1-[2-(2-chloroethoxy)phenylsulfonyl]-3-(4-methoxy-6-methyl-1,3,5-triazin-2-yl)urea;triasulfuron (ISO)

Endpoint summary

Description of key information

-Oral: LD50> 5000 mg/kg bw, females, rats, according to OECD TG 425, Petus 2014

-Inhalation: LC50 > 5.22 mg/L , male and females, rats, according to OECD TG 403, Durando 2018

-Dermal: LD50 > 2000 mg/kg bw, males and females, rats, according to OECD TG 402, Petus 2013

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

26 Jun 2012 to 17 Jul 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 425 (Acute Oral Toxicity: Up-and-Down Procedure)

Version / remarks:

2008

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1100 (Acute Oral Toxicity)

Version / remarks:

2002

GLP compliance:

yes (incl. QA statement)

Test type:

up-and-down procedure

Limit test:

yes

Species:

rat

Strain:

Wistar

Remarks:

CRL:(WI)

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS:
-Females nulliparous and non-pregnant: yes
-Age/weight at dosing: Young adult rats, 9-10 weeks old / 217-229 g
-Housing: Individual caging
-Diet: complete diet for rats ad libitum
-Water: Tap water from municipal supply, provided in 500 mL bottles ad libitum
-Acclimatisation period: At least 5 days

ENVIRONMENTAL CONDITIONS:
-Temperature: 21.9 - 25°C
-Humidity: 38 – 70 %
-Air changes: 15-20 air exchanges/hour
-Photoperiod: 12 hours daily, from 6.00 a.m. to 6.00 p.m.

IN-LIFE DATES: from 26 June 2012 to 17 July 2012

Route of administration:

oral: gavage

Vehicle:

CMC (carboxymethyl cellulose)

Remarks:

1%

Details on oral exposure:

VEHICLE
- Amount of vehicle: 10 mL/kg bw

Doses:

5000 mg/kg bw

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: animals were observed individually after dosing at 30 minutes, then 1, 2, 3, 4, and 6 hours after dosing and once each day for 14 days thereafter
- Necropsy of survivors performed: All animals were euthanised at the end of the observation period by exsanguination under pentobarbital anaesthesia. After examination of the external appearance the cranial, thoracic and abdominal cavities were opened and the appearance of the tissues and organs were observed. All gross pathological changes were recorded for each animal on the post mortem record sheets. The body weight of animals found dead were recorded at necropsy.
- Clinical signs including body weight: Individual observations were performed on the skin and fur, eyes and mucous membranes and also respiratory, circulatory, autonomic and central nervous system, somatomotor activity and behaviour pattern were assessed.
Particular attention was directed to observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma.
The body weights were recorded on Days -1, 0 (beginning of the experiment), 7 and 14

Statistics:

Mean and Standard deviation was calculated for body weight and body weight gain. The LD50 was calculated using the AOT425StatPgm program.

Key result

Sex:

female

Dose descriptor:

LD50

Effect level:

> 5 000 mL/kg bw

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No deaths occurred during the study

Clinical signs:

other:

Body weight:

other body weight observations

Remarks:

There were no treatment related effects on body weight or body weight gain

Gross pathology:

No treatment related macroscopic observations were recorded

Interpretation of results:

GHS criteria not met

Conclusions:

The acute oral median lethal dose (LD50) of the test item was greater than 5000 mg/kg bw (limit dose) in female CRL:(WI) rats.

Executive summary:

In an OECD TG 425 acute oral toxicity study,performed under GLP, fasted female CRL:(WI) rats, 9-10 weeks old were given a single oral (gavage) dose of the test item, at dose levels of 5000 mg/kg. Single animals were dosed sequentially at no less than approximately 48 hour intervals. Animals were observed individually for up to 14 days thereafter and necropsies were performed on all surviving animals at the end of the study. No deaths occurred during the study.

Treatment with the test substance at the dose level of 5000 mg/kg bw caused vocalisation in one animal who was symptom free from 48 hours after treatment. The other two animals showed no clinical signs. There were no treatment related body weight changes. Body weights were within the range commonly recorded for this strain and age. No treatment related macroscopic observations were recorded in any animals dosed at 5000 mg/kg bw.

Under the conditions of this study, the acute oral median lethal dose (LD50) of the test item was found to be above 5000 mg/kg bw in male CRL:(WI) rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 5 000 mg/kg bw

Quality of whole database:

GLP compliant OECD TG 425 study.

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 April 2018 to 5 May 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

2009

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

1998

Qualifier:

according to guideline

Guideline:

other: JMAFF 12-Nousan-8147

Version / remarks:

2000

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Version / remarks:

2014

GLP compliance:

yes (incl. QA statement)

Test type:

traditional method

Limit test:

yes

Species:

rat

Strain:

other: Sprague-Dawley derived, albino

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Sex: 7 male and 7 female, nulliparous and non-pregnant
- Age at study initiation: Young adult (8-10 weeks)
- Weight at study initiation: males 284-344 grams and females 199-221 grams
- Housing: suspended stainless steel caging; enrichment was placed in each cage
- Diet: 16% Protein Rodent Diet. Ad libitum except during exposure
- Water: Filtered tap water. Ad libitum
- Acclimatisation period: 10 or 15 days

ENVIRONMENTAL CONDITIONS
- Temperature: 20-23 °C
- Humidity: 39-62%
- Air changes: 13/hour
- Photoperiod: 12-hour light/dark cycle

IN-LIFE DATES: From: 12 April 2018 to 5 May 2018

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

2.28 µm

Geometric standard deviation (GSD):

2.24

Details on inhalation exposure:

Exposure conditions: Prior to initiation of the full inhalation study, pre-test trials were conducted to establish generation procedures to achieve, to the extent possible, the desired chamber and desired particle size distribution (mass median aerodynamic diameter between 1 and 4 μm).

Generation of the test atmosphere/chamber description: A nose-only inhalation chamber was used for exposure. Animals were individually housed in polycarbonate holding tubes which seal to the chamber with an “O” ring during exposure. The base unit terminates the chamber with a 0.5-inch diameter tube for discharged air.

Air Supply: Filtered generator air was supplied to the spray atomization nozzle by an air compressor, and measured with a Mass Flow Controller. Additional filtered mixing air from the same air compressor, measured with a Mass Flow Controller, was introduced into the chamber to help uniformly distribute the test atmosphere by creating a vortex at the chamber inlet. Chamber airflow was monitored throughout the exposure period and recorded periodically. The exposure was conducted under slight negative pressure.

Ambient Conditions: The temperature and relative humidity within the exposure chamber as well as the room were monitored continuously during exposure, and were measured with a temperature-humidity monitor. Temperature and relative humidity values were recorded every 15 minutes for the first hour of exposure and approximately every 15 or 30 minutes thereafter.

Atmosphere Generation: The test substance was aerosolized using a modified Wright Dust Generator. The test substance was packed into the dust container and compressed 1000 lbs/in2 using a lab press. The container was then fitted with a cutting head. Compressed generator and mixing air were supplied to the dust generator. The aerosolized dust was then fed directly into the chamber through the dust outlet assembly.

Chamber Concentration Measurements: Gravimetric samples were withdrawn at 6 intervals from the breathing zone of the animals. Samples were collected using 37 mm glass fiber filters (Whatman™ GF/B) in a filter holder attached by ¼ inch Tygon® tubing to a vacuum pump. Filter papers were weighed before and after collection to determine the mass collected. This value was divided by the total volume of air sampled to determine the chamber concentration. Sample airflows were measured using a Mass Flow Controller.

Particle Size Distribution: An eight-stage 1 ACFM Andersen Ambient Particle Sizing Sampler was used to assess the particle size distribution of the test atmosphere. Samples were withdrawn from the breathing zone of the animals at two intervals. The filter paper collection stages were weighed before and after sampling to determine the mass collected upon each stage. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) were determined graphically using two-cycle logarithmic probit axes.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Remarks on duration:

The exposure period was extended beyond 4 hours to allow the chamber to reach equilibrium (T99).

Concentrations:

Target concentration: 5.0 mg/L;
Achieved particulate concentration: 5.21 ± 0.40 mg/L (sighting); 5.22 ± 0.26 mg/L (main)

No. of animals per sex per dose:

2 sighting test
5 main test

Control animals:

no

Details on study design:

-Selection of animals: On the day of and prior to each exposure, the rats were examined for health and weighed. Fourteen healthy, naive rats not previously tested were selected for exposure. Two males and two females were selected for the sighting test at 5.0 mg/L and five males and five females were selected for the main test at 5.0 mg/L.
- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: prior to exposure (initial) and again on Days 1, 3, 7, and 14 (terminal)
- Necropsy of survivors performed: yes, Tissues and organs of the thoracic and abdominal cavities were examined.
- Clinical signs: All animals were observed for mortality during the exposure period. The animals were examined for signs of gross toxicity, and behavioral changes upon removal from the exposure tube and at least once daily thereafter for 14 days. Observations included gross evaluation of skin and fur, eyes and mucous membranes, respiratory, circulatory, autonomic and central nervous systems, somatomotor activity and behavior pattern. Particular attention was directed to observation of tremors, convulsions, salivation, diarrhea, and coma.
-Body weight: Individual body weights of the animals were recorded prior to test substance exposure (initial) and again on Days 1, 3, 7, and 14 (terminal);

Statistics:

Statistical analysis was limited to the calculation of the mean and standard deviation. Since
no death occurred at the limit dose, the LC50 was determined without the need of statistical
analysis. The Mass Median Aerodynamic Diameter (MMAD) and Geometric Standard Deviation (GSD) were calculated.

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.22 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

There were no mortalities at a concentration of 5.22 mg/L

Clinical signs:

irregular respiration

Remarks:

Sighting Test (5.21 mg/L): all animals recovered by Day 1 and appeared active and healthy for the remainder of the study Main Test (5.22 mg/L): all animals recovered by Day 3 and appeared active and healthy for the remainder of the study

Body weight:

All animals gained body weight during both the sighting and the main study

Gross pathology:

No gross abnormalities were noted for any of all the animals during both the sighting and the main study when necropsied at the conclusion of the 14-day observation period.

Interpretation of results:

GHS criteria not met

Conclusions:

The acute inhalation median lethal concentration (LC50) of the test item is greater than 5.22 mg/L in Sprague-Dawley derived, albino male and female rats.

Executive summary:

In an OECD TG 403 acute inhalation toxicity study, performed under GLP, groups of young adult Sprague-Dawley-derived, albino rats were exposed via the inhalation (nose-only exposure) route to the test item. Test atmospheres were analyzed for particulate concentration.

After establishing the desired generation procedures during the pre-test trials, fourteen healthy Sprague-Dawley rats were selected for test.  A sighting test with an initial exposure level of 5.0 mg/L was selected for testing using two animals per sex (2 males and 2 females).  Since all male and female rats survived the sighting test, an additional five animals per sex (5 males and 5 females) were selected for the main test with a 5.0 mg/L exposure level.  Chamber concentration and particle size distributions of the test atmosphere were determined periodically during the exposure period.  The animals were observed for mortality, signs of gross toxicity, and behavioral changes at least once daily for 14 days following exposure.  Body weights were recorded prior to exposure (initial) and again on Days 1, 3, 7, and 14 (terminal).  Necropsies were performed on all animals at terminal sacrifice.

There were no mortalities at a concentration of 5.22 mg/L. Following exposure, all animals of the sighting and main exhibited irregular respiration. However, all animals
recovered by Day 1 and Day 3 respectively, and appeared active and healthy for the remainder of the study. All animals gained body weight during the study and no gross abnormalities were noted for any of the animals when necropsied at the conclusion of the 14-day observation period.

Under the experimental conditions of this study, the acute inhalation median lethal concentration (LC₅₀) of the test item is greater than 5.22 mg/L in Sprague-Dawley derived, albino male and female rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

5.22 mg/L air

Physical form:

inhalation: dust

Quality of whole database:

GLP compliant OECD TG 402 study.

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

28 June 2012 to 12 July 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Version / remarks:

1987

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1200 (Acute Dermal Toxicity)

Version / remarks:

1998

Qualifier:

according to guideline

Guideline:

EU Method B.3 (Acute Toxicity (Dermal))

Version / remarks:

2008

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Wistar

Remarks:

CRL:(WI)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Young adult rats
- Weight at study initiation: Between 236 g and 273 g
- Housing: Individual caging
- Diet: Autoclavable complete diet for rats and mice – breeding and maintenance. Ad libitum
- Water: Tap water. Ad libitum
- Acclimatisation period: 7 days

ENVIRONMENTAL CONDITIONS
- Temperature: 21.2 – 27.5°C
- Humidity: 44 – 70 %
- Air changes: 15-20 air exchanges per hour
- Photoperiod: 12 hours daily, from 6.00 a.m. to 6.00 p.m.

IN-LIFE DATES: from 28 June to 12 July 2012

Type of coverage:

semiocclusive

Vehicle:

water

Remarks:

tap water

Details on dermal exposure:

TEST SITE
- Area of exposure: Back
- Pre-treatment: Approximately 24 hours before treatment an area on the back of the rat was shaven
- % coverage: Approximately 10 % area of the total body surface
- Type of wrap if used: Sterile gauze pads, a patch with adhesive hypoallergenic plaster and semi occlusive plastic wrap

REMOVAL OF TEST SUBSTANCE
- Washing: At the end of the exposure period, residual test item was removed, using body temperature water
- Time after start of exposure: 24 hours

VEHICLE
- Amount applied : 1 mL

Duration of exposure:

24 hours

Doses:

2000 mg/kg bw

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: A clinical examination was performed on the day of treatment, at 1 and 5 hours after the application of the test item, and once each day for 14 days thereafter. The body weight of all animals was recorded on Day 0 (beginning of the experiment) and on Days 7 and 14.
- Necropsy of survivors performed: All animals were subjected to gross macroscopic examination. After examination of the external appearance, the cranial, thoracic and abdominal cavities were opened and the appearance of the tissues and organs were observed
- Clinical signs including body weight: Observations included the skin and fur, eyes and mucous membranes, and also respiratory, circulatory, autonomic and central nervous system, and somatomotor activity and behaviour pattern. Particular attention was directed to the observation of tremors, convulsions, salivation, diarrhoea, lethargy, sleep and coma

Statistics:

Means and their standard deviations were calculated for body weight and body weight gain

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No mortality occurred after the 24-hour dermal exposure to the test item in CRL:(WI) Wistar rats

Clinical signs:

other:

Body weight:

other body weight observations

Remarks:

There were no effects on body weight and body weight gain during the observation period

Gross pathology:

There was no evidence of any test item related observations at a dose level of 2000 mg/kg bw at necropsy. Pelvic dilatation of the right kidney was incidentally seen in 1/10 animal

Interpretation of results:

GHS criteria not met

Conclusions:

The median lethal dose of the test item after single dermal administration was found to be greater than 2000 mg/kg bw in male and female CRL:(WI) Wistar rats

Executive summary:

In an OECD TG 402 acute toxicity study performed under GLP, single administration of the test item at a dose of 2000 mg/kg body weight was applied dermally to 5 male and 5 female CRL:(WI) rats, followed by a 14-day observation period. The test item was applied as supplied. The application period was 24 hours. Clinical observations were assessed in all animals at 1 and 5 hours after dosing and daily for 14 days thereafter. Body weight was measured prior to dosing on Day 0 and on Days 7 and 14. All animals were euthanized and subjected to a gross macroscopic examination at the end of the 14-day observation period (Day 14).

On test day 0, the test item was applied at a single dose of 2000 mg/kg body weight applied uniformly over the skin and remained on the skin throughout a 24- hour exposure period.

No mortality occurred during the study. No adverse clinical signs were observed after treatment with the test item or during the 14 day observation period and no treatment related skin irritation was observed in any animal throughout the study. Pelvic dilatation of the right kidney was incidentally seen in 1/10 animal.

The median lethal dose of the test item after a single dermal administration was found to be greater than 2000 mg/kg bw in male and female CRL:(WI) Wistar rats.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 2 000 mg/kg bw

Quality of whole database:

GLP compliant OECD TG 403 study.

Additional information

All available data were assessed and the studies representing the worst-case effects were included as key studies. Other studies are included as supporting information. Dosing with the test material in rats did not result in acute toxicity by the oral, dermal and inhalation routes of exposure. The key studies are considered to be worst-case and were selected for the CSA.

Acute oral toxicity
Two acute oral toxicity studies in rats for the test substance are available and one for a metabolite of the test substance. The key study was performed according to OECD TG 425 under GLP (Petus 2013). Three female CRL:(WI) rats were given a single oral (gavage) dose of 5000 mg/kg bw of the test material. Prior to dosing, the animals were fasted overnight. The animals were observed individually after dosing at 30 minutes, then 1, 2, 3, 4, and 6 hours after dosing and once each day for 14 days thereafter for any signs of systemic toxicity and their body weights were recorded regularly. All animals were examined macroscopically at the end of the study. No deaths occurred during the study.
Treatment with the test substance caused vocalisation in one animal who was symptom free from 48 hours after treatment. The other two animals showed no clinical signs. There were no treatment related body weight changes. Body weights were within the range commonly recorded for this strain and age. No treatment related macroscopic observations were recorded in any of the animals.
Upon an acute oral administration of the test material and over a 14-day post treatment observation period, the median LD50 in female rats was found to be > 5000 mg/kg bw.

The second acute oral study, performed in albino rats and according to OECD TG 401 under GLP (Kobel 1983) supports the conclusion that the test substance has no acute oral toxicity.

A metabolite of the test material was tested according to OECD TG 401 (Hartmann 1991). A LD50 in male rats greater than 2000 mg/kg bw and an LD50 in female greater than 1000 mg/kg bw was determined. This finding is not considered to affect the conclusion on the parent substance.

Acute inhalation toxicity
Two acute inhalation toxicity studies in rats are available. The key study was performed according to OECD TG 403 under GLP (Durando 2018). A sighting test with an initial exposure level of 5.0 mg/L was selected for testing on two animals per sex (2 males and 2 females). Since all male and female rats survived the sighting test, an additional five animals per sex (5 males and 5 females) were selected for the main test with a 5.0 mg/L exposure level. The animals were exposed for 4 hours using a nose-only exposure system, followed by a 14-day observation period. Clinical observations and body weights were recorded throughout the study and at the end of the scheduled period the animals were subjected to a gross examination post-mortem.
The mean achieved particulate concentration of the test material was 5.22 ± 0.26 mg/L. The MMAD was 5.00 μm ± 2.24 (GSD). There was no mortality in the study.
Irregular respiration was recorded in all animals in the sighting test, from which animals recovered by Day 1. Irregular respiration was also recorded in all animals in the main test and recovery occurred by Day 3.
All animals gained body weight during both the sighting and the main study. No gross abnormalities were noted for any of the animals of the sighting and main study when necropsied at the conclusion of the 14-day observation period.
The acute inhalation median LC50 of the test material in Sprague-Dawley derived, albino male and female rats was > 5.22 mg/L.

The other acute inhalation study was also performed according to OECD TG 403 (Kobel 1983). A similar maximum exposure level was reached in this study and no mortality occurred during the observation period of 14 days. Therefore, the LC50 was determined to be > 5.185 mg/L.

 

Acute dermal toxicity
Two acute dermal toxicity studies in rats are available. The key study was performed according to OECD TG 402 under GLP (Petus 2013). Ten (5 male and 5 female) CRL:(WI) rats were treated with a single semi-occlusive dermal application of test material at the limit dose of 2000 mg/kg bw. Sufficient water was used to dampen the test material to ensure good contact with the skin. The test item was applied as supplied. The application period was 24 hours. Clinical observations were assessed in all animals at 1 and 5 hours after dosing and daily for 14 days thereafter.
Body weight was measured prior to dosing on day 0 and on days 7 and 14. All animals were examined macroscopically at the end of the study.
No mortality occurred during the study. No adverse clinical signs and no effects on body weight and body weight gain were observed after treatment with the test item or during the 14-day observation period. No treatment related skin irritation was observed in any animal throughout the study. Pelvic dilatation of the right kidney was incidentally seen in one of ten animals.
The median LD50 of test material after a single dermal administration was > 2000 mg/kg bw in male and female CRL:(WI) Wistar rats.

The other acute dermal toxicity study was also performed according to OECD TG 402 (Kobel 1983). In this study a dose of 2000 mg/kg was applied under occlusive conditions. No mortality occurred during this study. Therefore, the LD50 was determined to be > 2000 mg/kg bw.

Justification for classification or non-classification

Based on the result of the acute oral, acute dermal and acute Inhalation toxicity study classification for acute toxicity is not warranted in accordance with EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation No. (EC) 1272/2008.