Benzimidazole

Endpoint summary

Description of key information

Acute oral Toxicity: 

In Acute oral toxicity,LD50 value for target substance1H-benzimidazole(51-17-2)was estimated to be 640 mg/kg bw in rats.Thus, based on the predictions on 1H-benzimidazole, it can be concluded that LD50 value is between 300-2000 mg/kg bw. Thus, comparing this value with the criteria of CLP regulation, 1H-benzimidazole can be classified as ‘Category IV’ of acute oral toxicity.

Acute Inhalation Toxicity: 

1H-benzimidazole (51-17-2) has very low vapour pressure (7.6x10-5 mmHg = 0.01018 Pa.),So the potential for the generation of inhalable vapours is very low. Also the normal conditions of use of this substance will not result in aerosols, particles or droplets of an inhalable size, so exposure to humans via the inhalatory route will be highly unlikely and therefore the acute inhalation toxicity end point was considered for waiver.

Acute Dermal Toxicity:

The acute dermal toxicity dose (LD50) for 1H-benzimidazole (51-17-2) was based on data available for the structurally and functionally similar read across chemicals. The LD50 value is greater than 2000 mg/kg bw. Thus, comparing this value with the criteria of CLP regulation, 1H-benzimidazole (51-17-2) cannot be classified for acute dermal toxicity. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

calculation (if not (Q)SAR)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

accepted calculation method

Justification for type of information:

Data is from Danish (Q) SAR Database

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Data is predicted using the Danish (Q)SAR Database

GLP compliance:

not specified

Test type:

other: not specified

Limit test:

no

Specific details on test material used for the study:

- Name of test material: Benzimidazole
- IUPAC name: 1H-benzimidazole
- Molecular formula: C7H6N2
- Molecular weight: 118.1384 g/mole
- Substance type: Organic
- Physical state: Solid

Species:

rat

Strain:

not specified

Sex:

not specified

Details on test animals or test system and environmental conditions:

No data

Route of administration:

oral: unspecified

Vehicle:

not specified

Details on oral exposure:

No data

Doses:

640 mg/kg bw

No. of animals per sex per dose:

No data

Control animals:

not specified

Details on study design:

No data

Statistics:

No data

Preliminary study:

no data

Sex:

not specified

Dose descriptor:

LD50

Effect level:

640 mg/kg bw

Based on:

test mat.

Remarks on result:

other: 50% mortality observed

Mortality:

No data

Clinical signs:

other: No data

Gross pathology:

No data

Other findings:

No data

Interpretation of results:

Category 4 based on GHS criteria

Conclusions:

Based on the QSAR prediction done using the Danish (Q)SAR Database, the LD50 was estimated to be 640 mg/kg bw on rat for substance 1H-benzimidazole (51-17-2).

Executive summary:

Based on the QSAR prediction done using the Danish (Q)SAR Database, the LD50 was estimated to be 640 mg/kg bw on rat for 1H-benzimidazole (51-17-2) having Reliability Index: 0.6(moderate prediction quality)

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

640 mg/kg bw

Quality of whole database:

Data is Klimisch 2 and from danish QSAR database

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Data waiving:

other justification

Justification for data waiving:

other:

Endpoint conclusion

Quality of whole database:

Waiver

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

data from handbook or collection of data

Remarks:

Experimental data of read across substances

Justification for type of information:

Data for the target chemical is summarized based on the structurally and functionally similar read across chemicals

Reason / purpose for cross-reference:

read-across source

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

WoE report is based on two acute dermal toxicity studies as- 1.and 2. Acute dermal toxicity test was carried out to study the effects of the test chemicals on rodents

GLP compliance:

not specified

Test type:

other: as mentioned below

Limit test:

no

Specific details on test material used for the study:

- Name of test material (IUPAC name): 1H-1,3-benzodiazole- Common name: benzimidazole- Molecular formula: C7H6N2- Molecular weight: g/mol- Smiles notation: c12c(nc[nH]1)cccc2- InChl: 1S/C7H6N2/c1-2-4-7-6(3-1)8-5-9-7/h1-5H,(H,8,9)- Substance type: Organic

Species:

rat

Strain:

other: 1.wistar 2.Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

1.TEST ANIMALS- Source: Institute for Industrial Research and Toxicology - Age at study initiation: 8 to 10 weeks- Weight at study initiation: 200±20g- Fasting period before study: Animals were fasted overnight prior to test and food was offered three hours after dosing.- Housing: Groups of three animals of same sex in polypropylene cages with stainless steel grill top, facilities for food and water bottle, and bedding of clean paddy husk.- Diet (e.g. ad libitum): Pelleted feed (ad libitum)- Water (e.g. ad libitum): Fresh and clean water filtered through ‘Aqua Guard on line water filter’, was kept in glass bottles Ad libitum- Acclimation period: The healthy wistar albino rats selected for study acclimatized to standard laboratory condition for period of one week under close Veterinary supervision.ENVIRONMENTAL CONDITIONS- Temperature (°C):22-25 degC- Humidity (%): 40-60% - Air changes (per hr): 10-15 air changes per hour- Photoperiod (hrs dark / hrs light):12 hours artificial fluorescent light and 12 hours dark.2.TEST ANIMALS- Source: National Institute of Biosciences, Pune.- Females nulliparous and non-pregnant: No data available- Age at study initiation: Young adult male and female rats aged between 8 – 12 weeks were used.- Weight at study initiation: The weight range of approximately 215.5 to 252.9 grams at initiation of dosing. Body weights at the start : MaleMean : 246.62 g (= 100 %)Minimum : 241.8 g (- 1.95 %)Maximum : 252.9 g (+ 2.55 %)Total No. of animals : 5FemaleMean : 219.46 g (= 100 %)Minimum : 215.5 g (- 1.80 %)Maximum : 222.8 g (+ 1.52 %)Total No. of animals : 5- Identification: Each rat was individually identified by the cage number.- Fasting period before study: No data available- Housing: The rats were individually housed in polycarbonate cages with paddy husk as bedding. - Diet (e.g. ad libitum): Rodent feed supplied by the Nutrivet Life Sciences, Pune, was provided ad libitum from individual feeders.- Water (e.g. ad libitum): Water was provided ad libitum from individual bottles attached to the cages. All water was from a local source and passed through the reverse osmosis membrane before use.- Acclimation period: 5 days.ENVIRONMENTAL CONDITIONS- Temperature (°C): 19.9 to 21.7 degree centigrade.- Humidity (%): 55.0% to 58.4%- Air changes (per hr): Ten to fifteen air changes per hour.- Photoperiod (hrs dark / hrs light): An artificial light and dark cycle of 12 hours each was provided to the room.IN-LIFE DATES: 14-06-2017 to 29-06-2017

Type of coverage:

other: 1.open 2.semiocclusive

Vehicle:

other: 1.unchanged (no vehicle) 2.Distilled water

Details on dermal exposure:

1. TEST SITE - Area of exposure: Back skin of total body surface area. - % coverage: Approximate 10 percent back skin of total body surface area. - Type of wrap if used: Adhesive tape. REMOVAL OF TEST SUBSTANCE - Washing (if done): The site of application was cleaned with lukewarm water - Time after start of exposure: No data TEST MATERIAL - Amount(s) applied (volume or weight with unit): 2000 mg/kg body weight. VEHICLE (no vehicle used) - Amount(s) applied (volume or weight with unit): none - Concentration (if solution):none2.TEST SITE - Area of exposure: Trunk (dorsal surface and sides from scapular to pelvic area) - % coverage: Approximately 10% of the body surface area. - Type of wrap if used: Porous gauze dressing and non-irritating tape. REMOVAL OF TEST SUBSTANCE - Washing (if done): Distilled water was used to remove residual test item. TEST MATERIAL - Amount(s) applied (volume or weight with unit): 2000 mg/kg bw - Constant volume or concentration used: No data available - For solids, paste formed: Yes VEHICLE - Amount(s) applied (volume or weight with unit): No data available - Concentration (if solution): No data available - Lot/batch no. (if required): No data available - Purity: No data available

Duration of exposure:

1.No data 2.24 hours

Doses:

1.Two groups:Group-I: 2000 mg/kg b.wt (limit test)Group-II: 2000 mg/kg b.wt (confirmatory test)2.A single dose of 2000 mg of the test item per kilogram of body weight was administered to ten rats (five males and five females).

No. of animals per sex per dose:

1.10 (5male & 5 female)2.10 (5/sex).

Control animals:

other: 1. no 2.not specified

Details on study design:

1.- Duration of observation period following administration: 14 days - Frequency of observations and weighing: Daily- Necropsy of survivors performed: yes- Other examinations performed: Body weight:The body weight of all the animals was observed weekly on day 0 (pre treatment), 7th and 14th (post treatment).Clinical signsThe treated animals were closely observed for clinical signs of intoxication, first 4 hours and thereafter for every 1 hrs interval for 24 hrs after dosing and twice a day for 14 days. All the rats were observed at least twice daily with the purpose of recording any symptoms of ill-health or behavioral changes. These observations included changes in skin and fur in the eyes and mucous membranes, respiratory, circulatory, central nervous and autonomic systems, somatomotor activity and behavioral changes. The following clinical signs were observed in female rats to characterize with erythema, hypersensitivity, edema etc. The clinical sign will be graded as 0 = Normal, + = Mild, ++= Moderate, +++ =High & ++++ = Severe.Mortality All the animals were observed for mortality at 30 minutes time interval for first six hours on the day of test compound administration and thereafter twice a day for 14 days.2.- Duration of observation period following administration: 14 days - Frequency of observations and weighing: Twice daily- Necropsy of survivors performed: Yes- Other examinations performed: Clinical Observations and General Appearance:Animals were observed for clinical signs, mortality, until sacrifice.Onset, duration and severity of any sign were recorded. The clinical signs and mortality observations were conducted at 10, 30, 60 minutes, 2, 4 and 6 hours on the day of dosing and once daily thereafter for 14 day. Daily observation was done as far as possible at the same time.The observations were included general clinical signs, observations of eyes, mucous membranes, respiratory, circulatory system and behavior pattern. Evaluation of Dermal Reaction:Dermal reaction was observed daily for study period of 14 days. Body weights:Individual animal body weights were recorded pre-test (prior to administration of the test item), day 7 and at termination on day 14. Gross Pathology:Necropsy was performed on animals surviving at the end of the study. Macroscopic examination of all the orifices, cavities and tissues were made and the findings were recorded. All animals surviving the study period were sacrificed by the carbon dioxide asphyxiation technique (day 15). Histopathology:No gross abnormalities were observed in animals sacrificed terminally hence, no histopathology was performed.

Statistics:

No data

Preliminary study:

No data

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Remarks on result:

other: no mortality was observed

Mortality:

1.The test chemical did not produce any mortality throughout the observation period of 14 days.2.Sex : MaleGroup I - Animal treated at the dose level of 2000 mg/kg body weight: All animals survived through the study period of 14 days.Sex : FemaleGroup I - Animal treated at the dose level of 2000 mg/kg body weight: All animals survived through the study period of 14 days.

Clinical signs:

other: 1.The test chemical did not elicit any clinical signs at the dose level of 2000 mg/kg b.wt. in entire observation period. 2.Sex : MaleGroup I - Animal treated at the dose level of 2000 mg/kg body weight did not result in any signs of toxicity during the s

Gross pathology:

1.NECROPSY FINDINGEXTERNAL i.Skin- Skin and hair coat was observed wet. ii.All external orifices- Normal B. INTERNAL i. Subcutaneous- No changes was observed.ii. Superficial and deep lymph nodes- No change in mesenteric lymph node.1.ABDOMINAL CAVITYi.Opening and general examination- In the abdominal cavity all the organs were present in normal position. ii.Spleen- No changes were recorded. iii.Digestive system- No gross changes were observed in stomach and intestine.iv.Liver and biliary ducts- No gross pathological changes were observedv.Excretory system- No gross pathological changes were observed. vi.Adrenal- Observed normal. vii.Male/female genital organs – Showed normal colour, consistency and no inflammatory changes.2. THORACIC CAVITYi.Opening and general examination- Thoracic cavity was found to be normal without any fluid, mucous or blood etc.ii.Lungs- No changes were recorded.iii.Heart- No changes were observed in color and consistency. Heart found normal.iv.Thyroid- Normal in shape, size and surface.3. CRANIAL CAVITYI.Brain- Normal in shape and size. 2.Gross pathological examination did not reveal any abnormalities in animals from 2000 mg/kg dose group.

Other findings:

1.no data2.- Other observations:Evaluation of Dermal ReactionSex : MaleGroup I - Animal treated at the dose level of 2000 mg/kg body weight did not result in any skin reaction during the study period of 14 days. Sex : FemaleGroup I - Animal treated at the dose level of 2000 mg/kg body weight did not result in any skin reaction during the study period of 14 days.

Interpretation of results:

other: not classified

Conclusions:

According to CLP regulation the test chemical 1H-benzimidazole (CAS no.:51-17-2) cannot be classified for acute dermal toxicity, as the LD50 value is >2000 mg/kg bw.

Executive summary:

Data available for the structurally and functionally similar read across chemicals has been reviewed to determine theAcute dermal toxicityof the test chemical1H-benzimidazole (CAS no.:51-17-2).The studies are as mentioned below:

1.The acute dermal toxicity study of test chemicalwas conducted on Wistar albino rats under OECD guideline-402Guideline for Testing of Chemicals.

LIMIT TEST (2000 mg/kg b.wt):

Ten healthy wistar albino rats of both sex (ranging b.wt 200±20 gm) selected for study after acclimatization. Approximate 10 percent back skin of total body surface area was prepared 24 hrs prior to application of test compound. The test chemicalwas applied dermally at the dose level of 2000 mg/kg b.wt for each animal. The treated animals were observed for clinical signs of intoxication and mortality at different time interval for a period of 14 days. The body weight of each rat was observed on day 0 (pre treatment), 7^thand 14^th(post treatment). The necropsy was performed on all animals at the termination of the study.The test compound applied at the dose level of 2000 mg/kg b.wt in Wistar albino rats did not show any clinical signs of toxicity throughout the observation period of 14 days.  Furthermore, no mortality was observed throughout the period of observation (14 days). The necropsy was performed on all animals at the termination of the study did not show any gross pathological changes.

CONFIRMATORY TEST:

After 72 hrs, a confirmatory test was conducted in same species of animals to confirm the limit test of test compound (OECD-402 guidelines).

Ten healthy Wistar albino rats of both sex (ranging b.wt 200±20 gm) selected for study after acclimatization. Approximate 10 percent back skin of total body surface area was prepared 24 hrs prior to application of test compound. The test chemicalwas applied dermally at the dose level of 2000 mg/kg b.wt for each animal. The treated animals were observed for clinical signs of intoxicationand mortality at different time interval for a period of 14 days. The body weight of each rat was observed on day 0 (pre treatment), 7^thand 14^th(post treatment). The necropsy was performed on all animals at the termination of the study.

Mortality & clinical signs

The test chemicaldid not produce any mortality at the tested dose level of 2000 mg/kg b.wt in wistar albino rats throughout the period of observation.Furthermore,the test compound did not elicit any clinical signs of toxicity during the entire the observation period.

Body weight

The body weight of each animal treated with test compound observed on day 0^th(pre treatment) and then 7^thand 14^th(post treatment) showed normal gain as compared to day 0.

Necropsy finding

Necropsy was conducted on day 15^th(end of study) did not reveal any significant gross pathological changes related to compound toxicity.

Conclusion

Result obtained from present investigation can be concluded that the test chemicalis acutely non toxic at the tested dose level of 2000 mg/kg b.wt in wistar albino rats when applied by dermal route and the acute dermal LD₅₀of test chemicalwas consideredto be more than 2000 mg/kg b.wt. (> 2000 mg/kg b.wt.).

2.The acute dermal toxicity profile of test chemical in Sprague Dawley rats. The test item was applied to shorn skin of 5 male and 5 female animals at 2000 mg/kg body weight. Administration of the test item at 2000 mg/kg did not result in any skin reaction at the site of application during the study period of 14 days. Administration of the test item did not result in any signs of toxicity and mortality during the study period of 14 days. Animals exhibited normal body weight gain through the study period of 14 days.Gross pathological examination did not reveal any abnormalities attributable to the treatment. Hence, The LD50 value was considered to be >2000 mg/kg bw,when male and female Sprague Dawley rats were semiocclusively treated with test chemical  by dermal application following 14 days of observation period according to OECD Guideline 402 (Acute Dermal Toxicity).

Thus, based on the above summarised studies,1H-benzimidazole (CAS no.:51-17-2)and it’s structurally and functionally similar read across substances, it can be concluded that LD50 value is greater than 2000 mg/kg bw. Thus, comparing this value with the criteria of CLP regulation,1H-benzimidazole (CAS no.:51-17-2)cannot be classified for acute dermal toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Quality of whole database:

Data is Klimisch 1 and from study report

Additional information

Acute oral toxicity:

In different studies, 1H-benzimidazole (CAS no 51-71-2) has been investigated for acute oral toxicity to a greater or lesser extent. Often are the studies based on in vivo experimental and estimations in rodents, i.e. most commonly in mice and rats for 1H-benzimidazole.The estimated data using the Danish (Q)SAR Database has also been compared with the experimental data. The studies are as mentioned below:

In a prediction done by using Danish (Q) SAR Database (2016), rats and mice treated with 1H-benzimidazole in the concentration of 640 mg/kg bw and 960 mg/kg bw orally. 50 % mortality was observed in treated rats at 640 mg/kg bw and in mice at 960 mg/kg bw. Therefore, Estimated LD50 was considered to be 640 mg/kg bw for rat and 960 mg/kg bw for mice when mice and rat were treated with 1H-benzimidazole orally.

 

The experimental study mentioned in peer-reviewed journal (2004) for the target chemical 1H-benzimidazole (CAS no 51-71-2)was designed and conducted for acute oral toxicity.In a acute oral toxicity study, Deer Mice (Peromyscus maniculatus) were treated with 1H-benzimidazole administered by gavage using water, corn oil, or 1.0% carbopol as carriers and observed for 3 days. No 50 % mortality were observed in treated mice at 470 mg/kg bw. Therefore, LD50 was considered to be > 470 mg/kg bw when Deer Mice (Peromyscus maniculatus) were treated with 1H-benzimidazole orally by gavage.

The above experimental and predicted studies are contradicted with the study conducted on mice and mentioned in authorised database (2017),handbook (2012) and secondary resource (2018) for the target chemical 1H-benzimidazole (CAS no 51 -71 -2).In a acute oral toxicity study, mice were treated with 1H-benzimidazole orally. 50 % mortality was observed in treated mice at 2910 mg/kg bw. Lungs, Thorax, or Respiration changes were observed in treated mice. Therefore, LD50 was considered to be 2910 mg/kg bw when mice were treated with 1H-benzimidazole orally.

From all the above experimental and predicted studies, maximum number of studies concluded that the LD50 value is between 300-2000 mg/kg bw, with detailed and reliable data. Thus, comparing this value with the criteria of CLP regulation,1H-benzimidazole (CAS no 51 -71 -2) can be classified as ‘Category IV’ of acute oral toxicity.

Acute Inhalation Toxicity: 

1H-benzimidazole (51-17-2) has very low vapour pressure (7.6x10-5 mmHg = 0.01018 Pa.),So the potential for the generation of inhalable vapours is very low. Also the normal conditions of use of this substance will not result in aerosols, particles or droplets of an inhalable size, so exposure to humans via the inhalatory route will be highly unlikely and therefore the acute inhalation toxicity end point was considered for waiver.

Acute Dermal Toxicity:

Data available for the structurally and functionally similar read across chemicals has been reviewed to determine theAcute dermal toxicityof the test chemical1H-benzimidazole (CAS no.:51-17-2).The studies are as mentioned below:

1.The acute dermal toxicity study of test chemicalwas conducted on Wistar albino rats under OECD guideline-402Guideline for Testing of Chemicals.

LIMIT TEST (2000 mg/kg b.wt):

Ten healthy wistar albino rats of both sex (ranging b.wt 200±20 gm) selected for study after acclimatization. Approximate 10 percent back skin of total body surface area was prepared 24 hrs prior to application of test compound. The test chemicalwas applied dermally at the dose level of 2000 mg/kg b.wt for each animal. The treated animals were observed for clinical signs of intoxication and mortality at different time interval for a period of 14 days. The body weight of each rat was observed on day 0 (pre treatment), 7thand 14th(post treatment). The necropsy was performed on all animals at the termination of the study.The test compound applied at the dose level of 2000 mg/kg b.wt in Wistar albino rats did not show any clinical signs of toxicity throughout the observation period of 14 days.  Furthermore, no mortality was observed throughout the period of observation (14 days). The necropsy was performed on all animals at the termination of the study did not show any gross pathological changes.

CONFIRMATORY TEST:

After 72 hrs, a confirmatory test was conducted in same species of animals to confirm the limit test of test compound (OECD-402 guidelines).

Ten healthy Wistar albino rats of both sex (ranging b.wt 200±20 gm) selected for study after acclimatization. Approximate 10 percent back skin of total body surface area was prepared 24 hrs prior to application of test compound. The test chemicalwas applied dermally at the dose level of 2000 mg/kg b.wt for each animal. The treated animals were observed for clinical signs of intoxicationand mortality at different time interval for a period of 14 days. The body weight of each rat was observed on day 0 (pre treatment), 7thand 14th(post treatment). The necropsy was performed on all animals at the termination of the study.

Mortality & clinical signs:

The test chemicaldid not produce any mortality at the tested dose level of 2000 mg/kg b.wt in wistar albino rats throughout the period of observation.Furthermore,the test compound did not elicit any clinical signs of toxicity during the entire the observation period.

Body weight:

The body weight of each animal treated with test compound observed on day 0th(pre treatment) and then 7thand 14th(post treatment) showed normal gain as compared to day 0.

Necropsy finding:

Necropsy was conducted on day 15th(end of study) did not reveal any significant gross pathological changes related to compound toxicity.

Conclusion:

Result obtained from present investigation can be concluded that the test chemicalis acutely non toxic at the tested dose level of 2000 mg/kg b.wt in wistar albino rats when applied by dermal route and the acute dermal LD50of test chemicalwas consideredto be more than 2000 mg/kg b.wt. (> 2000 mg/kg b.wt.).

2.The acute dermal toxicity profile of test chemical in Sprague Dawley rats. The test item was applied to shorn skin of 5 male and 5 female animals at 2000 mg/kg body weight. Administration of the test item at 2000 mg/kg did not result in any skin reaction at the site of application during the study period of 14 days. Administration of the test item did not result in any signs of toxicity and mortality during the study period of 14 days. Animals exhibited normal body weight gain through the study period of 14 days.Gross pathological examination did not reveal any abnormalities attributable to the treatment. Hence, The LD50 value was considered to be >2000 mg/kg bw,when male and female Sprague Dawley rats were semiocclusively treated with test chemical  by dermal application following 14 days of observation period according to OECD Guideline 402 (Acute Dermal Toxicity).

Thus, based on the above summarised studies,1H-benzimidazole (CAS no.:51-17-2)and it’s structurally and functionally similar read across substances, it can be concluded that LD50 value is greater than 2000 mg/kg bw. Thus, comparing this value with the criteria of CLP regulation,1H-benzimidazole (CAS no.:51-17-2)cannot be classified for acute dermal toxicity.

Justification for classification or non-classification

Based on the above experimental studies on 1H-benzimidazole (51-17-2) and it’s structurally and functionally similar read across substances, it can be concluded that LD50 value is between 300-2000 mg/kg bw for acute oral toxicity and >2000 mg/kg bw for dermal toxicity.Thus, comparing this value with the criteria of CLP regulation, 1H-benzimidazole (51-17-2) can be classified as ‘Category IV’ of acute oral toxicity and cannot be classified for acute dermal toxicity. For Acute inhalation toxicity wavier was added so, not possible to classify.