Ethyl 2-methylvalerate

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

22 April 22 to 13 May 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: - Study performed according to GLP - Study performed according to OECD Guideline 403 (Acute Inhalation Toxicity)

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Ethyl 2-methylvalerate

EC Number:

254-384-1

EC Name:

Ethyl 2-methylvalerate

Cas Number:

39255-32-8

Molecular formula:

C8H16O2

IUPAC Name:

ethyl 2-methylpentanoate

Constituent 2

Reference substance name:

Pentanoic acid, 2-methyl-, ethyl ester

IUPAC Name:

Pentanoic acid, 2-methyl-, ethyl ester

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): Ethyl 2-methylvalerate (Ethyl 2-methylpentanoate)
- Analytical purity: 99.94 (GC%) (Refer Certificate of Analysis in Appendix No. 8 of the attached report)
- Lot/batch No.: Batch No. H3-G-26
- Expiration date of the lot/batch: July 25, 2014
- Storage condition of test material: Storage Condition (at JRF): The test item was stored in its original container at 2 to 8°C in the dark.
- Other:
- Supplied by: Toyo Gosei Co., Ltd.
- Manufactured by: Toyo Gosei Co., Ltd.
- Date of Manufacture: July 26, 2011
- Appearance/Colour/Odour: Colorless liquid, Fruity odour
- Specific gravity: 0.855-0.875 (20/20°C)

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Animal Breeding Facility, Jai Research Foundation
- Age at study initiation: 10 to 11 weeks
- Weight at study initiation: At the start of the exposure the male rats weighed between 285 and 303 g, while the female rats weighed between 199 and 204 g
- Housing: Three rats/cage in polypropylene rat cages covered with stainless steel grid tops were used.
- Diet (e.g. ad libitum): Teklad certified Global High Fiber Feed for Rat/Mice manufactured by Harlan U.S.A., ad libitum.
- Water (e.g. ad libitum): UV sterilized water filtered through Kent Reverse Osmosis water filtration system, ad libitum.
- Acclimation period: Animals were acclimatised In the experimental room 7 days prior to the exposure. The rats were also acclimatised for a period of 2 hours one day prior to exposure in the rat restrainer tubes.

ENVIRONMENTAL CONDITIONS
(Temperature and relative humidity were recorded daily).
- Temperature (°C): 19 to 22
- Humidity (%):64 to 65
- Air changes (per hr): Minimum 15 per hour
- Photoperiod (hrs dark / hrs light): 12 hours artificial light and 12 hours darkness

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose/head only

Vehicle:

other: None identified

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: The dynamic inhalation equipment consists of an inhalation chamber, air compressor, air filters, flow meters, spray atomizer, continuous infusion syringe pump, cascade impactor, thermo-hygrometer, carbon dioxide monitor, oxygen monitor, open face sampler, transparent perspex rat exposure tubes and vacuum pump.

- Exposure chamber volume: The total capacity of the chamber is 63.5 litres.

- Method of holding animals in test chamber: Each rat was restrained in a single transparent perspex exposure tube with adjustable unit. The exposure tubes were accommodated in the port-holes of the inhalation chamber. The adjustable unit of the exposure tube was set so that the animals breathed ethyl 2-methylvalerate (ethyl 2- methylpentanoate) aerosols through the window panel of the exposure tube.

- Source and rate of air: The air inflow and outflow rates were maintained at 15 and 20 litres per minute, respectively and were monitored throughout the exposure period. The oxygen concentration inside the chamber was monitored continuously and recorded once per hour using the oxygen monitor, Uniphos 310. The chamber oxygen concentration recorded during the exposure period ranged between 20.6 and 20.8%.

- System of generating particulates/aerosols: Based on the trial exposure, ethyl 2-methylvalerate (ethyl 2-methylpentanoate) (undiluted) (stock concentration of 861.50 mg/mL - Refer Table 1 of the attached report) was loaded into a 60 mL infusion syringe and positioned on the infusion syringe pump. Ethyl 2-methylvalerate (ethyl 2-methylpentanoate) was infused into the spray atomizer where aerosols were formed and distributed into the inhalation chamber. The infusion rate was 40 mL/h.

- Method of particle size determination:
- Gravimetric Concentration Analysis: An open face sampler with glass microfibre papers was used to assess the breathing zone concentration. A suitable measured volume of air (1.77 litres per minute) was drawn twice from the inhalation chamber at the level of the breathing zone after an equilibration of the chamber for 15 minutes (at 30 and 150 minutes after the start of exposure). At the end of air sampling (1 minute), the glass microfibre papers with the test item were weighed to determine the concentration of ethyl 2-methylvalerate (ethyl 2-methylpentanoate) aerosols at the breathing zone of the rats (Table 2 of the attached report).
- Particle collection using a Seven Stage Cascade Impactor: The particle size was determined by using a seven-stage cascade impactor. Aerosols from the chamber are drawn into the cascade impactor (7 stages) with pre-weighed stainless steel collection plates using a vacuum pump. The sampling speed is maintained at 1.77 litres per minute. At the end of air sampling (1 minute), the collection plates with test item are disassembled and weighed. The increase in the weight of each collection plate is the mass of particles in the size range of that impact stage. The total mass of particles and the percent mass of particles in each size range is calculated. The mean cumulative percent particle size is calculated for a required particle size by adding the mean particle size distribution from 0 to that required particle size. Mass median aerodynamic diameter (MMAD) is calculated directly from percent particle size distribution (Figure 3 of the attached report).

- Treatment of exhaust air: No details provided in report -

- Temperature, humidity, pressure in air chamber: The temperature and relative humidity inside the chamber were monitored and recorded once per hour with the thermo-hygrometer. The chamber temperature during the exposure period was between 22.4 and 22.6°C, while the relative humidity was between 43.7 and 44.4%.

TEST ATMOSPHERE
- Brief description of analytical method used: Breathing zone concentration was analysed gravimetrically with an open face sampler using glass microfiber filters (GF/A).
- Samples taken from breathing zone: yes

VEHICLE
-No vehicle identified

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: See Table 4 of the attached report
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): The mass median aerodynamic diameter (MMAD) of ethyl 2-methylvalerate (ethyl 2-methylpentanoate) aerosols was determined to be 2.25 µm with a geometric standard deviation (GSD) of 2.63 (Table 4, Appendix 2 and Figure 3 of the attached report).

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: A trial exposure was conducted without rats for determining the breathing zone concentration and particle size of the test item for the main study. Study protocol states that for the limit study “rats will be exposed to an exposure concentration of 5 mg/L or greater”. Initially the infusion rate was 40 mL/h and air flow rate was 15 litres/minute. At 40 mL/h infusion rate breathing zone concentration and particle size were checked. Breathing zone concentration was found to be greater than 5 mg/L air and 50% particles were in the range of I to 4 micron. Thus an infusion rate of 40 mL/h for the test item and air flow rate of 15 litres/minute were selected for the main study.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Gravimetric analysis of experimental test atmospheres was conducted

Duration of exposure:

4 h

Concentrations:

5.967 mg/L air

No. of animals per sex per dose:

- Three male and three female healthy Wistar rats
- Females were nulliparous and non-pregnant

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
- Toxic Signs: All rats were observed for any signs of toxicity and mortality at hourly intervals during the 4 h exposure period and at 1 and 2 h after the exposure on the day of exposure. Subsequently, the surviving rats were observed twice a day for morbidity and mortality for a period of 14 days following exposure. The clinical signs were recorded once a day.
- Body weights: Body weights were recorded prior to exposure on day 0 and on days 1, 3, 7 and 14 post exposure.
- Necropsy of survivors performed: yes - All the rats at the end of the 14-day observation period were sacrificed by intraperitoneal administration of thiopentone sodium and subjected to gross pathological examination.

Statistics:

Statistical Analysis of Result: As this study was conducted as a limit study at the breathing zone concentration of 5.967 mg/L air, no statistical analysis was required to calculate the LC50.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.967 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortality was observed

Clinical signs:

other: No signs of toxicity were observed

Body weight:

Necropsy (Macroscopic Findings): External and internal examination of sacrificed rats revealed no abnormalities

Other findings:

Concentration Details of Ethyl 2-Methylvalerate (Ethyl 2-Methylpentanoate) in the Inhalation Chamber: The mean concentration of ethyl 2-metlylvalerate (ethyl 2-methylpentanoate) in the air at breathing zone for rats was 5.967 mg/L air. The mass median aerodynamic diameter (MMAD) of ethyl 2-methylvalerate (ethyl 2-methylpentanoate) aerosols was determined to be 2.25 µm with a geometric standard deviation (GSD) of 2.63

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

No mortality was observed in the treatment group rats (group I) exposed to the breathing zone concentration (5.967 mg/L air) of ethyl 2-methylvalerate (ethyl 2-methylpentanoate and the acute median lethal concentration (LC50) of ethyl 2-methylvalerate (ethyl 2-methylpentanoate) was found to be greater than 5.967 mg/L air. Ethyl 2-methylvalerate (ethyl 2-methylpentanoate) is being classified as follows:

Globally Harmonized System of Classification and Labelling of Chemicals (GHS 2011): Not Classified

Executive summary:

This study was performed to assess the acute inhalation toxicity (LC50) of ethyl 2-methylvalerate (ethyl 2-methylpentanoate) in Wistar rats. The method followed was as per the guidelines of the OECD No. 403 (September, 2009).

 

This study was conducted as a limit study. One group of rats, comprising three males and three females were used for the study. The rats from group I were exposed to the breathing zone concentration of ethyl 2-methylvalerate (ethyl 2-methylpentanoate) (5.967 mg/L air). The rats were exposed for 4 h followed by observation period of 14 days.

 

No sign of toxicity and no mortality were observed in group I rats exposed to the breathing zone concentration of 5.967 mg/L air.

 

Mean body weight of rats post exposure equalled or increased on days 1, 3, 7 and 14 in both the sexes of the rats when compared with pre-exposure (day 0) mean body weight.

 

All the treated rats at termination were subjected to gross pathological examination. External and visceral examination of terminally sacrificed rats did not reveal any lesion of pathological significance. In the absence of any pathological lesion in terminally sacrificed rats, it is concluded that the test item did not produce any treatment related effect at the dose level used in the present study.

Group No.	Breathing Zone Concentration (mg/L air)	Number of Rates Exposed		Mortality (%)
		Male	Female	Male	Female
1	5.967	3	3	0	0

No mortality was observed in the treatment group rats (group I) exposed to the breathing zone concentration (5.967 mg/L air) of ethyl 2-methylvalerate (ethyl 2-methylpentanoate). The acute median lethal concentration (LC50) of ethyl 2-methylvalerate (ethyl 2-methylpentanoate) was found to be greater than 5.967 mg/L air.

 

Ethyl 2-methylvalerate (ethyl 2-methylpentanoate) is therefore classified as follows:

 

Globally Harmonized System of Classification and Labelling of Chemicals (GHS 2011): Not Classified