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

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Table 3. Cholinesterase activity in rats given azinphos-methyl by gavage for 13 weeks
Cholinesterase
Cholinesterase activity (% inhibition relative to control values)
Dose (mg/kg bw per day)
0.22 0.86 3.44
Males Females Males Females Males Females
Plasma butyryl cholinesterase 18*** 3 16** 10 30*** 47***
Plasma acetyl cholinesterase 18** −3 14* 7 42*** 49***
Erythrocyte acetylcholinesterase 8* 9*** 17*** 29*** 77*** 78***
Brain cholinesterase 3 4 9* 3 67*** 64***
From Broadmeadow et al. (1987)
* p < 0.05; ** p < 0.01; *** p < 0.001.
Table 4. Cholinesterase activity in dogs a fed diets containing azinphos-methyl for 52 weeks
Cholinesterase
Cholinesterase activity (% inhibition relative to control values)
Dietary concentration (ppm)
0 5 25 125
Males Females Males Females Males Females Males Females
Plasma cholinesterase
Week 4 0 0 11 −18 12 14 37 52*
Week 13 0 0 13 −2 15 17 53** 58**
Week 26 0 0 14 −10 12 33 58** 57**
Week 52 0 0 11 12 12 30 53* 53**
Erythrocyte acetylcholinesterase
Week 4 0 0 −9 11 22 2 66** 86**
Week 13 0 0 8 16 40** 43** 87** 92**
Week 26 0 0 8 21 32 38** 88** 91**
Week 52 0 0 −5 15 27 35* 86** 86**
Brain cholinesterase 0 0 1 1 10 1 27** 20*
From Allen et al. (1990), Annex 1, reference 64, modified with reference to the original data.
a
n = 4
* p < 0.05; ** p < 0.01.
B6C3F 1
mice were fed diets containing azinphos-methyl. Groups of 50 male and 50 female Osborne-
Mendel rats were given diets containing azinphos-methyl for 80 weeks, and were then observed for 34
or 35 weeks. Males received azinphos-methyl at a time-weighted average dietary concentration of 78
or 156 ppm (equivalent to 6.25 and 12.5 mg/kg bw per day respectively), while females received 62.5
or 125 ppm (equivalent to 3.12 and 6.25 mg/kg bw per day respectively). Matched controls consisted
of 10 male and 10 female untreated rats; pooled controls consisted of matched controls combined
with 95 male and 95 female untreated rats from similar bioassays of 10 other chemicals. The study
in mice was of similar design; groups of 50 mice were treated for 80 weeks, then observed for 12 or
13 weeks, males received azinphos-methyl at a dietary concentration of 31.3 or 62.5 ppm (equivalent
to 4.7 and 9.4 mg/kg bw per day respectively) and females received 62.5 or 125 ppm (equivalent
to 9.4 and 18.75 mg/kg bw per day respectively), matched controls consisted of 10 males and 10
females, pooled controls comprised 130 males and 120 females. Typical signs of organophosphate
intoxication (hyperactivity, tremors and dyspnoea) were observed in a few animals of both species
AZINPHOS-METHYL 139–172 JMPR 2007