Sodium ethanolate

Repeated dose toxicity: inhalation

Administrative data

Endpoint:

short-term repeated dose toxicity: inhalation

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

weight of evidence

Study period:

1979

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Acceptably documented study which meets basic scientific principles and contains sufficient detail to be able to judge the results reliable as a contribution to the understanding of the repeat dose inhalation toxicity of this substance. Only a single limit dose used in males only and only limited (but important) end points studied, but a NOAEL was established.

Data source

Reference

Reference Type:

publication

Title:

"Influence of chronic ethanol vapour inhalation on hepatic parenchymal and Kupffer cell function.

Author:

Di Luzio NR, Stege TE

Year:

1979

Bibliographic source:

Alcoholism: Clin Exp Res 3 (3) 240

Materials and methods

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

Animals exposed daily to a single concentration of ethanol vapour for a period of up to 26 days with the focus on liver toxicity. Interim sacrifice timepoints included to allow intermediate changes in blood ethanol levels and clinical chemistry to be followed.

GLP compliance:

not specified

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Ethanol

EC Number:

200-578-6

EC Name:

Ethanol

Cas Number:

64-17-5

Molecular formula:

C2H6O

IUPAC Name:

ethanol

Details on test material:

absolute ethanol

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: no data
- Weight at study initiation: 200-300g
- Diet (ad libitum): Purina lab chow
- Water (ad libitum): tap

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure:

whole body

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Plexiglass chamber (9x12x24 in.)
- Method of holding animals in test chamber: not applicable
- Source and rate of air: 9.3litres/min
- Method of conditioning air: filtered and dried
- System of generating vapour: air passed through a 19 litre chamber holding ethanol (1.5-2.5 litres) at 37C
- Temperature, humidity, pressure in air chamber:
- Air flow rate: 9.3 litres/min

TEST ATMOSPHERE
- Brief description of analytical method used: see details below
- Samples taken from breathing zone: no

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Assayed twice daily, in triplicate, sampled from chamber exit. Analysis using FID GC.

Duration of treatment / exposure:

3, 6, 9, 26 day groups

Frequency of treatment:

continuous

Doses / concentrations

Remarks:

Doses / Concentrations:
20mg/l
Basis:

No. of animals per sex per dose:

10

Control animals:

other: concurrent vehicle and pyrazole treated.

Examinations

Observations and examinations performed and frequency:

CAGE SIDE OBSERVATIONS/DETAILED CLINICAL OBSERVATIONS: Yes, no further data.

BODY WEIGHT: Yes
- Time schedule for examinations: every 2-3 days

OPHTHALMOSCOPIC EXAMINATION: No

HAEMATOLOGY: Yes
- Time schedule for collection of blood: end of exposure from vena cava
- Anaesthetic used for blood collection: Yes (phenobarbital)
- Animals fasted: No data
- How many animals: all
- Parameters checked: blood ethanol level


CLINICAL CHEMISTRY: Yes.
- Time schedule for collection of blood: end of exposure from vena cava
- Animals fasted: No data
- How many animals: all
- Parameters checked:- plasma retention of sodium sulfobromopthalein - Plasma activity of glutamic pyruvic transaminase and - glutamic  oxalacetic transaminase - Liver triglycerides - Phagocytic function. Details of methods provided in reference.

URINALYSIS: No

NEUROBEHAVIOURAL EXAMINATION: No

Sacrifice and pathology:

- Liver, lung and spleen histopathology.

Statistics:

Statistical analysis by Student's t-test.

Results and discussion

Results of examinations

Clinical signs:

effects observed, treatment-related

Mortality:

mortality observed, treatment-related

Body weight and weight changes:

no effects observed

Ophthalmological findings:

not examined

Haematological findings:

effects observed, treatment-related

Clinical biochemistry findings:

effects observed, treatment-related

Urinalysis findings:

not examined

Behaviour (functional findings):

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Gross pathological findings:

not specified

Histopathological findings: non-neoplastic:

effects observed, treatment-related

Histopathological findings: neoplastic:

not examined

Details on results:

CLINICAL SIGNS AND MORTALITY
Initial exposure produced lethargy, ataxia and intoxication but animals adapted and appeared normal at the end of the study.

BODY WEIGHT AND WEIGHT GAIN
Ethanol exposure produced a small but not statistically significant retardation in bodyweight gain although not in the rate of gain.

HAEMATOLOGY
Blood ethanol levels in the ethanol-saline group peaked on day 9 at 126 +/- 40 mg/100ml and declined substantially 50-60% by day 26. In the ethanol-pyrazole group they peaked at 219 mg/100ml (+/- 35) on day 6 and then declined similarly to the ethanol-saline animals. No blood ethanol was measured in either the air-saline or air-pyrazole controls.
CLINICAL CHEMISTRY
Liver triglycerides were raised (doubled) for the ethanol groups at the earlier time points but were the same as the controls by day 26. Plasma tryiglycerides showed no consistent pattern. Plasma glutamic pyruvic transaminase levels were raised by 20% in the ethanol-saline group compared to the control.

HISTOPATHOLOGY: NON-NEOPLASTIC
Liver samples from the ethanol-saline group exhibited mild vacuolisaton for the early time periods, but this was not seen at 26 days. No other parameters were significantly effected between the ethanol-saline and air-saline groups.

Effect levels

Dose descriptor:

NOAEL

Effect level:

> 20 mg/L air

Sex:

male

Basis for effect level:

other: No biologically meaningful adverse changes noted.

Remarks on result:

not determinable

Remarks:

no NOAEL identified

Target system / organ toxicity

Critical effects observed:

not specified

Applicant's summary and conclusion

Executive summary:

In a study to examine the repeat dose toxicity of ethanol, rats were exposed to a single dose of ethanol vapour at 20mg/l for up to 26 days. Intermediate exposure groups were used to allow changes in clinical chemistry, histopathology and blood ethanol concentrations to be followed with time. The study found a number of transient effects (clinical signs, e.g lethary and ataxia, mild hepatic vacuolisation and changes to clinical chemistry parameters) but in animals exposed for the full 26 days, the only significant effect noted was an increase in plasma GPT levels, which, in isolation, was not regarded as biologically significant. It was noticeable that the blood ethanol levels in the animals exposed for 26 days were much lower than those exposed for shorter periods indicating pronounced induction of metabolic tolerance.