Distillation residue, butyl alcohols production, rectification

Repeated dose toxicity: inhalation

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

Study period:

1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Repeated-dose dermal toxicity, following OECD Guideline 413 (Repeated Dose Toxicity - inhalation), studies performed with the only identified and quantified constituent of the registered substance, 2-ethylhexanol. In the absence of data on the registered substance these studies serve as a good surrogate studies: a) it represents the effects of the only identified and quantified constituent of the substance, since the constituents of this registered UVCB-substance cannot be quantified and its composition varies to the degree that composition cannot be fixed. b) studies have been performed with good quality and data is published in a peer-reviewed journal. c) they provide adequate information on effect levels of 2-ethylhexanol when administered via inhalation route. e) further vertebrate testing should not bo commenced since based on the expected exposure based on the uses of this UVCB-substance to human, low vapour pressure of this substance in ambient temperatures and exposure via inhalation is not expected to be continuous therefore chronic effect levels are sufficient to meet the safe handling of this substance and adopted risk management measures (chapter 9 and 10 of CSR).

Data source

Reference

Reference Type:

publication

Title:

Unnamed

Year:

1998

Report date:

1998

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 413 (Subchronic Inhalation Toxicity: 90-Day Study)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Test material

Test material information

Constituent 1

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

Details on test material:

2-Ethylhexanol (CAS-No. 104-76-7) at a purity grade of 99.9%, as determined by gas chromatography, was used.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

Male and female rats, SPF-Wistar, Chbb: THOM (supplied by Dr K. Thomae GmbH, D-88400 Biberach/Riss, Germany) were used for the study. They were about 7 wk old on delivery. The mean body weight of the male animals was approximately 238 g (standard error of the mean of max. 2.3 g)
and of the female animals 170 g (standard errorof the mean of max. 2.2 g) at the start of the study. 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. The animals were randomly (WTALOC randomization program supplied by Instem) allocated to the test groups and identified by ear tattoos. During the exposure-free periods, the animals were housed individually in wire cages (type DIII, Becker and Co., D-44579 Castrop-Rauxel, Germany) in air-conditioned rooms (temperature range of 20±24 C, relative humidity range of 30-70%). The rooms were maintained with a 12-hr light/12-hr dark cycle. KLIBA rat/mouse laboratory diet 24-343-4 (KlingentalmuÈ hle, AG, CH-4303 Kaiseraugst, Switzerland) and tap water were provided ad lib. during the exposure-free period.

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 test groups were exposed to the different concentrations for 6 hr on workdays over a period of 90 days (65 exposures). A control group of 10 male and 10 female rats inhaled clean air under identical exposure conditions.

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 23.18C to 23.88C) were measured continuously. The relative humidity (mean relative humidity 41.8% to 46.2%) was checked and recorded once daily.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

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 m2 mm with 10% Triton305 on Supelcoport, 102/120 mesh, oven temperature: 1208C. C15-paraffin was used as the internal standard).

Duration of treatment / exposure:

6 hr on workdays over a period of 90 days (65 exposures).

Frequency of treatment:

6 hr on workdays over a period of 90 days (65 exposures).

Doses / concentrations

Doses / concentrations 1

Remarks:

Doses / Concentrations:
15 ppm
Basis:
analytical conc.

Doses / concentrations 2

Remarks:

Doses / Concentrations:
40 ppm
Basis:
analytical conc.

Doses / concentrations 3

Remarks:

Doses / Concentrations:
120 ppm
Basis:
analytical conc.

No. of animals per sex per dose:

10

Control animals:

yes

Details on study design:

Dose selection rationale: range-finding study performed earlier. Highest dose 120 ppm equals vapour saturation at 20 Celsius degrees.

Positive control:

no required

Examinations

Observations and examinations performed and frequency:

Individual body weights were recorded at the beginning of the pre-flow 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. All animals were examined for clinical signs and mortality during exposure and daily in the non-exposure times. Ophthalmological examinations were carried out prior to the beginning of the pre-flow period and at the termination of the study using an ophthalmoscope.

Blood for clinical pathology testing was collected in randomized order by retro-orbital bleeding. Haematology (white blood cells, red blood cells,
haemoglobin, haematocrit, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, platelets,
differential blood count) and clinical chemistry (sodium, potassium, chloride, inorganic phosphate, calcium, urea, creatinine, glucose, total bilirubin, total protein, albumin, globulins, triglycerides, cholesterol, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase) examinations were performed on day 94 of the study. A particle counter (S Plus model, Coulter, Krefeld, Germany) and an automatic analyser (Hitachi 737, Boehringer Company, Mannheim, Germany) were used for determinations of haematological and clinical chemistry parameters, respectively. For investigation of the clotting potential the thromboplastin time was measured. A ball coagulometer (KC 10 model, Amelung, Lemgo, Germany) was used for clotting analyses. 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).

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:

Analyses of the daily inhalation chamber concentrations revealed that the values obtained closely fit the desired nominal level.

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:

no effects observed

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:

no effects observed

Clinical biochemistry findings:

no effects observed

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:

no effects observed

Histopathological findings: neoplastic:

no effects observed

Details on results:

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 are incidental not dose-related and therefore of no toxicological relevance.

No clinical signs related to the treatment with EH were observed throughout the study period. The ophthalmological examinations revealed no effects associated with the exposure of the animals to the chemical. No deaths were recorded during the study.

The haematological or clinical biochemistry investigations showed no changes related to exposure to the chemical. 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.

There was no increase in the cyanide-insensitive-palmitoyl-CoA oxidation in any treatment group when compared with the control group.

No exposure-related organ weight changes were observed.

There were no macroscopic findings that could be attributed to the treatment with the chemical. All the histomorphological findings were considered to have occurred incidentally and were not associated with the exposure to EH.

Effect levels

Dose descriptor:

NOAEC

Effect level:

> 120 ppm

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: 120 ppm equals 638,4 mg/m3. No adverse effect seen in any of the doses. Highest dose correspond to vapour saturation at 20 Celsius degrees of 2-ethylhexanol.

Remarks on result:

not determinable

Remarks:

no NOAEC identified

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Conclusions:

In conclusion, it may be stated that in the present 90-day inhalation study no treatment-related toxic effects were observed in rats exposed to 2-Ethylhexanol vapour concentrations of up to 120 ppm. The concentration of 120 ppm corresponds to vapour saturation at 20 Celsius degrees. Higher concentrations are only obtainable as aerosols but are not relevant for occupational areas. In particular, there were no indications of any effects of a peroxisome induction or hepatotoxicity caused by EH as could be expected when considering the observations made after oral administration of the chemical to rats. Based on these results, for male and female Wistar rats the NOAEL of inhaled EH was 120 ppm corresponding to 638.4 mg/m3.