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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:
1992
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: see 'Remark'
Remarks:
It was not indicated in the available executive summary if the study was conducted according to an OECD guideline, but the methods described resemble those outlined in OECD guideline 408. It is unkown if the test was performed under GLP conditions. As only an executive summary is available and not the full report, the study was assigned a Klimisch 4 rating.

Data source

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

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
GLP compliance:
not specified
Limit test:
no

Test material

Reference
Name:
Unnamed
Type:
Constituent
Details on test material:
- Name of test material (as cited in study report): 2-ethylhexyl diphenyl phosphate, 50/50 mixture of Santicizer 141 and Disflamoll DPO
Specific details on test material used for the study:
NA

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: No data
- Weight at study initiation: No data
- Housing: In groups of two
- Diet (e.g. ad libitum): Ad libitum
- Water (e.g. ad libitum): Ad libitum

Administration / exposure

Route of administration:
oral: feed
Vehicle:
unchanged (no vehicle)
Details on oral exposure:
PREPARATION OF DOSING SOLUTIONS:
50/50 mixture of test articles was formulated into the diet on a weekly basis.

DIET PREPARATION
- Rate of preparation of diet (frequency): Weekly
- Mixing appropriate amounts with (Type of food): RM1 SQC FG
- Storage temperature of food: No data
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
EHDP/diet formulations were analysed for homogeneiity and stability prior to the study initiation, and EHDP-dietary levels were verified for all exposure level preparations
Duration of treatment / exposure:
90 days
Frequency of treatment:
Continuous
Doses / concentrationsopen allclose all
Remarks:
Doses / Concentrations:
0.001%, 0.005%, 0.010%, 0.025% and 0.625%
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
Males: 1, 3.6, 7.3, 17.3, 463 mg/kg bw/day
Basis:
nominal in diet
Remarks:
Doses / Concentrations:
Females: 1, 4.2, 8.4, 20.8, 532 mg/kg bw/day
Basis:
nominal in diet
No. of animals per sex per dose:
10
Control animals:
yes, plain diet
Details on study design:
- Dose selection rationale: Based on a previous 90-day repeated dose toxicity study with higher dose levels
- Satellite groups: An additional 10 males and 10 females were added to the control and high dose group
- Rationale for selecting satellite groups: To investigate reversibility of liver effects
- Post-exposure recovery period in satellite groups: 28 days
Positive control:
Not included

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS
- Time schedule: No data

BODY WEIGHT:
- Time schedule for examinations: Twice weekly

FOOD CONSUMPTION AND COMPOUND INTAKE:
- Food consumption for each animal determined and mean daily diet consumption: Yes, twice weekly
- Compound intake calculated: Yes

WATER CONSUMPTION:
- Time schedule for examinations: Twice weekly

HAEMATOLOGY:
- Time schedule for collection of blood: Day before autopsy
- Anaesthetic used for blood collection: No data
- Animals fasted: No data
- How many animals: Control and high dose group
- Parameters checked: total RBC count, total WBC count, Hb concentration, mean cell volume, hematocrit, mean cell hemoglobin, mean cell hemoglobin concentration and platelet count

CLINICAL CHEMISTRY:
- Time schedule for collection of blood: Day before autopsy
- Animals fasted: No data
- How many animals: Control and high dose group
- Parameters checked: glucose, urea, total protein, albumin, AlkP, ASAT, ALAT and gamma-GT

URINALYSIS:
- Time schedule for collection of urine: Week 6 and 13
- Metabolism cages used for collection of urine: No data
- Animals fasted: No data
- Parameters checked: pH, glucose, blood, bile salts, ketones, protein and urobilinogen, but also examined for volume, refractive index and sediment
Sacrifice and pathology:
GROSS PATHOLOGY:
Full gross necropsy was performed: External abnormalities or variations in the appearance of viscera were recorded.

Samples of livers of 5 males and 5 females of each group were taken and following parameters were determined: DNA content, palmitoyl-CoA oxidation, protein content, cytochrome P-450, 7-ethoxycoumarin-O-deethylase, 7-ethoxyresorufin-O-deethylase, and lauric acid 11- and 12- hydroxylase.

ORGAN WEIGHTS:
Weights of following organs were recorded:
Adrenal glands, brains, caecum (full and empty), heart, liver, kidneys, spleen, testes and ovaries.

HISTOPATHOLOGY:
Histological examinations were carried out on liver tissue of all groups, on adrenal gland tissue of the 0%, 0.025% and 0.625% groups and on the ovaries from the females of the 0%, 0.010%, 0.025% and 0.625% groups.
Other examinations:
Not performed
Statistics:
Not performed

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Food consumption and compound intake (if feeding study):
effects observed, treatment-related
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
effects observed, treatment-related
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Clinical biochemistry findings:
effects observed, treatment-related
Urinalysis findings:
no effects observed
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Gross pathological findings:
not specified
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY
No mortality was reported.

BODY WEIGHT AND WEIGHT GAIN
Body weight in males and females of the high dose group (0.625% 2-EHDPP in food) was significantly decreased. This also accounted for the recovery group.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
Food intake was significantly decreased for the females in the high dose group.

WATER CONSUMPTION
Water consumption was significantly decreased for the high dose group females.

HAEMATOLOGY
Hb, HCT, MCV was significantly decreased for high dose females, while WBC, lymphocytes and monocytes were significantly increased.
WBC, lymphocytes, monocytes and platelet count was significantly increased for the recovery group.

CLINICAL CHEMISTRY
Blood:
For the high dose group males ASAT was significantly decreased, while protein, albumin and gamma-GT were significantly increased.
For the females, AlkP, ALAT and ASAT were significantly decreased, whie glucose, protein, albumin, urea and gamma-GT were significantly increased.

In the recovery group, gamma-GT was significantly increased.

Liver:
Ethoxy resorufin-O-deethylase was significantly decreased for the males of the 0.025% dose group. This effect may be considered adaptive as it was reversed after 28 days.

DNA was significantly decreased for the high dose group males, while microsomal protein, ethoxy-coumarin-O-deethylase and ethoxy resorufin-O-deethylase were significantly increased.
In females, protein was significantly decreased, microsomal protein, microsomal P-450, ethoxy-coumarin-O-deethylase, ethoxy resorufin-O-deethylase and lauric acid 11-hydroxylase were significantly increased.

ORGAN WEIGHTS
In the 0.025% dose group, relative liver weight was significantly decreased for the males. This effect may be considered an adaptive response as it was reversed after 28 days.

In the high dose group, relative liver, full caecum, empty caecum, brain, kidney, heart and testes weight were significantly increased. For females, relative liver, adrenal, kidney, full caecum and empty caecum weight were significantly increased, while spleen and brain weight were significantly decreased.

In the recovery group, relative brain, full caecum, empty caecum and testes weight were significantly increased for males. For females, brain, liver, kidney and empty caecum weight were significantly increased.

HISTOPATHOLOGY: NON-NEOPLASTIC
In the high dose group males and femals, hypertrophy of the centribular cells of the liver and macrovesicular vacuolisation in the zona fasciculata of the adrenals was observed. For high dose females only, vacuolisation and hypertrophy/hyperplasia of interstitial glandular cells was observed.

Effect levels

open allclose all
Dose descriptor:
NOAEL
Effect level:
20.8 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
female
Basis for effect level:
other: Significant effects on body weight, water and food consumption, clinical chemistry and hematology, organ weights and histopathology in the high dose group (0.625% 2-EHDPP in food)
Dose descriptor:
NOAEL
Effect level:
7.3 mg/kg bw/day (nominal)
Based on:
test mat.
Sex:
male
Basis for effect level:
other: Alterations in liver enzyme activity and weight in the males of the subsequent dose group (0.025% 2-EHDPP in food)

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Concentrations of EHDP in diet were within the range of 10%.

Applicant's summary and conclusion

Conclusions:
Under the conditions of this study, a NOAEL of 7.3 and 20.8 mg/kg bw/day for males and females (0.010% and 0.025% 2-EHDPP in food) was established, due to significant effects on the liver (alterations in liver enzyme activity and weight) in the males of the subsequent dose group (0.025%) and significant effects on body weight, water and food consumption, clinical chemistry and hematology, organ weights and histopathology in the males and females of the highest dose group (0.625%).
Executive summary:

This study (equivalent to OECD 408) was performed to determine the toxicity of 2-ethylhexyl diphenyl phosphate at repeated exposure in rats. Doses of 0.001, 0.005, 0.010, 0.025 and 0.625% were used, corresponding to 1, 3.6, 7.3, 17.3, 463 and 1, 4.2, 8.4, 20.8, 532 mg/kg bw/day for males and females, respectively. Clinical signs, body weight, food and water consumption were recorded, clinical chemistry, haematology and urinalysis were performed, gross pathology and histopathology were performed and organ weights were determined.

No mortality was reported in the study. Males of the 0.025% dose group had significantly increased ethoxyresorufin-O-deethylase levels and a significantly decreased relative liver weight. These effects may be considered adaptive as they were reversible after 28 days. The high dose group (0.625%) males and females showed significant effects on body weight, water and food consumption, clinical chemistry and hematology, organ weights and histopathology.

Under the conditions of this study, a NOAEL of 7.3 and 20.8 mg/kg bw/day for males and females (0.010% and 0.025% 2-EHDPP in food) was established, due to significant effects on the liver (alterations in liver enzyme activity and weight) in the males of the subsequent dose group (0.025%) and significant effects on body weight, water and food consumption, clinical chemistry and hematology, organ weights and histopathology in the males and females of the highest dose group (0.625%).