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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
sub-chronic toxicity: oral
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17 Dec 1984 to 27 Feb 1987
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Well reported guideline study
Cross-reference
Reason / purpose:
reference to same study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
1987
Report Date:
1987

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
GLP compliance:
yes (incl. certificate)
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
Test substance: Tributoxyethyl phosphate (TBEP)
Source: Monsanto Industrial Chemicals Ltd
Lot No. MCI NB 21951892
Analytical purity: 98.7%

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Source: Charles River Breeding Laboratory, Portage, MI
- Age at study initiation: 54 days
- Weight at study initiation: 278-337g (males) and 169-219g (females).
- Fasting period before study: no data
- Housing: individually
- Diet: Purina Chow certified rodent Chow No. 5002 ad libitum)
- Water: ad libitum
- Acclimation period: 17 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 21-23
- Humidity (%): 40-60
- Air changes (per hr): no data
- Photoperiod (hrs dark / hrs light): 12/12


IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Feeds containing TBEP were analysed for homogeneity and stability prior to study initiation and were periodically examined throughout the study to verify the target dosage concentrations
Duration of treatment / exposure:
18 weeks
Frequency of treatment:
daily in the diet
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 300, 3000 or 10,000 ppm
Basis:
nominal in diet
No. of animals per sex per dose:
20
Control animals:
yes, concurrent no treatment

Examinations

Observations and examinations performed and frequency:
DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: Mortality/morbidity at least twice daily. Clinical signs at least weekly

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION AND COMPOUND INTAKE :
- Food consumption for each animal determined and mean daily diet consumption calculated as g food/kg body weight/day: Yes
- Compound intake calculated as time-weighted averages from the consumption and body weight gain data: No data


FOOD EFFICIENCY:
- Body weight gain in kg/food consumption in kg per unit time X 100 calculated as time-weighted averages from the consumption and body weight gain data: No data

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: At the start and termination of the study
- Dose groups that were examined: All animals at the start of the study and on all high dose and control animals at termination of the study

HAEMATOLOGY: Yes
- Time schedule for collection of blood: Weeks 9 & 18
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: 10 per sex per group
- Standard parameters were examined.

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: Weeks 9 & 18
- Animals fasted: No data
- How many animals: 10 per sex per group
- Standard parameters were examined.


URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
GROSS PATHOLOGY: Yes
HISTOPATHOLOGY: Yes
Statistics:
Bodyweight, food consumption, non-categorical clinical pathology, absolute organs weight: Dunnett's multiple comparison test (2-tailed); Bartlett's test to evaluate homogeneity of variances.
Relative body weight: Mann-Whitney Statistic and bonferroni inequality
Microscopic lesions: Fisher's exact test with Bonferroni inequality procedure

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):
effects observed, treatment-related
Food efficiency:
not specified
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
effects observed, treatment-related
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Details on results:
CLINICAL SIGNS AND MORTALITY
No clinical signs were reported. Death of one female was not related to treatment

BODY WEIGHT AND WEIGHT GAIN
Weight gain of treated animals was similar to controls

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
During the first week both sexes of the high and intermediate dose groups consumed less diet than controls. Throughout the remaining period all treatment groups concumed amounts of diet similar to the controls.

FOOD EFFICIENCY
no data

OPHTHALMOSCOPIC EXAMINATION
No effects

HAEMATOLOGY
Increased platelet counts (10,000 ppm both sexes)

CLINICAL CHEMISTRY
Increased serum gamma glutamyl transpeptidase and a depressed plasma cholinesterase in the 3000 and 10,000 ppm groups


ORGAN WEIGHTS
Increased liver weight (both absolute and relative in both sexes) was found at the top dose (10,000 ppm),

GROSS PATHOLOGY
No effects reported

HISTOPATHOLOGY: NON-NEOPLASTIC
Mild periportal hepatocellular hypertrophy and periportal vacuolisation in males only at 3000 and 10,000 ppm.

Effect levels

open allclose all
Dose descriptor:
NOEL
Effect level:
300 ppm
Sex:
male/female
Basis for effect level:
organ weights and organ / body weight ratios
Dose descriptor:
LOAEL
Effect level:
3 000 ppm
Sex:
male
Basis for effect level:
other: mild periportal hepatocellular hypertrophy and periportal vacuolisation

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Analyses confirmed both the homogeneity and stability of the low and high dose diets. Dietary analyses verified the following average inclusion rates of TBEP in the diets: 280 ppm (low); 3000 ppm (intermediate); 9,900 ppm (high dose).

Applicant's summary and conclusion

Conclusions:
An 18-week dietary exposure of TBEP to rats at target levels of 300, 3000 and 10,000 ppm resulted in treatment-related effects at the high dose level with minimal effects at the mid-dose level. Based upon the results of this study the No effect level of TBEP in the diet is considered to be at least 300 ppm (equivalent to approximately 20.4 mg/kg bw/day) for both sexes.
TBEP is not classified for repeat-dose toxicity according to the criteria of Annex VI Directive 67/748/EECor UN/EU GHS.
Executive summary:

In a subchronic study of the oral toxicity of TBEP (Reyna, 1987), the test substance was formulated into the diet and was administered to four groups of 20 male and 20 female Sprague-Dawley rats at target dietary concentrations of 0, 300, 3000 and 10,000 ppm for 18-weeks. Rats were 54-days old at the start of the study with an average weight range of 278-337g (males) and 169-219g (females). Feeds containing TBEP were analysed for homogeneity and stability prior to study initiation and were periodically examined throughout the study to verify the target dosage concentrations. Animals were randomly allocated to the treatment or control groups. Water and food was available ad libitum. Mortality/morbidity observations were performed at least twice daily. Bodyweight, food consumption and examination for signs of toxicity were carried out weekly. Ophthalmic examinations were performed on all animals at the start of the study and on all high dose and control animals at termination of the study. On weeks 9 and 18, blood samples were taken from the posterior vena cava of 10 randomly selected rats from each group. After 18 weeks the rats were killed and a detailed post-mortem conducted. Specific tissues/organs and any abnormalities were removed and taken for histology examination.

Analyses confirmed both the homogeneity and stability of the low and high dose diets. Dietary analyses verified the following average inclusion rates of TBEP in the diets: 280 ppm (low); 3000 ppm (intermediate); 9,900 ppm (high dose). There were no ophthalmic lesions attributable to ingestion of TBEP. All treatment group rats gained weight comparable to the controls. During the first week both sexes of the high and intermediate dose groups consumed less diet than controls. Throughout the remaining period all treatment groups consumed amounts of diet similar to the controls. One high dose female died during the study however the death was not attributed to exposure to TBEP. Haematological and clinical chemistry parameters were equivalent in dosed and control rats with the following exceptions: increased platelet counts (10,000 ppm both sexes) and increased serum gamma glutamyl transpeptidase and a depressed plasma cholinesterase in the 3000 and 10,000 ppm groups. Increased liver weight (both absolute and relative in both sexes) was found at the top dose (10,000 ppm), however microscopic examination revealed mild periportal hepatocellular hypertrophy and periportal vacuolisation in males only at 3000 and 10,000 ppm.

The liver was therefore the only target organ in this study, with treatment-related effects at the high dose levelof 10,000 ppm andminimal effects at the mid-dose levelof 3000 ppm. Based upon the results of this study the NOEL is considered to be at least 300 ppm TBEP in the diet (equivalent to approximately 20.4 mg/kg bw/day), for both sexes.

 

TBEP is not classified for repeat-dose toxicity according to the criteria of Annex VI Directive 67/748/EECor UN/EU GHS.