Sethoxydim Risk Assessment

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 (continued) 
Rats, SD, 6-weeks 
old, 10 males/dose 
group 
single oral dose of 
2596, 2960, 3375, 
3847, or 4386 mg/kg 
M1-S0 or 4167, 4564, 
5000, 5477, or 6000 
mg/kg M2-S0 by 
gavage (vehicle = 
Tween 80) 
These compounds are 
the main metabolites of 
NP-55 
LD
50
 = 3080 (2953-3175) mg/kg M1-S0 
LD
50
 = 5573 (4942 -7435) mg/kg M2-S0 
behavioral effects of M1-S0 included sedation, 
ataxia, lacrimation, salivation, incontinence of 
urine, decreased body temperature, and ptosis; 
behavioral effects of M2-S0 included sedation, 
hypotonia, ventral position, convulsion, tremor, 
ataxia, incontinence of urine, lacrimation, 
salivation, ptosis, decreased body temperature, 
and hematuria. 
Nishibe et 
al.  1980 
MRID 
00124804 
Gross pathological changes in dead rats 
exposed to M2-S0 included hemorrhages on the 
mucosa of the intestine; survivors appeared 
normal at the time of sacrifice. 
Rats, SD-SLC, 6 
weeks old, 5 males 
single gavage dose of 
5000 mg/kg MU-1 
suspended in distilled 
water with small 
amount of Tween 80 
LD
50
 >5000 mg/kg 
No behavioral effects; no gross pathological 
changes. 
Nishibe et 
al.  1981 
MRID 
00124805 
by; 14-day observation 
period 
Rats, S1c:SD, 
young adult males, 
mean body wgt = 
171± 7 g,  5 
rats/dose group 
single gavage doses of 
1000, 3000, or 5000 
mg/kg Me-MSO 
dissolved in distilled 
water; observation 
period of 14 days 
LD
50
 >5000 mg/kg 
Adverse effects included urine incontinence in 
one rat at 5000 mg/kg on the first day after 
dosing, a decrease in body weight of rats at 
5000 mg/kg for 2 days after dosing with full 
recovery by day 7, and death in one rat at 5000 
mg/kg on day 3. 
Nishibe et 
al.  1984a 
MRID 
00153603 
No gross pathological changes were observed in 
any rats. 
Rat, NOS 
LD
50
 = 2676-3125 mg/kg 
BASF 1982 
MRID 
00100536 
Mouse, NOS 
LD
50
 = 5600-6500 mg/kg 
BASF 1982 
MRID 
00100536 
Appendix 1 - 2 

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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 (continued) 
Mice, ICR, 6 
weeks old, males 
and females, 
10/sex/ dose group 
single gavage dose of 
0, 2836, 3687, 4793, 
6231, or 8100 mg/kg 
NP-55 suspended in 
0.5 % solution of CMC 
in distilled water 
w/0.2% Tween 80; 
14-day observation 
period. 
100% mortality at high dose 
LD
50
 = 5600 mg/kg (95% cl 5045-6216 mg/kg) 
(males) 
LD
50
 = 6300 mg/kg (95% cl 5294-7497 mg/kg) 
(females) 
Reportable effects include dose-related ataxia, 
loss of spontaneous movement and depression. 
These effects were transient in survivors. Signs 
of neurotoxicity included ataxa, convulsions, 
and hyporeflexia. 
At autopsy, common findings in lethal cases 
included hyperemia of the lungs and fading 
discoloration of the spleen and kidneys; atrophy 
of the spleen  in 1 male at 3687 mg/kg and 1 
male at 8100 mg/kg; and hyperemia of the 
small intestine in  1 male and 1 female at 6231 
mg/kg and in 2 male and 3 females at 8100 
mg/kg; no particular changes were observed in 
survivors. 
Bio-Medical 
Research 
Laboratories 
Co, Ltd 
1979 
EPA/OTS 
88-9200029 
76 
Additional notes on Bio-Medical Research Laboratories Co, Ltd 1979:  Study includes acute oral, 
intravenous, subcutaneous, and dermal toxicity data in mice.  Several detailed data tables provided. 
Appendix 1 - 3 

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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 (continued) 
Dog, beagle, 3 
single dose in gelatin 
LD
50 
.
5000 mg/kg (males) 
Nisso Inst. 
years old, males 
capsule of 0, 1250, 
LD
50
 = 2500-5000 mg/kg (females) 
1980a 
(bw = 9.5-14.8 kg) 
2500, or 5000 mg/kg 
Mortality (occurred on day 1 or 2 post dosing): 
and females (bw = 
NP-55; 14-day 
males - 0% (1250), 0% (2500), 50% (5000) 
EPA/OTS 
9.6-14.0 kg), 
observation period 
females - 0% (1250), 0% (2500), 66.7% (5000) 
288-920003 
2-3/sex/dose group 
026 
Ataxia, convulsions, and tremors lasting more 
than 24 hours were observed at 2500 and 5000 
mg/kg in both sexes. 
Pathology revealed dark reddish lungs and 
hemorrhages in stomach or intestine of dead 
dogs. 
ORAL-developmental 
Rats, 
daily gavage doses of 
No mortality, 100% pregnancy rates, no 
Ponnock 
Sprague-Dawley, 
0, 350, 450, 550, or 
maternal toxicity at dose levels up to 350 
1992 
mated females 
650 mg/kg/day 
mg/kg/day; decreased body weight gain at 450, 
MRID 
(mean wgt of 
sethoxydim suspension 
550, and 650 mg/kg/day; fetal body weights 
42627901 
224.6 g), 5/dose 
in a 1% 
decreased in 650 mg/kg/day group. Incidence of 
group 
carboxymethyl-cellulos 
fetuses with malformations comparable to 
e sodium salt vehicle 
historical control data. 
on days 6-15 of 
gestation 
Cause of excessive salivation in all treated rats 
was declared unknown. 
ORAL -reproduction/teratology 
Rats, Charles 
0, 40, 120, 360, or 
No effects on behavior, appearance, survival, 
IRDC 
River, weanling, 
1080 NP-55 ppm in the 
body weights, or food consumption in parental 
1980b 
12 males and 24 
diet for 23 weeks 
rats at any dose level; no changes in male or 
females/dose group 
female fertility indices, pup survival, or pup 
MRID 
body weights, compared with controls. 
00045867 
Cited as 
BASF 
(1980a) in 
IRIS 
Notes on IRDC 1980b: This is an INTERIM study.  The high dose level was increased to 2160 after 5 weeks 
and to 3420 after 4 more weeks, due to the lack of toxicological effects.  This 14-page fiche includes several 
tables of raw data. 
Appendix 1 - 4 

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