Pesticide residues in food — 2007: Toxicological ... - ipcs inchem

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Figure 1. Chemical structures of the two pairs of enantiomeric pairs of isomers comprising
lambda-cyhalothrin
From IPCS (1990)
Recovery of radioactivity was 81–91%. Approximately 30–40% and 40–60% of the orally
administered 14 C-benzyl-labelled material was recovered in urine and faeces respectively. No 14 CO 2
was detected in expired air. The proportions absorbed and the rate of excretion were similar at both
doses, although excretion in faeces tended to be slower at the higher dose. Peak blood concentrations
(approximately 0.6 and 6 µg/kg of cyhalothrin equivalents at 1 and 25 mg/kg bw, respectively) were
reached 7 h after dosing. By 48 h, the blood concentrations had depleted to less than 10% of the
peak value. In bile-duct cannulated rats, biliary excretion accounted for 4.8% of the total excretion
in males and 8.9% in females. The extent of absorption in rats equipped with a biliary fistula was
less than in intact rats, however absorption was increased in rats (four males) given replacement bile,
indicating that cyhalothrin is absorbed along with the fats of the oil formulation. In the males treated
with replacement bile, biliary excretion was 11.2%.
At the lower dose, 70% of the administered material was recovered within 24 h, and only 2–3%
of the administered radiolabel remained in the carcass after 7 days. At this time-point, the radiolabel
was distributed mainly in fat (11.5 µg/g at a dose of 25 mg/kg bw).
Elimination of radiolabel was slower after subcutaneous administration of 14 C-benzyl-labelled
cyhalothrin than after oral dosing; 58% of the radiolabel was still present in the carcass 7 days after
dosing. This was attributed to retention of the oil formulation in subcutaneous fat.
LAMBDA-CYHALOTHRIN 173–200 JMPR 2007