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

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weights of males were approximately 84% of the control value and of females were approximately
86% of the control value. During the recovery period, the body weights of the rats at 1600 ppm were
lower than control values, but the difference diminished with time. Feed intakes were not affected
by treatment, but water intake was reduced in males at 1600 ppm. No treatment-related ophthalmic
findings were seen during this study.
The haematological examinations did not give evidence of adverse effects on erythrocytes
or leukocytes. In females only, the clotting time was shortened after 1600 ppm. Clinical chemistry
revealed a higher protein and an increased cholesterol concentration in males and females at ≥ 400 ppm.
At 400 ppm, T3 concentrations were increased in males at week 3, but not at the end of the study at
100 and 400 ppm. At 1600 ppm, T3 concentrations and thyroid binding index (TBI) were increased in
week 3 and 12 of the study. Induction of liver enzymes was detected at 400 ppm (cytochrome P450,
N-DEM, O-DEM) and was more pronounced at 1600 ppm in both sexes (cytochrome P450, N-DEM,
O-DEM, ECOD, ALD, EROD) (Table 16).
Thiacloprid had no effect on cell counts, or cell size distribution of spleen and lymph node cells.
A slightly increased macrophage activation and increase of lipopolysaccharide (LPS) stimulated cells
in the spleen was observed at 1600 ppm. No treatment-related changes of antibody titres for IgA,
IgG and IgM were detected. Tests for a thiacloprid-mediated effect on cell proliferation in liver and
kidney cells did not reveal evidence for a specific effect.
Relative liver weights were increased at 400 ppm in males and at 1600 ppm in both sexes. Thyroid
weights were increased in males at the highest dose. Histopathologically, moderate hepatocellular
hypertrophy, associated with a change of perinuclear cytoplasm (the cytoplasm exhibited a fine
granular to vesicular structure), probably due to enzyme induction, was seen at 400 ppm and greater.
At the end of the recovery period, only 3 out of 10 males had minimal hepatocellular hypertrophy, but
cytoplasmic changes were no longer found (Table 16).
Table 16. Main findings of the 13-week study in rats fed diets containing thiacloprid
Finding
Dietary concentration (ppm)
Males
Females
0 25 100 400 1600 0 25 100 400 1600
Body weight (g):
Week 12 419 395 413 408 351** 220 228 236 209 190**
Week 17r 445 — — — 433 265 — — — 221**
Cholesterol (mmol/l):
Week 3 2.47 2.48 2.49 2.77 3.37** 2.37 2.38 2.46 2.73** 3.71**
Week 12 2.38 2.29 2.49 2.65 3.25** 1.88 1.95 1.92 2.17** 3.45**
Week 17r 2.55 — — — 2.12** 2.50 — — — 2.18
Protein (g/l):
Week 3 62.3 63.2 63.5 65.0* 65.5** 63.1 63.3 65.8* 66.1* 65.6*
Week 12 68.7 70.5 71.0 72.5** 76.5** 66.4 67.4 67.0 69.2 71.3**
Week 17r 72.4 — — — 72.5 71.0 — — — 68.9
T3 (nmol/l):
Week 3 1.59 1.81** 1.87** 1.94** 2.26** 1.70 1.78 1.87 1.86 1.90
Week 12 1.62 1.61 1.58 1.71 2.11** 1.69 1.60 1.70 1.75 1.96
Week 17r 1.58 — — — 1.57 1.60 — — — 1.63
T4 (nmol/l), week 3
Week 3 67 67 71 77** 75* 48 60 65* 57 48
THIACLOPRID X-X JMPR 2006