Lithium myristate

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2018-04-11 - 2018-05-14 (experimental phase)

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2019

Report date:

2019

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)

Version / remarks:

2009

Deviations:

yes

Remarks:

see "Principles of method if other than guideline"

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.52 (Acute Inhalation Toxicity - Acute Toxic Class Method)

Version / remarks:

2014

Deviations:

yes

Remarks:

see "Principles of method if other than guideline"

Principles of method if other than guideline:

The following deviations occurred:
It is recognised that the GSD in the sighting test was out of the target range that would generally be acceptable for this type of study (1.5 – 3.0). This deviation was slight (+ 0.02) and is considered to be due to the physical characteristics of the test item. As the particle size distributions are lower than 4μm this is considered not to affect the purpose or validity of this study.
The relative humidity within the exposure chamber during the exposures was found to be lower than the range specified in the inhalation test guidelines (30-70 %). The decreased humidity was considered to be unavoidable due to the effect of the test item on the humidity. This is considered to have not affected the purpose or validity of the study.

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Lithium myristate

EC Number:

243-743-8

EC Name:

Lithium myristate

Cas Number:

20336-96-3

Molecular formula:

C14H28O2.Li

IUPAC Name:

lithium myristate

Test material form:

solid

Specific details on test material used for the study:

In order to facilitate aerosolisation and reduce particle size, the test item was ground using a Retsch Planetary Ball Mill prior to use. The absorption of the test item was not determined.

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Envigo RMS (UK) Limited, Oxon, UK
- Females (if applicable) nulliparous and non-pregnant: yes
- Age at study initiation: 8 - 12 weeks
- Weight at study initiation: 200 - 350 g
- Fasting period before study: With the exception of the exposure period, free access to mains drinking water and food was allowed throughout the study
- Housing: The animals were housed in groups of up to three by sex in solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes
- Diet (e.g. ad libitum): free access to 2014C Teklad Global Rodent diet
- Water (e.g. ad libitum): free access to drinking water
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25 °C
- Humidity (%): 30 - 70 %
- Air changes (per hr): at least fifteen changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours continuous light and 12 hours darkness

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: unchanged (no vehicle)

Mass median aerodynamic diameter (MMAD):

3.36 µm

Geometric standard deviation (GSD):

2.81

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: cylindrical exposure chamber
- Exposure chamber volume: approximately 30 liters
- Method of holding animals in test chamber: each rat was individually held in a tapered, polycarbonate restraining tube fitted onto a single tier of the exposure chamber and sealed by means of a rubber ‘O’ ring; only the nose of each animal was exposed to the test atmosphere
- Source and rate of air: Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters before it was introduced to the SAG 410.
- System of generating particulates/aerosols: A dust atmosphere was produced from the test item using a SAG 410 Solid Aerosol Generator located adjacent to the exposure chamber. The SAG 410 was connected to a metered compressed air supply. Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters before it was introduced to the SAG 410.
- Method of particle size determination: The particle size of the generated atmosphere inside the exposure chamber was determined three times during the exposure period using a Marple Personal Cascade Impactor. This device consisted of six impactor stages (10.4, 7.7, 4.1, 1.3, 0.9 and 0.56 μm cut points) with stainless steel collection substrates and a backup glass fiber filter, housed in an aluminum sampler. The sampler was temporarily sealed in a sampling port in the animals’ breathing zone and a suitable, known volume of exposure chamber air was drawn through it using a vacuum pump.
The collection substrates and backup filter were weighed before and after sampling and the weight of test item, collected at each stage, calculated by difference.
The mean amount for each stage was used to determine the cumulative amount below each cut-off point size. In this way, the proportion (%) of aerosol less than 10.4, 7.7, 4.1, 1.3, 0.9 and 0.56 μm μm was calculated.
The resulting values were converted to probits and plotted against Log10 cut-point size. From this plot, the Mass Median Aerodynamic Diameter (MMAD) was determined (as the 50% point) and the geometric standard deviation was calculated. In addition the proportion (percentage) of aerosol less than 4 μm (considered to be the inhalable fraction) was determined.
- Treatment of exhaust air: The extract from the exposure chamber passed through a ‘scrubber’ trap and was connected with a high efficiency filter to a metered exhaust system. The chamber was maintained under negative pressure.
- Temperature, humidity, pressure in air chamber:

TEST ATMOSPHERE
- Brief description of analytical method used: The actual chamber concentration was measured at regular intervals during each exposure period. The gravimetric method used glass fiber filters placed in a filter holder. The holder was temporarily sealed in a vacant port in the exposure chamber in the animals’ breathing zone and a suitable, known volume of exposure chamber air was drawn through the filter using a vacuum pump.
Each filter was weighed before and after sampling in order to calculate the weight of collected test item. The difference in the two weights, divided by the volume of atmosphere sampled, gave the actual chamber concentration.
The nominal chamber concentration was calculated by dividing the mass of test item disseminated into the chamber by the total volume of air that flowed through the chamber during the exposure.

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: As insufficient data was available on the expected inhalation toxicity of the test item, a sighting test was performed to determine the initial exposure concentration. A group of two animals (one male and one female) was exposed to an aerosol atmosphere of the test item at a target concentration of 3.5 mg/L. Based on the results of the sighting test, a limit test was performed. A group of six animals (three males and three females) was exposed to an aerosol atmosphere of the test item at a target concentration of 5.0 mg/L.

Analytical verification of test atmosphere concentrations:

no

Remarks:

(gravimetric only)

Duration of exposure:

4 h

Concentrations:

Sighting:
Mean Achieved (mg/L): 3.50
Mean Mass Median Aerodynamic Diameter (µm): 3.86
Inhalable Fraction (%<4µm): 51.3
Geometric Standard Deviation: 3.02

Group 1:
Mean Achieved (mg/L): 5.12
Mean Mass Median Aerodynamic Diameter (µm): 3.36
Inhalable Fraction (%<4µm): 56.8
Geometric Standard Deviation: 2.81

No. of animals per sex per dose:

1 (sighting), 3 (limit test)

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days (sighting: 7 days)
- Frequency of observations and weighing:
Clinical signs: 1 hour after termination of exposure and subsequently once daily for duration of the observation period
Body weight: Days 1, 3, 7 and on Day 14 of the limit test
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Results and discussion

Preliminary study:

Mortality
None of the animals died.
Clinical Observations
Common abnormalities noted during the study included decreased respiratory rate, noisy respiration, ataxia, hunched posture, pilo-erection, areas of red/brown staining around the eyes, areas of red/brown staining of the snout and wet fur. Labored respiration was noted in the male and lethargy was noted in the female. Both animals recovered to appear normal on Day 2 post-exposure. The male subsequently exhibited sneezing on Day 3 and recovered to appear normal on Day 4 post-exposure.
Body Weight
Both animals showed body weight loss on Day 1 post-exposure, expected gains in body weight were noted during the remainder of the recovery period.
Necropsy
No macroscopic abnormalities were detected in the male. The following macroscopic abnormalities were detected at necropsy of the female:
Lungs – Dark patches.

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.12 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

None of the animals died in a group of six rats exposed to mean achieved atmosphere concentration of 5.12 mg/L.

Clinical signs:

other: Common abnormalities noted during the study included decreased respiratory rate, noisy respiration, hunched posture, pilo-erection, ataxia, lethargy, areas of red/brown staining around the eyes, areas of red/brown staining of the snout and wet fur. Areas

Body weight:

All animals showed body weight loss on Day 1 post-exposure and, with the exception of one female that showed no gain in body weight from Days 1 to 3, expected gains in body weight were noted during the remainder of the recovery period.

Gross pathology:

The following macroscopic abnormalities were detected at necropsy:
Lungs – Pale, abnormally red, abnormally dark, dark patches.
Liver – Dark, patchy pallor.
Kidneys – Pale, increased pelvic space.
The observed lung abnormalities were considered likely to be due to irritancy or local toxicity.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The study was performed in accordance with OECD Guideline 436 and EU Method B.52 with acceptable deviations not affecting the validity of the study and therefore reliability of Klimisch 1 has been assigned.
None of the animals died in a group of six rats exposed to mean achieved atmosphere concentration of 5.12 mg/L. It was therefore considered that the acute inhalation median lethal concentration (4 hour LC50) of the test item in the Wistar strain rat was greater than 5.12 mg/L.
The test item does not meet the criteria for classification according to the Globally Harmonized System of Classification and Labelling of Chemicals.

Executive summary:

A GLP study was performed to assess the acute inhalation toxicity of the test item. The method used was designed to be compatible with that described in the OECD Guideline 436 “Acute Inhalation Toxicity – Acute Toxic Class Method” and EU Method B.52. Acute Inhalation Toxicity – Acute Toxic Class Method.

As insufficient data was available on the expected inhalation toxicity of the test item, a sighting test was performed to determine the initial exposure concentration. A group of two animals (one male and one female) was exposed to an aerosol atmosphere of the test item at a target concentration of 3.5 mg/L.

Based on the results of the sighting test, a limit test was performed. A group of six animals (three males and three females) was exposed to an aerosol atmosphere of the test item at a target concentration of 5.0 mg/L.

The test item, a white solid, was ground prior to use in order to facilitate aerosolisation and reduce particle size. A dust atmosphere was produced from the test item using a SAG 410 Solid Aerosol Generator located adjacent to the exposure chamber. The SAG 410 was connected to a metered compressed air supply.

RccHanTM: WIST strain rats were exposed for 4 hours using a nose only exposure system followed by an observation period. The observation period was seven days for the sighting test, sufficient to ensure recovery of the animals, and fourteen days for the limit test.

Mortality

None of the animals died in a group of six rats exposed to mean achieved atmosphere concentration of 5.12 mg/L.

Clinical Observations

Sighting: Common abnormalities noted during the study included decreased respiratory rate, noisy respiration, ataxia, hunched posture, pilo-erection, areas of red/brown staining around the eyes, areas of red/brown staining of the snout and wet fur. Labored respiration was noted in the male and lethargy was noted in the female. Both animals recovered to appear normal on Day 2 post-exposure. The male subsequently exhibited sneezing on Day 3 and recovered to appear normal on Day 4 post-exposure.

Group 1: Common abnormalities noted during the study included decreased respiratory rate, noisy respiration, hunched posture, pilo-erection, ataxia, lethargy, areas of red/brown staining around the eyes, areas of red/brown staining of the snout and wet fur. Areas of red/brown staining around the head were noted in all males and areas of red/brown staining around the head and labored respiration were noted in one female. All animals recovered to appear normal on Day 3 post-exposure.

Body Weight

Sighting: Both animals showed body weight loss on Day 1 post-exposure, expected gains in body weight were noted during the remainder of the recovery period.

Group 1: All animals showed body weight loss on Day 1 post-exposure and, with the exception of one female that showed no gain in body weight from Days 1 to 3, expected gains in body weight were noted during the remainder of the recovery period.

Necropsy

Sighting: No macroscopic abnormalities were detected in the male. The following macroscopic abnormalities were detected at necropsy of the female:

Lungs – Dark patches.

Group 1: The following macroscopic abnormalities were detected at necropsy:

Lungs – Pale, abnormally red, abnormally dark, dark patches.

Liver – Dark, patchy pallor.

Kidneys – Pale, increased pelvic space.

The observed lung abnormalities were considered likely to be due to irritancy or local toxicity.

None of the animals died in a group of six rats exposed to mean achieved atmosphere concentration of 5.12 mg/L. It was therefore considered that the acute inhalation median lethal concentration (4 hour LC50) of the test item in the Wistar strain rat was greater than 5.12 mg/L.

The test item does not meet the criteria for classification according to the Globally Harmonized System of Classification and Labelling of Chemicals.