2-ethylhexyl diphenyl phosphate

Repeated dose toxicity: oral

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

Guideline:

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

GLP compliance:

not specified

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

2-ethylhexyl diphenyl phosphate

EC Number:

214-987-2

EC Name:

2-ethylhexyl diphenyl phosphate

Cas Number:

1241-94-7

Molecular formula:

C20H27O4P

IUPAC Name:

2-ethylhexyl diphenyl phosphate

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 or test system 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 / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
0.001%, 0.005%, 0.010%, 0.025% and 0.625%
Basis:
nominal in diet

Doses / concentrations 2

Remarks:

Doses / Concentrations:
Males: 1, 3.6, 7.3, 17.3, 463 mg/kg bw/day
Basis:
nominal in diet

Doses / concentrations 3

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

1

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)

2

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%).