Pesticide residues in food — 2006: Toxicological ... - ipcs inchem

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Haematological investigations did not reveal any remarkable differences between control and
test animals.
The clinical chemical investigations revealed a slight decrease in T4 concentrations in the males
at 1000 ppm in the 26-week, but not in the 52-week study (Table 20). Thyroxin-binding capacity and T3
concentrations were not altered. Thiacloprid did not cause an induction of microsomal liver enzymes
after 52 weeks. Urine analysis did not reveal any changes between control and treated animals.
Table 20. Relevant findings in dogs fed diets containing thiacloprid in the main study (52 weeks)
and the satellite study (26 weeks)
Finding
Dietary concentration (ppm)
Males
Females
0 40 100 250 1000 0 40 100 250 1000
Main study (52-weeks)
Body weight (kg), week 52 11.78 11.13 10.88 10.83 11.65 10.68 11.28 11.90 11.80 11.13
Body-weight gain (kg), weeks 1–52 3.00 2.33 2.00 1.98 2.25 2.38 2.83 3.55 3.27 2.40
T3 (nmol/l), week 26 1.92 1.93 1.83 1.79 1.79 1.86 1.95 1.91 1.77 1.72
T3 (nmol/l), week 52 1.61 1.55 1.58 1.57 1.72 1.47 1.55 1.65 1.47 1.71
T4 (nmol/l), week 26 23 21 21 19 15 23 23 22 20 20
T4 (nmol/l), week 52 15 17 17 20 14 18 21 22 21 20
Liver weight (g) 456.0 437.0 435.0 449.8 433.3 402.0 414.3 406.8 456.5 388.3
Relative liver weight (g/kg) 39.28 38.90 40.63 42.13 38.05 37.35 36.93 34.25 39.18 35.88
Prostate weight (g) 9.25 12.18 8.65 11.40 16.13 — — — — —
Relative prostate weight (g/kg) 0.795 1.063 0.808 1.048 1.333 — — — — —
Kidney/pigment, grade 1 2 3 2 3 1 2 2 2 2 0
Grade 2 2 1 2 0 1 2 2 2 1 0
Grade 3 0 0 0 1 2 0 0 0 1 4
Average grade 1.5 1.3 1.5 1.5 2.3 1.5 1.5 1.5 1.8 3.0
Satellite study (26-weeks)
T3 (nmol/l), week 26 1.77 — 1.71 — 1.82 — — — — —
T4 (nmol/l), week 26 23 — 19 — 16 — — — — —
Liver weight (g) 389.3 — 387.7 — 405.7 — — — — —
Relative liver weight (g/kg) 35.63 — 35.57 — 37.70 — — — — —
Prostate weight (g) 9.23 — 8.73 — 10.27 — — — — —
Relative prostate weight (g/kg) 0.800 — 0.803 — 0.957 — — — — —
From Wetzig & Geiss (1998)
Historical controls for absolute and relative prostate weights:
26 weeks (137 dogs): absolute weight (g) = 4.1 ± 2.15; relative weight (g/kg) = 0.380 ± 0.190
52 weeks (108 dogs): absolute weight (g) = 8.6 ± 3.44; relative weight (g/kg) = 0.735 ± 0.290
An increase in liver weights was observed in male dogs at the highest dose after the 26-week
treatment period but not after 52 weeks. Histopathology revealed hepatocellular cytoplasmic change
in all male dogs after 26 weeks but not after 52 weeks, indicating an adaptive response to xenobiotic
exposure that is later compensated for. In the kidneys, the severity of pigment (lipofuscin) deposition
in the proximal tubules was increased after 52 weeks at 1000 ppm. At interim necropsy after 26 weeks,
prostatic weights and sizes in the groups at 100 and 1000 ppm were not different from those of the
controls. After 52 weeks of treatment, mean prostatic weights (absolute and relative) and sizes in the
group of male animals at the highest dose were slightly increased compared with control values and with
THIACLOPRID X-X JMPR 2006