Sethoxydim Risk Assessment

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Appendix 1: Toxicity of Sethoxydim (NP-55) and Poast to experimental mammals [94-99% a.i. unless 
otherwise specified]. 
Animal 
Dose/Exposure 
Response  
Reference 
ORAL -acute 
Rats, Fischer 344, 
single gavage dose of 
LD
50
 = 3500 mg/kg (95% cl 3125-3920 mg/kg) 
Bio-Medical 
6 weeks old, males 
0, 2182, 2836, 3687, 
(males) 
Research 
(avg wgt 108.6 g) 
4793, 6231, or 8100 
LD
50
 = 3200 mg/kg (95% cl 2857-3584 mg/kg) 
Laboratories 
and females (avg 
mg/kg NP-55 
(females) 
Co, Ltd 
wgt 90.2 g), 
suspended in 0.5 % 
1980 
10/sex/dose group 
solution of CMC in 
Mortality observed at 2836 mg/kg; all animals 
EPA/OTS 
distilled water w/0.2% 
died at >4793 mg/kg. 
88-9200030 
Tween 80; 14-day 
22 
observation period. 
Reportable effects included tremors and 
convulsions in non-moribund rats, incontinence 
at 24-72 hours, and dose related depression. 
Additional notes on Bio-Medical Research Laboratories Co, Ltd 1980: Study includes acute oral, 
intravenous, subcutaneous, and dermal toxicity data in rats.  Several detailed data tables provided. 
Rats, SD-SLC, 6 
Single gavage dose of 
LD
50
 = 3125 mg/kg (95% cl 2957-3341 mg/kg) 
Bio-Medical 
weeks old, males 
2083, 2500, 2739, 300, 
(males) 
Research 
(avg bw 106 g) 
3286, or 3600 mg/kg 
LD
50
 = 2676 mg/kg (95% cl 2391-2919 mg/kg) 
Laboratories 
and females (avg 
NP-55 in males 
(females) 
Co, Ltd 
bw 133g), 
1980 
10/sex/dose group. 
Single gavage dose of 
Dose-dependent signs of neurotoxicity included 
EPA/OTS 
2200, 2569, 3000, 
tremor, ataxia, and sedation.  
88-9200030 
Used 94-99% a.i.  
3503, 4091, or 4777 
22 
mg/kg NP-55 in 
Gross pathological findings included some dark 
females 
reddish lungs and hemorrhages on the mucosa 
Also cited 
of the stomach; no abnormal changes were 
in Bryce­
14-day observation 
observed in rats that survived until termination 
land et al. 
period. 
of the study. 
1997 
Additional notes on Bio-Medical Research Laboratories Co, Ltd 1980: This acute toxicity study in rats is 
appended to the other acute toxicity studies in rats performed at this laboratory. 
Rats, 
single gavage dose of 
LD
50
 = 
.
5000 mg Poast/kg (males) 
Bio-Medical 
Sprague-Dawley, 
21.5, 46.4, 100, 215, 
LD
50
 = 
.
4390 mg Poast/kg (females) 
Research 
males and females, 
1000, 3160, 3830, 
LD
50
 = 
.
4920 mg Poast/kg (males and females) 
Laboratories 
5/sex/dose group 
4640, 5000, 6810 
[900, 790, and 855.6 mg/kg as a.i.] 
Co Ltd. 
mg/kg BAS 9052 OH 
Possible signs of neurotoxicity included 
1979 
(
Poast
, 18% a.i.); 
staggering and spastic gait; however, effects 
EPA/OTS 
14-day observation 
could be transient.  Report does not indicate 
88-9200030 
period 
how long the effects persisted or the number of 
89 
animals affected. 
Additional notes on Bio-Medical Research Laboratories Co Ltd.  1979: This study appears to be cited by 
Bryceland et al. 1997 as MRID 46326. 
Appendix 1 - 1 

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