4-methylmorpholine 4-oxide, monohydrate

Endpoint summary

Description of key information

It should be noted that all tests performed in the past, have used the 50% aqueous solution which is the marketed product.
Acute toxicity: oral:
A KL 1 acute oral toxicity test was performed in male and female Sprague Dawley rats according to a guideline similar to OECD Guideline 401 (Mallory VT, 1981). This study was selected as key study.

In addition, a supporting KL 2 study was available (Vinegar MB, 1977).

Derived LD50 (oral): 4600 mg/kg bw

Acute toxicity: inhalation
No reliable data were available. However, this endpoint is waived as specific data are available for the oral and dermal exposure route.

Acute toxicity: dermal
A KL 1 acute dermal toxicity test was performed in male and female New Zealand White rabbits according to a guideline similar to OECD Guideline 402 (Auletta CS, 1981).

This study was selected as key study.

Derived LD50 (dermal): >4000 mg/kg bw

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:

From September 9, 1981 through September 28, 1981

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

no

Specific details on test material used for the study:

- Name of test material (as cited in study report): 4236-43-5, Order #J-85
- Substance type: yellow liquid
- Purity: responsibility of the sponsor. It is confirmed by the Sponsor that the test has been performed with a 50% aqueous solution.
- Stability: There was no apparent change in the physical state of the test article during administration
- Other: Specific gravity = 1.136 g/mL

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Blue Spruce Farms, Altamont, New York
- Weight at study initiation: 180 - 360 grams after fasting. The weight variation in animals or between groups did not exceed +/- 20%
- Housing: Separate isolation by test system; rats were housed individually in stainless steel wire mesh cages. Size in accordance with Guide for the Care and Use of Laboratory Animals of the Institute of Laboratory Resources, National Research Council.
- Diet (e.g. ad libitum): Wayne Lab Blox, ad libitum, checked daily and added or replaced as needed. Feeders are designed to reduce soiling, briding, and scattering
- Water (e.g. ad libitum): Availability - fresh tap water, fit for human consumption, ad libitum, using an automatic watering system supplied by Edstrom Industries Inc., Waterford, Wisconsin
- Acclimation period: Five days
- Fasting period before study: 18 hours

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C +/- 3°C
- Humidity (%): 30 - 70
- Photoperiod (hrs dark / hrs light): 12 hours light, 12 hours dark

Route of administration:

oral: gavage

Vehicle:

water

Details on oral exposure:

MAXIMUM DOSE VOLUME APPLIED: 10 mL/kg

Doses:

7000, 8000, 9000 and 10000 mg/kg

No. of animals per sex per dose:

Five

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: The rats were observed approximately at one, two, four and twenty-four hours after dosing and twice daily for fourteen days for pharmacotoxic, CNS effects and mortality. On the seventh and fourteenth day body weights were recorded.
- Necropsy of survivors performed: yes: The surviving rats were sacrificed by CO2 inhalation and a gross necropsy performed.

Statistics:

no details

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

9 200 mg/kg bw

Based on:

test mat.

95% CL:

> 8 200 - <= 10 300

Sex:

male

Dose descriptor:

LD50

Effect level:

9 800 mg/kg bw

Based on:

test mat.

95% CL:

> 8 800 - <= 10 900

Sex:

female

Dose descriptor:

LD50

Effect level:

9 300 mg/kg bw

Based on:

test mat.

95% CL:

> 7 800 - <= 11 200

Mortality:

None of the animals died at the 7000 mg/kg dose level, two of the ten died at the 8000 mg/kg dose level (2 females), three of ten died at the 9000 mg/kg dose level (1 male, 2 females) and seven of ten died at the 10000 mg/kg dose level (3 males and 4 females).

Clinical signs:

other: Diarrhea, piloerection, abnormal gait, abnormal stance, decreased body tone, decreased activity and orange discoloration around the nose and genital areas.

Gross pathology:

Necropsy revealed distended fluid-filled stomachs and intestines (clear, tan, green, white or orange), mottled lungs, darkened thymuses and darkened lymph nodes. Terminal necropsy revealed no visible lesions in any of the remaining rats.

Interpretation of results:

GHS criteria not met

Conclusions:

The calculated acute oral LD50 for male and female rats treated with the substance, was determined to be 9200 mg/kg with 95% confidence limits of 8200 to 10300 mg/kg. The test solution used was a 50% aqueous solution of NMMO. The LD50 of the pure NMMO is therefore considered to be 4600 mg/kg. Based on the study results and the criteria of the CLP Regulation, this substance should not be classified for oral toxicity.

Executive summary:

In an acute oral toxicity study which was performed equivalent/similar to OECD TG 401, groups of five Sprague-Dawley rats/sex were given a single oral dose of 4-methylmorpholine 4-oxide (50% aqueous solution) by oral gavage at doses of 7000, 8000, 9000 and 10000 mg/kg bw. Animals were then observed for 14 days.

None of the animals died at the 7000 mg/kg dose level, two of the ten died at the 8000 mg/kg dose level (2 females), three of ten died at the 9000 mg/kg dose level (1 male, 2 females) and seven of ten died at the 10000 mg/kg dose level (3 males and 4 females). Necropsy revealed distended fluid-filled stomachs and intestines (clear, tan, green, white or orange), mottled lungs, darkened thymuses and darkened lymph nodes. Terminal necropsy revealed no visible lesions in any of the remaining rats. Clinical signs included Diarrhea, piloerection, abnormal gait, abnormal stance, decreased body tone, decreased activity and orange discoloration around the nose and genital areas.

The oral LD50 was calculated to be 9800 mg/kg bw for males and 9300 mg/kg bw for females. The combined oral LD50 was calculated to be 9200 mg/kg bw/day.

As a 50% aqueous solution is used, the combined LD50 for the pure NMMO is considered to be 4600 mg/kg bw. Based on the results of this study and according to the criteria of the CLP Regulation, the substance should not be classified for acute oral toxicity.

This acute oral study is classified as acceptable. It satisfies the guideline requirements for an acute oral toxicity study. Dose levels exceeded the current standards of oral toxicity testing.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

4 600 mg/kg bw

Quality of whole database:

reliable without restriction

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

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:

April 30 to May 14, 1981

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 402 (Acute Dermal Toxicity)

Deviations:

yes

Remarks:

Skin was abraded before exposure to the test substance.

GLP compliance:

not specified

Test type:

standard acute method

Limit test:

yes

Specific details on test material used for the study:

- Name of test material (as cited in study report): 4236-40-5
- Substance type: Yellow liquid
- Storage condition of test material: Room temperature
- Purity: 50% aqueous solution
- Other: Specific gravity: 1.136

Species:

rabbit

Strain:

New Zealand White

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Dutchland Laboratories, Inc., Denver, Pennsylvania
- Age at study initiation: Young adults
- Weight at study initiation: males: 2.8 to 2.9 kilograms; females: 3.4 to 3.9 kilograms
- Housing: Suspended stainless steel, animals individually housed
- Diet (e.g. ad libitum): Purina Rabbit Chow, ad libitum
- Water (e.g. ad libitum): Automatic watering system, ad libitum Municipal water supply (Elizabethtown Water Co.)
- Acclimation period: 38 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 17,8°C - 20,6 °C (64-69°F)
- Humidity (%): monitored daily, no more details specified
- Photoperiod (hrs dark / hrs light): 12 hours light, 12 hours dark

Type of coverage:

occlusive

Vehicle:

unchanged (no vehicle)

Details on dermal exposure:

TEST SITE
- Area of exposure: trunk (dorsal and ventral surface and sides from scapular to pelvic area)
- % coverage: at least 20% of the body surface area
- Type of wrap if used: The substance was applied directly onto the exposed skin of the animal, and spread evenly over the entire area. A layer of 8-ply gauze was then wrapped around the animal to cover the application site. The animal was then wrapped in an impervious plastic sleeve, designed to contain the test material without leakage or undue pressure. The sleeve was secured with masking tape and Elizabethan collars were placed on all animals.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): Following approximately 24 hours of exposure, wrappings were removed and the test site wipped free of excess test material. After 30 minutes, dermal observations were made.

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 8000 mg/kg at a dose volume of 7.0 mL/kg

Duration of exposure:

24 hours

Doses:

8000 mg/kg

No. of animals per sex per dose:

5

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
viability check: twice daily
observations of pharmacologic and toxicologic signs: approximately 1, 2, and 4 hours after dosing and daily thereafter for fourteen days
body weights: pre-dose, at the time of clipping (weights used for calculation of doses), days 7 and 14
skin irritation: approx. 30 min after removal of the occlusive wrapping and scored after Draize
- Necropsy of survivors performed: yes: all animals surviving at termination of the observation period (day 14) were killed by an intravenous overdose of sodium pentabarbital and examined grossly. All abnormalities were recorded but no tissues were saved

Key result

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 8 000 mg/kg bw

Based on:

test mat.

Mortality:

All of the animals survived the fourteen-day post-dose period.

Clinical signs:

other: Soft stool, fecal staining and staining of the ano-genital area were noted sporadically in single animals on Days 1 and 2. Several animals exhibited nasal discharge between Days 4 and 14.

Gross pathology:

Observations made at necropsy were similar to those seen in control animals in the laboratory or were considered to represent normal physiologic variations.

Other findings:

Irritation: after 24h animals exhibited well-defined or moderate to severe erythema, generally with very slight or slight edema.

Interpretation of results:

GHS criteria not met

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

All animals survived the fourteen-day post-dose period. The LD50 value of the substance is greater than 8000 mg/kg. As a 50% aqueous solution is used, the LD50 for the pure NMMO is considered to be greater than 4000 mg/kg.
Based on the results of this study and according to the criteria of the CLP Regulation, the substance should not be classified for acute dermal toxicity.

Executive summary:

In an acute dermal toxicity study performed equivalent or similar to OECD TG 402, groups of 5 New Zealand White rabbits/sex were dermally exposed to 4-methylmorpholine 4-oxide (50% aqueous solution) for 24 hours toat least 20% of the body surface area at a dose of 8000 mg/kg bw. Animals were then observed for 14 days.

There were no mortalities observed. All animals exhibited weight losses or showed no change in weight at Day 7, but all (except one female) gained weight between Days 7 and 14. However, two of the males exhibited overall weight loss at Day 14. Observations made at necropsy were similar to those seen in control animals in the laboratory or were considered to represent normal physiologic variations. After 24h, animals exhibited well-defined or moderate to severe erythema, generally with very slight or slight edema.

Based on these findings, the dermal LD50 for males and females was considered to be > 8000 mg/kg bw.

As a 50% aqueous solution is used, the LD50 for the pure NMMO is considered to be greater than 4000 mg/kg. Based on the results of this study and according to the criteria of the CLP Regulation, the substance should not be classified for acute dermal toxicity.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

> 4 000 mg/kg bw

Quality of whole database:

reliable with restrictions

Additional information

Acute toxicity: oral

Mallory VT (1981) investigated the acute oral toxicity via gavage of 7000, 8000, 9000 and 10000 mg/kg bw NMMO in male/female Sprague-Dawley rats (5 animals per sex and per dose), using an aqueous solution containing 50% NMMO. After 14 days of observation, none of the animals died at the 7000 mg/kg dose level, two of the ten died at the 8000 mg/kg dose level (2 females), three of ten died at the 9000 mg/kg dose level (1 male, 2 females) and seven of ten died at the 10000 mg/kg dose level (3 males and 4 females). The acute oral LD50 value was observed to be 9200 mg/kg bw. The test solution used was a 50% aqueous solution of NMMO. The LD50 of the pure NMMO is therefore considered to be 4600 mg/kg. Clinical signs included diarrhea, piloerection, abnormal gait, abnormal stance, decreased body tone, decreased activity and orange discoloration around the nose and genital areas. Necropsy revealed distended fluid-filled stomachs and intestines (clear, tan, green, white or orange), mottled lungs, darkened thymuses and darkened lymph nodes. Terminal necropsy revealed no visible lesions in any of the remaining rats.

This study is designated as key study.

In addition, one supporting KL 2 study reported an LD50 value in male/female rats of > 10000 mg/kg bw, based on a 85% purity.

Acute toxicity: inhalation

No reliable studies were available for the inhalation route. A waiver statement was added and justified as following: next to the oral route of exposure, for substances other than gases, the information mentioned under 8.5.2 to 8.5.3 shall be provided for at least one other route (REACH Regulation, column 2 adaptation of Annex VIII). For NMMO, a key study is available for the dermal route of exposure. Therefore, an acute inhalation toxicity study should not be performed.

Acute toxicity: dermal

Auletta CS (1981) investigated acute dermal toxicity of NMMO in New Zealand White male/female rabbits (5 animals per sex and per dose) after 24 hours of exposure to 8000 mg/kg bw. After 14 days of observation, an LD50 value of > 8000 mg/kg bw was reported. As a 50% aqueous solution is used, the LD50 for the pure NMMO is considered to be greater than 4000 mg/kg. All of the animals survived the fourteen-day post-dose period. Clinical signs observed during the limit test included soft stool, fecal staining and staining of the ano-genital area and were noted sporadically in single animals on days 1 and 2. Several animals exhibited nasal discharge between days 4 and 14. All animals exhibited weight losses or showed no change in weight at day 7, but all (except one female) gained weight between days 7 and 14. However, two of the males exhibited overall weight loss at day 14. In addition irritation was observed: after 24h animals exhibited well-defined or moderate to severe erhythema, generally with very slight or slight edema.

Observations made at necropsy were similar to those seen in control animals in the laboratory or were considered to represent normal physiologic variations.

Justification for classification or non-classification

Based on the available data and according to the DSD and CLP criteria NMMO should not be classified for acute oral and dermal toxicity.

No data were available to decide on the classification for the inhalation route.