Morpholine

Endpoint summary

Description of key information

The LD50/LC50 values derived from the key-studies were: LD50 (oral, rat) 1900 mg/kg bw, LD50 (dermal, rabbit) 500 mg/kg bw, LC50 (rat) 8000 mg/m³. 

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1967-02-06

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 401 (Acute Oral Toxicity)

Deviations:

not specified

Principles of method if other than guideline:

BASF-Test, see details in the section "Any other information on materials and methods incl. tables".

GLP compliance:

no

Remarks:

study was performed prior to GLP

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: young adult (based on body weight)
- Weight at study initiation: 180 to 288 g (male), 156 - 226 g (female)

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

VEHICLE
- Concentration in vehicle: 4 and 20 %

Doses:

1600, 2000, 2500 and 3200 mL/kg bw = 1600, 2000, 2500 and 3200 mg/kg bw (conversion in mg/kg bw is based on the density d=1.00 g/cm³)

No. of animals per sex per dose:

5 animals (at 1600, 2000 and 3200 mg/kg bw)
10 animals (at 2500 mg/kg bw)

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: several times on the day of application and daily thereafter
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, macroscopical examination

Statistics:

Not indicated.

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

ca. 1 900 mg/kg bw

Mortality:

See details in the section "Any other information on results incl. tables".

Clinical signs:

other: At 3200 and 2500 mg/kg bw: squatting posture, ruffled fur, abdominal position, shallow and irregular respiration, closed eyes. After 24 hours the surviving animals showed red crusted eyes and noses, and trembling gait with delayed motion of the hind limbs

Gross pathology:

Animals that died: 4x diarrhoea, 1x haemorrhagic enteritis
Sacrificed animals: no abnormalities

Mortality:

Dose (mg/kg bw)	Gender	1 h	24 h	48 h	7 days	14 days
3200	male	0/5	5/5	5/5	5/5	-
3200	female	0/5	5/5	5/5	5/5	-
2500	male	0/10	4/10	4/10	4/10	4/10
2500	female	0/10	10/10	10/10	10/10	10/10
2000	male	0/5	0/5	1/5	1/5	-
2000	female	0/5	5/5	5/5	5/5	-
1600	male	0/5	1/5	1/5	1/5	-
1600	female	0/5	1/5	1/5	1/5	-

The test substance caused dose dependent toxicity after a single ingestion and local irritations to exposed tissues.

Interpretation of results:

Category 4 based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 900 mg/kg bw

Quality of whole database:

similar to OECD TG 401

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

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 403 (Acute Inhalation Toxicity)

Deviations:

not specified

GLP compliance:

no

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

not specified

Sex:

not specified

Route of administration:

inhalation: vapour

Type of inhalation exposure:

not specified

Vehicle:

not specified

Analytical verification of test atmosphere concentrations:

not specified

Duration of exposure:

4 h

Concentrations:

6734 ppm ≈ 23,569 mg/m³

No. of animals per sex per dose:

6 animals

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Statistics:

No data

Key result

Sex:

not specified

Dose descriptor:

LC0

Effect level:

24 mg/L air

Exp. duration:

4 h

Mortality:

No deaths (0/6) were noted.

Clinical signs:

other: There were signs of irritation and stained hair

Body weight:

The body weight gain during the observation period was normal.

Gross pathology:

No gross lesions were noted at necropsy.

Other findings:

In a further study also reported in this publication 6 rats have been exposed to 8497 ppm (31 mg/L) of morpholine vapour in a 8-h exposure and one animal died. The survivors gained weight normally and had no visible lesions at autopsy.

Reference 2

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

15.09.1980 - 25.09.1980

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

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

Qualifier:

no guideline followed

Guideline:

other: no guideline required

GLP compliance:

yes

Test type:

other: Range finder

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Sprague-Dawley descended, C-D, (COBS) rats from Charles River Breeding Laboratories, Inc., Portage, Michigan.
- Weight at study initiation: 140-253 g
- Housing: The animals were housed in individual stainless steel wire-mesh cages in two 6-m³ inhalation chambers; one for controls; the other for exposed rats.
- Diet: Purina Lab Chow # 5001 was available ad libitum, except during exposure.
- Water: Tap water via automatic valves was available ad libitum, except during exposure.
- Acclimation period: The animals were quarantined 16 days prior to selection and initiation of exposure.

ENVIRONMENTAL CONDITIONS
- Temperature: 28.3 ± 2.7 °C
- Humidity: relative, 45 ± 5.7 %
- Photoperiod: 12-hour light/dark cycle

Route of administration:

inhalation: vapour

Type of inhalation exposure:

whole body

Vehicle:

not specified

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Exposures were made in 38-liter glass and stainless steel chambers operated dynamically at 10L/min. The controls were similarly "exposed" to air.
- Method of holding animals in test chamber: All rats were individually held in stainless steel wire-mesh cages.
- System of generating particulates/aerosols: Dried, filtered air was metered through the head space of cylindrical glass flasks, each containing a specific volume of liquid Morpholine. Volume of Morpholine in the flasks: 100 mL
- Temperature, humidity, pressure in air chamber: temperature was 28.3 ± 2.7 degree C and relative humidity 45 ± 5.7 %.
- Air flow rate: 10L/min

TEST ATMOSPHERE
- Brief description of analytical method used: Concentrations of Morpholine in each chamber were monitored semi-continuously (with half -hour logging) using a Miran Infrared Vapor Analyzer at 9.1 micron (analytical wave length). Water impinger samples for gas chromatographic peak-height analysis were collected during the third, fourth, and fifth hour of each exposure. An F&M 700 Gas Chromatograph (with 1/4 inch O.D. stainless steel column packed with Tenax and flame ionization detector) was employed.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Concentrations of Morpholine in each chamber were monitored semi-continuously (with half -hour logging) using a Miran Infrared Vapor Analyzer at 9.1 micron (analytical wave length). Water impinger samples for gas chromatographic peak-height analysis wer

Duration of exposure:

6 h

Concentrations:

5000 ppm (target analytical concentration)

No. of animals per sex per dose:

5 animals

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 9 days
- Necropsy of survivors performed: yes, brain, eye, nasopharynx, pharynx, trachea, lungs, kidneys, adrenals, heart, thyroid/ parathyroid, liver, spleen, stomach (including forestomach and fundus), duodenum, lleum, jejunum, colon, rectum, urinary bladder, muscle, testes, ovaries.
- Clinical signs including body weight

Statistics:

Not indicated.

Key result

Sex:

male/female

Dose descriptor:

other: lethal

Effect level:

18.1 mg/L air

Exp. duration:

6 h

Mortality:

9/10 animals died on day 1.

Clinical signs:

other: Blood around the nose and mouth, spasms and tremors, irritation of nose and eyes (mucous membranes)

Body weight:

No data

Gross pathology:

No gross lesions

Other findings:

9/10 animals in the target dose group of 5000 ppm died on day 1 of the study. So, only one exposure was conducted. The last animal in this group was sacrificed on day 3 of the study in moribund condition. Analytical concentration as measured by GC was 1300 ppm. A single measurement was taken only. By IR measurement a concentration of 1590 ppm was determined. This was noted to be the target dose of 5000 ppm. As daily nominal concentration for this dose group ca. 6500 ppm is listed in the study, too.
5000 ppm = ca. 18 mg/kg bw.

Reference 3

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1967-02-06

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 403 (Acute Inhalation Toxicity)

Deviations:

not specified

Principles of method if other than guideline:

BASF-Test, see details in the section "Any other information on materials and methods incl. tables".

GLP compliance:

no

Remarks:

study was performed prior to GLP

Test type:

standard acute method

Limit test:

no

Species:

rat

Strain:

not specified

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 151 g (mean)

Route of administration:

inhalation

Type of inhalation exposure:

not specified

Vehicle:

other: unchanged (no vehicle)

Details on inhalation exposure:

Please refer to the section "Any other information on materials and methods incl. tables".

Analytical verification of test atmosphere concentrations:

no

Duration of exposure:

1 h

Remarks on duration:

additional exposure times 3 h and 5.5 h

Concentrations:

1 h exposure: 35.1 mg/L air
3 h exposure: 28.8 mg/L air
5.5 h exposure: 21.14 mg/L air

No. of animals per sex per dose:

1 h exposure: 6
3 h and 5.5 h exposure: 3

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 7 days
- Frequency of observations: several times on the day of exposure and daily thereafter.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Key result

Sex:

male/female

Dose descriptor:

LC50

Exp. duration:

1 h

Remarks on result:

not determinable

Mortality:

1 h exposure: 0/12
3 h exposure: 2/6
5.5 h exposure: 6/6

Clinical signs:

other: Escape attempts, distinct irritation of mucous membrane, severe nose and eye discharge, dyspnoea, convulsions, widespread corrosion of nose and paws.

Body weight:

No evaluable data.

Gross pathology:

Animals that died: wet, ruffled fur, corrosive smell.
Sacrificed animals: no abnormalities observed.

The inhalation of a highly saturated vapor-air-mixture caused mortality after 3 h of exposure. There was indication that the test substance caused local irritation to exposed tissues including respiratory tract.

Reference 4

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

no data available

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

no guideline followed

Principles of method if other than guideline:

In an inhalation study rats have been exposed to morpholine.

GLP compliance:

not specified

Limit test:

no

Species:

rat

Strain:

not specified

Sex:

not specified

Route of administration:

inhalation

Type of inhalation exposure:

not specified

Vehicle:

not specified

Remarks on duration:

Exposure unspecified

No. of animals per sex per dose:

no data given

Control animals:

not specified

Sex:

male/female

Dose descriptor:

LC50

Effect level:

>= 7.8 - <= 8.2 mg/L air

Remarks on result:

other: Exposure unspecified

Sex:

male

Dose descriptor:

LC50

Effect level:

8.2 mg/L air

Remarks on result:

other: Exposure unspecified

Sex:

female

Dose descriptor:

LC50

Effect level:

7.8 mg/L air

Remarks on result:

other: Exposure unspecified

Other findings:

In this inhalation study with rats, LC50 values of 7.8 and 8.2 mg/L were obtained for female and male rats.

Reference 5

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

no data available

Reliability:

4 (not assignable)

Rationale for reliability incl. deficiencies:

abstract

Qualifier:

no guideline followed

Principles of method if other than guideline:

In an inhalation study mice have been exposed to morpholine.

GLP compliance:

not specified

Limit test:

no

Species:

mouse

Strain:

not specified

Sex:

not specified

Route of administration:

inhalation

Type of inhalation exposure:

not specified

Vehicle:

not specified

Remarks on duration:

no data given

No. of animals per sex per dose:

no data given

Control animals:

not specified

Sex:

male/female

Dose descriptor:

LC50

Effect level:

>= 5.2 - <= 6.9 mg/L air

Remarks on result:

other: Exposure unspecified

Sex:

male

Dose descriptor:

LC50

Effect level:

5.2 mg/L air

Remarks on result:

other: Exposure unspecified

Sex:

female

Dose descriptor:

LC50

Effect level:

6.9 mg/L air

Remarks on result:

other: Exposure unspecified

Other findings:

In this inhalation study with mice, LC50 values of 5.2 and 6.9 mg/L air were obtained for female and male mice.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LC50

Value:

8 000 mg/m³ air

Physical form:

inhalation: vapour

Quality of whole database:

WoE approach

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1954

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 402 (Acute Dermal Toxicity)

Deviations:

not specified

Principles of method if other than guideline:

according to Draize et al. (1944)

GLP compliance:

no

Remarks:

prior to GLP

Test type:

standard acute method

Limit test:

no

Species:

rabbit

Strain:

New Zealand White

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Weight at study initiation: 2.5 - 3.5 kg

Type of coverage:

occlusive

Vehicle:

not specified

Details on dermal exposure:

Penetration of rabbit skin was estimated by the one-day cuff method of Draize and associates. The fur was closely clipped over the entire trunk, and the close, retained beneath an impervious plastic film, contacted about 1/10 of the body surface.

Duration of exposure:

24 hours

Doses:

up to 20 mL/kg bw

No. of animals per sex per dose:

4 animals

Control animals:

not specified

Details on study design:

After 24 hours contact the film was removed. Mortality was considered complete after 14 additional days.

Statistics:

The most probable LD50 was estimated by the methods of Thompson (1947) and Weil (1952).

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

ca. 500 mg/kg bw

Remarks on result:

other: ≈ 0.5 mL/kg bw

Key result

Sex:

male

Dose descriptor:

LD50

Effect level:

>= 0.31 - <= 0.81 mL/kg bw

Remarks on result:

other: Limits of +/- 1.96 standard deviation using the method of Thompson

Mortality:

Death occurred within 14 days.

Clinical signs:

other: No data.

Gross pathology:

No data.

Interpretation of results:

Category 3 based on GHS criteria

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

500 mg/kg bw

Quality of whole database:

similar to OECD TG 403

Additional information

Acute toxicity: oral

The acute oral toxicity of Morpholine in the rat was examined in several toxicity studies. In general, oral administration of Morpholine to rats resulted in LD50 values within the range of 1000 to 2000 mg/kg bw (BASF AG, 1969; Shea, 1939; Smyth et al., 1954; Börzsönyi et al., 1981; Huntsman, 1981). Gastrointestinal and nasal haemorrhage were reported as clinical findings following oral Morpholine administration. When Morpholine was administered to 7 male rats at a neutral pH, no deaths occurred at 1000 mg/kg bw (Börzsönyi et al., 1981). In a supporting study on guinea-pigs (Shea, 1939) a lower LD50 of 900 mg/kg bw was observed.

The Huntsman study (1981) indicating LD50=1680 mg/kg bw ) is a key study here. The BASF study from 1967, where a LD50 of ca.1900 mg/kg bw was derived, has been identified as a second key study. These studies represent the most reliable studies. A reliable source of test material was used and the test was done according to a well described BASF method which was in compliance with the principles of OECD Guideline 401. The same holds true for the Huntsman study.

In the first key acute oral toxicity study (Huntsman, 1981), male Sprague Dawley rats were given a single dose (oral gavage) of Morpholine at 250, 500, 1000, 2000, or 4000 mg/kg bw. Animals were then observed for 3 days. The oral LD50 was estimated as 1680 mg/kg bw. In the second key study an acute oral toxicity study according to an internal BASF method was performed (BASF AG, 1967). Sprague Dawley rats were given a single oral dose of Morpholine diluted in water at 1600, 2000, 2500 or 3200 mg/kg bw. Animals were then observed for mortality and for clinical symptoms of toxicity for 14 days. All animals were subjected to necropsy. The oral LD50 was estimated as 1900 mg/kg bw.

Acute toxicity: dermal

In an acute dermal toxicity study (Smyth et al., 1954), male rabbits were exposed to Morpholine. The test material was applied in a single dose to the clipped skin of the trunk beneath an impervious plastic film. After 24 hour exposure the film was removed, and mortality was considered complete after 14 additional days. Death occurred within the observation period. Limits of ±1.96 standard deviation using the method of Thompson were 0.31 – 0.81 mL/kg bw. The LD50 determined in this study was 0.5 mL/kg bw. Due to the given specific density of Morpholine (1.0 g/cm3) a LD50 of 500 mg/kg bw was derived. This study is classified as acceptable. It satisfies the guideline requirement for an acute dermal study according OECD 402 in principle

In a supporting publication by Shea (1939), the dermal toxicity and skin absorption of Morpholine was assessed in 7 rabbits. Undiluted, unneutralized Morpholine was applied in a single dose of 900 mg/kg bw to the clipped skin of the midsection of 7 rabbits. The mortality incidence was 2/7. The 2 premature decedents had blackened necrotic skin and inflamed oedematous derma at the site of application, and severe burns of the underlying organs. The 5 surviving rabbits had severe burns at the site of treatment. This study is classified as acceptable supporting study.

Acute toxicity: inhalation

For the assessment of the acute inhalation potential of the test substance a weight of evidence approach was applied.

In an acute inhalation toxicity study according to an internal BASF method (BASF AG, 1967), male and female rats were exposed to Morpholine (99.4 %) vapour for a period of 1, 3 or 5.5 hours and observed for 7 days. All animals were subjected to necropsy. Exposure to Morpholine at vapour saturation concentrations resulted in 100 % lethality after 5.5 hours. Morpholine had irritating and corrosive properties. This acute inhalation toxicity study is classified as acceptable. It satisfies the guideline requirement for an acute oral study according to OECD 403 in principle.

In an acute inhalation study (ILO, 1972), 6 rats were exposed to approximately 24 mg/L. Morpholine for a period of 4 hours and then observed for 14 days. No mortality was observed. Signs of irritation and stained hair, but normal weight gain were noted during the 14 day observation period. No gross lesions were found at necropsy. This acute inhalation toxicity study is classified as acceptable supporting study.

In an acute inhalation toxicity study (Huntsman, 1981) young adult rats (5/sex) were whole body exposed to Morpholine for 6 hours at a nominal concentration of 5000 ppm (equivalent to approx. 18.1 mg/L). Blood around the nose and mouth, spasms and tremors, irritation of nose and eyes were observed during the study. 9/10 animals died on day 1 of the study (only one exposure was conducted). The last animal in this group was sacrificed in moribund condition on day 3 of the study. This study is classified as acceptable supporting study.

In an inhalation study with rats, LC50 values of 7.8 and 8.2 mg/L were obtained for female and male rats (Lam and Steen, 1978). In the same publication an inhalation study with mice was reported. Here, LC50 values of 5.2 and 6.9 mg/L air were obtained for female and male mice.

Conclusion

Exposure to Morpholine at vapour saturation concentrations resulted in 100% lethality after 5.5 h (BASF AG, 1967). Irritating and corrosive properties were noted. In studies using lower Morpholine concentrations, Lam & Van Stee (1978) obtained LC50 values of 8.2 and 7.8 mg/L for male and female rats, respectively (exposure period was not specified; Fed. Proc., 37: 679, abstract no. 2459: A re-evaluation of the toxicity of morpholine). Other authors reported no deaths at a three times higher dose level (24 mg/L) after an exposure period of 4 hours (ILO, 1972). 9/10 rats died after a single exposure to 18.1 mg/L for 6 hours (Huntsman, 1981). With regard to other species, reported LC50 values for mice are consistently in the range of ca. 5 - 7 mg/L (Lam and Van Stee, 1978). Based on these findings and using a conservative approach (here: reflecting the results of Lam & Van Stee, 1978), a LC50 value of ca. 8.0 mg/L for rat is derived.

Justification for classification or non-classification

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

The available data for acute toxicity are reliable and suitable for classification purposes under Regulation (EC) No 1272/2008. Based on this data, the substance is considered to be classified for acute oral toxicity Cat. 4 (H302), acute inhalation toxicity Cat.3 (H331) and for acute dermal toxicity Cat.3 (H311) under Regulation (EC) No 1272/2008, as amended for the fifteenth time in Regulation (EU) 2020/1182.

The substance is listed in Annex VI of Regulation (EC) No 1272/2008 concerning acute oral toxicity (Cat. 4, H302), acute inhalation toxicity (Cat.4, H332) and acute dermal toxicity (Cat.4, H312).