Registration Dossier
Registration Dossier
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EC number: 202-409-1 | CAS number: 95-31-8
Endpoint summary
Administrative data
Description of key information
- NOAEL = 100 mg/kg bw/day – equiv. OECD 408 – dietary - Monsanto (1985)
- NOAEL = 1000 mg/kg bw/day – equiv. OECD 407 – dietary – Monsanto (1979)
- LOAEL = 100 mg/kg bw/day – equiv. OECD 407 – gavage – Monsanto (1982)
- NOAEL = 40 mg/kg bw/day – OECD 422 – gavage – MHWJ (1997)
Key value for chemical safety assessment
- Toxic effect type:
- dose-dependent
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:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- other: GLP study, comparable to guideline study
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)
- Principles of method if other than guideline:
- Twenty male and twenty female Sprague-Dawley rates received 0, 100, 300 or 1000 mg N-tert-butylbenzothiazole-2-sulphenamide/kg bw by gavage. The animals were examined for mortality, overt signs of toxicity, body weight and food consumption. Clinical chemistry, haematological and urinalysis determinations were performed. At sacrifice animals were subjected to a complete gross necropsy and a microscopic examination for the control and high dose group performed.
- GLP compliance:
- yes
- Limit test:
- no
- Species:
- rat
- Strain:
- Sprague-Dawley
- Sex:
- male/female
- Details on test animals or test system and environmental conditions:
- The animals were ca. six week of age and weighed 175-213 g for males and 130-159 g for females at the start.
- Route of administration:
- oral: gavage
- Details on route of administration:
- Oral gavage is a commonly applied route of administration for studies of this type.
- Vehicle:
- corn oil
- Details on oral exposure:
- Dosing suspensions were prepared weekly. All animals were administered a constant volume of suspensions (0.5 ml of suspension per 100 g of body weight).
- Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- Samples were analysed weekly using a liquid chromatographic procedure. Analytical results demonstrated that the test material was stable and appropriate dose suspensions had been prepared.
- Duration of treatment / exposure:
- 90 d
- Frequency of treatment:
- daily
- Dose / conc.:
- 0 mg/kg bw/day (nominal)
- Remarks:
- Vehicle control
- Dose / conc.:
- 100 mg/kg bw/day (nominal)
- Remarks:
- Low
- Dose / conc.:
- 300 mg/kg bw/day (nominal)
- Remarks:
- Mid
- Dose / conc.:
- 1 000 mg/kg bw/day (nominal)
- Remarks:
- High
- No. of animals per sex per dose:
- 20 per dose and sex
- Control animals:
- yes, concurrent vehicle
- Details on study design:
- Post-exposure period: no
- Positive control:
- No.
- Observations and examinations performed and frequency:
- Examinations:
Mortality: twice daily observations
Body weight gain and food consumption: determination weekly
Clinical appearance: checked daily
Hematology (total erythrocyte count (RBC), total leukocyte count (WBC), platelets count (Plt), hematocrit (Hct), level of hemoglobin, red blod cell indices (MCV, MCH, MCHC), determination of the leukocyte differential, reticulocyte count
Clinical Chem.: albumin, total protein, blood urea nitrogen (BUN), total bilirubin, direct bilirubin, glucose, glutamic pyruvic transaminase (D-GPT/ALT), alkaline phosphatase, glutamic oxaloacetate transaminase (D-GOT/AST), gamma glutamyl transpeptidase (Gamma-GT, phosphorous, creatine, cholesterol (Chol), calcium, chloride, sodium, potassium and globulin
Urine analysis: pH, urine protein, blood, glucose, ketone, bilirubin, urobilinogen, urine specific gravity - Sacrifice and pathology:
- Organ weights:brain, kidney, liver, testes
Organs prepared: aorta, adrenal glands, bone and bone marrow, brain, epididymis, esophagus, eyes, heart, pancreas, prostate gland, pituitary gland, salivary gland, skin, small intestine, kidneys, colon, lesions, liver, lung, lymph node, mammary gland, muscle, nerve, spinal cord, spleen, stomach, testes, ovaries, thymus, thyroid, parathyroid, trachea, uterus, urinary bladder - Statistics:
- Quantitative data were analyzed by Dunnett's t-test to determine significant differences in treatment values versus control at the 95% confidence level. Organ weight/terminal body weights were analyzed by the Mann-Whitney U test and incidence of microscopic abnormalities with the Fischer exact test, both utilizing the Bonferri Inequality procedure.
- Clinical signs:
- effects observed, treatment-related
- Description (incidence and severity):
- Animals in all treatment groups salivated after dosing and mid and high dose animals salivated prior to dosing or sometimes resisted dosing. High dose females exhibited urine stained abdomens. Other than the above, no clinical signs or abnormal behavior related to treatment were observed. Due to the lack of gross or microscopic findings of gastrointestinal effects, the behavioral reactions were considered to be related to poor palatability of the test material rather than a toxic response.
- Mortality:
- no mortality observed
- Description (incidence):
- All animals survived three months of exposure to the test substance.
- Body weight and weight changes:
- effects observed, treatment-related
- Description (incidence and severity):
- Reduced body weights were noted for males at the middle and highest dose groups (300 and 1000 mg/kg bw/day, respectively). Most affected were the high dose group males with 13 weeks reduction at 99% statistical confidence. Middle group males were affected the final 11 out of 13 weeks, primarily at 95% statistical confidence. Body weights were unaffected for the low dose males (100 mg/kg bw/day) and all three female treatment groups as compared to controls.
There was a linear decrease in terminal body weights of males from Groups 1, 2 and 3. There were, however, essentially no changes in weights of females from treated groups as compared to controls. - Food consumption and compound intake (if feeding study):
- no effects observed
- Description (incidence and severity):
- Similar amounts of food were consumed by both sexes from all three treatment groups when compared to their control groups. Two exceptions were mid dose group males (300 mg/kg/day) at week 9 and high dose males (1,000 mg/kg/day) at week 1, however, these exceptions appear random and are probably not related to exposure with the test item.
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not specified
- Ophthalmological findings:
- not specified
- Haematological findings:
- effects observed, non-treatment-related
- Description (incidence and severity):
- There were several statistically significant changes in mean values for hematologic or serum chemistry parameters. Statistically significant increases in reticulocyte counts occurred in Group 2 males (300 mg/kg bw/d) and Group 3 (1000 mg/kg bw/d) females. These values remained well within normal limits and were of no toxicological significance.
- Clinical biochemistry findings:
- effects observed, treatment-related
- Description (incidence and severity):
- There were several statistically significant changes in mean values for hematologic or serum chemistry parameters. Depressions of SGOT and SGPT at 100 and 1000 mg/kg bw in females were probably artifactual due to high group mean values for these enzymes in control females. When clearly abnormal values for NFOO4 and NFO15 are deleted, a minimal (p 0.05) depression was found affecting only Group 1 females (100 mg/kg bw/d). These changes were not considered to be relevant. Minimal depressions in sodium affected all dose level of females and Group 2 (300 mg/kg bw/d) males. These were within normal range and were not considered to be toxicologically relevant. The only change which may have been biologically relevant was a mild increase in the mean cholesterol value for females from Group 3 (1000 mg/kg bw /d).
- Urinalysis findings:
- effects observed, treatment-related
- Description (incidence and severity):
- Urine specific gravity was increased in males from Group 3 (1000 mg/kg bw) and females from Groups 2 and 3 (300 and 1000 mg/kg bw/d). The increased values for males and females from Group 3 were statistically significant. There were increases in the occurrence of mild ketonuria in male Groups 1, 2 and 3.
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- effects observed, treatment-related
- Description (incidence and severity):
- The only significant changes in absolute organ weights were decreased mean brain weight in females from Group 3 (1000 mg/kg bw/d) and increased mean hepatic weight in females from Group 3 (1000 mg/kg bw/d). Organ to body weight ratios were increased in a dose related manner for all male organs for which weights were obtained (statistically significant in most instances) for Groups 2 and 3. Kidneys to body weight ratios were increased in females from Group 3 (statistically significant) as were liver to body weight ratios in females from Groups 2 and 3 (300 and 1000 mg/kg bw/d).
- Gross pathological findings:
- no effects observed
- Description (incidence and severity):
- There were no gross lesions associated with chemical administration.
- Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- no effects observed
- Description (incidence and severity):
- There were no microscopic lesions with an apparent association with chemical administration.
- Histopathological findings: neoplastic:
- not specified
- Dose descriptor:
- NOAEL
- Effect level:
- 100 mg/kg bw/day (nominal)
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: no adverse effects
- Dose descriptor:
- LOAEL
- Effect level:
- 300 mg/kg bw/day (nominal)
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: decreased body weight in males, increase in urine specific gravity in females
- Key result
- Critical effects observed:
- no
- Conclusions:
- 100 mg/kg bw/day produced no toxicologically significant changes and is therefore set as NOAEL.
The LOAEL is set at 300 mg/kg bw/day, based on decreased body weight in males, an increase in urine specific gravity in females and increase in relative liver and kidney organ weights.
NB. Some parameters (neurobehavioral examinations, endocrine parameters) are not present in the current study when compared to the modern OECD 408 test guideline. A testing proposal is in place for an OECD 443 EOGRTS, which will provide fully up to date data on not only reproduction endpoints but also endocrine and systemic toxicity. - Executive summary:
Study design
The test substance was administered orally by gavage to four groups of 20 male and 20 female Sprague-Dawley rats at doses of 0, 100, 300 or 1000 mg/kg/day for 3 months.
Results
All animals survived the treatment period. changes appearently associated with the test substance exposure at 1000 mg/kg7day included increased urine specific gravity and decreased body weights among males. Females at this dose level had stained abdomens, increased urine specific gravity, elevated cholesterol values, and increased liver weights. Middle dose level (300 mg/kg/day) males had decreased body weight and females had increased urine specific gravity.
Conclusion
100 mg/kg bw/day produced no toxicologically significant changes and is therefore set as NOAEL.
The LOAEL is set at 300 mg/kg bw/day, based on decreased body weight in males, an increase in urine specific gravity in females and increase in relative liver and kidney organ weights.
Reference
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed
- Dose descriptor:
- NOAEL
- 100 mg/kg bw/day
- Study duration:
- subchronic
- Species:
- rat
- Quality of whole database:
- The endpoint is concluded based on a key subchronic toxicity study on TBBS conducted to GLP and test guideline (OECD 408). It has been evaluated to be of good quality (Klimisch score = 1). Further supporting evidence is available from Supporting studies of good quality (Klimisch scores 1 & 2) conducted to test guideline or good scientific principle, and well documented.
Repeated dose toxicity: inhalation - systemic effects
Link to relevant study records
- Endpoint:
- short-term repeated dose toxicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- other information
- Reliability:
- 3 (not reliable)
- Rationale for reliability incl. deficiencies:
- significant methodological deficiencies
- Remarks:
- Accpetable documented study report with restriction (test substance purity not indicated; the study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract was presumably not given. The biologically relevance of findings from this study, especially systemic effects are questionable, whereas local effects noted in the inhalation study could be used for supporting purpose.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
- Principles of method if other than guideline:
- In a four-week pilot inhalation study male and female rats were exposed to the dust atmosphere of Santocure NS 6 (N-tert-butylbenzothiazole-2-sulphenamide) hours per day, 5 days per week for 20 or 21 exposures during a 29-day experimental period. The mean nominal exposure concentrations for groups III, IV and V were 0.058, 0.172 or 0.524 mg/liter, respectively. The equivalent aerodynamic diameter was 8.4 micrometers.
- GLP compliance:
- no
- Limit test:
- no
- Species:
- rat
- Strain:
- Sprague-Dawley
- Sex:
- male/female
- Route of administration:
- inhalation
- Type of inhalation exposure:
- whole body
- Vehicle:
- air
- Mass median aerodynamic diameter (MMAD):
- 8.4 µm
- Remarks on MMAD:
- MMAD / GSD: aerodynamic mass medium diameter: 8.4 micrometer with a geometric standard deviation of 4.31
- Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- The concentration of the airborne dusts in the chamber atmosphere was determined analytically using the fiberglass filter sampling technique.
- Duration of treatment / exposure:
- 4 weeks
- Frequency of treatment:
- 6 hours/day, 5 days/week
- Remarks:
- Doses / Concentrations:
0.0, 0.0024, 0.029, and 0.084 mg/l
Basis: - No. of animals per sex per dose:
- 10 animals per dose and sex
- Control animals:
- yes
- Details on study design:
- Post-exposure period: no
- Positive control:
- None.
- Observations and examinations performed and frequency:
- Clinical signs (ocular and nasal irritation, respiratory distress), body weights, food consumption, clinical chemistry, hematology, biochemistry, urinalysis.
- Sacrifice and pathology:
- At the termination of the study the rats from all groups were sacrificed for gross and histopathological examinations.
- Statistics:
- All statistical analysis compared the treatment group with the control group.
- Clinical signs:
- effects observed, treatment-related
- Description (incidence and severity):
- Nasal irritation was observed in the rats and ranged in severity from slight to marked. The symptom was usually present after exposure and had generally disappeared by the following morning. The severity of nasal irritation appeared to be concentration dependent during the first half of the study, several rats in the highest dose group exhibited an urogenital discharge. This symptom was observed after exposure and was still apparent the following morning. Alopecia was observed in two rats of the highest dose group.
- Mortality:
- no mortality observed
- Body weight and weight changes:
- no effects observed
- Description (incidence and severity):
- No effects.
- Food consumption and compound intake (if feeding study):
- no effects observed
- Description (incidence and severity):
- No effects.
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not specified
- Ophthalmological findings:
- not specified
- Haematological findings:
- no effects observed
- Description (incidence and severity):
- No effects.
- Clinical biochemistry findings:
- effects observed, treatment-related
- Description (incidence and severity):
- at 0.029 and 0.084 mg/l: SGOT values for males and females were significant elevated compared to control (II).
at 0.0024 mg/l: SGOT values were comparable to control all other parameters appeared comparable to one or both control groups. - Urinalysis findings:
- no effects observed
- Description (incidence and severity):
- No effects.
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Description (incidence and severity):
- Some variations in absolute and rel. weights, but the variations did not appear to be dose dependent and there were no compound related microscopic alterations associated with the involved tissue, therefore the biological signifcance of the variations could not be determined
- Gross pathological findings:
- no effects observed
- Description (incidence and severity):
- No gross lesions interpreted as compound induced observed in any animal at necropsy.
- Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- 0.084 mg/l: brown pigments within sinusoidal macrophages in lymph nodes (6/20)was slightly increased when compared to controls (2 control I, 1 control II)concurrent erythrophagocytosis in the lymph nodes was also slightly increased in the Santocure NS treated group (4/20) as compared to controls (0 control T, 1 control II) Very slight to moderate focal to multifocal hepatocellular necrosis was observed in 3/20 animals; an associated acute inflammatory infiltrate was present in 2 of the 3 affected animals. This lesions was not present in controls While the previously described lesions may represent a compound effect, they have been observed in control rats at the facility and therefore the possibility that they are spontaneous in origin cannot be excluded.
The occurence and incidence of all other microscopic lesions were similar to that observed in controls. - Histopathological findings: neoplastic:
- not examined
- Dose descriptor:
- other:
- Effect level:
- 0.029 mg/L air
- Sex:
- male/female
- Basis for effect level:
- other: see 'Remark'
- Remarks on result:
- not measured/tested
- Remarks:
- Effect level not specified
- Critical effects observed:
- not specified
- Conclusions:
- Study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract was presumably not given. The biologically relevance of findings from this study, especially systemic effects are questionable.
- Executive summary:
In a four-week pilot inhalation study male and female rats were exposed to the dust atmosphere of Santocure NS 6 (N-tert-butylbenzothiazole-2-sulphenamide) hours per day, 5 days per week for 20 or 21 exposures during a 29-day experimental period. The mean nominal exposure concentrations for groups III, IV and V were 0.058, 0.172 or 0.524 mg/liter, respectively. The equivalent aerodynamic diameter was 8.4 micrometers.
The study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract was presumably not given. The biologically relevance of findings from this study, especially systemic effects are questionable.
Reference
Nominal concentrations: 0.058, 0.17 and 0.52 mg/l
Analytical concentrations: mean analytical concentrations: 0.0024, 0.029 and 0.084 mg/l
Gravimetric concentrations: mean gravimetric concentrations: 0.0024, 0.028, 0.088 mg/l
Dust particle size distribution analyses: the equivalent aerodynamic mass medium diameter: 8.4 µm , geometric standard deviation of 4.31
Clinical studies Appearance and general behavior: Nasal irritation was observed in the rats and ranged in severity from slight to marked. The symptom was usually present after exposure and had generally disappeared by the following morning. The severity of nasal irritation appeared to be concentration dependent during the first half of the study, several rats in the highest dose group exhibited an urogenital discharge. This symptom was observed after exposure and was still apparent the following morning. Alopecia was observed in two rats of the highest dose group.
Body weights: no effects.
Food consumption: no time or test material related differences were observed.
Hematology: no effects.
Blood chemistry:
at 0.029 and 0.084 mg/l: SGOT values for males and females were significant elevated compared to control (II).
at 0.0024 mg/l: SGOT values were comparable to control all other parameters appeared comparable to one or both control groups.
Urinalysis: no effects.
Gross pathology: No gross lesions interpreted as compound induced observed in any animal at necropsy.
Organ weights: Some variations in absolute and rel. weights, but the variations did not appear to be dose dependent and there were no compound related microscopic alterations associated with the involved tissue, therefore the biological signifcance of the variations could not be determined.
Histopathology: 0.084 mg/l: brown pigments within sinusoidal macrophages in lymph nodes (6/20)was slightly increased when compared to controls (2 control I, 1 control II)concurrent erythrophagocytosis in the lymph nodes was also slightly increased in the Santocure NS treated group (4/20) as compared to controls (0 control T, 1 control II) Very slight to moderate focal to multifocal hepatocellular necrosis was observed in 3/20 animals; an associated acute inflammatory infiltrate was present in 2 of the 3 affected animals. This lesions was not present in controls While the previously described lesions may represent a compound effect, they have been observed in control rats at the facility and therefore the possibility that they are spontaneous in origin cannot be excluded.
The occurence and incidence of all other microscopic lesions were similar to that observed in controls.
Histological examinations of treated animals (highest dose group) of the nasal turbinate area, trachea, lung and olfactory bulb revealed no biologically relevant differences compared to the controls.
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed
- Dose descriptor:
- NOAEC
- 29 mg/m³
- Study duration:
- subacute
- Species:
- rat
- Quality of whole database:
- Klimisch 3 rated study with significant methodological restrictions (test substance purity not indicated; the study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract was presumably not given. Effects noted should be used for supporting purposes only.
Repeated dose toxicity: inhalation - local effects
Link to relevant study records
- Endpoint:
- short-term repeated dose toxicity: inhalation
- Type of information:
- experimental study
- Adequacy of study:
- other information
- Reliability:
- 3 (not reliable)
- Rationale for reliability incl. deficiencies:
- significant methodological deficiencies
- Remarks:
- Accpetable documented study report with restriction (test substance purity not indicated; the study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract was presumably not given. The biologically relevance of findings from this study, especially systemic effects are questionable, whereas local effects noted in the inhalation study could be used for supporting purpose.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 412 (Subacute Inhalation Toxicity: 28-Day Study)
- Principles of method if other than guideline:
- In a four-week pilot inhalation study male and female rats were exposed to the dust atmosphere of Santocure NS 6 (N-tert-butylbenzothiazole-2-sulphenamide) hours per day, 5 days per week for 20 or 21 exposures during a 29-day experimental period. The mean nominal exposure concentrations for groups III, IV and V were 0.058, 0.172 or 0.524 mg/liter, respectively. The equivalent aerodynamic diameter was 8.4 micrometers.
- GLP compliance:
- no
- Limit test:
- no
- Species:
- rat
- Strain:
- Sprague-Dawley
- Sex:
- male/female
- Route of administration:
- inhalation
- Type of inhalation exposure:
- whole body
- Vehicle:
- air
- Mass median aerodynamic diameter (MMAD):
- 8.4 µm
- Remarks on MMAD:
- MMAD / GSD: aerodynamic mass medium diameter: 8.4 micrometer with a geometric standard deviation of 4.31
- Analytical verification of doses or concentrations:
- yes
- Details on analytical verification of doses or concentrations:
- The concentration of the airborne dusts in the chamber atmosphere was determined analytically using the fiberglass filter sampling technique.
- Duration of treatment / exposure:
- 4 weeks
- Frequency of treatment:
- 6 hours/day, 5 days/week
- Remarks:
- Doses / Concentrations:
0.0, 0.0024, 0.029, and 0.084 mg/l
Basis: - No. of animals per sex per dose:
- 10 animals per dose and sex
- Control animals:
- yes
- Details on study design:
- Post-exposure period: no
- Positive control:
- None.
- Observations and examinations performed and frequency:
- Clinical signs (ocular and nasal irritation, respiratory distress), body weights, food consumption, clinical chemistry, hematology, biochemistry, urinalysis.
- Sacrifice and pathology:
- At the termination of the study the rats from all groups were sacrificed for gross and histopathological examinations.
- Statistics:
- All statistical analysis compared the treatment group with the control group.
- Clinical signs:
- effects observed, treatment-related
- Description (incidence and severity):
- Nasal irritation was observed in the rats and ranged in severity from slight to marked. The symptom was usually present after exposure and had generally disappeared by the following morning. The severity of nasal irritation appeared to be concentration dependent during the first half of the study, several rats in the highest dose group exhibited an urogenital discharge. This symptom was observed after exposure and was still apparent the following morning. Alopecia was observed in two rats of the highest dose group.
- Mortality:
- no mortality observed
- Body weight and weight changes:
- no effects observed
- Description (incidence and severity):
- No effects.
- Food consumption and compound intake (if feeding study):
- no effects observed
- Description (incidence and severity):
- No effects.
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not specified
- Ophthalmological findings:
- not specified
- Haematological findings:
- no effects observed
- Description (incidence and severity):
- No effects.
- Clinical biochemistry findings:
- effects observed, treatment-related
- Description (incidence and severity):
- at 0.029 and 0.084 mg/l: SGOT values for males and females were significant elevated compared to control (II).
at 0.0024 mg/l: SGOT values were comparable to control all other parameters appeared comparable to one or both control groups. - Urinalysis findings:
- no effects observed
- Description (incidence and severity):
- No effects.
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Description (incidence and severity):
- Some variations in absolute and rel. weights, but the variations did not appear to be dose dependent and there were no compound related microscopic alterations associated with the involved tissue, therefore the biological signifcance of the variations could not be determined
- Gross pathological findings:
- no effects observed
- Description (incidence and severity):
- No gross lesions interpreted as compound induced observed in any animal at necropsy.
- Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- 0.084 mg/l: brown pigments within sinusoidal macrophages in lymph nodes (6/20)was slightly increased when compared to controls (2 control I, 1 control II)concurrent erythrophagocytosis in the lymph nodes was also slightly increased in the Santocure NS treated group (4/20) as compared to controls (0 control T, 1 control II) Very slight to moderate focal to multifocal hepatocellular necrosis was observed in 3/20 animals; an associated acute inflammatory infiltrate was present in 2 of the 3 affected animals. This lesions was not present in controls While the previously described lesions may represent a compound effect, they have been observed in control rats at the facility and therefore the possibility that they are spontaneous in origin cannot be excluded.
The occurence and incidence of all other microscopic lesions were similar to that observed in controls. - Histopathological findings: neoplastic:
- not examined
- Dose descriptor:
- other:
- Effect level:
- 0.029 mg/L air
- Sex:
- male/female
- Basis for effect level:
- other: see 'Remark'
- Remarks on result:
- not measured/tested
- Remarks:
- Effect level not specified
- Critical effects observed:
- not specified
- Conclusions:
- Study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract was presumably not given. The biologically relevance of findings from this study, especially systemic effects are questionable.
- Executive summary:
In a four-week pilot inhalation study male and female rats were exposed to the dust atmosphere of Santocure NS 6 (N-tert-butylbenzothiazole-2-sulphenamide) hours per day, 5 days per week for 20 or 21 exposures during a 29-day experimental period. The mean nominal exposure concentrations for groups III, IV and V were 0.058, 0.172 or 0.524 mg/liter, respectively. The equivalent aerodynamic diameter was 8.4 micrometers.
The study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract was presumably not given. The biologically relevance of findings from this study, especially systemic effects are questionable.
Reference
Nominal concentrations: 0.058, 0.17 and 0.52 mg/l
Analytical concentrations: mean analytical concentrations: 0.0024, 0.029 and 0.084 mg/l
Gravimetric concentrations: mean gravimetric concentrations: 0.0024, 0.028, 0.088 mg/l
Dust particle size distribution analyses: the equivalent aerodynamic mass medium diameter: 8.4 µm , geometric standard deviation of 4.31
Clinical studies Appearance and general behavior: Nasal irritation was observed in the rats and ranged in severity from slight to marked. The symptom was usually present after exposure and had generally disappeared by the following morning. The severity of nasal irritation appeared to be concentration dependent during the first half of the study, several rats in the highest dose group exhibited an urogenital discharge. This symptom was observed after exposure and was still apparent the following morning. Alopecia was observed in two rats of the highest dose group.
Body weights: no effects.
Food consumption: no time or test material related differences were observed.
Hematology: no effects.
Blood chemistry:
at 0.029 and 0.084 mg/l: SGOT values for males and females were significant elevated compared to control (II).
at 0.0024 mg/l: SGOT values were comparable to control all other parameters appeared comparable to one or both control groups.
Urinalysis: no effects.
Gross pathology: No gross lesions interpreted as compound induced observed in any animal at necropsy.
Organ weights: Some variations in absolute and rel. weights, but the variations did not appear to be dose dependent and there were no compound related microscopic alterations associated with the involved tissue, therefore the biological signifcance of the variations could not be determined.
Histopathology: 0.084 mg/l: brown pigments within sinusoidal macrophages in lymph nodes (6/20)was slightly increased when compared to controls (2 control I, 1 control II)concurrent erythrophagocytosis in the lymph nodes was also slightly increased in the Santocure NS treated group (4/20) as compared to controls (0 control T, 1 control II) Very slight to moderate focal to multifocal hepatocellular necrosis was observed in 3/20 animals; an associated acute inflammatory infiltrate was present in 2 of the 3 affected animals. This lesions was not present in controls While the previously described lesions may represent a compound effect, they have been observed in control rats at the facility and therefore the possibility that they are spontaneous in origin cannot be excluded.
The occurence and incidence of all other microscopic lesions were similar to that observed in controls.
Histological examinations of treated animals (highest dose group) of the nasal turbinate area, trachea, lung and olfactory bulb revealed no biologically relevant differences compared to the controls.
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- NOAEC
- 84 mg/m³
- Study duration:
- subacute
- Species:
- rat
- Quality of whole database:
- Klimisch 3 rated study with significant methodological restrictions (test substance purity not indicated; the study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract was presumably not given. Effects noted should be used for supporting purposes only.
Repeated dose toxicity: dermal - systemic effects
Link to relevant study records
- Endpoint:
- short-term repeated dose toxicity: dermal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Remarks:
- TG compliant study undertaken to GLP.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)
- Deviations:
- yes
- Remarks:
- animals tested: one-half with intact skin, one-half with abraded skin
- Principles of method if other than guideline:
- Santocure NS (N-tert-butylbenzothiazole-2-sulphenamide) was administered by dermal application to 3 groups of 10 male and 10 female rabbits, one-half with intact skin and one-half with abraded skin, five days per week for 3 consecutive weeks at dose levels of 125, 500 or 2000 mg/kg. An identical control group was treated with saline. Criteria evaluated for treatment effect included mortality, pharmacotoxic signs, body weights, dermal irritation, hematological and clinical biochemical determinations, organ weights and macroscopic and selected microscopic evaluation of tissue.
- GLP compliance:
- yes
- Limit test:
- no
- Species:
- rabbit
- Strain:
- New Zealand White
- Sex:
- male/female
- Type of coverage:
- semiocclusive
- Vehicle:
- physiological saline
- Details on exposure:
- The test article, Santocure NS (N-tert-butylbenzothiazole-2-sulphenamide), was ground with a mortar and pesle and then moinstened with saline and mixed into a spreadable paste. It was applied evenly over each test site with a glass stirring rod at dosage levels of 125, 500 or 2000 mg/kg bw.
- Analytical verification of doses or concentrations:
- not specified
- Duration of treatment / exposure:
- 21 d
- Frequency of treatment:
- Five days per week for 3 consecutive weeks.
- Remarks:
- Doses / Concentrations:
0, 125, 500, or 2000 mg/kg bw/d
Basis: - No. of animals per sex per dose:
- Five per sex and dose with intact skin, 5 per sex and dose with abraded skin.
- Control animals:
- yes
- Details on study design:
- Post-exposure period: no
- Observations and examinations performed and frequency:
- Dosing was repeated once daily, five days per week for three consecutive weeks. Individual doses were adjusted weekly based on the body weight obtained at the beginning of each study week.
General observations: rabbits were observed once daily for signs of dermal irritation, daily observations for pharmacotoxic signs and other findings, the rabbits were observed for mortality twice daily.
Body weight: recorded weekly.
Hematology: hemoglobin, hemocrit, erythrocyte count, total leucocyte count, platelet count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), reticulocytes, differential leucocyte count.
Biochemistry: glucose, blood urea nitrogen, serum glutamic oxaloacetic transaminase (SGOT), alkaline phosphatase, albumin, serum glutamic pyruvic transaminase (SGPT), total protein, cacium, cholesterol, total bilirubin, creatinine, lactic dehydrogenase (LDH), sodium, potassium, chloride and globulin. - Sacrifice and pathology:
- Pathology: gross pathology.
Organ weights: liver, kidneys, heart, testes, ovaries, thyroid/parathyroid, adrenals and brain, pituitary.
Histopathology: treated and untreated skin, liver, kidneys and any gross lesions.
Recorded: erythema (score 0 to 3), edema (0 to3), atonia (0 to 3), coriaceousness (0 to 3), fissuring (0 to 3), eschar, exfoliation. - Clinical signs:
- no effects observed
- Description (incidence and severity):
- No effects with the exception of a few spontaneous observations noted in all groups.
- Dermal irritation:
- effects observed, treatment-related
- Description (incidence and severity):
- Dermal irritation: The majority of rabbits in both the control and test groups exhibited no dermal irritation except for the following observations:
control group: a few rabbits exhibited very slight erythema, atonia and desquamation, and red raised areas and dry chappped areas on the shaved backs.
125 mg/kg bw/d: a few rabbits exhibited very slight to slight erythema, very slight desquamation and dry chapped areas on the shaven backs.
500 mg/kg bw/d: a few rabbits exhibited very slight erythema, very slight to slight desquamation and red and chapped areas on the shaven backs 2000 mg/kg bw/d: very slight to slight erythema and desquamation and very slight edema were exhibited by a few rabbits. - Mortality:
- no mortality observed
- Description (incidence):
- No mortality were observed.
- Body weight and weight changes:
- no effects observed
- Food consumption and compound intake (if feeding study):
- not specified
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not specified
- Ophthalmological findings:
- not examined
- Haematological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- Lymphocytes increased, neutrophiles, segmented decreased.
No other differences were noted in any of the treated animals compared to control (one male at 125/mg/kg bw/d and one male at 500 mg/kg bw/d had signs of aregenerative anemia) - Clinical biochemistry findings:
- effects observed, treatment-related
- Description (incidence and severity):
- Statistically significant differences compared to control were noted in:
125 mg/kg bw/d (males): total bilirubin decreased
2000 mg/kg bw/d (males): total bilirubin decreased 2000 mg/kg bw/d (females): LDH decreased no other differences were noted in any treatment group when compared to control - Urinalysis findings:
- not specified
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Description (incidence and severity):
- No statistically significant variations in the organ weights were noted in any of the test groups.
- Gross pathological findings:
- no effects observed
- Description (incidence and severity):
- No treatment related effects on skin at the application site in any of the rabbits from the test groups.
- Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- 2000 mg/kg bw/d: slight to moderate acanthosis and hyperkeratosis.
125, 500 mg/kg bw/d: the intensity of the acanthosis and hyperkeratosis was much less as in the highest dose group or almost similar to that observed in the control group.
Control group and treated animals: dermal inflammatory cell infiltration in all animals control and treated animals; however severity of this lesion was judged to be slightly greater in the 2000 mg/kg bw/d group compared to control. In the other two lower dosage groups, the intensity of this lesion was almost simular to that in the control group
Authors concluded: compound related effects consisting of acanthosis, hyperkeratosis and dermal inflammatory cell infiltrate were seen in the treated skin of rabbits from the 2000 mg/kg bw/d group but not in the two lower dosage groups in which these lesions were judged to be almost similar to those occurring in the control group. - Histopathological findings: neoplastic:
- not examined
- Other effects:
- no effects observed
- Dose descriptor:
- NOAEL
- Remarks:
- systemic
- Effect level:
- > 2 000 mg/kg bw/day
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: No biologically relevant systemic effects
- Dose descriptor:
- NOAEL
- Remarks:
- local
- Effect level:
- 500 mg/kg bw/day (nominal)
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: Acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration in the treated skin of rabbits from the 2000 mg/kg
- Dose descriptor:
- LOAEL
- Remarks:
- local effects
- Effect level:
- 2 000 mg/kg bw/day
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: Acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration in the treated skin of rabbits from the 2000 mg/kg
- Critical effects observed:
- yes
- Lowest effective dose / conc.:
- 2 000 mg/kg bw/day
- System:
- other: skin
- Organ:
- skin
- Treatment related:
- yes
- Dose response relationship:
- yes
- Executive summary:
Study Design
Santocure NS (N-tert-butylbenzothiazole-2-sulphenamide) was administered by dermal application to 3 groups of 10 male and 10 female rabbits, one-half with intact skin and one-half with abraded skin, five days per week for 3 consecutive weeks at dose levels of 125, 500 or 2000 mg/kg. An identical control group was treated with saline. Criteria evaluated for treatment effect included mortality, pharmacotoxic signs, body weights, dermal irritation, hematological and clinical biochemical determinations, organ weights and macroscopic and selected microscopic evaluation of tissue.
Results
No mortality occurred in this study. The majority of rabbits in both the control and test groups appeared nomal with the exception of a few rabbits in all dose groups exhibiting occasional spontaneous pharmatoxic signs. No statistical significance was noted in body weights. No remarkable changes or differences in dermal irritation were observed between control and test groups. Statistically significant changes in hematological values occured in the 500 mg/kg males in lymphocytes and segmented neutrophils. A few statistically significant changes occurred in the biochemical values; 125 and 2000 mg/kg males showed a decrease in total bilirubin and 2000 mg/kg females showed a decrease in LDH.
No compound related macroscopic lesions or statistically significant organ weight variations were observed in this study.
Microscopically, compound related lesions consisting of acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration were seen in the treated skin of rabbits from the 2000 mg/kg group. All other microscopic lesions observed were incidental in nature and not related to the application of the test substance.
Conclusion
Based on the results of the study, effects levels were determined as:
NOAEL for systemic effects: > 2000 mg/kg bw/day
NOAEL for local effects: 500 mg/kg bw/day
LOAEL for local effects: 2000 mg/kg bw/day, based on the recording of acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration in the treated skin of rabbits at this dose level.
Reference
General observations: No effects with the exception of a few spontaneous observations noted in all groups (control group: a few rabbits exhibited hair loss around neck in area of collar, right eye: red, swollen and clear discharge, possible anorexia, mucoid diarrhea and brown stain around anogenital region; treated animals: signs of mucoid stool, brown stain around the anogenital region, hair loss on neck in area of collar and soft stool were observed for all of the dosage levels; possible nasal congestion, diarrhea, mucoid diarrhea, soft stool, clear ocular discharge, possible anorexia and a spontaneous injury to back (impaired use hind leg) were also exhibited in the test groups.
Mortality: No mortality were observed.
Dermal irritation: The majority of rabbits in both the control and test groups exhibited no dermal irritation except for the following observations:
control group: a few rabbits exhibited very slight erythema, atonia and desquamation, and red raised areas and dry chappped areas on the shaved backs.
125 mg/kg bw/d: a few rabbits exhibited very slight to slight erythema, very slight desquamation and dry chapped areas on the shaven backs.
500 mg/kg bw/d: a few rabbits exhibited very slight erythema, very slight to slight desquamation and red and chapped areas on the shaven backs 2000 mg/kg bw/d: very slight to slight erythema and desquamation and very slight edema were exhibited by a few rabbits.
Body weights: No effects
Hematology: 500 mg/kg bw/d (males):
Lymphocytes increased, neutrophiles, segmented decreased.
no other differences were noted in any of the treated animals compared to control (one male at 125/mg/kg bw/d and one male at 500 mg/kg bw/d had signs of aregenerative anemia).
Biochemistry: Statistically significant differences compared to control were noted in:
125 mg/kg bw/d (males): total bilirubin decreased.
2000 mg/kg bw/d (males): total bilirubin decreased 2000 mg/kg bw/d (females): LDH decreased no other differences were noted in any treatment group when compared to control.
Macroscopic pathology: No treatment related effects on skin at the application site in any of the rabbits from the test groups.
Organ weights: No statistically significant variations in the organ weights were noted in any of the test groups.
Histopathology:
2000 mg/kg bw/d: slight to moderate acanthosis and hyperkeratosis.
125, 500 mg/kg bw/d: the intensity of the acanthosis and hyperkeratosis was much less as in the highest dose group or almost similar to that observed in the control group.
Control group and treated animals: dermal inflammatory cell infiltration in all animals control and treated animals; however severity of this lesion was judged to be slightly greater in the 2000 mg/kg bw/d group compared to control. In the other two lower dosage groups, the intensity of this lesion was almost simular to that in the control group
Authors concluded: compound related effects consisting of acanthosis, hyperkeratosis and dermal inflammatory cell infiltrate were seen in the treated skin of rabbits from the 2000 mg/kg bw/d group but not in the two lower dosage groups in which these lesions were judged to be almost similar to those occuring in the control group.
Endpoint conclusion
- Endpoint conclusion:
- no adverse effect observed
- Dose descriptor:
- NOAEL
- 2 000 mg/kg bw/day
- Study duration:
- subacute
- Species:
- rabbit
- Quality of whole database:
- The available study is GLP and assigned high quality (Klimisch 1)
Repeated dose toxicity: dermal - local effects
Link to relevant study records
- Endpoint:
- short-term repeated dose toxicity: dermal
- Type of information:
- experimental study
- Adequacy of study:
- key study
- Reliability:
- 1 (reliable without restriction)
- Rationale for reliability incl. deficiencies:
- guideline study
- Remarks:
- TG compliant study undertaken to GLP.
- Qualifier:
- equivalent or similar to guideline
- Guideline:
- OECD Guideline 410 (Repeated Dose Dermal Toxicity: 21/28-Day Study)
- Deviations:
- yes
- Remarks:
- animals tested: one-half with intact skin, one-half with abraded skin
- Principles of method if other than guideline:
- Santocure NS (N-tert-butylbenzothiazole-2-sulphenamide) was administered by dermal application to 3 groups of 10 male and 10 female rabbits, one-half with intact skin and one-half with abraded skin, five days per week for 3 consecutive weeks at dose levels of 125, 500 or 2000 mg/kg. An identical control group was treated with saline. Criteria evaluated for treatment effect included mortality, pharmacotoxic signs, body weights, dermal irritation, hematological and clinical biochemical determinations, organ weights and macroscopic and selected microscopic evaluation of tissue.
- GLP compliance:
- yes
- Limit test:
- no
- Species:
- rabbit
- Strain:
- New Zealand White
- Sex:
- male/female
- Type of coverage:
- semiocclusive
- Vehicle:
- physiological saline
- Details on exposure:
- The test article, Santocure NS (N-tert-butylbenzothiazole-2-sulphenamide), was ground with a mortar and pesle and then moinstened with saline and mixed into a spreadable paste. It was applied evenly over each test site with a glass stirring rod at dosage levels of 125, 500 or 2000 mg/kg bw.
- Analytical verification of doses or concentrations:
- not specified
- Duration of treatment / exposure:
- 21 d
- Frequency of treatment:
- Five days per week for 3 consecutive weeks.
- Remarks:
- Doses / Concentrations:
0, 125, 500, or 2000 mg/kg bw/d
Basis: - No. of animals per sex per dose:
- Five per sex and dose with intact skin, 5 per sex and dose with abraded skin.
- Control animals:
- yes
- Details on study design:
- Post-exposure period: no
- Observations and examinations performed and frequency:
- Dosing was repeated once daily, five days per week for three consecutive weeks. Individual doses were adjusted weekly based on the body weight obtained at the beginning of each study week.
General observations: rabbits were observed once daily for signs of dermal irritation, daily observations for pharmacotoxic signs and other findings, the rabbits were observed for mortality twice daily.
Body weight: recorded weekly.
Hematology: hemoglobin, hemocrit, erythrocyte count, total leucocyte count, platelet count, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), reticulocytes, differential leucocyte count.
Biochemistry: glucose, blood urea nitrogen, serum glutamic oxaloacetic transaminase (SGOT), alkaline phosphatase, albumin, serum glutamic pyruvic transaminase (SGPT), total protein, cacium, cholesterol, total bilirubin, creatinine, lactic dehydrogenase (LDH), sodium, potassium, chloride and globulin. - Sacrifice and pathology:
- Pathology: gross pathology.
Organ weights: liver, kidneys, heart, testes, ovaries, thyroid/parathyroid, adrenals and brain, pituitary.
Histopathology: treated and untreated skin, liver, kidneys and any gross lesions.
Recorded: erythema (score 0 to 3), edema (0 to3), atonia (0 to 3), coriaceousness (0 to 3), fissuring (0 to 3), eschar, exfoliation. - Clinical signs:
- no effects observed
- Description (incidence and severity):
- No effects with the exception of a few spontaneous observations noted in all groups.
- Dermal irritation:
- effects observed, treatment-related
- Description (incidence and severity):
- Dermal irritation: The majority of rabbits in both the control and test groups exhibited no dermal irritation except for the following observations:
control group: a few rabbits exhibited very slight erythema, atonia and desquamation, and red raised areas and dry chappped areas on the shaved backs.
125 mg/kg bw/d: a few rabbits exhibited very slight to slight erythema, very slight desquamation and dry chapped areas on the shaven backs.
500 mg/kg bw/d: a few rabbits exhibited very slight erythema, very slight to slight desquamation and red and chapped areas on the shaven backs 2000 mg/kg bw/d: very slight to slight erythema and desquamation and very slight edema were exhibited by a few rabbits. - Mortality:
- no mortality observed
- Description (incidence):
- No mortality were observed.
- Body weight and weight changes:
- no effects observed
- Food consumption and compound intake (if feeding study):
- not specified
- Food efficiency:
- not specified
- Water consumption and compound intake (if drinking water study):
- not specified
- Ophthalmological findings:
- not examined
- Haematological findings:
- effects observed, treatment-related
- Description (incidence and severity):
- Lymphocytes increased, neutrophiles, segmented decreased.
No other differences were noted in any of the treated animals compared to control (one male at 125/mg/kg bw/d and one male at 500 mg/kg bw/d had signs of aregenerative anemia) - Clinical biochemistry findings:
- effects observed, treatment-related
- Description (incidence and severity):
- Statistically significant differences compared to control were noted in:
125 mg/kg bw/d (males): total bilirubin decreased
2000 mg/kg bw/d (males): total bilirubin decreased 2000 mg/kg bw/d (females): LDH decreased no other differences were noted in any treatment group when compared to control - Urinalysis findings:
- not specified
- Behaviour (functional findings):
- not examined
- Immunological findings:
- not examined
- Organ weight findings including organ / body weight ratios:
- no effects observed
- Description (incidence and severity):
- No statistically significant variations in the organ weights were noted in any of the test groups.
- Gross pathological findings:
- no effects observed
- Description (incidence and severity):
- No treatment related effects on skin at the application site in any of the rabbits from the test groups.
- Neuropathological findings:
- not examined
- Histopathological findings: non-neoplastic:
- effects observed, treatment-related
- Description (incidence and severity):
- 2000 mg/kg bw/d: slight to moderate acanthosis and hyperkeratosis.
125, 500 mg/kg bw/d: the intensity of the acanthosis and hyperkeratosis was much less as in the highest dose group or almost similar to that observed in the control group.
Control group and treated animals: dermal inflammatory cell infiltration in all animals control and treated animals; however severity of this lesion was judged to be slightly greater in the 2000 mg/kg bw/d group compared to control. In the other two lower dosage groups, the intensity of this lesion was almost simular to that in the control group
Authors concluded: compound related effects consisting of acanthosis, hyperkeratosis and dermal inflammatory cell infiltrate were seen in the treated skin of rabbits from the 2000 mg/kg bw/d group but not in the two lower dosage groups in which these lesions were judged to be almost similar to those occurring in the control group. - Histopathological findings: neoplastic:
- not examined
- Other effects:
- no effects observed
- Dose descriptor:
- NOAEL
- Remarks:
- systemic
- Effect level:
- > 2 000 mg/kg bw/day
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: No biologically relevant systemic effects
- Dose descriptor:
- NOAEL
- Remarks:
- local
- Effect level:
- 500 mg/kg bw/day (nominal)
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: Acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration in the treated skin of rabbits from the 2000 mg/kg
- Dose descriptor:
- LOAEL
- Remarks:
- local effects
- Effect level:
- 2 000 mg/kg bw/day
- Based on:
- test mat.
- Sex:
- male/female
- Basis for effect level:
- other: Acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration in the treated skin of rabbits from the 2000 mg/kg
- Critical effects observed:
- yes
- Lowest effective dose / conc.:
- 2 000 mg/kg bw/day
- System:
- other: skin
- Organ:
- skin
- Treatment related:
- yes
- Dose response relationship:
- yes
- Executive summary:
Study Design
Santocure NS (N-tert-butylbenzothiazole-2-sulphenamide) was administered by dermal application to 3 groups of 10 male and 10 female rabbits, one-half with intact skin and one-half with abraded skin, five days per week for 3 consecutive weeks at dose levels of 125, 500 or 2000 mg/kg. An identical control group was treated with saline. Criteria evaluated for treatment effect included mortality, pharmacotoxic signs, body weights, dermal irritation, hematological and clinical biochemical determinations, organ weights and macroscopic and selected microscopic evaluation of tissue.
Results
No mortality occurred in this study. The majority of rabbits in both the control and test groups appeared nomal with the exception of a few rabbits in all dose groups exhibiting occasional spontaneous pharmatoxic signs. No statistical significance was noted in body weights. No remarkable changes or differences in dermal irritation were observed between control and test groups. Statistically significant changes in hematological values occured in the 500 mg/kg males in lymphocytes and segmented neutrophils. A few statistically significant changes occurred in the biochemical values; 125 and 2000 mg/kg males showed a decrease in total bilirubin and 2000 mg/kg females showed a decrease in LDH.
No compound related macroscopic lesions or statistically significant organ weight variations were observed in this study.
Microscopically, compound related lesions consisting of acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration were seen in the treated skin of rabbits from the 2000 mg/kg group. All other microscopic lesions observed were incidental in nature and not related to the application of the test substance.
Conclusion
Based on the results of the study, effects levels were determined as:
NOAEL for systemic effects: > 2000 mg/kg bw/day
NOAEL for local effects: 500 mg/kg bw/day
LOAEL for local effects: 2000 mg/kg bw/day, based on the recording of acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration in the treated skin of rabbits at this dose level.
Reference
General observations: No effects with the exception of a few spontaneous observations noted in all groups (control group: a few rabbits exhibited hair loss around neck in area of collar, right eye: red, swollen and clear discharge, possible anorexia, mucoid diarrhea and brown stain around anogenital region; treated animals: signs of mucoid stool, brown stain around the anogenital region, hair loss on neck in area of collar and soft stool were observed for all of the dosage levels; possible nasal congestion, diarrhea, mucoid diarrhea, soft stool, clear ocular discharge, possible anorexia and a spontaneous injury to back (impaired use hind leg) were also exhibited in the test groups.
Mortality: No mortality were observed.
Dermal irritation: The majority of rabbits in both the control and test groups exhibited no dermal irritation except for the following observations:
control group: a few rabbits exhibited very slight erythema, atonia and desquamation, and red raised areas and dry chappped areas on the shaved backs.
125 mg/kg bw/d: a few rabbits exhibited very slight to slight erythema, very slight desquamation and dry chapped areas on the shaven backs.
500 mg/kg bw/d: a few rabbits exhibited very slight erythema, very slight to slight desquamation and red and chapped areas on the shaven backs 2000 mg/kg bw/d: very slight to slight erythema and desquamation and very slight edema were exhibited by a few rabbits.
Body weights: No effects
Hematology: 500 mg/kg bw/d (males):
Lymphocytes increased, neutrophiles, segmented decreased.
no other differences were noted in any of the treated animals compared to control (one male at 125/mg/kg bw/d and one male at 500 mg/kg bw/d had signs of aregenerative anemia).
Biochemistry: Statistically significant differences compared to control were noted in:
125 mg/kg bw/d (males): total bilirubin decreased.
2000 mg/kg bw/d (males): total bilirubin decreased 2000 mg/kg bw/d (females): LDH decreased no other differences were noted in any treatment group when compared to control.
Macroscopic pathology: No treatment related effects on skin at the application site in any of the rabbits from the test groups.
Organ weights: No statistically significant variations in the organ weights were noted in any of the test groups.
Histopathology:
2000 mg/kg bw/d: slight to moderate acanthosis and hyperkeratosis.
125, 500 mg/kg bw/d: the intensity of the acanthosis and hyperkeratosis was much less as in the highest dose group or almost similar to that observed in the control group.
Control group and treated animals: dermal inflammatory cell infiltration in all animals control and treated animals; however severity of this lesion was judged to be slightly greater in the 2000 mg/kg bw/d group compared to control. In the other two lower dosage groups, the intensity of this lesion was almost simular to that in the control group
Authors concluded: compound related effects consisting of acanthosis, hyperkeratosis and dermal inflammatory cell infiltrate were seen in the treated skin of rabbits from the 2000 mg/kg bw/d group but not in the two lower dosage groups in which these lesions were judged to be almost similar to those occuring in the control group.
Endpoint conclusion
- Endpoint conclusion:
- adverse effect observed
- Dose descriptor:
- NOAEL
- 6 mg/cm²
- Study duration:
- subacute
- Species:
- rabbit
- Quality of whole database:
- The available study is GLP and assigned high quality (Klimisch 1)
Additional information
Repeated dose toxicity: oral
The repeated dose toxicity of TBBS was evaluated in several feeding studies and a gavage study. These are summarised below.
1. Monsanto 1985: Dietary subchronic toxicity study (key, K1)
In a subchronic study similar to OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents) 20 male and 20 female rats received 0, 100, 300, and 1000 m/kg bw/day in corn oil vehicle (Monsanto, 1985).
All animals survived three months of exposure to the test substance. Animals in all treatment groups salivated after dosing and mid and high dose animals salivated prior to dosing or sometimes resisted dosing. High dose females exhibited urine stained abdomens. Other than the above, no clinical signs or abnormal behaviour related to treatment were observed. Due to the lack of gross or microscopic findings of gastrointestinal effects, the behavioural reactions were considered to be related to poor palatability of the test material rather than a toxic response.
Reduced body weights were noted for males at the middle and highest dose groups (300 and 1000 mg/kg bw/day, respectively). Most affected were the high dose group males with a significant reduction over 13 weeks of exposure. Mid-dose group (300 mg/kg bw/day) males were affected the final 11 out of 13 weeks. Body weights were unaffected for the low dose males (100 mg/kg bw/day) and all three female treatment groups as compared to controls. Similar amounts of food were consumed by both sexes from all three treatment groups when compared to their control groups.
Notable changes in absolute organ weights were decreased mean brain weight in females from Group 3 (1000 mg/kg bw/day) and increased mean hepatic weight in females from Group 3 (1000 mg/kg bw/day). Organ to body weight ratios were increased in a dose related manner for all male organs for which weights were obtained (statistically significant in most instances) for Groups 2 and 3. Kidneys to body weight ratios were increased in females from Group 3 (statistically significant) as were liver to body weight ratios in females from Groups 2 and 3 (300 and 1000 mg/kg bw/day). There were no gross or microscopic lesions with an apparent association to the test item. No test substance-related adverse effects on the reproductive organs were indicated.
There were several statistically significant changes in mean values for hematologic or serum chemistry parameters. However, the only change which may have been biologically relevant was a mild increase in the mean cholesterol value for females from Group 3 (1000 mg/kg bw /day). Urine specific gravity was increased in males from Group 3 (1000 mg/kg bw/day) and females from Groups 2 and 3 (300 and 1000 mg/kg bw/day). The increased values for males and females from Group 3 were statistically significant. There were increases in the occurrence of mild ketonuria in male Groups 1, 2 and 3.
The NOAEL was 100 mg/kg bw/day. The LOAEL was 300 mg/kg bw/day based on decreased body weight in males, an increase in urine specific gravity in females and increase in relative liver and kidney organ weights.
In this study, some parameters (neurobehavioral examinations, endocrine parameters) are not present in the current study when compared to the modern OECD 408 test guideline. A testing proposal is in place for an OECD 443 EOGRTS, which will provide fully up to date data on not only reproduction endpoints but also endocrine and systemic toxicity. (information current as of January 2023).
2. Monsanto 1979: Dietary subacute toxicity study (supp, K2)
In a 28-day feeding dose range finding study (Monstanto, 1979) 5 Sprague Dawley rats per dose and sex received 0, 100, 300, 1000, and 3000 mg//kg bw/day TBBS. The rats were observed daily for signs of toxicity and mortality. Detailed observations, and individual body weights and food consumption were recorded weekly.
1/5 females of the 3000 mg/kg bw/day group died (during week 2 of the study). There were no further mortalities. No change in clinical observations was noted between control and dosed animals up to 1000 mg/kg bw/day.
At 3000 mg/kg bw/day, marked decreases in body weight and food consumption were observed in male and female animals (body weight males -44.4 %, females -20%; food consumption males -43 %, females -26.5%). In males dosed at 1000 mg/kg bw/day a decrease in body weight gain was observed (male -11.3%, female -2.2%). At necropsy, no compound-related gross lesions were observed.
No compound-related gross pathologic lesions were seen at necropsy in rats up to 1000 mg/kg bw/day. The NOAEL was 1000 mg/kg bw/day, and the LOAEL at 3000 mg/kg bw/day based on significant bodyweight decrease and severity of clinical observations.
3. Monsanto 1982: Dietary Subacute toxicity study (supp, K2)
In a 30-day range finding study similar in design to OECD 407 (Monsanto, 1982), rats 5 per dose and sex received 0,10, 50, 300, 1000, 3000 mg/kg bw/day TBBS via gavage, using corn oil as a vehicle. The highest dose was not tolerated; all animals were found dead or sacrificed moribund during the first week of the study. No other deaths occurred during the study. Clinical observations at the high dose included anogenital staining, distention of the abdomen, tremors and a reduction in fecal production (and food consumption). At 1000 and 300 mg/kg bw/day, several animals were observed with anogenital staining, and post-dose salivation (a common observation in gavage studies).
In male animals, decreases in body weight gain and food consumption were observed at all dose levels above 100 mg/kg bw/day. These led to a mean reduction in body weight gain of 5 and 12 % in animals dosed at 300 and 1000 mg/kg bw/day, respectively. No bodyweight effects were observed in female animals. In male and female animals dosed at 1000 mg/kg bw/day, significant reduction in food consumption was observed in week 1 (19% and 9%, respectively), improving through the following weeks. In males, food consumption did not recover to levels comparable with controls. However, in females, food consumption surpassed that of control at termination of the study.
At doses > 100 mg/kg bw/day, absolute and relative liver weights and liver:brain weight ratio were elevated in females but not males. In males and females elevated absolute and relative kidney weights, kidney to brain weight ratio at 100 mg/kg bw/day were observed. A LOAEL of 100 mg/kg bw was noted based on an increased absolute and relative kidney weights (females) and reduced absolute and relative heart weights (males). In males at 100, 300, 1000 mg/kg bw/day and females at 1000 mg/kg bw/day reduced absolute and relative heart weights, reduced heart to brain weight ratio were observed. Testis weights were elevated at 1000 mg/kg bw/day.
The LOAEL was set at 100 mg/kg bw/day, based on a decrease in heart weight in female animals.
4. MHWJ 1997: Gavage Subacute toxicity study (supp, K2)
TBBS was studied for oral toxicity in rats in an OECD 422 combined repeat dose and reproductive/developmental toxicity screening test at doses of 0, 40, 200 or 1000 mg/kg bw/day. The test item was administered via gavage, in 5% gum arabic vehicle. Males were exposed for 42 days, and females from 14 days prior to mating until day 3 of lactation. Clinical observations, body weight, food consumption, hematology, clinical chemistry, gross pathology and histopathology were recorded.
In the males, temporary salivation after each administration was observed at doses ≥ 200 mg/kg. At 1000 mg/kg bw/day, suppression of food consumption and body weight gain was recorded. At autopsy after 42 days treatment, the number of animals with eosinophilic bodies in the kidney was increased in all treated groups, with dose-related increases in degree of markedness. In conjunction, an increase in absolute and relative kidney weights was noted in the 1000 mg/kg bw/day group. Although slight hypertrophy of hepatocytes in the central zone was observed in groups dosed ≥ 200 mg/kg bw/day, test-item related increases in relative liver weight were only present in the 1000 mg/kg bw/day group. Decrease in fatty change of hepatocytes in the periportal zone was also observed in the livers of animals dosed at 1000 mg/kg bw/day. In groups dosed ≥ 200 mg/kg bw/day, slight increases in the total bilirubin concentration and dose-dependent increase in hemosiderin deposits in the spleen were observed. In addition, hemoglobin and hematocrit value were slightly decreased and hemolytic anemia was induced in the 1000 mg/kg bw/day group.
In the females, temporary salivation after each administration was observed groups dosed ≥ 200 mg/kg bw/day. Food consumption was decreased in the 1000 mg/kg group prior to mating and during pregnancy. During gestation, this was presented alongside a slight suppression of body weight gain. At autopsy on postpartum day 4, slight vacuolar degeneration in proximal tubules of the kidney was observed at ≥ 200 mg/kg bw/day, as well as slight increase in the relative kidney weight. Slight hypertrophy of hepatocytes in the central zone in animals ≥ 200 mg/kg bw/day and relative liver weights in the 1000 mg/kg bw/day group were found. Deposits of brown pigment in the spleen in the 1000 mg/kg bw/day group tended to increase.
Based on an increase in eosinophilic bodies in the kidney at 40 mg/kg bw/day in male animals, no NOAEL was defined, and the LOAEL was set at this level. For Female animals, a NOAEL of 40 mg/kg/day was identified and a LOAEL of 200 mg/kg bw/day set, based on histopathological changes in the liver and kidney.
It is considered reasonable within the scientific literature to identify eosinophilic bodies as hyaline droplets in α2u-globulin nephropathy in routine toxicity studies, as they have been recognized to be a sequence of changes associated with accumulation of α2u-globulin (Hamamura et. al., 2017). Based on this and the lack of concomitant adverse histology in the kidney (but without confirmatory immunohistochemistry for α2u-globulin) it may be considered that the NOAEL/LOAEL values for male animals are particularly conservative. It is also notable that whilst the incidence of eosinophilic bodies was increased, the severity of lesions was comparable with findings in control animals. Based on this, a NOAEL of 40 mg/kg bw/day for males and females is suggested.
Repeated dose toxicity: inhalation
In a subacute inhalation study (Monsanto Co. 1981) male and female Sprague-Dawley rats were exposed to the dust of TBBS six hours per day, 5 days per week during a 29-day experimental period. The mean nominal exposure concentrations were 0.058, 0.17, 0.52 mg/l (corresponding to mean analytical concentrations of 0.0024, 0.029 and 0.084 mg/l). The equivalent aerodynamic diameter was 8.4 µm with a geometric standard deviation of 4.31. This distribution of TBBS particle sizes was above the recommendations in current inhalation guideline tests. Immediately after some of the 6-hours exposure periods, the rats exhibited nasal irritation in relation to the concentration. By the following morning this symptom had generally disappeared. Urogenital discharge and alopecia were observed in some rats of the highest dose group during the first half of the study. This symptom was observed after exposure and was still apparent the following morning (no more data). The biological relevance of this finding is questionable. No body weight effects were observed and no significant differences in food consumption were revealed. No compound induced gross pathologic lesions or organ weight variations were observed in any animals at necropsy. Haematology and urinalysis were all within the normal rage of variation. Of the blood chemistry parameters measured, SGOT values were significant elevated at 0.029 (males 25 %, females 15 %) and 0.084 mg/ml (males 23 %, females 23 %) as compared to controls. Microscopic evaluations were done for both control groups and the highest dose group (0.084 mg/l); histological data for the low and mid dose groups (0.0024, 0.029 mg/l) are missing. Microscopic lesions were present in lymph nodes (brown pigment in sinusoidal macrophages and liver (focal/multifocal hepatocellular necrosis with inflammation) at low incidences. However, these effects seen in a few high dose group animals were also observed in controls (at lower incidence) from this study or have been observed in control rats from other studies at this facility.
The biological relevance of the increase of SGOT values is questionable because no relevant changes in organ weight was observed and the microscopic lesions noted were of low incidence and were also observed in control rats. In summary, the study is limited concerning the recommended particle-size distribution given in current guidelines. To allow for exposure of all relevant regions of the respiratory tract, aerosols with mass median aerodynamic diameters (MMAD) ranging from 1 to 3 µm are recommended. The MMAD used was above the recommendations given (8.4 µm) and therefore, a limited systemic exposure seems reasonable. Thus, the findings of this study should be used as supporting evidence only.
Repeated dose toxicity: dermal
The test substance TBBS was administered by dermal application to three groups of 10 male and female rabbits, one-half with intact skin and one-half with abraded skin, five days per week for three consecutive weeks at dose levels of 125, 500 and 2000 mg/kg bw and day. An identical control group was treated with saline. Criteria evaluated for treatment effect included mortality, pharmacotoxic signs, body weights, dermal irritation, haematological and clinical biochemical determinations, organ weights and macroscopic and selected microscopic evaluation of tissue. No mortality occurred in this study. The majority of rabbits in both control and test groups appeared normal with the exception of a few rabbits in all groups exhibiting occasional spontaneous pharmacotoxic signs. No statistical significance difference was noted in body weights. No remarkable changes or differences in dermal irritation were observed between the control and test groups. Statistically significant changes in haematological values occurred in the 500 mg/kg bw and day males in lymphocytes and segmented neutrophils. A few statistically significant changes occurred in the biochemical values; 125 and 2000 mg/kg bw and day males showed a decrease in total bilirubin and 2000 mg/kg bw and day females showed a decrease in LDH. No compound related macroscopic lesions or statistically significant organ weight variations were observed in this study. Microscopically, compound-related lesions consisting of acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration were seen in the treated skin of rabbits from the 2000 mg/kg bw and day group. All other microscopic lesions observed were incidental in nature and not related to the application of the test substance (Monsanto Co 1981).
Based on these findings a NOAEL systemic of 2000 mg/kg bw/d and a NOAEL local of 500 mg/kg bw and day are suggested.
In conclusion:
Oral
Several repeated dose gavage toxicity studies were conducted to evaluate the toxicity of the test substance TBBS. Temporary salivation after test substance administration, a reduction of food consumption and body weight gain were noted consistently in the high dose groups. Moreover, an increase in absolute and/or relative kidney and liver weights were noted in treated animals. The increase incidence of eosinophilic bodies in all treated male rats noted in the TG 422 study (MHWJ 1997) was considered as questionable because the incidence was increase but the severity was comparable with findings from the control group.
The subchronic gavage study (90 day-study) is considered to be the most relevant study for risk assessment and thus based on the findings of this study a NOAEL oral of 100 mg/kg bw/day is suggested.
Inhalation
The inhalation toxicity of TBBS was examined in a subacute inhalation study (Monsanto Co. 1981). The study is limited concerning the recommended particle-size distribution given in current guidelines and thus an exposure of all relevant regions of the respiratory tract might not have been given. The biologically relevance of sporadic findings reported, especially systemic effects are questionable. In light of these limitations the data from the oral subchronic toxicity study (NOAEL: 100 mg/kg bw/day, Monsanto 1985) will be used for calculation of the systemic DNEL; whereas local effects noted in the inhalation study will be used as supporting evidence. Based on the fact that signs of nasal irritation observed at clinical examination were reversible, only short in duration and could not be correlated to histopathological effects, no toxicological significance was attached to this finding and thus, no relevant local effects were observed up to 0.084 mg/l.
Dermal
The dermal toxicity of the test substance TBBS was evaluated in a 21-day dermal toxicity study (Monsanto Co. 1981). No death or systemic toxicity was indicated in any of the treated animals. No effects on body weight or dermal irritation were noted. Some incidental changes in haematology and biochemistry was observed. No compound related macroscopic lesions or statistically significant organ weight variations were found in this study. However, microscopically, compound-related lesions consisting of acanthosis, hyperkeratosis, and dermal inflammatory cell infiltration were seen in the treated skin of rabbits from the 2000 mg/kg dose group. Thus, a NOAEL dermal systemic of 2000 mg/kg bw/day and a NOAEL dermal local of 500 mg/kg bw/day were considered.
References:
Hamamura M, Oshikata T, Katoku K, Tsuchitani M, Yamaguchi R. Two types of deposits, hyaline droplets and eosinophilic bodies, associated with α2u-globulin accumulation in the rat kidney. J Toxicol Pathol. 2017 Oct;30(4):275-282. doi: 10.1293/tox.2017-0023. Epub 2017 Jul 8. PMID: 29097837; PMCID: PMC5660949.
Justification for classification or non-classification
Harmonised classification:
The substance has no harmonised classification according to the Regulation (EC) No. 1272/2008 (CLP).
Self-classification:
Based on the current dataset, no classification is required according to the classification criteria of Regulation (EC) No. 1272/2008 (CLP). None of the category members is classified for repeated dose toxicity. An OECD 408 study is planned on category member CBS. The dossier will be updated as soon as the new study becomes available.
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