thiacloprid (ISO);(Z)-3-(6-chloro-3-pyridylmethyl)-1,3-thiazolidin-2-ylidenecyanamide;{(2Z)-3-[(6-chloropyridin-3-yl)methyl]-1,3-thiazolidin-2-ylidene}cyanamide

Endpoint summary

Description of key information

Oral (US-EPA-FIFRA, Guideline 81-8(SS)), rat: LD50 = 177 mg/kg bw (males and females)

Inhalation (OECD 403), rat: LC50 > 2.535 mg/L (males) and LC50 = ca. 1.223 mg/L (females)

Dermal (OECD 402), rat: LD50 > 2000 mg/kg bw (males and females)

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Remarks:

Preliminary dose range-finder included in the acute oral neurotoxicity screening study 95-412-GI (please refer to M-000894-03-1 in chapter 7.9.1)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

main study: 29 Jan - 16 Feb 1996

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data provided as summary within an reliable acute oral neurotoxicity screening study; however considered reliable and suitable for assessment of the acute oral toxicity.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Version / remarks:

adopted 1987

Deviations:

yes

Remarks:

only summarized data available

Principles of method if other than guideline:

The present study was intended as dose range-finding study to define the most appropriate dose levels for a further acute oral neurotoxicity screening study. Accordingly, the data referring to the present study are part of the study No. 95-412-GI as available for the acute oral neurotoxicity screening study, included in IUCLID chapter 7.9.1.

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

other: not specified, but Wistar assumed

Sex:

male/female

Details on test animals or test system and environmental conditions:

No details available from the data source.

Route of administration:

oral: gavage

Vehicle:

not specified

Details on oral exposure:

No details on the experimental design are available from the data source, however, it is hardly assumed that these were similar to those as described from the main screening study. With respect to the screening study, the test substance was administered by gavage as a single dose in 0.5% methylcellulose-0.4% Tween 80 in deionized water, at a dosing volume of 10 mL/kg bw.

Doses:

27, 36, 85, 244 and 526 mg/kg bw (analytically-confirmed doses)

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

None

Statistics:

Not specified

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 85 - < 244 mg/kg bw

Based on:

test mat.

Remarks on result:

other: 0% mortality at 85 mg/kg bw and 100 % mortality at the next dose level of 244 mg/kg bw

Mortality:

27, 36 and 85 mg/kg bw: no deaths occurred in both sexes
244 and 526 mg/kg bw: 100% mortality in both sexes

Clinical signs:

other: 27 mg/kg bw: no clinical signs were observed 36 mg/kg bw: slight repetitive chewing movements (males) 85 mg/kg bw: slight repetitive chewing movements (both sexes), slight tremors (males) and slight oral and nasal stains (female) 244 mg/kg bw: tremors, de

Gross pathology:

No information on gross pathology was provided.

Other findings:

Neurotoxicity:
The time of peak neurobehavioral effects (within the first eight hours following treatment) was estimated to be approximately 4 h following treatment.

Interpretation of results:

Category 3 based on GHS criteria

Conclusions:

The present study was intended as dose range-finding study to define the most appropriate dose levels for a further acute oral neurotoxicity screening study. The data referring to the present study are part of the study No. 95-412-GI, as available for the acute oral neurotoxicity screening study included in IUCLID chapter 7.9.1. The test conduct of the range finding study was in principle similar to OECD TG 401, and analytically-confirmed doses of 27, 36, 85, 244 and 526 mg/kg bw were tested using five rats/sex/dose level. Clinical signs of toxicity were reported, starting from 36 mg/kg bw, which basically consisted of repetitive chewing movements, slight tremors and oral and nasal stains. At the two highest dose levels of 244 and 526 mg/kg bw, the toxic effects further included decreased activity, cool-to-touch body, dilated pupils and clear lacrimation. At 244 mg/kg bw, locomotor incoordination (ataxia) was reported for one female. Clinical signs were generally apparent in both sexes within 2 - 4 h following treatment and recovered in survivors by the following day. Clinical signs were generally comparable for males and females at a given dose level, indicating similar sensitivity for both sexes. With respect to neurotoxicity, it was reported that the time of peak neurobehavioral effects (within the first eight hours following treatment) could be estimated to be approximately four hours following treatment.
Whereas no mortality occurred at doses from 27 to 85 mg/kg bw, 100% mortality was observed at the two highest dose levels of 244 and 526 mg/kg bw, which generally occurred within 24 h after dosing. Thus, a LD50 for acute oral toxicity in the range > 85 - < 244 mg/kg bw is expected. Referring to the CLP classification and labelling criteria (CLP, Annex I), this falls in the range of > 50 - =< 300 mg/kg bw and thus, would trigger a classification for acute oral toxicity as Cat 3 H301.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

177 mg/kg bw

Quality of whole database:

The available information comprises an adequate and reliable study, and is thus sufficient to fulfill the standard information requirements set out in Annex VII, 8.5, of Regulation (EC) No 1907/2006.

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:

21 Sep - 13 Oct 1994

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

adopted 2009

Deviations:

yes

Remarks:

MMAD and GSD slightly out of range

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

adopted 1981

Deviations:

no

GLP compliance:

yes

Test type:

traditional method

Limit test:

no

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan-Winkelmann, Borchen, Germany
- Females nulliparous and non-pregnant: yes
- Rationale for use of males: male and female rats were used in this study
- Age at study initiation: 2 - 3 months
- Weight at study initiation: 160.0 - 210.0 g (males), 162.0 - 191.0 g (females)
- Housing: individually in Makrolon Type II cages equipped with type S8/15 low dust wood granulate (Ssniff, Soest, Germany) as bedding material
- Diet: Altromin 1324 pellets maintenance diet for rats and mice (Altromin GmbH, Lage, Germany), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 5 days
- Method of randomisation in assigning animals to test and control groups: computerized list of random numbers

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24
- Humidity (%): approx. 50
- Air changes (per hr): approx. 10
- Photoperiod (hrs dark / hrs light): 12 / 12

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

clean air

Mass median aerodynamic diameter (MMAD):

>= 3.1 - <= 9.1 µm

Geometric standard deviation (GSD):

>= 1.7 - <= 3.5

Remark on MMAD/GSD:

MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 3.1 µm / 1.7 µm (0.080 mg/L), 3.1 µm / 1.7 µm (0.481 mg/L), 5.8 µm / 3.5 µm (1.523 mg/L), 9.1 µm / 2.4 µm (2.535 mg/L)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Plexiglas exposure tubes
- Exposure chamber volume: about 3.8 L
- Method of holding animals in test chamber: plexiglas exposure tubes that were chosen to fit the size of the animals
- Source and rate of air (airflow): 28 L/min
- Method of conditioning air: via compressed air dryer, i.e. water, dust and oil were removed
- System of generating particulates/aerosols: EXACTOMAT 4200 (TSE, Bad Homburg, Germany) and for the lower concentrations (0.080 and 0.481 mg/L) a Wright-Dust-Feeder (BGI Inc., Waltham, MA, USA)
- Method of particle size determination: Cascade impactors
- Treatment of exhaust air: purified via cotton-wool/activated charcoal and HEPA filters
- Temperature, humidity, pressure in air chamber: 23 - 24 °C, 10 - 38%, not specified

TEST ATMOSPHERE
- Brief description of analytical method and equipment used: test-substance concentration was determined by gravimetric analysis using cellulose-acetate filters (Sartorius, Göttingen, Germany)
- Samples taken from breathing zone: yes, once per hour
- Time needed for equilibrium of exposure concentration before animal exposure: < 1 min

VEHICLE
- Composition of vehicle: conditioned air


TEST ATMOSPHERE
- Particle size distribution: number of particles < 3 µm: 49% (0.080 mg/L), 48% (0.481 mg/L), 31% (1.523 mg/L), 10% (2.535 mg/L)
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 3.1 µm / 1.7 µm (0.080 mg/L), 3.1 µm / 1.7 µm (0.481 mg/L), 5.8 µm / 3.5 µm (1.523 mg/L), 9.1 µm / 2.4 µm (2.535 mg/L)

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

0.080, 0.481, 1.523 and 2.535 mg/L

No. of animals per sex per dose:

5

Control animals:

yes

Remarks:

Control studies are performed regularly under GLP conditions, but not assigned to a specific study.

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: body weights were measured before exposure, on days 3, 7 and weekly thereafter. Individual weights were also recorded at death, if applicable. Appearance and behavior were examined several times on the day of exposure and twice daily thereafter (once on weekends)
- Necropsy of survivors performed: yes
- Other examinations performed: rectal temperature, reflex measurements

Statistics:

Please refer to 'any other information on materials and methods incl. tables' section for details.

Key result

Sex:

female

Dose descriptor:

LC50

Effect level:

ca. 1.223 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

> 2.535 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

Mortality was not observed in males at any dose level and not in females of the control, 0.080 and 0.481 mg/L dose groups. At 1.523 mg/L 3/5 females died 1 to 2 days after exposure and at 2.535 mg/L 4/5 females died 1 to 7 days after exposure.

Clinical signs:

other: Please refer to 'any other information on results incl. tables' section for details.

Body weight:

Males and females of the 0.080 mg/L dose group tolerated the exposure without marked effects on body weights when compared to controls. However, at levels of 0.481 mg/L of test item and higher doses, rats lost body weight during the first three days after exposure (2.535 mg/L dosed females lost body weight until one week after exposure). Thereafter, all rats gained body weight until the close of the study, but body weight gain was overall reduced at dose levels of 0.481 mg/L and higher when compared to controls.

Gross pathology:

In rats sacrificed at the end of the observation period (survivors), no compound-related increase in the incidence of macroscopical findings could be observed. In rats sacrificed during the observation period, lungs with reddish colour and red foci, intestine with red mucosa, reddish-slimy content, pale and lobulated livers and red appearance of renal pelvis was observed.

Other findings:

All animals showed normal reflexes, except for some alteration in reflexes in the 1.523 mg/L dose group (males and females). Rectal temperature was concentration-dependently decreased in animals exposed to the test item when compared to controls. Changes observed in the 0.080 mg/L dose group were considered toxicologically not relevant.

Clinical signs

No clinical signs were observed in the control and 0.080 mg/L dose group. At 0.481 mg/mL, bradypnoea, tremor, reduced motility, haircoat ungroomed and piloerection were observed starting from 4 h and lasting until 2 days after exposure. In the 1.523 mg/mL groups, bradypnoea, laboured breathing pattern, rales, prostration (lying on side or belly), blepharospasm, mydriasis, chromodacryorrhea, tremor, reduced motility, apathy, haircoar ungroomed and piloerection were noted from 4 h and lasting until 4 (females) or 6 (males) days after exposure. In the top dose group (2.535 mg/mL), bradypnoea, dyspnoea, laboured breathing pattern, rales, nose/snout area with red encrustation, salivation, blepharospasm, mydriasis, tremor, reduced motility, haircoat ungroomed and piloerection were observed from 4 h until 4 (males) or 6 (females) days after study.

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

The study was performed in accordance to OECD TG 403 under GLP conditions and is considered reliable. Under the conditions chosen, the acute inhalation LC50 was above 2.535 mg/L for male Wistar rats and approximately 1.223 mg/L for female Wistar rats. According to criteria of the CLP Regulation (EU) No. 1272/2008, classification of the test item for acute inhalation toxicity category 4 (H332) is needed.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

ca. 1.223 mg/L air

Physical form:

inhalation: dust / mist

Quality of whole database:

The available information comprises an adequate and reliable study, and is thus, sufficient to fulfil the standard information requirements set out in Annex VIII, 8.5, of Regulation (EC) No 1907/2006.

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:

22 Jun - 6 Jul 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity: Fixed Dose Procedure)

Version / remarks:

adopted 2017

Deviations:

yes

Remarks:

Some deviations to the current guideline exist: male and females were tested, all animals were tested simultaneously, and it was not stated how many percent of the skin were covered, females exceeded the recommended age.

Qualifier:

according to guideline

Guideline:

OECD Guideline 402 (Acute Dermal Toxicity)

Version / remarks:

adopted 1987

Deviations:

no

GLP compliance:

yes

Test type:

fixed dose procedure

Limit test:

yes

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Winkelmann GmbH, Paderborn, Germany
- Females nulliparous and non-pregnant: yes
- Age at study initiation: 10 weeks (males) and 14 - 16 weeks (females)
- Weight at study initiation: 245 - 256 g (males) and 208 - 218 g (females)
- Fasting period before study: not indicated
- Housing: during testing period individually in polycarbonate cages type IIA, during acclimatization in groups in polycarbonate cages type III (<180g five animals >180g max. three animals per cage), both with low-dust wood granules type S 8/15 (Ssniff, Spezialdiäten GmbH, Soest/Westphalia, Germany)
- Historical data: available
- Diet: Altromin® 1324 Diet for Rats and Mice (Altromin GmbH and Co. KG, Lage, Germany), ad libitum
- Water: tap water, ad libitum
- Acclimation period: at least 7 days
- Microbiological status when known: no pathogens detected

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 3
- Humidity (%): 40 - 70
- Air changes (per hr): at least 10
- Photoperiod (hrs dark / hrs light): 12/12

Type of coverage:

occlusive

Vehicle:

other: 0.9% NaCl solution

Details on dermal exposure:

TEST SITE
- Area of exposure: 3.5 x 4.5 cm (males) and 4.0 x 4.0 cm (females)
- % coverage: not indicated
- Type of wrap if used: The paste of the test substance and 0.9% NaCl solution was formed on a piece of aluminum foil. It was then applied with the foil and fixed in place with an occlusive dressing (fermoflex®).

REMOVAL OF TEST SUBSTANCE
- Washing: soap and water
- Time after start of exposure: 24 h

TEST MATERIAL
- Amount applied: 2000 mg/kg bw
- Constant volume or concentration used: no
- For solids, paste formed: yes

VEHICLE: NaCl solution
- Amount applied : 1.0 mL per g test substance
- Concentration: 0.9%

Duration of exposure:

24 h

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: Appearance and behavior was recorded several times on the day of treatment, and at least once a day thereafter. The body weights of the rats were recorded on day 1 before administration and then weekly.
- Necropsy of survivors performed: yes
- Clinical signs including body weight: yes, appearance, behavior, reactivity, motility, reflexes, gait, paralysis, spasms, tremors etc., respiratory frequency, heart rate, pallor, posture and gastrointestinal functions

Statistics:

No statistical analysis was performed.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

no indication of skin irritation up to the relevant limit dose level

Mortality:

No mortality occurred until the end of the observation period. Please refer to Attachment 1.

Clinical signs:

other: No clinical signs and no local skin reactions were observed.

Gross pathology:

No gross pathologic changes were observed in animals killed at the end of the study period.

Interpretation of results:

GHS criteria not met

Conclusions:

The dermal LD50 for male and female rats was >2000 mg/kg bwt. The test substance caused no systemic toxicity to Wistar rats following acute dermal application. The study is considered valid.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 2 000 mg/kg bw

Quality of whole database:

The available information comprises an adequate and reliable study, and is thus, sufficient to fulfil the standard information requirements set out in Annex VIII, 8.5, of Regulation (EC) No 1907/2006.

Additional information

To assess acute toxicity of the test substance, data after oral, inhalation and dermal exposure to the test substance are considered.

 

Acute toxicity: oral

An acute oral neurotoxicity screening study conducted according to the US-EPA-FIFRA Guideline 81-8(SS) and GLP is available, which is included in IUCLID chapter 7.9.1 (M-000894-03-1). Within this study, a preliminary dose range finding experiment is mentioned, which is considered suitable for inclusion as key entry with respect to acute oral toxicity. In fact, the preliminary experiment was intended as dose range-finding study to define the most appropriate dose levels for an acute oral neurotoxicity screening study. Accordingly, the data referring to this experiment are part of the acute oral neurotoxicity screening study No. 95-412-GI, included in IUCLID chapter 7.9.1. The test conduct of the range finding study was in principle similar to OECD TG 401, and analytically confirmed doses of 27, 36, 85, 244 and 526 mg/kg bw were tested using five rats/sex/dose level. No details on the experimental design are available from the data source, however, it is hardly assumed that these were similar to those as described from the main screening study. With respect to the screening study, the test substance was administered by gavage as a single dose in 0.5% methylcellulose-0.4% Tween 80 in deionized water, at a dosing volume of 10 mL/kg bw. Clinical signs of toxicity were reported, starting from 36 mg/kg bw, which basically consisted of repetitive chewing movements, slight tremors and oral and nasal stains. At the two highest dose levels of 244 and 526 mg/kg bw, the toxic effects further included decreased activity, cool-to-touch body, dilated pupils and clear lacrimation. At 244 mg/kg bw, locomotor incoordination (ataxia) was reported for one female. Clinical signs were generally apparent in both sexes within 2-4 h following treatment and recovered in survivors by the following day. Clinical signs were generally comparable for males and females at a given dose level, indicating similar sensitivity for both sexes. With respect to neurotoxicity, it was reported that the time of peak neurobehavioral effects (within the first eight hours following treatment) could be estimated to be approximately four hours following treatment. Whereas no mortality occurred at doses from 27 to 85 mg/kg bw, 100% mortality was observed at the two highest dose levels of 244 and 526 mg/kg bw, which generally occurred within 24 h after dosing. Thus, a LD50 for acute oral toxicity in the range > 85 - < 244 mg/kg bw is expected. Referring to the CLP classification and labelling criteria (CLP Annex I), this falls in the range of > 50 - =< 300 mg/kg bw and thus, would trigger a classification for acute oral toxicity as Cat 3 H301.

This is further supported by the findings of the acute oral neurotoxicity screening study conducted according to the US-EPA-FIFRA Guideline 81-8(SS). Based on the results of the dose range-finding experiment, the nominal doses selected for the screening study were set at 0, 20, 50 and 100 mg/kg bw for both sexes. The highest dose was selected to produce clear evidence of toxicity without mortality. The middle dose was selected to produce somewhat less toxicity and the low dose was chosen to produce no evidence of exposure. Thus, for the screening study, four dose groups (12 rats/sex/dose level) were administered the test substance at nominal doses of 0 (vehicle), 20, 50 or 100 mg/kg bw for both sexes. The test substance was administered by gavage as a single dose in 0.5% methylcellulose-0.4% Tween 80 in deionized water, at a dosing volume of 10 mL/kg bw. All 12 animals/sex/dose level were used for neurobehavioral testing and were sacrificed 15 days after exposure, the day following the final FOB and motor activity tests. Analytical monitoring revealed that the measured doses of the test item for both sexes were about 106% to 110% of the nominal dose level. Based on these results, the analytically confirmed doses were 0, 22, 53, and 109 mg/kg bw for both sexes. With respect to the results of the study, the focus here is kept on the clinical signs of toxicity and the mortality; for the remaining data, please refer to chapter 7.9.1. Treatment-related clinical signs of toxicity were evident in females of the middle dose group and in males and females of the high dose group. In fact, the only evidence of toxicity reported for the middle dose consisted of one female with dilated pupils. Treatment-related clinical signs of toxicity reported for both gender in the high dose groups consisted of tremors, decreased activity, locomotor incoordination (ataxia), dilated pupils, cool-to-touch body, urine stain and ptosis of the eyelids. Additional effects also attributed to treatment in females that received the high dose consisted of red nasal stain, oral stain, clear nasal discharge and clear lacrimation. Treatment-related signs in both sexes were generally apparent only on the day of treatment (Day 0) and resolved for most signs by day 1 following treatment. All treatment-related clinical signs resolved by Day 5. Thus, the clinical toxicity profile in the screening study was in line with that of the range-finding experiment. With respect to mortality, all animals survived until scheduled terminal sacrifice.

Since both, the range-finding and the screening study showed similar clinical toxicity profile, the results of both in terms of mortality were combined in order to assess an acute median lethal oral dose level (LD50 value). The basis for the calculation was 100% mortality at an analytically confirmed dose level of 244 mg/kg bw (source: dose-range finding study) and 0% mortality at an analytically confirmed dose level of 109 mg/kg bw (screening study). The resulting LD50 value for male and female rats was 177 mg/kg bw. Referring to the CLP classification and labelling criteria (CLP Annex I), the LD50 value of 177 mg/kg bw is in line with the classification as Cat 3 H301 for acute oral toxicity as derived from the range-finding experiment.

The acute oral toxicity of the test substance was determined according to OECD guideline 401 and in compliance with GLP (M-000796-01-1). Groups of 5 fasted Wistar rats/sex/dose were administered single oral doses of 62.5, 300, 700 and 1000 mg/kg bw (males) and 62.5, 100, 300 and 500 mg/kg bw (females). No deaths occurred in either sex at the lowest dose tested. The lowest lethal doses were 700 mg/kg bw in males and 300 mg/kg bw in females. Mortality occurred on Day 2 – 3 /males) and Day 2 – 8 (females) after administration. The low dose of 62.5 mg/kg bw was tolerated without clinical signs by male and female rats. At the dose of 100 mg/kg bw and above observed clinical signs included: piloerection, constipation, decreased motility and reactivity, poor reflexes, spastic gait, spasmodic state, convulsions, tremor, tachypnea, dyspnea, labored breathing, diarrhea, increased salivation, narrowed palpebral fissure, closed eyelids, red excretion out of the nose and red incrusted snout. These clinical signs occurred within 25 min and 8 days after treatment. The majority of these observations resolved by Day 8 of the study. No effects on body weights were observed with exception of one female rat treated with 300 mg/kg bw. This female showed a transient depression in body weight, however, this was not regarded as toxicologically relevant. All animals that died showed a body weight loss prior to death. The surviving animals showed similar body weight gain between the treatment and control group. No gross pathological changes were observed in the survivals. Based on the mortalities observed during the study, the LD50 value (acute median lethal oral dose) was 836 mg/kg bw in males and 444 mg/kg bw in females.

Similar results to those summarized above were noted in a pilot oral toxicity study with Wistar rats (M-000703-01-4), which was not included as a study summary. This non-GLP compliant study was conducted according to OECD guideline 401 and is summarized here, for the purpose of data completeness. The test substance was orally administered by gavage generally to groups of five males and five female non-fasted Wistar rats. Male rats received a single dose of 140, 225, 370, 600 and 700 mg/kg bw, and females were treated with 100, 140, 225, 370, 425, 500 and 600 mg/kg bw. Additionally, one female each received 1000, 2500 and 5000 mg/kg bw of the test substance, respectively. No deaths occurred up to and including 370 mg/kg bw for male rats and 225 mg/kg bw for female rats. Accordingly, the lowest doses for which some mortality was observed were 600 mg/kg bw in males and 370 mg/kg bw in females. All females died after single oral treatment with ≥ 500 mg/kg bw of the test item. The main clinical signs were decreased motility and reactivity, poor reflexes, spastic gait, spasmodic state, convulsions, tremor, tachypnea, dyspnea, laboured breathing, diarrhea, increased salivation, narrowed palpebral fissure, red incrusted margins of eyes. Depending on the dose, clinical signs started 59 minutes to 4 hours after administration, and lasted up to 6 days. A transient effect on body weight gain was observed in both sexes after 4 days and after 8 days from 600 mg/kg bw (males) and 370 mg/kg bw (females). There was no indication of test article-related grossly visible organ lesions at necropsy. Based on the observed mortalities, the LD50 value was 621 mg/kg bw in males and 396 mg/kg bw in females.

The acute oral toxicity of the test substance was also investigated in a second species, and the study is summarised here for the purpose of data completeness (M-009210-01-1). In a GLP-compliant guideline study (EPA, Subdivision F, 81-1, adopted in 1984), groups of 5mice/sex/dose were orally treated with single doses of 70, 100, 140, 200 and 280 mg/kg bw of the test item. No deaths occurred in either sex at the lowest dose tested. Therefore, the lowest lethal dose was 100 mg/kg bw in both sexes. Death occurred primary from 40 min to 1 day after administration of the test item. Observed clinical signs included abnormal respiration, tremor, sedation, cyanosis, vocalization and titubation. In general, symptoms in survived mice disappeared within 1 day after treatment. Mean body weights in all dose groups increased during the study and were similar to those of the control group. There were no abnormal macroscopical findings, which were regarded to be relevant to administration of test substance. Based on the mortality, the LD50 value of test substance was determined to be 127 mg/kg bw for male mice and 147 mg/kg bw for female mice, respectively.

In conclusion, following oral exposure acute toxicity was observed in rats and mice. In rats the LD50 value was 177 mg/kg bw (both sexes) and in mice 127 mg/kg and 147 mg/kg bw for males and females, respectively. Thus, the test substance exhibited similar mortality rates in rats and mice. The test substance meets the classification criteria for acute oral toxicity, category 3 (Acute tox. 3, H301). This is in line with the harmonized classification.

Acute toxicity: inhalation

A GLP-conform acute inhalation toxicity study was performed according to OECD guideline 403 (M-000815-01-1), with minor guideline deviations. Five Wistar rats/sex/dose were exposed to the test item (aerosolized dust) via the nose-only procedure to a single dose for 4 h. Dose groups comprised a control (air only), 0.080, 0.481, 1.523 and 2.535 mg/L air (analytical concentration). The test article concentrations were determined by gravimetric analysis. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) corresponding to the dosage groups were (MMAD / GSD): 3.1 µm / 1.7 µm (0.080 mg/L), 3.1 µm / 1.7 µm (0.481 mg/L), 5.8 µm / 3.5 µm (1.523 mg/L) and 9.1 µm / 2.4 µm (2.535 mg/L). Post exposure, all animals were observed for a period of 14 days. No clinical signs were observed in the control and 0.080 mg/L dose group. At 0.481 mg/mL, bradypnoea, tremor, reduced motility, haircoat ungroomed and piloerection were observed starting from 4 h and lasting until 2 days after exposure. In the 1.523 mg/mL groups, bradypnoea, laboured breathing pattern, rales, prostration (lying on side or belly), blepharospasm, mydriasis, chromodacryorrhea, tremor, reduced motility, apathy, haircoar ungroomed and piloerection were noted from 4 h and lasting until 4 (females) or 6 (males) days after exposure. In the top dose group (2.535 mg/mL), bradypnoea, dyspnoea, laboured breathing pattern, rales, nose/snout area with red encrustation, salivation, blepharospasm, mydriasis, tremor, reduced motility, haircoat ungroomed and piloerection were observed from 4 h until 4 (males) or 6 (females) days after study. Males and females of the 0.080 mg/L dose group tolerated the exposure without marked effects on body weights when compared to controls. However, at levels of 0.481 mg/L of test item and higher doses, rats lost body weight during the first three days after exposure (2.535 mg/L dosed females lost body weight until one week after exposure). Thereafter, all rats gained body weight until the close of the study, but body weight gain was overall reduced at dose levels of 0.481 mg/L and higher when compared to controls. All animals showed normal reflexes, except for some alteration in reflexes in the 1.523 mg/L dosage group (males and females). Rectal temperature was concentration dependently decreased in animals exposed to the test item when compared to controls. Changes observed in the 0.080 mg/L dose group were considered toxicologically not relevant. Mortality was not observed in male rats at any dose level. Of the female rats, no animal in the control, 0.080 and 0.481 mg/L group died. However, at 1.523 mg/L 3/5 females died 1 to 2 days after exposure and at 2.535 mg/L 4/5 females died 1 to 7 days after exposure. In those animals which died due to treatment or were sacrificed during the observation period, lungs with reddish colour and red foci, intestine with red mucosa, reddish-slimy content, pale and lobulated livers and red appearance of renal pelvis was observed. In all surviving animals, no compound-related increase in the incidence of macroscopic findings could be observed. The LC50 value derived from this study was greater than 2.535 mg/L air for male rats and ca. 1.223 mg/L air for female rats.

 

Acute toxicity: dermal

A GLP-conform acute dermal toxicity study was performed according to OECD guideline 402 (M-000808-01-1). A limit dose of 2000 mg/kg bw was topically applied for 24 h to the clipped skin of 5 male and 5 female Wistar rats under occlusive dressing. Neither mortality nor clinical signs of systemic toxicity were observed until the end of the 14-day observation period. No effect on body weight, appearance or behavior occurred. Further, macroscopical examinations did not reveal abnormalities. No local skin irritation was observed at the test site. The acute dermal toxicity  LD50 value is > 2000 mg/kg bw for male and female rats.

Justification for classification or non-classification

The available data on acute oral toxicity and acute inhalation toxicity meet the criteria for classification according to Regulation (EC) 1272/2008 and are therefore sufficient for classification of the test substance for acute oral toxicity category 3 (Acute Tox. 3, H301) and acute inhalation toxicity category 4 (Acute Tox. 4, H332).