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Toxicological information

Repeated dose toxicity: oral

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Administrative data

Endpoint:
short-term repeated dose toxicity: oral
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
weight of evidence
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Acceptable, well documented publication comparable to guideline study with acceptable restrictions. No neurology, opthalmoscopy and urine analysis performed.

Data source

Reference
Reference Type:
publication
Title:
Prechronic Toxicity Studies on 2-Ethylhexanol in F334 Rats and B6C3F1 Mice
Author:
Astill, B.D. et al.
Year:
1996
Bibliographic source:
FUNDAMENTAL AND APPLIED TOXICOLOGY 29, 31-39

Materials and methods

Test guideline
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 408 (Repeated Dose 90-Day Oral Toxicity in Rodents)
Deviations:
yes
Remarks:
no neurology, opthalmoscopy and urine analysis performed
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-Ethylhexanol
- Boiling point: 184-185ºC
- Water solubility: 0.01%
- Analytical purity: 99.8% (GC)

Test animals

Species:
rat
Strain:
Fischer 344
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 36-37 days
- Weight at study initiation: Mean body weight ranges at dosing were (male) 105-114 g and (female) 86-97 g.
- Housing: singly in stainless steel wire cages
- Diet: Kliba rats/mice/hamster maintenance diet, "A" 343 Meal, Klingentalmühle AG, Kaiseraugst, Switzerland, ad libitum
- Water: ad libitum
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20-24
- Humidity (%): 30-70
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:
oral: gavage
Vehicle:
other: Cremophor EL
Details on oral exposure:
Doses were prepared daily by dispersing 2EH in an aqueous solution of Cremophor EL (5 µg/100 mL) by ultra high speed sonication for 1 min. Homogeneity was maintained by magnetic stirring throughout dosing. Dose volumes were 10 mL/kg, based on weekly body weights. Controls were given 5.0 ml/kg of vehicle.
The dose delivery system, established by prior studies in rats and mice (Astill et al., 1993), was oral gavage of an aqueous emulsion of 2EH stabilized by a nonionic surfactant. This system provided the most stable dose formulation and minimized gastrointestinal tract irritation and inflammation.
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Concentrations and homogeneity were checked by gas chromatographic analysis of samples from each dose level periodically.
Duration of treatment / exposure:
13 weeks
Frequency of treatment:
daily on 5 consecutive days per week
Doses / concentrations
Remarks:
Doses / Concentrations:
0, 25, 125, 250, and 500 mg/kg
Basis:

No. of animals per sex per dose:
10
Control animals:
yes, concurrent vehicle
Details on study design:
- Dose selection rationale:
In preliminary subacute studies (11 days) rats were given 0, 100, 330, 1000 and 1500 mg/kg bw/d. Mortality occurred at 1000 and 1500 mg/kg bw/d. The only effects observed at 330 mg/kg were increased relative kidney weights in females, inflammatory edema in the forestomach of one female rat, and a decreased thymus size in males and females. The 11-day dose level free of any treatment-related effects was thus 100 mg/kg.

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: twice daily, or once daily on non-treatment days

DETAILED CLINICAL OBSERVATIONS: Yes
- Time schedule: daily

BODY WEIGHT: Yes
- Time schedule for examinations: weekly

FOOD CONSUMPTION: Yes, weekly

WATER CONSUMPTION AND COMPOUND INTAKE (if drinking water study): No

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: on days 29 and 84
- Animals fasted: Yes
- How many animals:
- Parameters checked: leucocytes, erythrocytes, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, platelets and differential leucocytes, and reticulocytes

CLINICAL CHEMISTRY: Yes
- Time schedule for collection of blood: on days 29 and 84
- Animals fasted: Yes
- How many animals:
- Parameters checked: ALAT, ASAT, gamma-GT, AP, Glucose, Urea, total protein, albumin, Creatinine, Cholesterol, Triglycerides, total bilirubin, sodium, potassium, calcium, chloride

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

ORGAN WEIGHTS: Yes, at termination
Sacrifice and pathology:
Moribund animals were euthanized; dead and euthanized animals were immediately necropsied and assessed grossly.
GROSS PATHOLOGY: Yes, adrenals, brains, kidneys, livers, stomachs, testes, and ovaries from all animals were weighed, and with other organs and tissues listed in U.S. EPA Health Effects Guidelines (1987b) fixed in 4% formalin.
HISTOPATHOLOGY: Yes, All tissues from high dose and control animals were stained with hematoxylin—eosin and examined microscopically.
Lungs, livers (including gallbladders in mice), spleens, kidneys, stomachs, sternums, femurs, and femur bone marrows were examined microscopically at intermediate dose levels. Skin, eyes, female mammary glands, thigh musculatures, and extraorbital lacrymatory glands were not examined in the absence of signs of toxicity. Livers were also stained with oil red for lipid content and examined microscopically.
Statistics:
Means and standard deviations were calculated for body weights, food and water consumption, clinical pathology results, and organ weights. Values for test groups were compared with controls in the main study by ANOVA followed by Dunnett's test (Dunnett, 1955, 1964).

Results and discussion

Results of examinations

Clinical signs:
no effects observed
Mortality:
no mortality observed
Body weight and weight changes:
effects observed, treatment-related
Description (incidence and severity):
decrease in males and females at 500 mg/kg bw/d
Food consumption and compound intake (if feeding study):
no effects observed
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
not examined
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
at 500 mg/kg bw/d increase of reticulocytes
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
females at 250 mg/kg bw/d decrease in serum ALAT
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
effects observed, treatment-related
Description (incidence and severity):
changes at 250 mg/kg bw/d
Gross pathological findings:
effects observed, treatment-related
Description (incidence and severity):
at 500 mg/kg bw/d in forestomach
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
at 500 mg/kg bw/d in liver
Details on results:
CLINICAL SIGNS AND MORTALITY
One female mouse at 250 mg/kg died during treatment; there were no other mortalities or clinical findings differing from controls in rats at any treatment level.

BODY WEIGHT AND WEIGHT GAIN
There was decreased weight gain in male and female rats at 500 mg/kg, starting at Week 4 in males and Week 11 in females, amounting to weight
losses of 7% in males and 6% in females by Week 13.

FOOD CONSUMPTION AND COMPOUND INTAKE (if feeding study)
There were no differences from controls at any treatment level in food consumption in rats.

HAEMATOLOGY
There was a 25% increase in reticulocyte numbers in male and female rats at 500 mg/kg.

CLINICAL CHEMISTRY
Differences from controls in treated rats were seen mostly at 84 days (data not shown). Females at 250 and 500 mg/kg/d had 30 and 36% decreases in serum ALT activities, respectively. Females at 500 mg/kg had a 16% decrease in serum cholesterol concentration and males at 500 mg/kg had 13% decreases in total protein and albumin concentrations.

ORGAN WEIGHTS
Significant differences from controls in rats were moderate and limited to the brain, kidneys, liver, stomach, and testes at 250 and 500 mg/kg. Male rat relative brain weights inincreased by 6% at 500 mg/kg, male kidney weights by 8% at 250 and 16% at 500 mg/kg, male liver weights by 8% at 250 and 29% at 500 mg/kg, male stomach weights by 11% at 500 mg/kg, and testis weights by 5.5% at 500 mg/kg. Female rat kidney weights increased by 5% at 250 and 6% at 500 mg/kg, female liver weights by 8% at 250 and 15% at 500 mg/kg, and female stomach weights by 6% at 250 and 16% at 500 mg/kg.

GROSS PATHOLOGY
Gross lesions differing from controls in both species were seen at 500 mg/kg only. In rats 2/10 males and 4/10 females exhibited single
or multiple slightly elevated foci in the forestomach. There were no other gross findings in either species.

HISTOPATHOLOGY: NON-NEOPLASTIC
Dose-related findings in rats (data not shown) were limited to the forestomach and liver at 500 mg/kg. There was a generalized acanthosis
of the forestomach mucosa in 1/10 males with ballooning degeneration of the epithelial wall and acanthosis of the forestomach mucosa in 2/10 males and 5/10 females. There was a moderate decrease in hepatic peripheral lobular fatty infiltration in 4/10 males and 2/10 females and adrenal beta-cell hyperplasia in 3/10 female rats.

Effect levels

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Dose descriptor:
NOAEL
Effect level:
125 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: no effects on: clinical signs; mortality; body weight; food consumption; haematology; clinical chemistry; gross pathology; organ weights; histopathology;
Dose descriptor:
LOAEL
Effect level:
250 mg/kg bw/day (actual dose received)
Based on:
test mat.
Sex:
male/female
Basis for effect level:
other: decreased serum ALAT and changes in organ weights

Target system / organ toxicity

Critical effects observed:
not specified

Applicant's summary and conclusion