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EC number: 209-502-6 | CAS number: 583-39-1
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
Endpoint summary
Administrative data
Description of key information
The substance should be classified for specific target organ toxicity after repeated exposure.
Key value for chemical safety assessment
Repeated dose toxicity: via oral route - systemic effects
Link to relevant study records
- Endpoint:
- sub-chronic toxicity: oral
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 2012
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: see 'Remark'
- Remarks:
- A reliable secondary source, summaring 2-mercaptobenzimidazole properties, was used. However, the primary sources were not revisited in order to verify their contents; for this reason reliability score 2 was used. The used secondary source has been updated on 2012; therefore it covers the most updated literature on the substance.
- Qualifier:
- no guideline available
- Principles of method if other than guideline:
- Guideline for the 28-Day Repeat dose toxicity test of chemicals (Japan)
- GLP compliance:
- not specified
- Species:
- rat
- Strain:
- Crj: CD(SD)
- Sex:
- male/female
- Route of administration:
- oral: gavage
- Vehicle:
- CMC (carboxymethyl cellulose)
- Duration of treatment / exposure:
- 28 days
- No. of animals per sex per dose:
- Males, 10 or 15 (0, 40 mg/kg)
Females, 10 or 15 (0, 40 mg/kg) - Dose descriptor:
- NOEL
- Effect level:
- < 1.2 mg/kg diet
- Based on:
- test mat.
- Sex:
- male/female
- Critical effects observed:
- not specified
- Conclusions:
- According to Directive 67/548/EEC and to Regulation (EC) n. 1272/2008, the substance should be classified for specific target organ toxicity after repeated exposure.
Reference
One female receiving 40 mg/kg died on Day 24 of the administration. Suppression of body weight gain was found in males given 12 mg/kg from Day 18, in males given 40 mg/kg from Day 11 and in females given 40 mg/kg from Day 15 of the administration. Lower than normal body weights were continuously obtained for both sexes receiving 40 mg/kg during the recovery period. Lower food consumption was noted for males given 12 mg/kg from Week 2 and for both sexes given 40 mg/kg from Week 1. Lower food consumption values were also continuously obtained for both sexes given 40 mg/kg during the recovery period. Increased urine volume was noted in males given 40 mg/kg, and lower values for urinary specific gravity in males receiving 12 mg/kg or more. Both retuned to normal during the recovery period. On hematological examination, the following changes were found : lower values for platelet and reticulocyte counts and higher MCHC values in males given 12 mg/ kg or more and in females given 40 mg/kg, lower MCV values in males given 12 mg/kg or more, lower RBC counts in females given 12 mg/kg or more, lower values for HCT and prolonged PT in both sexes receiving 40 mg/kg, prolonged APTT in males given 40 mg/kg, and lower WBC counts in females given 40 mg/kg. After the recovery period, lower HCT values and RBC counts were also found in both sexes given 40 mg/kg and in the high dose, respectively, and lower RBC, HGB and WBC count receiving were newly found in males, both sexes and males, respectively, 40 mg/kg. On blood chemical analysis, the following changes were found : lowered values of K in both sexes given 4 mg/kg or more, lowered Ca in males given 4 mg/kg or more, lowered Cl and GOT in both sexes given 12 mg/kg or more, higher TP, BUN, CRE and T-CHO in males receiving 12 mg/kg or more and in the 40 mg/kg females, higher values for γ-GTP and ALB in both sexes given 40 mg/kg, lower values for α2-globulin, and β-globulin TG and IP in males given 12 mg/kg or more, higher values for albumin, the A/G ratio and T-Bil in males receiving 40 mg/kg, higher GLU in females given 40 mg/kg and elevated Na in females receiving 12 mg/kg or more. After the recovery period, decreased GOT and b-globulin were also found in males receiving 40 mg/kg, and increased Na was newly found in males of the same group. Enlargement of thyroids was found in both sexes receiving 4 mg/kg or more at necropsy, and also after the recovery period. Higher values for absolute and relative thyroid weights were found in males receiving 4 mg/kg or more and in females given 12 mg/ kg or more. After the recovery period, elevated values for both parameters were still found, albeit to a lesser extent, in both sexes given 40 mg/kg. On histopathological examination, both sexes receiving 1.2 mg/kg or more showed hyperplasia/hypertrophy of follicular cells in the thyroids. Animals receiving 40 mg/kg showed vacuolization of cortical cells in the adrenal glands. The histopathological changes in the thyroids and adrenal glands were still present although weaker in degree after the recovery period. Based on the above results, we conclude that 2-mercaptobenzimidazole affects the thyroids, hematopoietic functions, and hepatic functions, renal functions. NOELs of 2-mercaptobenzimidazole for 28-day repeat dose oral administration are considered to be less than 1.2 mg/kg for both sexes under the conditions of the present study.
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed
- Study duration:
- subchronic
- Species:
- rat
Repeated dose toxicity: inhalation - systemic effects
Link to relevant study records
- Endpoint:
- sub-chronic toxicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- weight of evidence
- Study period:
- 2012
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- other: see 'Remark'
- Remarks:
- A reliable secondary source, summarising 2-mercaptobenzimidazole properties, was used. However the primary sources were not revisited in order to verify their contents; for this reason reliability score 2 was used. The used secondary source has been updated on 2012; therefore it covers the most updated literature on the substance.
- Qualifier:
- no guideline available
- Principles of method if other than guideline:
- It is not specified
- GLP compliance:
- not specified
- Species:
- rat
- Strain:
- Fischer 344
- Sex:
- not specified
- Route of administration:
- inhalation
- Type of inhalation exposure:
- not specified
- Vehicle:
- not specified
- Details on results:
- Exposure-related histopathologic changes included pituitary cytoplasmic vacuolization, adrenal cortex necrosis, lymphoid depletion, thymic atrophy, liver cell hypertrophy, renal mineralization and tubular atrophy, and hypocellularity of the bone marrow.
- Dose descriptor:
- dose level:
- Effect level:
- >= 25 mg/m³ air
- Based on:
- test mat.
- Sex:
- not specified
- Basis for effect level:
- other: see 'Remark'
- Dose descriptor:
- dose level:
- Effect level:
- >= 6.2 mg/L air
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: Increased thyroid weight and thyroid follicular cell hyperplasia
- Dose descriptor:
- dose level:
- Effect level:
- ca. 3.1 mg/L air
- Based on:
- test mat.
- Sex:
- not specified
- Basis for effect level:
- other: Thyroid follicular cell hyperplasia was also seen in rats at 3.1 mg/m3
- Critical effects observed:
- not specified
- Conclusions:
- According to Directive 67/548/EEC and to Regulation (EC) n. 1272/2008, the substance should be classified for specific target organ toxicity after repeated exposure.
Reference
2-Mercaptobenzimidazole (2-MBI), used in rubber processing, is a suspect carcinogen structurally related to ethylene
thiourea. The inhalation toxicity of 2-MBI was evaluated in male and female F344/N rats exposed 6 hr/day, 5 days/week
to respirable aerosols generated by spray atomization of aqueous suspensions of the 2-MBI powder and subsequent
drying of the resulting aerosols. Twelve exposures at target concentrations of 0, 6.3, 12.5, 25.0, 50.0, or 100 mg/m3 of
2-MBI produced a dose-related reduction in body weight gains, thyroid follicular cell hyperplasia, adrenal cortex fatty
change, and pituitary atrophy. Sub-chronic exposures were conducted at target concentrations of 0, 3.1, 6.2, 12.5, 25.0,
and 50.0 mg/m3 of 2-MBI. Rats at greater than or equal to 25 mg/m3 displayed hunched posture, hypoactivity, and
reduced body weight gain, with compound related mortality at the highest exposure level. Anemia; increased SGPT,
SGOT, alkaline phosphatase, sorbitol dehydrogenase, BUN, and cholesterol; and reduced free fatty acid were seen in
rats at greater than or equal to 25 mg/m3. Increased thyroid weight and thyroid follicular cell hyperplasia were noted in
both sexes at greater than or equal to 6.2 mg/m3, with reduced triiodothyronine and thyroxine levels in both sexes at
greater than or equal to 12.5 mg/m3. Thyroid follicular cell hyperplasia was also seen in rats at 3.1 mg/m3. Thymus
weights were significantly reduced in both sexes at all exposure levels with liver weight increases at greater than or
equal to 6.2 mg/m3. Exposure-related histopathologic changes included pituitary cytoplasmic vacuolization, adrenal
cortex necrosis, lymphoid depletion, thymic atrophy, liver cell hypertrophy, renal mineralization and tubular atrophy, and
hypocellularity of the bone marrow.
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed
- Study duration:
- subchronic
- Species:
- rat
Additional information
The substance should be classified for specific target organ toxicity after oral and inhalation repeated exposure due to thyroid adverse effects.
Justification for selection of repeated dose toxicity via oral route - systemic effects endpoint:
This study shows all necessary information to evaluate the hazard of the substance.
Justification for selection of repeated dose toxicity inhalation - systemic effects endpoint:
This study shows all necessary information to evaluate the hazard of the substance.
Justification for classification or non-classification
According to Directive 67/548/EEC and to Regulation (EC) n. 1272/2008, the substance should be classified for specific target organ toxicity after repeated exposure.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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