Morpholine

Endpoint summary

Description of key information

Morpholine is alkaline and is corrosive to skin and mucous membranes.

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Reference 1

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03. Jan 1967 - 11. Jan 1967

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Deviations:

not specified

Principles of method if other than guideline:

BASF Test, see details in remarks on material and methods

GLP compliance:

no

Species:

rabbit

Strain:

Vienna White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 3.22 and 2.94 kg

Type of coverage:

occlusive

Preparation of test site:

clipped

Vehicle:

unchanged (no vehicle)

Controls:

other: untreated skin of the same animals served as control.

Duration of treatment / exposure:

1, 5, 15 min or 20 hours

Observation period:

8 days

Number of animals:

2 animals

Details on study design:

TEST SITE
- Area of exposure: 2.5 x 2.5 cm

REMOVAL OF TEST SUBSTANCE
- Washing (if done): conc. Lutrol and 50 % Lutrol solution
- Time after start of exposure: 1, 5 or 15 min post exposure

Irritation parameter:

overall irritation score

Remarks:

1 min exposure

Basis:

mean

Time point:

other: 8 days

Score:

1

Max. score:

3

Reversibility:

not reversible

Remarks on result:

positive indication of irritation

Irritation parameter:

overall irritation score

Remarks:

5 and 15 minutes

Basis:

mean

Time point:

other: 8 days

Score:

2

Max. score:

3

Reversibility:

not reversible

Remarks on result:

positive indication of irritation

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

not measured/tested

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

not measured/tested

Irritant / corrosive response data:

The application of the test substance for 1 min caused in 1 animal haemorrhagic areas and leathery-like necrosis at the end of the observation period.
The application for 5 min caused after 24 hours parchment-like necrosis in 1 animal and haemorrhagic areas after 24 hours and leathery-like necrosis after 8 days.
The application of the test substance for 15 min caused haemorrhagic areas, oedema and parchment-like necrosis after 24 hours which declined to leathery-like necrosis after 8 days.
Leathery-like necrosis was considered as a full-thickness necrosis.

Interpretation of results:

Category 1 (corrosive) based on GHS criteria

Reference 2

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 20-23, 1997

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:

test control not performed

GLP compliance:

yes (incl. QA statement)

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Covance,The Development Services Company, Denver, PA, USA
- Age at study initiation: 19-21 weeks
- Weight at study initiation: 2.710-3.278 kg
- Housing: rabbits were housed individually in stainless steel cages
- Diet: PMI Certified Lab Rabbit HF Diet
- Water: fresh water, ad libitum
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature: 16-21°C
- Humidity: 25-70 %
- Photoperiod: 12 hours light/12 hours dark

Type of coverage:

occlusive

Preparation of test site:

shaved

Vehicle:

unchanged (no vehicle)

Controls:

not specified

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 0.5 mL/site

Duration of treatment / exposure:

3 min

Observation period:

3 and 55 min

Number of animals:

6 animals (3 males, 3 females)

Details on study design:

TEST SITE
- Area of exposure: dorsal area of the trunk (clipped free of fur)

REMOVAL OF TEST SUBSTANCE
- Washing: no data
- Time after start of exposure: 3 min

SCORING SYSTEM:
Draize Evaluation of Dermal Irritation

Irritation parameter:

erythema score

Basis:

animal: 2/6

Time point:

other: immediate after exposure

Score:

>= 2

Max. score:

4

Remarks on result:

other: well-defined erythema

Irritation parameter:

erythema score

Basis:

animal: 4/6

Time point:

other: immediate after exposure

Score:

>= 1

Max. score:

4

Remarks on result:

other: very slight erythema

Irritation parameter:

edema score

Basis:

animal: 3/6

Time point:

other: immediate after exposure

Score:

>= 1

Max. score:

4

Remarks on result:

other: very slight edema

Irritation parameter:

edema score

Basis:

animal: 3/6

Time point:

other: immediate after exposure

Score:

>= 0

Max. score:

4

Irritation parameter:

erythema score

Basis:

animal: 6/6

Time point:

other: 55min

Score:

>= 4

Max. score:

4

Remarks on result:

other: severe erythema, necrosis

Irritation parameter:

edema score

Basis:

animal: 6/6

Time point:

other: 55min

Score:

>= 4

Max. score:

4

Remarks on result:

other: severe edema, necrosis

Irritation parameter:

erythema score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

not measured/tested

Irritation parameter:

edema score

Basis:

mean

Time point:

24/48/72 h

Remarks on result:

not measured/tested

Irritant / corrosive response data:

In all animals severe erythema, severe oedema and necrosis was observed after 55 min.

Interpretation of results:

Category 1A (corrosive) based on GHS criteria

Reference 3

Endpoint:

skin corrosion: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro skin irritation study does not need to be conducted because adequate data from an in vivo skin irritation study are available

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (corrosive)

Eye irritation

Link to relevant study records

Reference

Reference 1

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

03. Jan 1967 - 11. Jan 1967

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Principles of method if other than guideline:

BASF-Test, see details in remarks on material and methods.

GLP compliance:

no

Species:

rabbit

Strain:

Vienna White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 2.82 and 2.97 kg

Vehicle:

unchanged (no vehicle)

Controls:

other: The adjacent eye served as saline control.

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 50 µL

Duration of treatment / exposure:

Single application

Observation period (in vivo):

8 days

Number of animals or in vitro replicates:

2 animals

Irritation parameter:

cornea opacity score

Basis:

mean

Time point:

24/48/72 h

Score:

1.2

Max. score:

4

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

iris score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

2

Reversibility:

other: no effects

Irritation parameter:

conjunctivae score

Basis:

mean

Time point:

24/48/72 h

Score:

1.6

Max. score:

3

Reversibility:

not fully reversible within: 8 days

Irritation parameter:

chemosis score

Basis:

mean

Time point:

24/48/72 h

Score:

0

Max. score:

4

Reversibility:

fully reversible within: 24 h

Findings animal1/animal2 (50 µL):

Time	Opacity	Iritis	Erythema	Chemosis
1h	1/1	0/0	2/2	2/2
24h	1/1	0/0	2/2	0/0
48h	1/1	0/0	1/2	0/0
72h	2/1	0/0	1/2	0/0
8d	2/0	0/0	1/3	0/0

Mean values over 24 h, 48 h and 72 h:

Animal1: Opacity: 1.3; Chemosis: 0; Erythema: 1.3; Iritis: 0

Animal2: Opacity: 1; Chemosis: 0; Erythema: 2; Iritis: 0

The application of 50 µL test substance caused initially chemosis and moderate opacity and erythema. The corneal opacity and erythema effects were not reversible within the 8 day observation period. One animal developed ingrowing vessels at the end of the observation period.

Findings animal1/animal2 (100 µL):

Time	Opacity	Iritis	Erythema	Chemosis
1h	1/1	0/0	2/2	2/2
24h	2/2	0/0	2/2	2/2
48h	2/2	2/2	2/2	2/2
72h	2/2	2/2	2/2	2/2
8d	3/3	2/2	2/2	2/2

Mean values over 24 h, 48 h and 72 h:

Animal1: Opacity: 2; Chemosis: 2; Erythema: 2; Iritis: 1.3

Animal2: Opacity: 2; Chemosis: 2; Erythema: 2; Iritis: 1.3

The applicaton of 100 µL test substance caused moderate to severe corneal opacity, erythema and chemosis. After 48 hours iritis and after 6 days staphyloma was noted. The effects were not reversible within the 8 day observation period Severe corneal opacity and iritis are considered to be irreversible effects to ophthalmic tissue.

The original BASF grading was converted into the numerical grading according to the OECD Draize system.

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Reference 2

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

GLP compliance:

yes

Species:

rabbit

Strain:

not specified

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Housing: individual in cages
- Diet: controlled access
- Water: ad libitum
- Acclimation period: appr. one week

ENVIRONMENTAL CONDITIONS
- Temperature: 20 ± 3 °C
- Humidity: 50 ± 20 %
- Photoperiod: 12 hours dark/12 hours light

Vehicle:

unchanged (no vehicle)

Controls:

other: the adjacent eye served as control.

Amount / concentration applied:

TEST MATERIAL
- Amount applied: 0.1 mL
- Concentration: undiluted

Duration of treatment / exposure:

single application,
exposure period: 4 seconds, 30 seconds, 24 hours

Observation period (in vivo):

21 days

Number of animals or in vitro replicates:

3 animals per exposure period

Details on study design:

REMOVAL OF TEST SUBSTANCE
If necessary, the treated eye was washed with tap water, at least 24 hous after treatment.

SCORING SYSTEM: according to OECD GL 405

TOOL USED TO ASSESS SCORE: biomicroscope / fluorescein / ophthalmoscope

Irritation parameter:

conjunctivae score

Remarks:

(exposure 4 s)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 2 - <= 2.3

Max. score:

3

Irritation parameter:

conjunctivae score

Remarks:

(exposure 30 s)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 2 - <= 2.7

Max. score:

3

Irritation parameter:

conjunctivae score

Remarks:

(exposure 24 h )

Basis:

mean

Time point:

24/48/72 h

Score:

>= 2.7 - <= 3

Max. score:

3

Irritation parameter:

chemosis score

Remarks:

(exposure 4 s)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 1 - <= 2.3

Max. score:

4

Irritation parameter:

chemosis score

Remarks:

(exposure 30 s)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 1 - <= 2.3

Max. score:

4

Irritation parameter:

chemosis score

Remarks:

(exposure 24 h)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 2.7 - <= 3.7

Max. score:

4

Irritation parameter:

cornea opacity score

Remarks:

(exposure 4 s)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 1.7 - <= 2.3

Max. score:

4

Irritation parameter:

cornea opacity score

Remarks:

(exposure 30 s)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 1.3 - <= 2

Max. score:

4

Irritation parameter:

cornea opacity score

Remarks:

(exposure 24 h)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 1.3 - <= 1.7

Max. score:

4

Irritation parameter:

iris score

Remarks:

(exposure 4 s)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 0.5 - <= 0.7

Max. score:

2

Irritation parameter:

iris score

Remarks:

(exposure 30 s)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 0.3 - <= 0.5

Max. score:

2

Irritation parameter:

iris score

Remarks:

(exposure 24 h)

Basis:

mean

Time point:

24/48/72 h

Score:

>= 0 - <= 0.3

Max. score:

2

Irritant / corrosive response data:

All expositions with Morpholine (for 4 s, 30 s, and 24 h) resulted in eye irritation of animals. In addition, rabbits showed necrosis around the eyes. After an exposure time of 24 hours burns (corrosion) were observed. In 2 rabbits corrosion was noted both inside and around the eyes after 30 seconds of exposure. After an observation period of 21 days eye injuries were still observed in one animal.
 
Exposure group 24 hours:
All animals showed necrosis in the eye and loss of fur, sores, redness, and scarring on the front of the upper eyelids outside. In one animal eye injuries were cleared within 10 days and detachment of the outer layers of the cornea were observed.
 
Exposure group 30 s:
In all animals whitish secretions were observed both in and around the eyes.In 2/3 animals eye injuries were cleared within 10 days and detachment of the outer layers of the cornea were observed. In the 2 animals where corrosion was noted, hair loss was also observed.
 
Exposure group 4 s:
In all animals whitish secretions were observed both in and around the eyes. In 2/3 animals eye injuries were cleared within 10 days and detachment of the outer layers of the cornea were observed. One rabbit showed a pale flash film, perhaps with scars.

Interpretation of results:

Category 1 (irreversible effects on the eye) based on GHS criteria

Reference 3

Endpoint:

eye irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

an in vitro eye irritation study does not need to be conducted because adequate data from an in vivo eye irritation study are available

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irreversible damage)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Skin irritation

In a primary dermal irritation study (Huntsman, 1997), 0.5 mL of Morpholine was applied to one site on the clipped dorsal trunk of 6 New Zealand White rabbits (3 males and 3 females) for an exposure period of 3 minutes. Observations for responses were recorded immediately after unwrap and at 55 minutes. Grading of irritation was performed according to the method of Draize. Following an exposure period of 3 minutes, severe erythema, severe oedema and necrosis were observed. Therefore, Morpholine was considered to be a severe irritant and was considered as corrosive according to DOT classification (Packaging group 1). This study is classified as key study. It satisfies the requirements of OECD test guideline 404.

In a further key skin irritation/corrosion study (BASF AG, 1967), 2 Vienna White rabbits were treated with Morpholine (99.2 %) for 1, 5, 15 min or 20 hours using occlusive conditions. An application site of 2.5 cm² was covered with the liquid test substance. The animals were observed for 3 weeks and skin changes were recorded daily. The application of the test substance for 1 min caused in 1 animal haemorrhagic areas and leathery-like necrosis at the end of the observation period. The application for 5 min caused after 24 hours parchment-like necrosis in 1 animal and haemorrhagic area after 24 hours and leathery-like necrosis after 8 days. The application of the test substance for 15 min caused haemorrhagic areas, oedema and parchment-like necrosis after 24 hours which declined to leathery-like necrosis after 8 days. Leathery-like necrosis was considered as a full-thickness necrosis. This study is classified as acceptable. It generally satisfies the guideline requirements for OECD 404.

In a supporting skin irritation/corrosion study (Loden et al., 1985), 3 albino rabbits were treated with aqueous solutions of 2, 20, 40 or 60 % Morpholine. The skin reactions to treatment were evaluated after 0.5, 24, 48 and 72 hours. A 2% solution of Morpholine caused skin irritation after 72 hours, whereas 40 and 60% solutions immediately caused reddening of the skin. This study is classified as acceptable. It satisfies the guideline requirement of OECD test guideline 404.

In a comparative study (Wang & Suskind, 1988), the irritant potential of Morpholine was measured by applying 0.1 g mixture (0.1, 0.5, 2, 5 and 10 % Morpholine in petrolatum) to guinea pig skin for 24 hours. Observations were made 1, 24 and 48 hours after removal of the test material, and no noticeable effects were found. This study is classified as acceptable guideline study.

In a supporting primary dermal irritation study (Huntsman, 1993), 0.5 mL Morpholine was applied to the shaved skin of 6 male New Zealand White rabbits for exposure durations of 3 min, 60 min, 4 hours and 24 hours using a semiocclusive dressing. Following patch removal, the animals were observed for a period of 14 days. The scoring of reactions was performed according to Draize. The primary dermal irritation index was assessed. Severe erythema, severe oedema and necrosis were noted under the conditions of this study. Based on these results, Morpholine was considered as corrosive. This study is classified as acceptable. It satisfies the requirements for OECD test guideline 404.

In a primary dermal irritation study (Huntsman, 1993) using a semiocclusive dressing, 0.5 mL Morpholine was applied to the shaved skin of one male and one female New Zealand White rabbit for exposure duration of 4 hours. In this supporting study results were reported at 4 h and 48 h after exposure. Morpholine was considered to be corrosive. This study is classified as acceptable.

Eye irritation

In a primary eye irritation study (Koch et al., 1985), 100 µL of undiluted Morpholine (99 %) was instilled into the conjunctival sac of the left eye of 3 rabbits. The eyes were washed out after 24 hours. Further exposure times were 4 and 30 seconds, respectively (3 rabbits/exposure time). Animals were observed for 21 days. Irritation was scored according to OECD guideline 405. All three expositions gave rise to eye irritation. All animals showed necrosis in and around the eyes. After an exposure time of 24 hours burns (corrosion) were observed. Two of the animals also gave rise to corrosion both inside and around the eyes at 30 seconds of exposure. After the observation period eye injuries were still observed in one animal. The authors classified Morpholine as irritant substance; however, corrosive effects in several animals were observed. Thus, Morpholine can be regarded as a corrosive substance. This study is classified acceptable. It satisfies the requirement of OECD test guideline 405.

In this acute eye irritation/corrosion study (BASF AG, 1967), the eyes of 2 Vienna White rabbits were exposed by application of 50 µL undiluted Morpholine (99.2 %) into the conjunctival sac. In a second attempt, 2 animals were treated with an additional 50 µL of the test substance 5 min after the first application. The animals were observed after 10 min, 1 and 3 hours on the day of treatment and up to 8 days afterwards. The eyes were not washed out after 24 hours. Overall, the treatment caused oedema, opacity, staphyloma and corrosion of the eye mucous membranes within 24 hours. Morpholine was graded as corrosive under the conditions of this study. This study is classified as acceptable. It satisfies the requirements of OECD test guideline 405.

In a supporting eye irritation study by Smyth et al. (1954), in which eyes of 7 New Zealand White rabbits were treated with 0.5 mL Morpholine. Based on the outcomes of this study Morpholine was considered as irritating to the rabbit eye. This study is classified an acceptable supporting study.

With regard to other test animals, in-life clinical examinations in rats exposed to up to 0.54 g/m³ (150 ppm) Morpholine revealed increased incidences in inflammation of the cornea at week 103 of a chronic inhalation study (Huntsman 2147-102, cf. 7.5.3). Findings included keratitis, oedema, abrasion, scarring, and ulceration with or without neovascularization and corneal epithelial hyperplasia. A high incidence of retinal degeneration was observed, primarily in female animals, which was probably an age-related light-induced retinal degeneration.

Supportingly, the eye irritating property of DIPA/110-97-4 was also found using other laboratory methods: in vitro Short Time Exposure test by Takahashi et al., 2011 (Toxicology in vitro 25; p.1425-1334), Hansen solubility parameter to predict results of the RhCE method by Ito et al., 2021 (Toxicology in vitro 70, 105039).

Respiratory irritation

Studies of acute inhalation toxicity of Morpholine revealed irritation of the mucous membranes. In a key study there is indication that the test substance causes local irritation to exposed tissues including respiratory tract (BASF AG XVI/352, cf. 7.2.2). A further study noticed irritation of nose and eyes (mucous membranes) after exposure of rats to Morpholine for 6 hours to whole body at a nominal concentration of 5000 ppm equivalent to ca. 18.1 mg/L; 9/10 animals died after one treatment (Huntsman 2147-100, cf. 7.2.2).

Justification for classification or non-classification

Classification, Labeling, and Packaging Regulation (EC) No 1272/2008

The available experimental test data are reliable and suitable for the purpose of classification under Regulation (EC) No 1272/2008. Based on this information, the test item is considered to be classified for skin and eye irritation Cat. 1A (H314) and Cat. 1 (H318), respectively under Regulation (EC) No. 1272/2008, as amended for the fifteenth time in Regulation (EU) 2020/1182.

The substance is already listed in Annex VI of Regulation (EC) No 1272/2008 concerning skin and eye irritation (Cat. 1B, H314).