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

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Thyroid weight (mg):
Week 12 6 8 9 9 10* 7 8 6 7 8
Week 17r 8 — — — 10 8 — — — 8
Thyroid weight, relative
(mg/100 g bw)
Week 12 1 2 2* 2 3** 3 3 2 3 4
Week 17r 2 — — — 2 3 — — — 4
Liver cell hypertrophy:
Week 12 0 0 0 9 10 0 0 0 2 10
Week 17r 0 — — — 3 0 — — — 0
Liver cell cytoplasmic
change, week 12
0 0 0 9 10 0 0 0 2 10
From Kroetlinger & Geiss (1997)
* p < 0.05; ** p < 0.01.
ALD, aldrin epoxidase; ECOD, 7-ethoxycoumarin deethylase; EH, epoxide hydrolase; EROD, 7-ethoxyresorufin
d eethylase; GST, glutathione-S-transferase; N-DEM, N-demethylase; O-DEM, O-demethylase; r, recovery group; T3,
triiodothyronine TBI, thyroid binding index; UDP-GT, uridine diphosphate glucuronosyl transferase.
The NOAEL was established at 400 ppm (equal to 28.6 and 35.6 mg/kg bw in males and
females, respectively) on the basis of reduced body weight, clinical chemistry changes (increased
cholesterol and protein concentrations in plasma) and thyroid effects (increased weight) at 1600 ppm,
the highest dose tested (Kroetlinger & Geiss, 1997).
In a pilot study on inhalation toxicity, groups of 10 male and 10 female Wistar (Hsd Win:WU)
rats were exposed (nose only) to aerosolized thiacloprid (purity, 97.2%) at analytical concentrations
of 0, 1.97, 19 or 205 mg/m³ air under dynamic conditions for 6 h per day on five consecutive days.
The exposure period was followed by a recovery period of 3 days (interim sacrifice, 50% of the
animals) or 2 weeks (terminal sacrifice). The MMADs (GSDs) of the particles were 3.3 μm (2.3),
2.9 μm (2.1) or 3.3 μm (1.8) at 1.97, 19 or 205 mg/m³ air, respectively. Between 44–55% of aerosol
mass was less than 3 μm.
Clinical observations, body weight and feed intake were recorded at suitable time-points.
Reflexes and the rectal temperatures were evaluated during the course of the study. Fifty per cent of
the animals were sacrificed on the third post-exposure day. The remaining animals were sacrificed
at the end of the 2-week observation period after exposure. All the animals received a macroscopic
examination at necropsy. The following organs were removed and weighed: brain, kidneys, liver,
thymus, thyroid, heart, lung, and spleen. Liver samples were taken for enzyme determinations.
At each sacrifice, blood was sampled for basic haematological and biochemical determinations.
Histopathology was not performed in this study.
No deaths occurred during the study. Clinical signs were observed at the highest dose and
included ungroomed pelt, piloerection, reduced motility, tremor, bradypnea, laboured breathing
pattern, flaccid appearance, mydriasis and emaciation. Based on the respiratory effects, the report
concluded that the test aerosol had a minor potential to act as an upper respiratory tract irritant. All
animals showed normal reflexes. An increase in grip strength was observed in both males and females
at 19 mg/m³ and greater on day 4, but this finding was not confirmed by grip measurements made
3 days later. Rectal temperatures were significantly reduced at 205 mg/m³.
Significant reductions in body weight were observed in both sexes at 205 mg/m³ on day 4 (last
exposure day) and day 7 (third day after exposure). Thereafter, the body weights of the control
and treatment groups were similar. Feed intake was reduced in both sexes at 205 mg/m³ on day 4
(last exposure day).
THIACLOPRID X-X JMPR 2006