Reaction mass of 2-methylbutyl acetate and pentyl acetate

Endpoint summary

Description of key information

Skin irritation: mean 24 -72h erythema and edema scores: 1.7 and 0.6, respectively, fully reversible by day 10 or 7 (UCC, 1983)

Eye irritation: not irritant

Respiratory irritation: no histopathological alterations even after high dose, sub-chronic exposure. Sensory irritation observed in several species (RD 50 values app. 6 -8 mg/L (rats, mice), lacrimation in cats and guinea pigs at 11mg/l (no lower concentration tested), slight effects on nose, throat, eyes in humans at 1 mg/L

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:

10983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

GLP compliance:

no

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

The animals are maintained on appropriate commercial diet and municipal water. Both are available ad libitum except when animals are restrained.

Type of coverage:

occlusive

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Amount / concentration applied:

0.5 ml

Duration of treatment / exposure:

4 hr

Observation period:

Skin reaction is scored, by the method of Draize (given below), at one hour, one day, 2 days, 3 days and possibly 7 days after dosing.

Number of animals:

6 (3 males, 3 females)

Details on study design:

Male or female New Zealand White rabbits are dosed with 0.5 ml. The dose is applied to the clipped, intact skin under a gauze patch and is loosely covered with impervious sheeting. The test material is applied to each of 6 rabbits, which are restrained for the 4-hr contact period. Excess sample is removed after contact. Skin reaction is scored, by the method of Draize, at one hour, one day, 2 days, 3 days and possibly 7 days after dosing.

Irritation parameter:

erythema score

Basis:

mean

Time point:

other: 24, 48 and 72 hours

Score:

1.7

Max. score:

2

Reversibility:

fully reversible within: 10 days

Irritation parameter:

edema score

Basis:

mean

Time point:

other: 24, 48 and 72 hours

Score:

0.6

Max. score:

1

Reversibility:

fully reversible within: 7 days

Irritant / corrosive response data:

Application of 0.5 ml of primary amyl acetate to covered rabbit skin resulted in well-defined erythema on 6 of 6 animals (Table 1). Slight edema was evident on day 5. By 7 days only 2 rabbits had erythema (slight), none had edema, but all 6 had desquamation. Minor desquamation persisted on 5 rabbits through 14 days.

Other effects:

No additional information available.

Table 1 Results of skin irritation test

Time	Mean score
	Erythema and Eschar Formation	Edema
5 hours	0.2	0.2
1 day	2.0	0.5
2 days	1.8	0.8
3 days	1.2	0.3
7 days	0.3	0.0
10 days	0.0	0.0
14 days	0.0	0.0

Minor desquamation was observed on days 7 - 14. It became less evident at 10 and 14 days.

Scoring was by the Draize method

Interpretation of results:

Category 3 (mild irritant) based on GHS criteria

Conclusions:

Application of the sample to covered skin resulted in minor irritation, not meeting the EU criteria for classification.

Executive summary:

The skin irritation potential of primary amyl acetate was examined. Application of the sample to covered skin resulted in minor irritation.

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:

1983

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

no guideline available

Principles of method if other than guideline:

Eye irritation potential was examined by placing 0.1 ml of primary amyl acetate into the eye of 6 rabbits. Eyes were examined at various times for 7 days after dosing.

GLP compliance:

no

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

The animals are maintained on appropriate commercial diet and municipal water. Both are available ad libitum.

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Amount / concentration applied:

0.1 ml and 0.01 ml

Duration of treatment / exposure:

24 hr

Observation period (in vivo):

Eyes are scored by the attached system at one hour, approximately 6 hours, one day, 2 days and 3 days after dosing.

Number of animals or in vitro replicates:

Six eyes are dosed per test volume.

Details on study design:

Male or female New Zealand White rabbits are dosed with volumes of 0.1, 0.01 and 0.005 ml (liquid or solid). The dose is instilled into the lower conjunctival sac of one eye per animal or is placed directly on the eye. The eyelids are held together for one second. Six eyes are dosed per test volume. The eyes are scored by the attached system at one hour, approximately 6 hours, one day, 2 days and 3 days after dosing. Additional readings are made if necessary. Fluorescein (2%) staining is used to determine corneal injury before dosing and at readings after one day.

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

0

Reversibility:

other: no effects observed

Remarks on result:

other: 0.1 ml test substance applied

Irritation parameter:

iris score

Basis:

mean

Time point:

other: 24, 48 and 72 hours

Score:

0

Max. score:

0

Reversibility:

other: no effects observed

Remarks on result:

other: 0.1 ml test substance applied

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

other: 24, 48 and 72 hours

Score:

0.4

Max. score:

1

Reversibility:

fully reversible within: 7 days

Remarks on result:

other: 0.1 ml test substance applied

Irritation parameter:

chemosis score

Basis:

mean

Time point:

other: 24, 48 and 72 hours

Score:

0.1

Max. score:

2

Reversibility:

fully reversible within: 48 hours

Remarks on result:

other: 0.1 ml test substance applied

Irritant / corrosive response data:

In 6 rabbit eyes, doses of 0.1 ml produced minor conjunctival irritation, but no corneal injury or iritis. Slight conjunctival irritation persisted in one eye through 3 days. At 7 days, all eyes were normal. Instillation of 0.01 ml resulted in slight conjunctival irritation in 6 eyes within one hour. Four
eyes remained irritated at 6 hours, but only one had slight conjuncival irritation at 24 hours. Very slight irritation persisted in this eye through 3 days.

Interpretation of results:

GHS criteria not met

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Additional information

Skin irritation/corrosion:

In one study comparable to OECD 404, 0.5 ml of undiluted test substance were applied to the skin of 3 male and 3 female rabbits for 4 hours under occlusive conditions. Excess sample was removed after contact and the skin reactions were scored according to Draize, up to 14 days after dosing. The mean 24 -48 -72 -hour erythema and edema scores were 1.7 or 0.6. Reactions were completely reversible within 10 or 7 days, respectively (Union Carbide Corporation, 1983)

In the 2 additional supporting studies, the dermal irritation of test substance was examined by placing 0.01 ml on open skin of rabbits (Union Carbide Corporation, 1955) or by applying 0.01 ml test substance to clipped uncovered intact skin of 5 rabbit bellies (Union Carbide Corporation, 1976). In both studies, the application sites were examined only after 24 hours for any evidence of irritation. 3/5 animals of the first study showed no skin reaction, while one had moderate and another marked erythema. A trace of irritation was also noted in the second study. The results, though not sufficient by themselves to assess classification, support the only slight irritation potential observed in the key study.

Eye irritation:

Unchanged test substance (0.005, 0.01 or 0.1 ml; 6 animals per test volume) was instilled into the lower conjunctival sac of one eye per animal or placed directly on the eye, and the eyelids were held together for one second (no wash out performed; Union Carbide Corporation, 1983). The eyes were scored according to Draize, after 1 hour, 6 hours, 1 day, 2 days and 3 days after dosing (additional readings when necessary; 2% Fluorescein staining was used to determine corneal injury before dosing and at readings after one day). Doses of 0.1 ml produced minor conjunctival irritation in 6/6 animals (persistent in 1 animal for 3 days), but no corneal injury or iritis. All effects were reversible within 7 days. Instillation of 0.01 ml resulted in slight conjunctival irritation in 6/6 animals within one hour (persistent for 6 hours, but only one had slight conjunctival irritation after 24 hours; a very slight irritation persisted in this eye through 3 days).

 

In the two additional Union Carbide Corporation studies, the eye irritation potential of test substance was examined by instilling 0.5 ml to rabbit eyes (Union Carbide Corporation, 1955). The treated eyes were then examined after 24 /18-24 hours for any evidence of irritation. While moderately severe eye burns were observed in the first study (Union Carbide Corporation, 1955), only a trace of injury was observed in the second study. Both studies used five times the amount required according to OECD guidelines and provide only very limited information on results. Consequently, the study described above was used for classifcation of the registered substance.

The in vivo results are supported by two interconnected studies (Alepee et al., 2019), which gathered data obtained with several in vitro assays for amy acetate:

SkinEthic™ HCE EIT: No prediction can be made

EpiOcular™ EIT: No Cat.

BCOP LLBO: No prediction can be made

BCOP LLBO opacity > 145 (Cat. 1): No

STE: No Cat.

The in vitro tests show only a very slight irritative potential of amyl acetate, clearly supporting a non classification for eye damage/irritation.

Respiratory irritation:

As described in the section for acute and repeated dose toxicity, there were no alterations in the nasal or lung tissue indicative of respiratory irritation. This includes histopathological evaluations after a 90-days exposure to 500ppm of the reaction mass (2.6mg/L) and no gross lesions after 90 days at up to 1200 ppm (6.2mg/L, no histopathology performed). There are however several studies that describe sensory irritation in several species including human, that lasts only for the period of exposure and lessens after repeated exposures to the test substance. Data are presented for all isomers of pentyl acetate, since the results are very similar. The identity of the tested isomer is not always clear. E.g., amyl acetate might be pentyl acetate, but might also refer to a commercially available mixture of isomers.

Even though most studies lack critical details or were only performed with a very limited number of animals, the reported data are very similar for all species. In mice, rats, and humans, where respiratory effects have been examined, these were reported around 5 – 8 mg/L. Lacrimation, salivation, and/or squinting were observed in humans, cats, guinea pigs, and rabbits at and above app. 10 mg/L. Though often no lower concentration were tested, effects in the lowest concentration were slight. Longer durations did not worsen the effects, but there were hints of lessening of effects. In subjective evaluations, humans reported slight effects on nose, eye, and throat already at 1mg/L. Narcosis does not occur, except for very high exposures and long exposure durations.

Animal data:

In the first study by Silver (1992), ethmoid nerve stimulation and changes in breathing rate were directly measured via electrodes in 7 anesthetized rats that were exposed to a concentration series from 252 to 3600 ppm of amyl acetate for 10 seconds each. Nerve activity returned to baseline levels immediately after cessation of exposure. The NOAEC was 440ppm (2.3mg/L) for ethmoid nerve stimulation and 815 ppm (4.2mg/L) for effects on breathing rates. The LOAECs were 650 ppm (3.4 mg/L) and 1562 ppm (8.1 mg/L), respectively.

Muller and Greff (1984) cite unpublished data they likely generated themselves of an experiment performed also according to the method by Alarie. RD 50 values are reported for n-amyl acetate (pentyl acetate) and isoamylacetate (3-methyl butyl acetate). They were 8.3mg/L and 5.6 mg/L, respectively. These values agree well with the values obtained by Alarie, 1981, who reports an RD 50 value for amyl acetate of 8mg/L in mice.

6 guinea pigs per group were exposed to 1-methylbutyl acetate (CAS 626-38-0) at concentrations from 11 mg/L to 55.6mg/L for up to 810 minutes (Patty, 1936). 11mg/L only led to signs of irritation, i.e., rubbing of the nose and squinting almost immediately after the start of exposure. At higher concentrations, lacrimation, incoordination, and narcosis was also observed. The time until signs were exhibited decreased with increasing concentrations. At above 50mg/L, some of the animals died. Death was due to a state of narcosis which terminated in death rather than to the irritation of the lungs. No animals died following exposure; they either died during exposure or survived the exposure and the 4- or 8-day post-exposure observation period.

A rabbit and a cat exposed to 6.2mg/L exhibited partly or fully closed eyes, and the cat also salivated at the beginning as a response to sensory irritation (Lehmann, 1913). No signs of drowsiness or narcosis were observed. At higher concentrations (up to 21 - 35mg/L), cats showed reduced activity up to narcosis and subsequent weight loss, while rabbits were almost unaffected.

These data are supported by a study by Flury and Wirth (1934), in which cats and mice were exposed for various durations to several concentrations ranging from 10 mg/L to 37 mg/L for mice and from 11.6 to 56 mg/L for cats. The concentration causing narcosis after 6h was 20mg/L for mice and 24 mg/L for cats. Cats showed salivation and lacrimation after exposure to all doses, though severity seemed to increase up to 15.4mg/L. In narcotic animals, reflexes returned 15 - 30 minutes after cessation of exposure. Except for reduced food consumption resulting in reduced body weight and possibly diarrhea at high concentrations in cats, there were no other observations after the end of the exposure period that could be related to treatment. For mice, no symptoms have been reported.

Human data

Nelson et al. (1943) exposed 10 human volunteers per group to 100, 200, and 300 ppm of amyl acetate for 3-5 min. After exposure, each individual was asked to rate the effect on nose, eyes, and throat according to the following scale: no reaction, slightly irritating, very irritating. The odor was listed as absent, definite, moderate, strong, or overpowering. Finally, each person was asked, if they could imagine to work in this atmosphere for 8 hours. Slight eye and nose effects were still reported at 200ppm. 100 ppm was judged to be an acceptable working environment by most, though slight throat discomfort was still experienced. This study was used by MAK, SCOEL and in other countries to derive an OEL of 50 ppm.

Though Flury and Wirth (1934) exposed only 2-4 volunteers (limited information on exposure available), the reported symptoms match the observations of Nelson et al. At 1mg/L (200ppm) slight effects on nose, eyes, throat, and trachea were described, which worsened at 10mg/L. At the higher concentration, lacrimation, coughing, and shallow breathing were also observed.

Lehmann (1913) exposed two young, healthy volunteers for 30 min to 5mg/L (app. 960 ppm). The test subjects reported irritation of the throat and coughing at the beginning, which was later replaced by a dry feeling in the throat. Eye irritation and enhanced secretion of the nose were also reported. No headaches occurred, and the pulse remained normal.

Justification for classification or non-classification

Considering the results for skin and eye irritation, the available data are conclusive and do not trigger classification according to REGULATION (EC) No 1272/2008 (CLP).

No histopathological alterations were observed in acute and subchronic studies in rats. There were no hints for erythema, edema, or inflammation that would require classification. All effects observed are the result of sensory irritation not leading to adverse effects and thus not requiring classification.