Triisobutyl phosphate

Repeated dose toxicity: oral

Administrative data

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Data source

Reference

Reference 1

Reference Type:

other company data

Title:

Unnamed

Year:

1991

Report date:

1990

Reference 2

Reference Type:

other company data

Title:

Unnamed

Year:

1990

Report date:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity Study in Rodents)

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

Triisobutyl phosphate

EC Number:

204-798-3

EC Name:

Triisobutyl phosphate

Cas Number:

126-71-6

Molecular formula:

C12H27O4P

IUPAC Name:

triisobutyl phosphate

Specific details on test material used for the study:

- Name of test material: Triisobutyl Phosphate (TIBP)
- Source: Monsanto Chemical Company, 800 North Lindbergh Boulevard, St. Louis, MO 63167
- EHL Substance Identification Code : T890095
- Physical state: Clear, slightly yellow liquid
- Analytical purity: 99.7% (weight)
- Lot/batch No.: 257790

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratory, Portage MI
- Age at study initiation: Approximately six weeks
- Weight at study initiation: Males; 170.0 - 217.9 g. Females; 132.4 - 174.1 g.
- Fasting period before study: not specified
- Housing: Individual stainless steel cages with wire mesh bottoms suspended over paper bedding.
- Diet (e.g. ad libitum): Purina; Mills Certified RODENT CHOW #5002
- Water (ad libitum): St. Louis public water supply
- Acclimation period: Fifteen days (Assigned Lot Number; L89097)

Administration / exposure

Route of administration:

oral: feed

Vehicle:

unchanged (no vehicle)

Details on oral exposure:

PREPARATION OF DOSING SOLUTIONS:
The neat test miaterial was mixed thoroughly with the basal , diet using high speed mixers.

DIET PREPARATION
- Rate of preparation of diet: Approximately weekly
- Mixing appropriate amounts with (Purina Mills): T-1 (200 ppm);. T-2 (1000 ppm); T-3 (5000 ppm)

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Stability of Neat Test Material: Analyses by gas chromatography using a nitrogen/phosphorus detector prior to the first use and after the last use
Diet Mixture Stability: Analysis of T-1 and T-3 level samples stored at room temperature (open container, 7 and 14 days) or kept frozen, closed container, 35 days)
Homogeneity of Diet Mixtures: Analysis of duplicate samples from top, middle and bottom of mixer of T-1 and T-3 diets prepared for the first week of the study
Dietary Level Verification: Gas chromatography with a nitrogen/phosphorus detector, all dietary levels for preparations 1 , 2 and 3; at least one level/week there after.

Duration of treatment / exposure:

13 weeks

Frequency of treatment:

continuous in diet

Doses / concentrations

Doses / concentrations 1

Dose / conc.:

200 ppm

Remarks:

nominal in diet
according to 13.9 mg/kg bw/day in males and 16.8 mg/kg bw/day in females

Doses / concentrations 2

Dose / conc.:

1 000 ppm

Remarks:

nominal in diet
according to 68.4 mg/kg bw/day in males and 84.3 mg/kg bw/day in females

Doses / concentrations 3

Dose / conc.:

5 000 ppm

Remarks:

nominal in diet
according to 346.1 mg/kg bw/day in males and 403.9 mg/kg bw/day in females

No. of animals per sex per dose:

160 (80 males, 80 females); plus 10/sex at pretest.
Groups consisted: 30/sex

Control animals:

yes, concurrent no treatment

Details on study design:

- Dose selection rationale: not specified
- Rationale for animal assignment: Computer randomization by weight

Positive control:

No

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS: Yes
- Time schedule: Checks for Mortality and Moribundity: Twice daily (AM and PM)

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Once weekly

BODY WEIGHT: Yes
- Time schedule for examinations: Once weekly

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study):
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes, weekly
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: Yes, weekly

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Once at pretest, and just prior, to terminal sacrifice
- Dose groups that were examined: All at pretest; all high level and control animals just prior to week 13 sacrifice

HAEMATOLOGY AND CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Pretest and at termination of test material administration
- Anaesthetic used for blood collection: Yes, osterior vena cava of C02-anesthetized
- Animals fasted: Yes
- How many animals: Ten/sex, pretest; ten/sex/level week-13

Sacrifice and pathology:

GROSS PATHOLOGY: Yes
Animals Examined: All
Scheduled Sacrifices: Day 29, Days 91-92 and Day 147

HISTOPATHOLOGY: Yes
Tissues Examined: All retained tissues from control and T-3 levels

Statistics:

The following statistical procedures were used to detect statistically significant differences between treated animals and their respective controls:
- Dunnett's Multiple Comparison Test (two-tailed): Inlife body weights, cumulative body weight changes changes and food consumption
- EHL decision-tree analysis: Hematology data, clinical chemistry data, terminal body weights, absolute organ weights and organ/body weight ratios were evaluated by decision-tree statistical analyses which, depending on the results of tests for normality and homogeneity of variances (Bartlett's Test), utilized either parametric [Dunnett's Test and Linear Regression] or nonparametric [Kruskal-Wallis, Jonckheere's and/or Mann-Whitney Tests] routines to detect differences and analyze for trend.
- Fisher's Exact Test (one-tailed) with Bonferroni Inequality Procedure: Incidence of microscopic lesions
- Other statistical routines used for some data included Grubbs Test to detect outliers

Results and discussion

Results of examinations

Clinical signs:

no effects observed

Description (incidence and severity):

There were no clinical signs considered to be related to administration of the test material.

Mortality:

no mortality observed

Description (incidence):

There were no deaths in this study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

There were no statistically significant differences in group mean body weights of treated animals when compared with controls at any time during the study.

Food consumption and compound intake (if feeding study):

effects observed, non-treatment-related

Description (incidence and severity):

On a grams of food per day (GM/DAY) basis, there was decreased food consumption by both sexes at the highest dose level during the first week of the study (approximately 90% of control mean values for both sexes) and in high level females only during week 13. Food consumption by all treated groups was comparable to or greater than that of controls at all other times of the study.

Ophthalmological findings:

no effects observed

Description (incidence and severity):

There were no lesions observed in treated animals in this study.

Haematological findings:

effects observed, non-treatment-related

Description (incidence and severity):

The only alteration of hematologic parameters considered possibly related to treatment was a decrease in neutrophil counts in T-3 level males (neutrophil counts in T-3 level females were also decreased but were not statistically different from controls). Increased MCH in T-3 level males and MCHC in T-2 and T-3 level males were also statistically different from controls. Changes in parameters (other than neutrophils) were small in magnitude, and in the absence of any other corraborative findings, were of doubtful toxicologic significance.

Clinical biochemistry findings:

effects observed, non-treatment-related

Description (incidence and severity):

The only clinical chemistry alteration considered possibly related to treatment was a statistically significant increase of cholesterol (mean value was 131% of control mean) in T-3 level males. Other small but statistically significant changes included increased chloride in T-3 level females and increased BUN in T-2 level animals of both sexes. These latter changes were not considered related to treatment due to their small magnitude or lack of dose-relationship.

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

There were no organ weight alterations (absolute and/or relative to body weight) considered related to treatment.

Gross pathological findings:

no effects observed

Description (incidence and severity):

There were no gross necropsy findings considered related to treatment.

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

There were no treatment related microscopic lesions observed.

Effect levels

1

Dose descriptor:

NOEL

Effect level:

210 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

female

Basis for effect level:

other: The observed effects, seen at the highest dose level of 5000 mg/kg diet, could not conclusively be determined as toxicological relevant (acc BAuA evaluation of this study 2007).

2

Dose descriptor:

NOEL

Effect level:

170 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male

Basis for effect level:

other: The observed effects, seen at the highest dose level of 5000 mg/kg diet, could not conclusively be determined as toxicological relevant (acc BAuA evaluation of this study 2007).

Target system / organ toxicity

Critical effects observed:

not specified