Ethanol

Endpoint summary

Description of key information

Skin irritation: All acute 4 hour exposure animal exposure studies show not irritating in animals and humans. In humans, repeat dose studies show ed no problem with repeated application over a whole day under occlusive conditions for up to 12 days. After this, irritation starts to occur. Acute 24 hour animal exposure studies show mixed results, with six indicating no classification (mild to moderate irritation) and one classification based on odema formation.  There is some evidence for persistence of low grade erythema until day 7 at least following these long exposures.  A 24 hours GLP study is used as they key study for skin irritation.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1986-07-22 to 1986-07-29

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

yes

Remarks:

, treatment time is 24 hours instead of 4 hours. 0.2 ml of test substance dosed instead of 0.5ml

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Hazelton Research Animals
- Age at study initiation: Not available
- Weight at study initiation: rabbits of either sex weighing > or = 2.0 kg
- Housing: As per the S.O.P.
- Diet (e.g. ad libitum): As per the S.O.P.
- Water (e.g. ad libitum): As per the S.O.P.
- Acclimation period: minimum of 7 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): As per the S.O.P.
- Humidity (%): As per the S.O.P.
- Air changes (per hr): As per the S.O.P.
- Photoperiod (hrs dark / hrs light): As per the S.O.P.


IN-LIFE DATES: From:1986-07-22 To: 1986-07-29

Type of coverage:

occlusive

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

not required

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit):0.2 ml
- Concentration (if solution): 100% Ethanol/water solution

Duration of treatment / exposure:

Five New Zealand albino rabbits weighing > or =to 2.0 kg were dosed with ten 16 mm Hill Top Chamber containing 0.2 ml of the test substance were placed within the punched holes for 24 hours exposure for 5 consecutive days. The skin reaction were also evaluated for 72 hour the final treatment.

Observation period:

24 hour

Number of animals:

5 animals

Details on study design:

TEST SITE
- Area of exposure: between the front and rear legs about 3 cm off the dorsal midline
- % coverage: two strips of 6 inch scanpore tape placed in parallel on the back
- Type of wrap if used: continuous wrap of 1/2 inch adhesive tape.


REMOVAL OF TEST SUBSTANCE
- Washing (if done): 24 hours
- Time after start of exposure: 24 hours


SCORING SYSTEM: Erythema and eschar scoring from 0-4 with 0 = no erythema, 1 = very slight erythema, 2 = well defined erythema, 3 = moderate to severe erythema, 4 = severe erythema to slight eschar formation.

Edema scoring from 0-4 with 0 = no edema, 1 = very slight edema, 2 = slight edema, 3 = moderate edema, 4 = severe edema.

Primary irritation index: 0-2 = mild, 2-5 = moderately irritating, 5-6 = moderately to severely irritating, 6-8 = severely irritating

Irritation parameter:

primary dermal irritation index (PDII)

Basis:

mean

Time point:

other: Average of 1, 2, 3, 4, 5, and 7 day scores

Score:

0

Max. score:

8

Reversibility:

other: No erythema / edema observed

Remarks on result:

other: Intact skin site

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Remarks:

Intact skin site

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

no indication of irritation

Remarks:

intact skin site

Irritant / corrosive response data:

PII 0 at an average of 1, 2, 3, 4, 5 and 7 day

Other effects:

None

Eryteham	Edema	Observation Time (hrs)	Primary Irritation Index
0.00	0.00	Average of 1, 2, 3, 4, 5, and 7 days scores	0.00

Interpretation of results:

not irritating

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Ethanol is non-irritating .

Executive summary:

In a guideline and GLP skin irritation study, 0.2 ml of ethyl alcohol was applied to an intact skin test site on each of five New Zealand albino rabbits using two strips of 6 inch scanpor tape with a continuous wrap of 1/2 inch adhesive tape for 24 hours. After 24 hours exposure (longer than required by the guideline) the test sites were exposed and wiped. The sites were examined for erythema and edema at 1, 2, 3, 4, 5 and 7 days. Alcohol was found to produce no significant irritation and was therefore concluded to be non irritating to rabbit skin.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

before 1998

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

Source is a published peer reviewed tabulation of detailed results from in house eye irritation studies performed to guideline that is intended as a reference work for the development of in vitro studies. The work is published by a reputable organisation and is therefore considered reliable.

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Deviations:

not specified

GLP compliance:

not specified

Remarks:

Study indicated to be to GLP but no test laboratory named.

Species:

rabbit

Strain:

not specified

Details on test animals or tissues and environmental conditions:

no data

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

Concentration: 100 % active substance
- instillation of 0.1 ml

Duration of treatment / exposure:

single instillation

Observation period (in vivo):

Up to 21 days unless symptoms disappeared first.

Number of animals or in vitro replicates:

3

Details on study design:

SCORING SYSTEM: Standard Draize grading scale for lesions.

Irritation parameter:

cornea opacity score

Basis:

animal #1

Time point:

24/48/72 h

Score:

1.33

Max. score:

4

Reversibility:

fully reversible within: 4 days

Irritation parameter:

cornea opacity score

Basis:

animal #2

Time point:

24/48/72 h

Score:

1.67

Max. score:

4

Reversibility:

fully reversible within: 4 days

Irritation parameter:

cornea opacity score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0.17

Max. score:

4

Reversibility:

fully reversible within: 2 days

Irritation parameter:

iris score

Basis:

animal #1

Time point:

24/48/72 h

Score:

1

Max. score:

2

Reversibility:

fully reversible within: 4 days

Irritation parameter:

iris score

Basis:

animal #2

Time point:

24/48/72 h

Score:

0.33

Max. score:

2

Reversibility:

fully reversible within: 3 days

Irritation parameter:

iris score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

2

Remarks on result:

no indication of irritation

Irritation parameter:

conjunctivae score

Basis:

animal #1

Time point:

24/48/72 h

Score:

2.67

Max. score:

3

Reversibility:

fully reversible within: 14 days

Remarks:

no observations made between 7 nd 14 days

Irritation parameter:

conjunctivae score

Basis:

animal #2

Time point:

24/48/72 h

Score:

2.33

Max. score:

3

Reversibility:

fully reversible within: 14 days

Remarks:

No observations made between days 7 and 14

Irritation parameter:

conjunctivae score

Basis:

animal #3

Time point:

24/48/72 h

Score:

1.33

Max. score:

3

Reversibility:

fully reversible within: 4 days

Irritation parameter:

chemosis score

Basis:

animal #1

Time point:

24/48/72 h

Score:

2

Max. score:

4

Reversibility:

fully reversible within: 14 days

Remarks:

No observations made between days 7 and 14

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

24/48/72 h

Score:

1.67

Max. score:

4

Reversibility:

fully reversible within: 7 days

Irritation parameter:

chemosis score

Basis:

animal #3

Time point:

24/48/72 h

Score:

0.17

Max. score:

4

Reversibility:

fully reversible within: 2 days

Irritant / corrosive response data:

Individual animal observations reported. Full reversal of all symptoms in animals occurred within 14 days. Most persistent effect was conjunctival redness, still present, grade 1, at 7 daysin 2 animals (last observation time before 14 day observation). One animal showed full recovery of all symptoms by day 4.

Other effects:

none reported.

The MMAS (modified maximum average score is calculated per animal from the 24 hour observations based corneal effects (capacity x area x 5), iris effects (x5) and conjunctival effects (redness + chemosis + discharge scores). The total possible is 80 (cornea) + iris (10) plus conjunctivae (20), ie a maximum of 110.

Average scores (all animals)

	Day 1	Day 2	Day 3
Corneal opacity	1.33	1.33	0.66
Iritis	0.33	0.66	0.33
Conjunctival redness	2.66	2.00	1.66
Chemosis	1.66	1.66	0.66

Average scores (worst two animals)

	ANIMAL #1 (average days 1,2,3)	ANIMAL #2 (average days 1,2,3)
Corneal opacity	1.33	1.66
Iritis	1	0.33
Conjunctival redness	2.66	2.33
Chemosis	2	1.66

Based on the criteria for classification, only the conjunctival redness in animal one is meets the criteria for the definition of a significant occular lesions would be regarded as significant but such a response in only one animal is not regarded as sufficient for classification as an eye irritant under directive 67/548. The average results across all 3 animals are not sufficient either. However, the criteria for classification under GHS are more stringent and a positive response is seen under these criteria for corneal opacity (2 animals >1) and conjunctival redness (2 animals >2), hence classification as an eye irritant (category 2) is required.

Interpretation of results:

Category 2A (irritating to eyes)

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

Substance clearly shows reversible eye irritant properties

Executive summary:

In a reference handbook of peer reviewed, guideline GLP eye irritation study results in rabbits, ethanol was found to cause eye irritation. All symptoms reversed within 14 days. The response was not sufficiently severe to trigger classification under the criteria of directive 67/548 but was sufficient with respect to the corneal and conjunctival effects to trigger classification as a reversible eye irritant (category 2) under the EU GHS regulation.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

SKIN IRRITATION

In a skin irritation study that followed OECD guidelines (apart from a smaller application volume but longer exposure period) and that was performed to GLP, 0.2 ml of ethyl alcohol was applied to an intact skin test site on each of five New Zealand albino rabbits using two strips of 6 inch scanpor tape with a continuous wrap of 1/2 inch adhesive tape for 24 hours. After 24 hours exposure (longer than required by the guideline) the test sites were exposed and wiped. The sites were examined for erythema and edema at 1, 2, 3, 4, 5 and 7 days. Ethyl alcohol was found to produce no significant irritation and was therefore concluded to be non irritating to rabbit skin. Three further studies (two reported in the same study report) performed to the same protocol showed very slight erythema and no edema at the intact sites of test animals. The erythematous responses was only seen to any significant level in two studies and one of these was a delayed reponse from day 4 onwards in 3/5 animals. When seen, these mild erythematous responses persisted until the end of the observation period on day 7.

In a guideline 4 hour skin irritation study using rabbits, ethanol caused mild transient irritation (very slight, barely perceptible erythema) which disappeared within 48 hours of application. In a study that was similar to the Draize protocol for skin irritancy testing, rabbits were exposed to liquid ethanol for a period of 24 hours under occlusive conditions. Only slight irritation was seen, only a marginally worse result than was also seen in the distilled water control. As observations were only made for 24 hours, reversibility could not be assessed. In a study that was designed to be as similar as possible to the Draize protocol for skin irritancy testing, human male volunteers were exposed to liquid ethanol for a period of 24 hours under occlusive conditions, using the forearm as the site of exposure. No irritation was seen. Up to 4 -hour covered skin patch tests were conducted in 31 human volunteers. A reaction determined to be indicative of irritation was seen in just one individual compared to 15 of the 31 volunteers who reacted to similar patches with a known irritant.

In a study to a US Federal regulations protocol, rabbits were subjected to a dermal irritation test by occluded exposure to ethanol for a period of 24 hours followed by an 8 day observation period. No erythema was seen but marked odema was observed, which persisted and, if anything appeared to be getting worse at the end of the observation period. Based on these results, the test substance would seem to require classification as an irritant according to regulation 1272/2008 (Cat. 2) standards. The level of odema did not appear sufficient to trigger classification alone although there was some suggestion of a delayed reaction after day 3. However, it must be borne in mind that the exposure was for 24 hours under occlusive conditions - far longer than required for the OECD or REACH testing guideline of 4 hours for this end point and observation was for only 8 days and not the recommended 14 days. The result must be considered ambiguous or equivocal, particularly since similar observations are not seen in other studies with more appropriate durations of exposure. In another study to the same protocol, only mild erythema and odema was observed that fully resolved by the end of the observation period. Based on these results, the test substance would not require classification as an irritant according to regulation 1272/2008. In a third similar study with the same 24 hour occluded exposure conditions, no odema was seen along with very slight erythema which persisted to the end of the 48 hour observation period. In a study that approximated to guideline but for which a full study report is not available, ethyl alcohol (undiluted SDA #40 Alcohol) produced moderate primary irritation by the rabbit closed patch technique, using both abraded and non-abraded skin sites. Exposure time was uncertain but assumed to be 24 hours. Observation times were not sufficiently long to determine reversibility of the mild to moderate lesions seen. There was no significant difference between the reaction of the non abraded and abraded skin test sites. These results in combination and considering that the exposure was for 24 hours under occlusive conditions rather than the 4 hours normally used for this end point, suggest that classification as a skin irritant is not warranted.

In a study that was designed to assess the potential for skin irritation under severe repeated dose conditions, ethanol was applied under occlusive conditions to the skin (backs) of male human volunteers for a period of 21 days. The application was repeated daily and the response checked from the previous dose before each fresh application. No irritation was seen until day 13, after which the irritation response slowly increased, initially as erythema until by day 19 erythema plus induration were also seen. A similar lack of irritation following repeated application was seen in a test of ethanol-containing gels for hand disinfection. The forearm skin of 13 female volunteers was treated every 20 minues, for 6 consecutive hours, with five gels containing between 70 - 80% ethanol. There was no evidence of skin irritation for any of the gels when the application sites were assessed 1 or 24 hour following the treatments.

Overall, the results indicate that ethanol has a low potential to irritate the skin of humans under anything other than extreme and unrealistic exposure conditions

EYE IRRITATION

In an OECD guideline acute eye irritation study in rabbits, ethanol was found to cause moderate eye irritation that fully reversed within 8 days. No interim washing stage done 24 hours from instillation. The level of response was sufficient in terms of the level of conjunctival redness seen to trigger classification as a category 2 irritant under regulation 1272/2008. In a reference handbook of peer reviewed, guideline GLP eye irritation study results in rabbits, ethanol was found to cause eye irritation. All symptoms reversed within 14 days. In another guideline eye irritation study in rabbits, for which only basic but key details are reported, ethanol was also found to cause eye irritation.. This study did not include sufficient observations to be able to judge reversibility. In an eye irritation study which was carried out according to guideline but for which only very basic results are available, ethanol was found to cause marked eye irritation in rabbits. The study also examined the impact of washing on the severity of the response seen. The results from this clearly showed that rinsing after exposure decreases the immediate acute response slightly but dramatically decreases the length of time for which effects persist. This strongly supports washing to mitigate eye irritation response.

In an acute eye irritation study in rabbits that followed a US Federal guideline, ethanol was found to cause significant eye irritation. No interim washing stage done 24 hours from instillation. Observations were only carried out for 8 days. Six animals were tested. It is not possible to use the criteria for the responses of 2 out of 3 animals for comparison with the classification criteria. If the worst 4 of 6 results are examined, the response seen in all four measured parameters would be sufficient to trigger classification as a category 2 irritant. In another acute eye irritation study to exactly the same guideline, similar results were obtained. In this case, the average response of 2 of the 3 animals was sufficiently severe in terms of conjunctival effects and chemosis observed that classification as an eye irritant would be warranted under regulation 1272/2008.

Ethanol has also been tested in diluted form. In an OECD and GLP irritation study, a 40% solution of ethanol was instilled into the conjuctival sac of three New Zealand albino rabbits and the treated eyes not washed following instillation. This produced slight conjunctival erythema, slight to moderate chemosis; and slight corneal opacity that cleared in 7 days. The maximium primary irritation score seen in any animal and at any timepoint was 3.0 at 1 and 24 hours. When the study was repeated but with washing within 10 seconds after instillation of the test material, effectively identical results were seen. In an old but well reported study, four rabbits were instilled with 0.1 ml of 40% Ethyl alcohol into the conjunctival sac of the eye of the rabbit. 40% Ethyl alcohol caused only slight, temporary conjunctival irritation in 1 hour which is cleared in 3 to 4 days. In another old but well reported study, 0.1 ml of 25% and 50% ethyl alcohol in water were instilled into the conjunctival sac of one eye of the rabbit. For 25% ethyl alcohol all three animals showed low level conjunctival irritation within one hour. Two animals recovered within 24 hours and the 3rd animal by 48 hours. For 50% ethyl alcohol, all three animals again showed conjunctival irritation within one hour. One animal recovered within 48 hours, one animal within 72 hours and the 3rd animal recovered at day 4. It can be concluded from these studies that ethanol at 25% solution in water is a negligible occular irritant and at 50% a mild occular irritant.

Effects on eye irritation: irritating

Justification for classification or non-classification

Taken in total, the available data point clearly toward the substance not meeting the criteria for classification as a skin irritant. The degree of acute response in all studies approximating to guideline study was insufficient to warrant labelling as a skin irritant either under the EU GHS regulation. Direct comparison of the results against the EU classification criteria is not possible for the other studies. There was some evidence for persistence of erythamatous response where seen, albeit only very mild, at least to day 7 following exposure, but these responses were seen in studies following 24 hour exposures. The slight response seen in the animals study and the lack of response in the human volunteer study strongly suggest that this substance will not meet the criteria for classification as a skin irritant and that it has minimal acute skin irritation potential. There is some evidence from the human volunteer study that repeated application under extreme occlusive conditions can lead to chronic irritation. The risk phrase EUH066 could be considered but since the reaction in humans is neither skin dryness, flaking or cracking, this does not appear to be appropriate.

There is clear evidence that ethanol is an eye irritant. The data shows that the irritation response is sufficiently severe with respect to a number of end points to trigger classification as a reversible eye irritant (category 2) under the EU regulation 1272/2008, because of the more severe criteria (lower thresholds of effects triggering classification). The results per study and per end point are shown in the table below:

Testing of pure ethanol. Classification triggered for effects seen under regulation 1272/2008

Study	Iritis	Corneal effects	Conjunctival redness	Chemosis
BASF 78/810	No	No	Yes	Yes*
BASF 77/793	Yes*	Yes*	Yes*	Yes*
BASF 83/64	No	No	Yes*	No
ECETOC	No	Yes	Yes	No
Jacobs	No	Yes	Yes	No

*=just meets threshold.

It is quite clear that the conjunctival effects trigger classification, in this case as a reversible eye irritant (cat 2, H319) even without taking into account the fact that in 3 of the 5 studies, corneal effects were severe enough to trigger classification. However, there are also a number of studies available using diluted ethanol which also show that the irritancy effect diminishes rapidly with dilution. The table below clearly demonstrates that none of the studies carried out with ethanol concentrations of 50% or less produced and effect that would be sufficient to trigger classification. In fact, the relatively mild response at 50% and the fact that classification is only just triggered at 100% suggests that dilutions up to 70-80% are unlikely to produce effects sufficient to warrant classification. (This is supported by an examination of all of the data for conjunctival effects – the one consistent response indicating classification. A plot of conjunctival redness score per animal versus concentration produces a scattergraph. Plotting a curve through the outermost points, a worse case assumption, indicates that the trigger for classification, a score of 2, is not reached until a concentration of around 70%. However, taking a very conservative position, it is clearly supported by the data that mixtures of 50% ethanol do not produce levels of eye irritation warranting classification, therefore a cut off for mixtures of 50% is proposed.

Testing of diluted ethanol. Classification triggered for effects seen under regulation 1272/2008

Ethanol concentration	Iritis	Corneal effects	Conjunctival redness	Chemosis
50%	No	No	No	No
40%	No	No	No	No
40%	No	No	No	No
25%	No	No	No	No