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

455
Table 3. Residual radioactivity in organs and tissues of rats 48 h after dosing with 14 C-methylene
labelled thiacloprid
Organ/tissue
Residual radioactivity (μg/g equivalent)
1 mg/kg (iv) 1 mg/kg (gavage) 1 mg/kg (repeated
doses, gavage)
100 mg/kg (gavage)
Males Females Males Females Males Females Males Females
Erythrocytes 0.0029 0.0035 0.0030 0.0036 0.0027 0.0032 0.4118 9.572
Plasma 0.0031 0.0042 0.0032 0.0041 0.0030 0.0035 0.4265 11.97
Spleen 0.0040 0.0032 0.0032 0.0031 0.0033 0.0032 0.3510 8.395
Gastrointestinal tract 0.0209 0.0193 0.0086 0.0140 0.0127 0.0116 5.5612 215.5
Liver 0.0147 0.0148 0.0165 0.0140 0.0178 0.0171 2.0905 30.23
Kidney 0.0093 0.0173 0.0109 0.0160 0.0136 0.0195 1.4715 23.04
Fat 0.0019 0.0033 0.0020 0.0016 0.0015 0.0016 0.2810 6.747
Testes 0.0022 — 0.0020 — 0.0017 — 0.2796 —
Uterus — 0.0059 — 0.0029 — 0.0032 — 8.763
Muscle 0.0022 0.0022 0.0022 0.0025 0.0018 0.0020 0.2489 9.865
Bone 0.0024 0.0033 0.0022 0.0034 0.0026 0.0044 0.3112 5.223
Heart 0.0029 0.0031 0.0027 0.0034 0.0024 0.0031 0.4028 12.33
Lung 0.0057 0.0064 0.0065 0.0066 0.0047 0.0056 0.7116 13.15
Brain 0.0014 0.0019 0.0013 0.0018 0.0013 0.0018 0.1623 7.129
Skin 0.0041 0.0044 0.0060 0.0042 0.0032 0.0048 0.5190 10.07
Carcass 0.0025 0.0032 0.0035 0.0041 0.0022 0.0027 0.3095 10.47
From Klein & Bornatsch (1998)
iv, intravenous
[ 14 C-Methylene]thiacloprid was found to be rapidly and extensively absorbed in rats given a
dose at 1.0 mg/kg. No significant differences in the extent or route of excretion were noted between
dose groups or sexes, with the exception of females at the highest dose. Findings in this group were
consistent with delayed absorption or faecal excretion. The results suggested that thiacloprid at a dose
of 1 mg/kg bw is completely absorbed after oral administration in rats (Klein & Bornatsch, 1998).
In a study on the distribution of thiacloprid, male Wistar rats (one per time-point) were given
a single dose of [ 14 C-methylene]thiacloprid (in 0.5% tragacanth) at 5.0 mg/kg bw by gavage. An
additional rat was given a single intravenous dose at 1.0 mg/kg bw. The distribution of radioactivity
was investigated at 5 min (intravenous dose) and at 1, 4, 8, 24 and 48 h (gavage dose) by whole-body
autoradiography. Tissue concentrations of radioactivity were quantified using radioluminography.
Results indicated a rapid and even distribution of the radioactivity immediately (5 min) after
intravenous injection. At this time, the concentration in the blood was already lower than in many of
the organs, e.g. liver, kidney, muscle, preputial gland, adrenals, thyroid, salivary gland, and the walls
of the aorta.
Thiacloprid was readily absorbed from the gastrointestinal tract, since radioactivity was found
in all tissues and organs 1 h after oral administration. The general pattern of distribution observed
1 h after administering the parent compound was maintained throughout the investigation period
of 48 h. Four hours after dosing, the radioactivity content of the stomach was still high, but faecal
excretion had already commenced. The concentration of radioactivity in the kidney at 4 h and 8 h after
dosing was consistent with the high proportion and rate of the renal excretion of the radioactivity.
At later stages of the study, i.e. 24 h and 48 h after dosing, the most prominent feature, apart from
THIACLOPRID X-X JMPR 2006