b metabolites in tangerines, USA. Report (R 159) submitted by
Upjohn & Boots to FAO. (Unpublished)
van Adrichem, J.C.J. & Vogelezang, H.P. Residue-onderzoek amitraz op
1981 tomaat no toepassing van Asepta Tetranyx d.m.v, puls- of
swingfog. Rapport 1017/81 submitted by Aseptafabriek BV to
FAO. (Unpublished)