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

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The histopathological investigations of the nervous system and skeletal musculature revealed
evidence of substance-related damage in males and females at 500 ppm and greater. The following
findings were made: an increased incidence of cholesterol clefts in the nerve roots of the spinal
cord (females at 1000 ppm), of radiculoneuropathy (females at 500 and 1000 ppm), of sciatic nerve
degeneration (both sexes at 500 and 1000 ppm), skeletal muscle atrophy (in females at 500 and
1000 ppm) and degeneration as well as mononuclear infiltrates in the sciatic nerve (in females at
1000 ppm). All these findings are known to occur spontaneously in old rats and are termed spinal
radiculoneuropathy or degenerative myelopathy and may be exacerbated by xenobiotics (Greaves,
1990). An increased incidence of cholesterol clefts was seen in the space between the anterior pituitary
and the pars intermedia in males at 500 or 1000 ppm. In the mesenteric lymph nodes, there was a
significant increase in the incidence of sinus histiocytosis in females at 1000 ppm (Table 25).
Table 25. Relevant non-neoplastic findings in a long-term study in rats fed diets containing
t hiacloprid
Finding
Dietary concentration (ppm)
Males
Females
0 25 50 500 1000 0 25 50 500 1000
Interim sacrifi ce
Liver weight (g), week 52 18.5 17.4 17.1 19.4 19.3 9.0 10.1 9.7 9.5 9.5
Relative liver weight (g/100g), week 52 3.5 3.3 3.3 3.6 3.8 3.3 3.2 3.3 3.5 3.8**
Liver; No. examined 10 10 10 10 10 10 10 10 10 10
Hepatocellular hypertrophy 0 0 0 5 9 0 0 0 5 8
Focal fat infiltration 0 0 0 5 7 0 1 2 0 0
Thyroid; No. examined 10 10 10 10 10 10 10 10 10 10
Hypertrophy 1 1 1 7 8 0 0 0 0 4
Colloid clumping 3 5 3 10 10 1 1 1 1 8
Terminal sacrifi ce
Liver weight (g) 16.9 17.1 16.7 17.4 20.2** 12.0 11.5 10.9 11.0 12.0
Relative. weight (g/100g) 3.4 3.3 3.2 3.6 4.4** 3.9 3.5 3.6 3.9 4.5**
Liver; No. examined 50 50 50 50 50 50 50 50 50 50
Biliary cyst/s 3 3 0 5 3 6 3 3 10 9
Cytoplasmic change 0 0 8** 41** 47** 0 1 0 30** 34**
Centrilobular hypertrophy 0 0 12** 44** 49** 0 1 0 30** 36**
Mixed eosinophilic clear-cell foci 1 2 5* 15** 22** 2 1 3 6 10**
Basophilic foci 16 9 9 6 7 19 19 19 6 2
Clear cell foci 33 34 33 36 33 15 14 15 7 4
Necrosis 7 4 1 2 2 9 3 6 12 15
Vacuolation 8 14 8 12 24** 6 7 4 3 4
Thyroid; No. examined 50 50 50 50 49 50 50 50 50 48
Follicular cell hyperplasia 1 2 2 6 3 0 0 1 1 3*
Follicular epithelium hypertrophy 12 10 22* 27** 34** 6 2 6 16** 23**
Colloid alteration 17 16 21 37** 41** 6 2 5 17** 28**
Pigment 16 11 23 30** 32** 0 0 2 4* 4*
Spinal cord; No. examined 50 50 50 50 50 50 50 50 50 50
Radiculoneuropathy 33 35 43 39 33 31 32 32 37 39*
Cholesterol clefts 9 11 8 14 11 3 4 8 4 13**
THIACLOPRID X-X JMPR 2006