ethametsulfuron-methyl (ISO); methyl 2-[(4-ethoxy-6-methylamino-1,3,5-triazin-2-yl)carbamoylsulfamoyl]benzoate

Acute Toxicity: oral

Administrative data

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

test procedure in accordance with national standard methods

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1991

Report date:

1991

Materials and methods

Principles of method if other than guideline:

The purpose of this study was to determine if the LD50 of the test substance exceeded 5000 mg/kg. If all animals dosed at 5000 mg/kg survive the 15-day test period, the LD50 is assumed to be greater than 5000 mg/kg. In addition, clinical signs of abnormality and gross pathologic changes observed in the dosed animals were used in assessing the toxicity of the test material.

Single oral doses of the test material, as suspensions in Mazola® corn oil, were administered by intragastric intubation to a group of 5 male and 5 female rats at a dose rate of 5000 mg/kg of body weight. Rats were fasted approximately 24 hours prior to dosing, with food being returned to the animals approximately one hour after dosing. Individual dose volumes were calculated using fasted body weights obtained prior to dosing. Observations for mortality were made daily throughout the study. Rats were weighed and observed daily (weekends excluded) for clinical signs of toxicity. At study termination, 3 rats per sex were necropsied.

GLP compliance:

yes

Test type:

fixed dose procedure

Test material

Test material information

Constituent 1

Reference substance name:

Reference substance 002

Cas Number:

97780-06-8

Test material form:

solid

Details on test material:

-Purity: 96.8%

Test animals

Species:

rat

Strain:

other: Crl:CD®(SD)BR

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Kingston, New York
- Females (if applicable) nulliparous and non-pregnant: No data are available on females
- Age at study initiation: Approximately 7 weeks old
- Weight at study initiation: Males: 214g Range: [207-219g] and Females: 166g [Range: 157-173g]
- Fasting period before study: 24 hours prior to dosing
- Housing: Rats were housed singly in suspended, stainless steel, wire-mesh cages
- Diet (e.g. ad libitum): Purina Certified Rodent Chow® #5002
- Water (e.g. ad libitum): No data are available on source of the water
- Acclimation period: Approximately one week

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 23° ± 2°C
- Humidity (%): 50% ± 10%
- Air changes (per hr): No data are available
- Photoperiod (hrs dark / hrs light): 12-hour light/12-hour dark cycle

Administration / exposure

Route of administration:

oral: gavage

Vehicle:

corn oil

Remarks:

Mazola®

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 300 mg/mL
- Amount of vehicle (if gavage): Males: 3.6 mL; Females: 2.8 mL
- Justification for choice of vehicle: Not provided
- Lot/batch no. (if required): Not provided
- Purity: Not provided

Doses:

5000 mg/kg

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: daily (weekends excluded)
- Necropsy of survivors performed: yes (3 rats per sex)
- Other examinations performed: clinical signs, body weights

Statistics:

No

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: no deaths at the highest dose tested

Mortality:

No deaths were recorded

Clinical signs:

other: There were no clinical signs of toxicity observed in any of the rats throughout the study.

Gross pathology:

Gross pathological examination of rats killed after a 14-day observation period revealed no specific organ toxicity.

Any other information on results incl. tables

Male rats (All weights are in grams)

 

Animal #	Initial weight	Fasted weight	Weight on Day 1	Weight on Day 4	Weight on Day 5	Weight on Day 6	Weight on Day 7	Weight on Day 8	Weight on Day 11	Weight on Day 12	Weight on Day 13	Weight on Day 14
398420	243	214	244	266	275	279	284	295	319	326	332	337
398421	240	211	231	258	260	269	276	284	323	318	323	333
398422	246	218	235	269	277	281	291	300	312	328	333	331
398423	238	207	229	261	265	268	276	283	308	323	327	327
398424	248	219	242	270	277	280	283	290	310	318	330	328

 

Female rats (All weights are in grams)

 

Animal #	Initial weight	Fasted weight	Weight on Day 1	Weight on Day 4	Weight on Day 5	Weight on Day 6	Weight on Day 7	Weight on Day 8	Weight on Day 11	Weight on Day 12	Weight on Day 13	Weight on Day 14
398571	185	164	181	200	209	205	207	213	227	228	225	220
398572	181	157	174	186	186	181	189	191	201	203	202	202
398573	188	166	188	197	205	206	207	207	218	217	218	215
398574	188	170	188	203	207	206	204	212	228	225	232	233
398575	196	173	191	212	205	216	222	226	241	244	240	236

 

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

LD50 (rats) > 5000 mg/kg

Executive summary:

The purpose of this study was to determine if the LD50 of the test substance exceeded 5000 mg/kg. If all animals dosed at 5000 mg/kg survive the 15-day test period, the LD50 is assumed to be greater than 5000 mg/kg. In addition, clinical signs of abnormality and gross pathologic changes observed in the dosed animals were used in assessing the toxicity of the test material.

There were no mortalities associated with the dose given. The LD50 for both male and female rats was greater than 5000 mg/kg of body weight, the highest dose tested. Other than sporadic, slight, weight losses (up to 3% of previously measured body weights) there were no clinical signs of toxicity observed in any of the rats throughout the study. Gross pathological examination of rats killed after a 14-day observation period revealed no specific organ toxicity.