The results of metabolism studies with goats and poultry indicated that teflubenzuron per se was the main terminal residue.
Dairy cattle (Table 35). Cameron and Puglis (1989a) fed dairy cows (4/treatment) with teflubenzuron for a period of 28 days with 10 ppm, 30 ppm or 100 ppm in the diet. Three cows in each test group were slaughtered 17-24 h after the final administration. Two additional cows fed at the highest level were maintained on the basal diet for a further 7 or 14 days after the end of dosing to provide data on depletion. Milk samples were taken from three days before administration to termination. Samples of milk and tissues (subcutaneous fat, peritoneal fat, liver, kidney, skeletal muscle) were analysed for residues of teflubenzuron. Liver samples were also analysed for the metabolite E-115, 1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluoro-3-hydroxybenzoyl)urea.
The results of the analyses are given in Table 35. Low concentrations of teflubenzuron were detected in the liver and/or kidney of some animals. There was no indication of any correlation with the feeding level (or with the withdrawal time in the high-dose group); positive values were found in the liver of one control animal and the kidney of another. All residues were below 0.05 mg/kg. Residues of the metabolite E-115 in liver samples were 0.05 mg/kg (LOD).
Peritoneal fat contained only low residues of teflubenzuron (all <0.03 mg/kg). Two positive samples were from the control group. There was little evidence of any dose-related trend. Residue concentrations at or close to the LOD (0.01 mg/kg) were recorded in subcutaneous fat in the high-dose group. No residues were found in any muscle or milk samples (<0.01 mg/kg).
Table 35. Residues in dairy cattle dosed with teflubenzuron (Cameron and Puglis, 1989a).
|
Group |
Cow |
Teflubenzuron, mg/kg |
|||||
|
Kidney |
Liver |
Muscle |
Peritoneal fat |
Subcutaneous fat |
Milk |
||
|
A (control) |
1 |
0.015 |
<0.01 |
<0.01 |
0.026 |
<0.01 |
<0.01 |
|
|
2 |
0.01 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
|
|
3 |
<0.01 |
0.017 |
<0.01 |
0.024 |
<0.01 |
<0.01 |
|
B (10 ppm) |
4 |
0.018 |
0.025 |
<0.01 |
0.015 |
<0.01 |
<0.01 |
|
|
5 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
|
|
6 |
<0.01 |
<0.01 |
<0.01 |
0.028 |
<0.01 |
<0.01 |
|
C (30 ppm) |
7 |
<0.01 |
<0.01 |
<0.01 |
0.015 |
<0.01 |
<0.01 |
|
|
8 |
<0.01 |
<0.01 |
<0.01 |
0.017 |
<0.01 |
<0.01 |
|
|
9 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
|
D (100 ppm) |
10 |
<0.01 |
<0.01 |
<0.01 |
0.011 |
<0.01 |
<0.01 |
|
|
11 |
<0.01 |
0.01 |
<0.01 |
0.015 |
<0.01 |
<0.01 |
|
|
12 |
0.017 |
0.01 |
<0.01 |
0.015 |
<0.01 |
<0.01 |
|
7 days withdrawal |
13 |
0.041 |
0.01 |
<0.01 |
0.016 |
<0.01 |
<0.01 |
|
14 days withdrawal |
14 |
<0.01 |
0.01 |
<0.01 |
0.020 |
0.016 |
<0.01 |
Poultry (Tables 36 and 37). Groups often domestic hens were fed teflubenzuron at levels of 0.5 or 1.5 ppm and a group of 30 at 5 ppm in the diet for 28 days by Cameron and Puglis (1989b). An 18-day acclimatization period was followed by a 28-day treatment period and 7- and 14-day withdrawal periods (two groups of birds treated with 5 ppm). Eggs were collected for analysis. On day 28 ten hens from each group were slaughtered and the remaining hens in the highest dose group placed on a residue-free diet and slaughtered 7 or 14 days later. Samples of eggs and tissues were analysed for teflubenzuron and liver samples also for the metabolite 1-(3,5-dichloro-2,4-difluorophenyl)-3-(2,6-difluoro-3-hydroxybenzoyl)urea (E-115).
Table 36 shows the results of the analyses of eggs. Residues of teflubenzuron were detected in all treated groups and a dose-related trend was observed. Residues above the LOD (0.01 mg/kg) were first measured at day 14 in the 0.5 and 1.5 ppm groups and at day 3 in the high-dose group. Residues in the highest dose group declined during the withdrawal period and were below the LOD after 42 days.
Table 36. Residues of teflubenzuron in eggs (Cameron and Puglis, 1989b).
|
Day |
Teflubenzuron, mg/kg |
|||
|
Dose group A (control) |
Dose group B (0.5 ppm) |
Dose group C (1.5 ppm) |
Dose group D (5 ppm) |
|
|
-1 |
<0.01 |
<0.01 |
<0.01 |
<0.01 |
|
3 |
|
|
|
0.03 |
|
5 |
- |
- |
- |
0.11 |
|
7 |
<0.01 |
<0.01 |
<0.01 |
0.14 |
|
10 |
- |
- |
- |
0.16 |
|
14 |
<0.01 |
0.04 |
0.06 |
0.28 |
|
17 |
- |
- |
- |
0.29 |
|
21 |
<0.01 |
0.03 |
0.08 |
0.20 |
|
24 |
- |
- |
- |
0.29 |
|
26 |
- |
- |
- |
0.30 |
|
28 |
<0.01 |
0.03 |
0.08 |
0.22 |
|
30 |
- |
- |
- |
0.17 |
|
35 |
- |
- |
- |
0.08 |
|
42 |
- |
- |
- |
<0.01 |
The results of the tissue analyses are given in Table 37. Teflubenzuron was found in all types of tissue analysed, at levels which increased with the dose. The highest concentrations occurred in abdominal fat (0.7 mg/kg in the highest dose group).
The results indicated that residues of teflubenzuron in the liver persisted after 7 or 14 days withdrawal, although it should be noted that high residues were found in the livers of control birds as well. In other tissues residues of teflubenzuron declined when treatment was stopped. Residues of the metabolite E-115 in liver samples were below the LOD (0.05 mg/kg).
Table 37. Residues in hens dosed with teflubenzuron (Cameron and Puglis, 1989b).
|
Group |
Teflubenzuron, mg/kg, mean |
||||
|
Kidney |
Liver |
Muscle |
Abdominal fat |
Subcutaneous fat (skin + underlying fat) |
|
|
A (control) |
- |
0.37 |
<0.01 |
<0.01 |
<0.01 |
|
B (0.5 ppm) |
0.015 |
0.041 |
<0.01 |
0.077 |
0.028 |
|
C (1.5 ppm) |
0.016 |
0.043 |
0.014 |
0.23 |
0.081 |
|
D (5 ppm) |
0.036 |
0.081 |
0.038 |
0.70 |
0.32 |
|
7 days withdrawal |
<0.01 |
0.086 |
<0.01 |
0.016 |
<0.01 |
|
14 days withdrawal |
0.014 |
0.092 |
<0.01 |
<0.01 |
<0.01 |
