Potassium tert-butanolate

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

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

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Study was conducted according to NTP standard, is well documented and suitable for assessement.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1995

Materials and methods

Principles of method if other than guideline:

Study was performed as a dose-finding study for a 2-yr study.

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-methylpropan-2-ol

EC Number:

200-889-7

EC Name:

2-methylpropan-2-ol

Cas Number:

75-65-0

Molecular formula:

C4H10O

IUPAC Name:

2-methylpropan-2-ol

Details on test material:

- Name of test material (as cited in study report): t-butyl alcohol
- Physical state: clear colorless liquid
- Analytical purity: > 99 %
- Lot/batch No.: F112784
- Stability: bulk chemical is stable for 2 weeks
- Stability under test conditions: The stability of the dose formulations was at least 3 weeks at room temperature when stored in the dark and at least 3 days at room temperature under normal room light.
- Storage condition of test material: it should be protected from light at temperatures up to 60 °C
- Other: t-Butyl alcohol was manufactured by FBC Chemical Corp., Lancaster, NY, USA; On the first, middle, and last mixes, dosage analyses (gas chromatography) both prior to and after dosing confirmed that the dosage formulations were within ±10% of the target concentrations.

Test animals

Species:

mouse

Strain:

B6C3F1

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Frederick Cancer Research Facility (Frederick, MD, USA)
- Age at study initiation: approximately 6 weeks old
- Weight at study initiation: male: 22.3 g; female: 17.5 g
- Housing: single housing
- Diet (e.g. ad libitum): ad libitum
- Water (e.g. ad libitum): deionized water; ad libitum
- Acclimation period/quarantine: 13 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 12-30 °C
- Humidity (%): 31-56 %
- Air changes (per hr): 10/hour
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

oral: drinking water

Vehicle:

water

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS: The solutions were prepared by mixing t-butyl alcohol with deionized water. The stability studies of a 0.5 mg/mL dose formulations were performed by the analytical chemistry laboratory using the technique of gas chromatography. The stability was at least 3 weeks at room temperature when stored in the dark and for at least 3 days at room temperature under normal room light.

Analytical verification of doses or concentrations:

yes

Duration of treatment / exposure:

94-95 days

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
0, 2.5, 5, 10, 20, or 40 mg/mL
Basis:
nominal in water

No. of animals per sex per dose:

10 animals/dose and sex

Control animals:

yes, concurrent vehicle

Details on study design:

- Dose selection rationale: The chosen doses were based on an unpublished 14-day study previously conducted for NTP.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: weekly

BODY WEIGHT: Yes
- Time schedule for examinations: initially, than weekly, and at the end of the study

FOOD EFFICIENCY:
- Body weight gain: Yes

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: weekly

HAEMATOLOGY: Yes
- Time schedule for collection of blood: at the end of the study
- How many animals: all animals
- Parameters checked were: hematocrit, hemoglobin, erythrocytes, mean cell volume, mean cell hemoglobin, mean cell hemoglobin concentration, platelets, reticulocytes, leukocytes, segmented neutrophils, bands, lymphocytes, monocytes, eosinophils


OTHER: Samples were collected to analyse sperm morphology and vaginal cytology from all mice in all exposure groups. Here, sperm count, morphology, and motility were determined. The right cauda, right epididymis, and right testis were weighed. Vaginal samples were collected for up to 7 consecutive days prior to the end of studies from all female animals to analyse vaginal cytology. The parameters were: relative frequency of estrous stages and estrous cycle length.
Organ weights were determined from brain, heart, right kidney, liver, lungs, and thymus
Tissues examined: adrenal gland, bone (marrow, femur, sternum), brain, esophagus, gallbladder, heart, large intestine (cecum, colon, rectum), small intestine (duodenum, jejunum, ileum), kidney, liver, lung, lymph node (mandibular and mesenteric), mammary gland, nose, ovary, pancreas, pituitary gland, parathyroid gland, prostate gland, salivary gland, skin, spleen, stomach (forestomach and glandular stomach), testis (epididymis and seminal vesicle), thymus, thyroid gland, trachea, urinary bladder, and uterus.

Sacrifice and pathology:

Animals were sacrificed by carbon dioxide
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes, on all mice in the 0 and 40 mg/mL groups, on 20 mg/mL male mice, and on one 2.5 mg/mL female mouse

Results and discussion

Results of examinations

Details on results:

CLINICAL SIGNS AND MORTALITY: One vehicle male, and one 2.5 and one 20 mg/mL female died. 6/10 male animals and 4/10 females died at 40 mg/mL. As written by the authors, the deaths of two male and one female at the given dose of 40 mg/mL were attributed to exposure to t-butyl alcohol; all other deaths were considered unrelated to chemical administration. Clinical signs included emaciation, ataxia, and hypoactivity at 40 mg/mL in males and emaciation at 40 mg/mL in females

BODY WEIGHT AND WEIGHT GAIN: Significantly reduced body weight gain occurred in males at 20 mg/mL (30 %) and at 40 mg/mL (54 %) and in females at a concentration of 40 mg/mL (27 %). At a dose of 10 mg/kg, a not significant decrease in body weight gain occurred indicating dose-dependency.

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Resulted in no significant or dose-related changes compared to control group

HAEMATOLOGY: Erythrocyte counts and hemoglobin as well as hematocrit values were minimally increased in male animals at a concentration of 40 mg/mL, and (less consistently) at an applied dose of 20 mg/mL in males and females, suggesting hemoconcentration resulting from slight dehydration.

ORGAN WEIGHTS: Absolute and relative kidney weights at a concentration of 40 mg/mL in females were significantly greater than those of the controls.

HISTOPATHOLOGY: NON-NEOPLASTIC: Hyperplasia of the urinary bladder transitional epithelium was present in all male and three female mice at the dose of 40 mg/mL and in six male animals receiving 20 mg/mL. Chronic inflammation of the urinary bladder could be shown in all males and six females receiving 40 mg/mL and six male animals at 20 mg/mL. But in general, urinary bladder lesions were higher in males than in females.

OTHER FINDINGS: No significant changes regarding sperm morphology or motility or the percentage of time spent in the various estrous cycles occurred; however, estrous cycle length was significantly increased in females receiving 40 mg/mL test substance.

Effect levels

1

Dose descriptor:

NOAEL

Effect level:

ca. 10 other: mg/mL drinking water

Based on:

test mat.

Sex:

male

Basis for effect level:

other: decreased body weight gain

2

Dose descriptor:

NOEL

Effect level:

ca. 10 other: mg/mL drinking water

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: Hyperplasia of the transitional epithelium of the urinary bladder and urinary bladder inflammation, increased hematology data for hemoglobin, hematocrit, and erythrocytes

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Executive summary:

In summary, the urinary tract is the target tissue for t-butyl alcohol toxicity in mice.