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

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and motor activity. In each study, five rats of each sex were killed on day 15 and brain, eyes, muscle,
nerves, spinal cord and spinal ganglia were analysed.
One male rat in each of the groups at 20 and 40 mg/kg bw of the additional study was found
dead on the day after dosing. Clinical signs were seen in male rats dosed at 20 and 40 mg/kg bw. The
signs (similar in both studies) developed between 3 to 8 h after dosing and resolved by 3 days after
dosing. The signs included abnormal/splayed gait, thrashing, prostration, vocalization, piloerection,
hunched posture, unkempt appearance, soiled/stained body areas and diarrhoea. The signs in females
were similar but lower in frequency. In addition to these signs there were also isolated cases of
twitching, tremors, abasia, hypersensitivity, pale eyes, soft faeces and thinning of the fur. During the
FOB conducted 5 h after dosing, gait abnormalities and clinical signs of increased reactivity were
seen in most male rats at 20 and 40 mg/kg bw. In females the signs were less frequent. In the groups
at 20 and 40 mg/kg bw there was an increase in very slight to slight sporadic fibre degeneration
in the sciatic nerve. The changes were more frequent in the proximal than in the distal part of the
nerve.
The NOAEL was 4 mg/kg bw on the basis of death, clinical signs, findings in the FOB and
degenerative changes to the sciatic nerve at doses of 20 mg/kg bw and higher (JECFA, 1996; Fokkema,
1994b).
Zeta-cypermethrin
5. Toxicological studies
5.1 Acute toxicity
(a)
Oral and dermal toxicity
The acute toxicity of zeta-cypermethrin is summarized in Table 10.
Clinical signs induced by zeta-cypermethrin were similar to those induced by cypermethrin,
i ncluding tremors, staggered gait, writhing, abnormal posture, squinting eyes, walking on toes,
splayed hindlimbs and clonic convulsions, mainly confined to the first 24 h after dosing (Freeman,
1999a; Freeman, 1999b)
Table 10. Studies of acute toxicity with zeta-cypermethrin
Species Sex Strain Route Vehicle Purity (%) LD 50
(mg/kg bw) Reference
Rat M SD Oral 5% in corn oil 88.2 134 Freeman (1989)
F
86
Rat M SD Oral 5% in corn oil 91.2 257 Freeman (1999a)
F
367
Rat M SD Oral 5% in corn oil 86.0 269 Freeman (1999b)
F
285
Rabbit M NZW Dermal Undiluted 88.2 > 2000 Freeman (1990b)
F
F, female; M, male; NZW, New Zealand White.
(b)
Dermal and ocular irritation
After the application of zeta-cypermethrin technical (0.5 ml; purity, 88.2%) to the intact skin
of New Zealand White rabbits (three of each sex) for 4 h under semi-occlusive dressings, erythema
CYPERMETHRINS X-X JMPR 2006