Ethanol

Developmental toxicity / teratogenicity

Administrative data

Endpoint:

developmental toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1985

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: A published study which contains sufficient experimental detail to be able to judge it as reliable. Basic experimental detail provided.

Data source

Reference

Reference Type:

publication

Title:

Teratological assessment of methanol and ethanol at high inhalation level in rats.

Author:

Nelson, B., Brightwell, W., MacKenzie, D., et al.

Year:

1985

Bibliographic source:

Fundam Appl Toxicol 5:727-736.

Materials and methods

Test guideline

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 414 (Prenatal Developmental Toxicity Study)

Deviations:

yes

Remarks:

low number of pregnant females, no detailed examination of dams

GLP compliance:

not specified

Limit test:

no

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:

- Name of test material (as cited in study report): ethanol absolute-200 proof
- Analytical purity: 96.5%
- Impurities (identity and concentrations): Analysis for water and benzene detected none.

Test animals

Species:

rat

Strain:

Sprague-Dawley

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories
- Age at study initiation: not stated
- Weight at study initiation: 200-300g
- Fasting period before study: no
- Housing: 3 per cage in stainless-steel cages except whilst in chamber
- Diet (e.g. ad libitum): purina or comparable-grade lab chow ad libitum
- Water (e.g. ad libitum): tap water ad libitum
- Acclimation period:1-2 weeks


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 24
- Humidity (%): 20-60
- Air changes (per hr):
- Photoperiod (hrs dark / hrs light):12/12


IN-LIFE DATES: From: To:

Administration / exposure

Route of administration:

inhalation

Type of inhalation exposure (if applicable):

whole body

Vehicle:

other: air in chamber

Details on exposure:

0.5m3 Hinner-type exposure chambers under negative pressure. Controls were placed in similar cage as the exposed animals with adjacent exposure chamber for the same hours.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

Two methods used: Continuously by a Miran 1A general purpose infrared analyzer (Wilkes/Foxboro Analytical), on an hourly basis; and concentration samples taken from chamber atmosphere by charcoal tube. Sampling times 10-30 mins. 5-10 samples/week. Analysed by NIOSH 1977b-No. S-56 Method with slight modifications.

Details on mating procedure:

Virgin females were housed with males and vaginal smears were taken.

Duration of treatment / exposure:

7 hours per day in exposure chamber on gestation days 1-19. Animals left in the chambers for degassing for approximately 1/2 hr after vapor generation terminated.

Frequency of treatment:

daily

Doses / concentrations

Remarks:

Doses / Concentrations:
10,000, 16,000 or 20,000 ppm (Doses are calculated to be equivalent to 17, 29 and 28 g/kg bodyweight.)
Basis:
nominal conc.

No. of animals per sex per dose:

not explicitly stated but approximately 16.

Control animals:

not specified

Details on study design:

Sex: female

Duration of test: Days 1-19 of gestation

Examinations

Maternal examinations:

Blood levels

Ovaries and uterine content:

No maternal organs were examined

Fetal examinations:

Foetuses were examined externally and internally for malformations; implants and resorptions were recorded as was litter weight.

Statistics:

Kruskal-Wallis analysis of variance or Fisher's test.

Results and discussion

Results: maternal animals

Maternal developmental toxicity

Details on maternal toxic effects:

Maternal toxic effects:yes

Details on maternal toxic effects:
No mortality occurred. Food consumption was lowered in the high-dose group. Clinical signs observed included complete narcosis (described as severe toxicity) in the highest dose induced. The lower doses did not cause narcosis but caused hyperactivity after exposure. Maternal weight gains were not affected by treatment. Blood alcohol levels ranged from 0.02 to 0.03 mg/ml at 10000 ppm, 0.42 to 0.84 mg/ml at 16000ppm and 1.48 to 1.93 mg/ml at 20000 ppm. Measurements were made on non-pregnant rats and represent the ranges of the average values measured at days 1, 10 and 19.

Effect levels (maternal animals)

1

Dose descriptor:

NOAEL

Effect level:

16 000 ppm

Basis for effect level:

other: maternal toxicity

2

Dose descriptor:

LOAEL

Effect level:

20 000 ppm

Basis for effect level:

other: maternal toxicity

Results (fetuses)

Details on embryotoxic / teratogenic effects:

Embryotoxic / teratogenic effects:no effects

Details on embryotoxic / teratogenic effects:
The number of pregnant per dose level were 15/15, 15/15, 15/16 and 14/16 in the control, low, medium and high dosage groups. The number of resorptions were not affected by ethanol inhalation. The number of implantations were 14-16/litter in all ethanol-treated groups and 15/litter in the control group. The number of corpora lutea were 14-16/litter. LItter weights were not significantly affected by ethanol treatments. The sex ratio did not differ significantly from controls. Grossly visible abnormalities are given in detail but the frequency of each did not differ significantly between groups. More litters contained abnormal foetuses in the 20,000 ppm group compared to controls but differences were only of borderline statistical significance.

Effect levels (fetuses)

Dose descriptor:

NOAEL

Effect level:

>= 20 000 ppm

Basis for effect level:

other: teratogenicity

Fetal abnormalities

Abnormalities:

not specified

Overall developmental toxicity

Developmental effects observed:

not specified

Any other information on results incl. tables

Maternal LOAEL effect was narcosis and lowered food consumption.

Development LOAEL effect – none seen

Development NOAEL effect – visceral or skeletal malformations or variants.

Maternal data are not given for the following: Number aborting; (Duration of pregnancy not relevant); bodyweights; haematology and blood chemistry findings; gross pathology in dams; organ weight changes; histopathology incidence and severity.

Foetal data are not given for the following: litter size; number viable; postnatal growth (not applicable) and postnatal survival (not applicable).

Applicant's summary and conclusion

Conclusions:

No definite evidence of malformations due to ethanol exposure were seen although the incidence of abnormal changes at the highest concentration was of borderline statistical significance. There was clear maternal toxicity at this concentration however.

Executive summary:

Pregnant female rats were exposed to ethanol by inhalation at concentrations of 10000, 16000, or 20000ppm in a chamber for 7 hours per day on gestation days 1 -19. On day 20 the animals were euthanized and their fetuses examined. There was no definite increase in malformations at any level of ethanol exposure, although the incidence in the 20000ppm group was of borderline significance. There was clear maternal toxicity evident at the highest dose (narcosis, food intake reduction).

Synposis

NOAEL (maternal toxicity) :16,000ppm (30,400mg/m3)

NOAEL (teratogenicity): 20,000ppm (38,000mg/m3)