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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
1992
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: This study was conducted in accordance with GLP and according to OECD guideline 408.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1991
Report Date:
1992

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Qualifier:
according to
Guideline:
other: TSCA (EPA-1985) Subchronic Oral Toxicity - Rodent Test Guidelines, Section 4
GLP compliance:
yes
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): Tripropylene Glycol n-Butyl Ether
- Physical state: Clear liquid
- Analytical purity: 97.7%

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratory, Kingston, NY
- Age at study initiation: 5 weeks
- Weight at study initiation:
- Fasting period before study:
- Housing: Animals were housed in suspended, stainless steel cages with wire mesh floors. Rats were assigned one/cage to test groups
- Diet ( ad libitum): A basal diet of Purina Certified Chow #5002, Purina Mills Inc. St. Louis, Missouri
- Acclimation period: 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): Standard conditions
- Humidity (%): Standard conditions
- Air changes (per hr): Standard conditions
- Photoperiod (hrs dark / hrs light): Standard conditions


Administration / exposure

Route of administration:
oral: drinking water
Vehicle:
water
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
See the attchment-1
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
daily
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
100 mg/kg/day
Basis:
nominal in water
Remarks:
Doses / Concentrations:
350 mg/kg/day
Basis:
nominal in water
Remarks:
Doses / Concentrations:
1000 mg/kg/day
Basis:
nominal in water
No. of animals per sex per dose:
10/sex/dose
Control animals:
yes
Details on study design:
- Dose selection rationale: Dose levels were selected based on the results of the palatability probe study
- Post-exposure recovery period in satellite groups: 4 weeks recovery period

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Once daily
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Prior to start of study and weekly thereafter
BODY WEIGHT: Yes
- Time schedule for examinations: weekly
FOOD CONSUMPTION: weekly
WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): Yes
- Time schedule for examinations: weekly
OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Prior to start of study and at necropsy
- Dose groups that were examined: All dose groups
HAEMATOLOGY: Yes
- Time schedule for collection of blood: After 13 weeks of exposure
- Anesthetic used for blood collection: Yes (Methoxyflurane)
- Animals fasted: Yes
- How many animals: 40 males and 40 females for Regular study. 20 males and 20 females for recovery group
- Parameters checked: RBC, HGB, HCT, PLAT, WBC (Differential count)
CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: After 13 weeks of exposure
- Animals fasted: Yes
- How many animals: 40 males and 40 females for Regular study. 20 males and 20 females for recovery group
- Parameters checked: AP, ALT, AST, CK, BUN, CREAT, TP, ALB, GLOB, CHOL, TRIG, TRILI, Na, K, P, CL, and Ca
URINALYSIS: Yes
- Time schedule for collection of urine: One week prior to necropsy
- Animals fasted: No
- Parameters checked: Specific gravity, pH, Bbilirubin, glucose, protein, ketones, blood, and urobilinogen
NEUROBEHAVIOURAL EXAMINATION: Yes
- Time schedule for examinations: Prior to start to study and approximately monthly intervals throughout the study
- Dose groups that were examined: All dose groups
- Battery of functions tested: sensory activity

Sacrifice and pathology:
GROSS PATHOLOGY: Yes
All surviving rats were presented for necropsy following an overnight fast after approximately 13 weeks on study. Tracheas were exposed and clamped prior to decapitation. Eyes were examined in situ by visual inspection of cornea, lens and other internal components via placement of a moistened glass slide on the corneal surface and illuminating with a fluorescent light. Lungs were distended to an approximately normal inspiratory volume with neutral, phosphate buffered 10 % formalin solution by tracheal instillation using a hand operated syringe. The nasal cavity was flushed by a similar method via pharyngeal duct. Samples of tissues were preserved in formalin

HISTOPATHOLOGY: Yes
Tissues were prepared for light microscopic evaluation by standard procedures, sectioned by 6 µm thick and stained with hematoxylin and eosin. A complete histologic evaluation of all tissues (with the exception of auditory sebaceous gland and bone joint) was made on all control and high dose animals. In addition, microscopic examination of tissues in the lower dose levels included liver, kidneys, adrenals, lungs, and all gross lesions.
Other examinations:
Organ weights: Weights of the brain, heart, liver, kidneys, adrenals, ovaries and testes were recorded .
Statistics:
Descriptive statistics only (means and standard deviations) were reported for feed/water consumption and leukocyte differential counts. Body weights, organ weights, clinical chemistry, appropriate hematology and urinary specific gravity data were evaluated by Bartlett's test for equality of variances. Based on the outcome of Bartlett's test exploratory data analyses were performed by a parametric or nonparametric analysis of variance (ANOVA), followed respectively by Dennett’s test or the Wilcoxon Rank-Sum test with a Bonferroni correction for multiple comparisons. Statistical outliers were identified by a sequential test, but routinely excluded only from other analyses only for documented, scientifically sound reasons, unrelated to treatment.

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
no effects observed
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
no effects observed
Ophthalmological findings:
no effects observed
Haematological findings:
no effects observed
Clinical biochemistry findings:
no effects observed
Urinalysis findings:
no effects observed
Behaviour (functional findings):
no effects observed
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
no effects observed
Histopathological findings: neoplastic:
not examined
Details on results:
CLINICAL SIGNS AND MORTALITY: There were no treatment related alterations in behavior or demeanor were observed in any dose level.

BODY WEIGHT AND WEIGHT GAIN: Body weights for males and females given 1000 mg/kg/day were lower than the controls and were statistically identified throughout most of the exposure period. No statistically significant treatment related effects on body weights were observed in males and females given 350 or 100 mg/kg/day.

FOOD CONSUMPTION: Feed consumption for males and females given 1000 mg/kg/day were slightly decreased throughout the entire exposure period. The decreased feed consumption observed at this dose level and was considered to the decreased growth of these animals. No significant effects on feed consumption was observed in males or females given 350 or 100 mg/kg/day. Feed consumption of males and females in the 1000 mg/kg/day dose group were equal or greater than the controls during the four week recovery period.

WATER CONSUMPTION AND COMPOUND INTAKE:
Water consumption for male and female rats was decreased in a dose related manner at all dose levels throughout most of the exposure period. The lower water consumption of animals given TPnB was attributed to reduced water palatability. The decreased water consumption observed in males and females given 1000 mg/kg/day was considered to have contributed to the decreased growth rate of these high dose animals. The lower water consumption observed at 350 and 100 mg/kg/day was not considered to be biologically significant as body weights were not affected at these dose levels. No differences in water consumption were observed between the control and high dose males and females during 4 week recovery period.

OPHTHALMOSCOPIC EXAMINATION: There were no treatment related effects were seen at any dose level.

HAEMATOLOGY: There were a number statistically significant differences in hematologic parameters of high dose males and females at the end 13 week exposure period and at the end of the 4 week recovery period. These changes included decreased RBC count, HGB concentration, HCT or PLAT count in males in the 13 week and 4 week recovery period. Although shown to be statistically significant, none of these differences were judged to be biologically or toxicologically significant due to minor differences in values and the lack of correlative histopathologic lesions in bone marrow and spleen. All of the values statistically identified were also within historical control values. These differences ascribed to reduced feed consumption and growth secondary to decreased palatability of the drinking water, rather than a toxicologic response to test material administration.

CLINICAL CHEMISTRY: There were a number statistically significant differences in clinical chemistry parameters of males and females in the 350 or 1000 mg/kg/day group following 13 week exposure period and in males and females in the 1000 mg/kg/day group from the 4 week recovery period. The statistically significant decreases in ALT in males and females given 350 and 1000 mg/kg/day, increases in TP, ALB and GLOB in males given 350 and 1000 mg/kg/day, and increase in GLUC in females in the recovery group given 1000 mg/kg/day were within historical control values and considered normal variations in these parameters. The statistically significant decreases in AP and AST activity, rather than the decreases that occurred in this study. Minor but statistically identified increases in cholesterol in males given 350 and 1000 mg/kg/day and females given 1000 mg/kg/day were believed to be secondary alterations associated with changes in liver cell morphology and physiology. The slight but statistically identified increases in Ca and decrease in K in males given 1000 mg/kg/day were interpreted to be within physiologic levels for this electrolyte.

URINALYSIS: Male and female rats given 1000 or 350 mg/kg/day also had apparent increase in the incidence of +++ or ++ protein in the urine when compared to the control group. The increases in specific gravity and urine protein content were not associated with the severity of renal tubular degeneration noted in individual TPnB treated rats, and therefore were not considered of toxicologic significance. Since renal toxicity and reduced renal function would be expected to produce a decrease in specific gravity, the increases in specific gravity observed in males given 1000 mg/kg/day and females given 1000 or 350 mg/kg/day were attributed to the lower water consumption of these animals. In addition, the urine specific gravity of males given 1000 mg/kg/day and females given 1000 or 350 mg/kg/day was within the range of historical control values, which further supports a lack of a significant treatment related effect on this parameter. No effects on urinary parameters were observed in males or females given 100 mg/kg/day.
No effects were attributed to treatment related effect on these parameters of males or females from the 1000 mg/kg/day dose group at the end of 4 week recovery period. The increased incidence of +++ and ++ protein in the urine of high dose males and females from 13 week study was not present following the 4 week recovery period.

NEUROBEHAVIOUR: There were no treatment related alterations in behavior or demeanor were observed in any dose level.

ORGAN WEIGHTS: Treatment related statistically significant increases in absolute and relative liver weights were observed in males given 100, 350, 1000 mg/kg/day and in females given 350 or 1000 mg/kg/day. Absolute and relative kidney weights were statistically increased at 1000 mg/kg/day in males and 350 and 1000 mg/kg/day in females when compared to controls. The changes in adrenal and heart weight were judged to be incidental and random as they were not associated with histopathological alterations. There were no other statistically identified changes in organ weights in the 13-week study.
Statistically significant increases in relative liver and kidney weights in male given 1000 mg/kg/day and absolute and relative kidney weights in female given 1000 mg/kg/day were observed following 4 week recovery period.The effect observed on the adrenals of the males in the 13 week exposure group were not present in 4 week recovery period. All other organ weight changes were considered to be of no toxicological significance as they were not associated with histopathologic alterations.

GROSS PATHOLOGY: Gross pathologic observations of rats given TPnB for 13 weeks followed by a 4 week recovery period shows number of alterations occurred in isolated instances in rats from various treatment groups. None of these observations were interpreted to be treatment related.

HISTOPATHOLOGY: NON-NEOPLASTIC: Effects related to TPnB occurred in the liver and kidneys of male rats given 1000 mg/kg/day and only in liver of females given 1000 mg/kg/day. Liver effects consisted of an increase in size of hepatocytes in centribular region of hepatic lobule and were accompanied by altered staining of the cytoplasm. These effects were accompanied by an increase in liver weight og male and female rats. This alteration was not accompanied by evidence of hepatocellular degeneration and was interpreted to be an adaptive change, possibly associated with the metabolism of TPnB. treatment related histologic liver effects were not observed in rats given 100 or 350 mg/kg/day. A slight increase in the severity of renal tubular degeneration occurred in the kidneys of three of ten males’ rats given 1000 mg/kg/day, as compared to the control male rats. This degree of change represents a minimal difference in severity over that seen in the control male rats. Alterations were not observed in sections of bone marrow or spleen that correlated with the hematologic differences statistically identified in male and female rats given 1000 mg/kg/day.
Liver alterations previously identified in male and female rats given 1000 mg/kg/day for 13 weeks were not present in male and female rats given 1000 mg/kg/day followed by a 4 week period recovery. These data indicate that the liver alteration induced by 1000 mg/kg/day TPnB was reversible. One male given 1000 mg/kg/day dose followed by 4 week recovery period had a greater degree of renal tubular degeneration than occurred in concurrent controls. The incidence was lower than seen in the 13 week study also indicating that the renal lesion was reversible.



Effect levels

Dose descriptor:
NOAEL
Effect level:
1 000 other: mg/kg
Sex:
male/female
Basis for effect level:
other: Overall effects

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion

Conclusions:
Based on results of this study the NOAEL for male and female rats was 1000 mg/kg/day.
Executive summary:

Tripropylene Glycol n-Butyl Ether (TPnB) colorless liquid was administered in the drinking water to groups of 10 male and 10 female Fischer rats at concentrations formulated to provide dose levels of 0, 100. 350 and1000 mg/kg/day. Additional groups of 10 rats per sex were given TPnB in the drinking water for 13 weeks at dose levels of 0 and 1000 mg/kg/day and then were given tap water for a 4 week recovery period.

Rats were received from Charles River Breeding Laboratory, , . .Rats were kept for an acclimatization period of 7 days. Rats were housed singly in stainless steel cages with wire bottoms. A standard laboratory diet of Purina Certified Chow #5002, Purina Mills Inc. St. Louis, Missouri was supplied to rats.

Monitored for effects included general appearance and demeanor, functional observation battery, body weights, feed and water consumption, clinical chemistry, hematology, urinalysis, necropsy, organ weights and histopathology.

Body weights for males and females given 1000 mg/kg/day were lower than the controls and were statistically identified throughout most of the exposure period. No statistically significant treatment related effects on body weights were observed in males and females given 350 or 100 mg/kg/day. There were no treatment related alterations in behavior or demeanors were observed in any dose level.

Feed consumption for males and females given 1000 mg/kg/day were slightly decreased throughout the entire exposure period. The decreased feed consumption observed at this dose level and was considered to the decreased growth of these animals. No significant effect on feed consumption was observed in males or females given 350 or 100 mg/kg/day. Feed consumption of males and females in the 1000 mg/kg/day dose group were equal or greater than the controls during the four week recovery period.

Water consumption for male and female rats was decreased in a dose related manner at all dose levels throughout most of the exposure period. The lower water consumption of animals given TPnB was attributed to reduced water palatability. The decreased water consumption observed in males and females given 1000 mg/kg/day was considered to have contributed to the decreased growth rate of these high dose animals. The lower water consumption observed at 350 and 100 mg/kg/day was not considered to be biologically significant as body weights were not affected at these dose levels. No differences in water consumption were observed between the control and high dose males and females during 4 week recovery period.

There were a number statistically significant differences in hematologic parameters of high dose males and females at the end 13 week exposure period and at the end of the 4 week recovery period. These changes included decreased RBC count, HGB concentration, HCT or PLAT count in males in the 13 week and 4 week recovery period. Although shown to be statistically significant, none of these differences were judged to be biologically or toxicologically significant due to minor differences in values and the lack of correlative histopathologic lesions in bone marrow and spleen. All of the values statistically identified were also within historical control values. These differences ascribed to reduced feed consumption and growth secondary to decreased palatability of the drinking water, rather than a toxicologic response to test material administration.

There were a number statistically significant differences in clinical chemistry parameters of males and females in the 350 or 1000 mg/kg/day group following 13 week exposure period and in males and females in the 1000 mg/kg/day group from the 4 week recovery period. The statistically significant decreases in ALT in males and females given 350 and 1000 mg/kg/day, increases in TP, ALB and GLOB in males given 350 and 1000 mg/kg/day, and increase in GLUC in females in the recovery group given 1000 mg/kg/day were within historical control values and considered normal variations in these parameters. The statistically significant decreases in AP and AST activity, rather than the decreases that occurred in this study. Minor but statistically identified increases in cholesterol in males given 350 and 1000 mg/kg/day and females given 1000 mg/kg/day were believed to be secondary alterations associated with changes in liver cell morphology and physiology. The slight but statistically identified increases in Ca and decrease in K in males given 1000 mg/kg/day were interpreted to be within physiologic levels for this electrolyte.

Male and female rats given 1000 or 350 mg/kg/day also had apparent increase in the incidence of +++ or ++ protein in the urine when compared to the control group. The increases in specific gravity and urine protein content were not associated with the severity of renal tubular degeneration noted in individual TPnB treated rats, and therefore were not considered of toxicologic significance. Since renal toxicity and reduced renal function would be expected to produce a decrease in specific gravity, the increases in specific gravity observed in males given 1000 mg/kg/day and females given 1000 or 350 mg/kg/day were attributed to the lower water consumption of these animals. In addition, the urine specific gravity of males given 1000 mg/kg/day and females given 1000 or 350 mg/kg/day was within the range of historical control values, which further supports a lack of a significant treatment related effect on this parameter. No effects on urinary parameters were observed in males or females given 100 mg/kg/day.

No effects were attributed to treatment related effect on these parameters of males or females from the 1000 mg/kg/day dose group at the end of 4 week recovery period. The increased incidence of +++ and ++ protein in the urine of high dose males and females from 13 week study was not present following the 4 week recovery period.

Treatment related statistically significant increases in absolute and relative liver weights were observed in males given 100, 350, 1000 mg/kg/day and in females given 350 or 1000 mg/kg/day. Absolute and relative kidney weights were statistically increased at 1000 mg/kg/day in males and 350 and 1000 mg/kg/day in females when compared to controls. The changes in adrenal and heart weight were judged to be incidental and random as they were not associated with histopathological alterations. There were no other statistically identified changes in organ weights in the 13-week study.

Statistically significant increases in relative liver and kidney weights in male given 1000 mg/kg/day and absolute and relative kidney weights in female given 1000 mg/kg/day were observed following 4 week recovery period. The effect observed on the adrenals of the males in the 13 week exposure group was not present in 4 week recovery period. All other organ weight changes were considered to be of no toxicological significance as they were not associated with histopathologic alterations.

Gross pathologic observations of rats given TPnB for 13 weeks followed by a 4 week recovery period shows number of alterations occurred in isolated instances in rats from various treatment groups. None of these observations were interpreted to be treatment related.

Effects related to TPnB occurred in the liver and kidneys of male rats given 1000 mg/kg/day and only in liver of females given 1000 mg/kg/day. Liver effects consisted of an increase in size of hepatocytes in centribular region of hepatic lobule and were accompanied by altered staining of the cytoplasm. These effects were accompanied by an increase in liver weight og male and female rats. This alteration was not accompanied by evidence of hepatocellular degeneration and was interpreted to be an adaptive change, possibly associated with the metabolism of TPnB. treatment related histologic liver effects were not observed in rats given 100 or 350 mg/kg/day. A slight increase in the severity of renal tubular degeneration occurred in the kidneys of three of ten males’ rats given 1000 mg/kg/day, as compared to the control male rats. This degree of change represents a minimal difference in severity over that seen in the control male rats. Alterations were not observed in sections of bone marrow or spleen that correlated with the hematologic differences statistically identified in male and female rats given 1000 mg/kg/day.

Liver alterations previously identified in male and female rats given 1000 mg/kg/day for 13 weeks were not present in male and female rats given 1000 mg/kg/day followed by a 4 week period recovery. These data indicate that the liver alteration induced by 1000 mg/kg/day TPnB was reversible. One male given 1000 mg/kg/day dose followed by 4 week recovery period had a greater degree of renal tubular degeneration than occurred in concurrent controls. The incidence was lower than seen in the 13 week study also indicating that the renal lesion was reversible.

Based on results of this study the NOAEL for male and female rats was 1000 mg/kg/day.