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

490
Sciatic nerve; No. examined 50 50 49 48 49 48 50 50 49 50.0
Degeneration 24 28 26 37** 34* 20 18 19 28 36**
Eyes; No. examined 50 50 50 50 50 50 50 50 50 50
Retinal atrophy 17 21 19 19 25 15 20 24* 25* 32**
Lens degeneration 21 27 22 21 22 9 18 16 20** 30**
Pituitary gland 50 50 50 50 50 50 50 50 50 50
Cholesterol clefts 0 1 2 4* 4* 0 0 0 0 0
Ovaries; No. examined 50 49 50 48 50
Cyst/s 16 15 19 22 24
Mammary gland; No. examined 50 50 50 50 50 50 50 50 50 50
Lacteal cyst/s 1 3 4 1 1 18 15 10 12 6
Galactocele 0 0 0 0 0 3 3 4 2 0
Mesenteric lymph node; No. examined 50 50 48 49 50 49 50 49 50 48
Sinus histiocytosis 8 5 9 7 13 12 10 14 19 25**
Skeletal muscle; No. examined 50 50 50 50 50 50 50 50 50 50
Atrophy 19 19 16 20 25 6 3 5 14* 20**
Degeneration 9 14 16 14 14 9 5 10 10 18*
Mononuclear infiltration 5 5 7 1 7 0 1 2 2 4*
From Bomhard et al., (1998)
* p < 0.05; ** p < 0.01.
Retinal degeneration and degeneration of lens fibres were seen in the eyes of controls and dosed
animals. These age-related changes were significantly increased in females at 50 ppm (retinal atrophy)
or 500 ppm (degeneration of lens fibres) and greater. However, since the incidences for these findings
at 50 and 500 ppm were within the range for historical controls from studies conducted at the same
laboratory (range for retinal atrophy: males, 3–21 out of 50 animals; females, 12–29 out of 50 animals;
range for degeneration of lens fibres: males, 5–38 out of 50 animals; females, 6–23 out of 50 animals),
only the increased incidences at 1000 ppm in females were considered to be treatment-related.
In the thyroid, the incidence of hypertrophy of the follicular epithelium was significantly
increased in males at 50 ppm and greater and in females at 500 ppm and greater. Colloid alteration
(clumping, inhomogenous colloid) and pigment in the follicular epithelium were significantly
increased in both sexes at 500 ppm and greater. In males, there was an increase of follicular cell
hyperplasias (Table 25) and a significant increase in thyroid follicular cell adenomas at 500 and
1000 ppm (Table 26), while in females, hyperplasias were significantly increased at 1000 ppm.
These effects on the thyroid were considered to be secondary effects of enzyme induction on
the liver, especially of UDP-GT, which leads to increased degradation and biliary excretion of
circulating thyroid hormones. The resulting thyroid hyperactivity was documented by the increased
concentrations of TSH in males at 500 ppm and greater and in females at 1000 ppm.
Table 26. Neoplastic findings in a long-term study in rats fed diets containing thiacloprid
Finding
Dietary concentration (ppm)
Males
Females
0 25 50 500 1000 0 25 50 500 1000
Thyroid; No. examined 50 50 50 50 49 50 50 50 50 48
C-cell adenoma (b) 10 4 — 8 9 7 6 7 5 3
Follicular cell adenoma (b) — — 1 5* 8** — 1 1 1 2
C-cell carcinoma (m) — — — 1 — — — — — —
THIACLOPRID X-X JMPR 2006