Registration Dossier

Administrative data

Endpoint:
sub-chronic toxicity: inhalation
Type of information:
migrated information: read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: GLP-Guideline study with acceptable restrictions Publication with summarized results

Data source

Reference
Reference Type:
publication
Title:
Unnamed
Year:
1998

Materials and methods

Test guideline
Qualifier:
according to guideline
Guideline:
OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)
Deviations:
yes
Remarks:
no neurobehaviour, no urine analysis performed, results only given as summary, no detailed data
Principles of method if other than guideline:
A 90-day subchronic inhalation toxicity study was performed on Wistar rats in accordance to OECD testing guidelines to evaluate the toxicological profile of 2-ethylhexanol, potential target organs, and a no-observable-adverse-eect-level (NOAEL).
GLP compliance:
yes
Limit test:
no

Test material

Constituent 1
Chemical structure
Reference substance name:
2-ethylhexan-1-ol
EC Number:
203-234-3
EC Name:
2-ethylhexan-1-ol
Cas Number:
104-76-7
Molecular formula:
C8H18O
IUPAC Name:
2-ethylhexan-1-ol
Details on test material:
- Name of test material (as cited in study report): EH
- CAS No. of test material (as cited in study report): 104-76-7
- Analytical purity: 99.9%

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals or test system and environmental conditions:
TEST ANIMALS
- Source: Dr K. Thomae GmbH, D-88400 Biberach/Riss, Germany
- Age at study initiation: 7 weeks
- Weight at study initiation: males 238 g +/- max 2.3 g; females 170 g +/- max. 2.2 g
- Housing: The animals were kept individually in wire cages in the inhalation chambers. To accustom the animals to the exposure conditions, they were exposed in the inhalation chambers to supply air for 5 days before the exposure period.

During the exposure-free periods, the animals were housed individually in wire cages (type D III, Becker and Co., D-44579 Castrop-Rauxel, Germany)
KLIBA rat/mouse laboratory diet 24-343-4 (Klingentalmühle, AG, CH-4303 Kaiseraugst, Switzerland) and tap water were provided ad lib. during the exposure-free period.

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

The animals were randomly (WTALOC randomization program supplied by Instem) allocated to the test groups and identified by ear tattoos (Klimisch, 1986).

Administration / exposure

Route of administration:
inhalation: vapour
Type of inhalation exposure:
whole body
Vehicle:
clean air
Remarks on MMAD:
MMAD / GSD: not applicable
Details on inhalation exposure:
The different EH inhalation chamber concentrations were achieved by conveying the substance via continuously operating metering pumps to evaporators. For 15, 40 and 120 ppm EH the vapour generation was carried out in a thermostated glass container (maintained at 46.4±50.48C) with a downstream mixing unit. 40 and 120 ppm atmospheres were generated by means of a two-component atomizer using compressed air and evaporation of the EH-aerosol. The warmed air of the control group (45.78C) and the vapour-air mixture of the EH groups were then mixed with the overall stream and distributed to a horizontal-flow whole-body exposure system (inhalation chamber glass/steel construction with volumes of approx. 1.1 m3, manufactured by BASF AG, Ludwigshafen, Germany). In the inhalation chamber of the control group, the exhaust air system was set lower (positive pressure), in the EH inhalation chambers the exhaust air system was set higher than the supply air system (negative pressure). Pressure (mean chamber pressure from -10.2 to 10.1 Pascal) and temperature (mean temperature 23.1ºC to 23.8ºC) were measured continuously. The relative humidity (mean relative humidity 41.8% to 46.2%) was checked and recorded once daily. Samples of the inhalation atmospheres were analysed at intervals of about 15 min by gas chromatography (Hewlett-Packard gas chromatograph Model HP 5880 A with automatic sampler HP 7671 A, FID, column:1 m x 2 mm with 10% Triton_305 on Supelcoport, 102/120 mesh, oven temperature: 120ºC. C15-paraffin was used as the internal standard).
Analytical verification of doses or concentrations:
yes
Details on analytical verification of doses or concentrations:
Analyses of the daily inhalation chamber concentrations revealed that the values obtained closely fit the desired nominal level.
Duration of treatment / exposure:
90 days
Frequency of treatment:
daily, 6 hours per day, 5 days a week
The test groups were exposed to the different concentrations for 6 hr on workdays over a period of 90 days (65 exposures).
Doses / concentrations
Remarks:
Doses / Concentrations:
15, 40 and 120 ppm
Basis:

No. of animals per sex per dose:
10
Control animals:
other: concurrent clean air
Details on study design:
- Dose selection rationale: The highest dose corresponded to the vapour saturation at 20ºC. Higher concentrations are only obtainable as aerosols but are not relevant for occupational areas. The intermediate concentration of 40 ppm and the low concentration of 15 ppm were selected to obtain a concentration-effect relationship and a NOAEL.

Examinations

Observations and examinations performed and frequency:
CAGE SIDE OBSERVATIONS: Yes
- Time schedule: All animals were examined for clinical signs and mortality during exposure and daily in the non-exposure times.

BODY WEIGHT: Yes
- Time schedule for examinations: Individual body weights were recorded at the beginning of the preflow period, 1 day before commencement of the exposure period and then weekly throughout the study. The difference between the body weight on the day of weighing and that of the preceding weighing was calculated as group mean average (body weight gain). This value was defined as body weight change.

FOOD CONSUMPTION: No

OPHTHALMOSCOPIC EXAMINATION: Yes
- Time schedule for examinations: Ophthalmological examinations were carried out prior to the beginning of the preflow period and at the termination of the study using an ophthalmoscope.

HAEMATOLOGY: Yes, blood for clinical pathology testing was collected in randomized order by retro-orbital bleeding.
- Time schedule for collection of blood: on day 94 of the study
- Anaesthetic used for blood collection: Yes (identity) / No / No data
- Animals fasted: Yes / No / No data
- How many animals:
- Parameters checked: white blood cells, red blood cells, haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, platelets, differential blood count, thromboplastin time

CLINICAL CHEMISTRY: Yes, blood for clinical pathology testing was collected in randomized order by retro-orbital bleeding.
- Time schedule for collection of blood: on day 94 of the study
- Animals fasted: Yes / No / No data
- How many animals:
- Parameters checked : (sodium, potassium, chloride, inorganic phosphate, calcium, urea, creatinine, glucose, total bilirubin, total protein, albumin, globulins, triglycerides, cholesterol, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No
Sacrifice and pathology:
At the end of the 90-day exposure period all animals were necropsied and assessed by gross pathology postmortem.
The body weight and the weight of the lungs, liver, kidneys, adrenal glands and testes were determined.
Organs or tissues required by guidelines to be tested as well as all gross lesions were fixed in a 4% formaldehyde solution.
Histological examination and assessment of findings were carried out after histotechnical processing and staining with haematoxylin and eosin.
Other examinations:
For determination of cyanide-insensitive palmitoyl-CoA oxidation (Lazarow, 1981), which was carried out in liver homogenates taken after the animals had been killed, an automatic enzyme analyser (ACP 5040, Eppendorf, Hamburg, Germany) was used. Protein concentrations in liver homogenates were determined (Lowry et al., 1951).
Statistics:
Mean values and standard deviation were calculated for body weight and body weight change, haematological and clinical biochemistry parameters as well as for absolute and relative organ weights. The organ weights were statistically evaluated using the Dunnett's test (Dunnett, 1955 and 1964) for comparison of the exposure groups with the control group. The analysis of variance (Cochran, 1957) with subsequent Dunnett's test (Dunnett, 1955 and 1964) was used to compare body weight, body weight change as well as haematological and clinical biochemistry data of the treatment groups with those of the control group.

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):
no adverse effects
Food consumption and compound intake (if feeding study):
not examined
Food efficiency:
not examined
Water consumption and compound intake (if drinking water study):
not examined
Ophthalmological findings:
no effects observed
Haematological findings:
effects observed, treatment-related
Description (incidence and severity):
no adverse effects
Clinical biochemistry findings:
effects observed, treatment-related
Description (incidence and severity):
no adverse effects
Urinalysis findings:
not examined
Behaviour (functional findings):
not examined
Organ weight findings including organ / body weight ratios:
no effects observed
Gross pathological findings:
no effects observed
Histopathological findings: non-neoplastic:
effects observed, treatment-related
Description (incidence and severity):
non-adverse effects
Histopathological findings: neoplastic:
no effects observed
Details on results:
CLINICAL SIGNS AND MORTALITY
No clinical signs related to the treatment with EH were observed throughout the study period. No deaths were recorded during the study.

BODY WEIGHT AND WEIGHT GAIN
The body weight gain of the female animals of the 40 ppm and 120 ppm exposure groups was decreased in comparison to the control group on day 37. The males of the 15 ppm exposure group showed a statistically significantly higher increase in body weight on day 93 compared to the control group. The differences in body weight/ body weight gain were incidental not dose-related and therefore of no toxicological relevance.

OPHTHALMOSCOPIC EXAMINATION
The ophthalmological examinations revealed no effects associated with the exposure of the animals to the chemical.

HAEMATOLOGY and CLINICAL CHEMISTRY
The haematological or clinical biochemistry investigations showed no changes related to exposure to the chemical (data not shown). The only differences observed were in the values for bilirubin in males exposed to 120 ppm (4.07 mmol/litre compared with 2.99 mmol/litre in the controls) and for glucose in females exposed to 15 ppm (6.98 mmol/litre compared with 7.81 mmol/litre in the controls). Both findings, however, are considered to be of no toxicological significance, since they occurred only in one sex. The changes in the values for bilirubin were only registered in males, for glucose only in females. Additionally, with regard to the value for glucose, no relationship to the administered substance concentration was observed.

ORGAN WEIGHTS
No exposure-related organ weight changes were observed (data not shown).

GROSS PATHOLOGY
There were no macroscopic findings that could be attributed to the treatment with the chemical.

HISTOPATHOLOGY: NON-NEOPLASTIC
All the histomorphological findings were considered to have occurred incidentally and were not associated with the exposure to EH.

Effect levels

open allclose all
Dose descriptor:
NOAEC
Effect level:
120 ppm
Based on:
test mat.
Remarks:
corresponding to the vapour saturation
Sex:
male/female
Basis for effect level:
other: No substance-related adverse effects were observed for body weight, body weight gain, mortality, organ weights, ophthalmoscopy, clinical biochemistry and haematological parameters including clotting time, necropsy and histological examination.
Dose descriptor:
NOAEC
Effect level:
638.4 mg/m³ air
Based on:
test mat.
Remarks:
corresponding to the vapour saturation
Sex:
male/female
Basis for effect level:
other: No substance-related adverse effects were observed for body weight, body weight gain, mortality, organ weights, ophthalmoscopy, clinical biochemistry and haematological parameters including clotting time, necropsy and histological examination.

Target system / organ toxicity

Critical effects observed:
not specified

Any other information on results incl. tables

Cyanide-insensitive palmitoyl-CoA oxidation, a marker for peroxisome proliferation, was found elevated in a subchronic study in Fischer 344 rats after gavage application of 500 mg/kg but not under the conditions of this 90-day subchronic inhalation study.

Applicant's summary and conclusion

Executive summary:

A 90-day subchronic inhalation toxicity study was performed on Wistar rats with 2-ethylhexan-1-ol (CAS No. 104-76-7) in accordance to OECD guideline 413 (Klimisch, 1998). 10 males and 10 females per group were exposed to 2-ethylhexanol vapours at concentrations of 15, 40 and 120 ppm (the latter corresponding to the vapour saturation at 20ºC) 6 hours/day on working days for 90 days. The respective controls inhaled clean air under the same conditions. No substance-related adverse effects were observed for body weight, body weight gain, mortality, organ weights, ophthalmoscopy, clinical biochemistry and haematological parameters including clotting time. There were no findings related to the treatment with 2-ethylhexanol either at necropsy or at histological examination. The highest concentration tested under these conditions (120 ppm) was found to be the NOAEL for male and female rats.