3-methoxy-N,N-dimethylpropionamide

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

07 October 2011 - 25 October 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Version / remarks:

07 September 2009

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method B.2 (Acute Toxicity (Inhalation))

Version / remarks:

2008

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

August 1998

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Test type:

acute toxic class method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

3-methoxy-N,N-dimethylpropionamide

EC Number:

258-420-7

EC Name:

3-methoxy-N,N-dimethylpropionamide

Cas Number:

53185-52-7

Molecular formula:

C6H13NO2

IUPAC Name:

3-methoxy-N,N-dimethylpropanamide

Test material form:

liquid

Details on test material:

- Appearance: Clear colourless liquid
- Storage condition of test material: Room temperature (15-25°C)

Test animals

Species:

rat

Strain:

other: Crl: WI (from SPF colony)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Research Model and Services, Germany GmbH (Sandhofer Weg 7, D-97633, Sulzfeld).
- Females nulliparous and non-pregnant: yes
- Age at study initiation: 8 weeks
- Weight at study initiation: 311-328 g (males); 212-234 g (females)
- Fasting period before study: no
- Housing: group housing of 5 animals/sex in Polycarbonate solid floor cages
- Diet: free access to Autoclavable Complete Feed for Rats and Mice- Breeding and Maintenance (SM R/M-Z+H from SNIFF Spezialdiäten GmbH, D-59494 Soest, Germany)
- Water: free access to tap water from the municipal supply
- Acclimation period: 12 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.5 - 24.9
- Humidity (%): 35 - 64
- Air changes (per hr): at least 15
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

3.48 µm

Geometric standard deviation (GSD):

1.97

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: TSE Rodent Exposure System (TSE Systems GmbH, Bad Homburg, Germany). This system comprises of two concentric anodised aluminium chambers and a computer control system incorporating pressure detectors and mass flow controllers.
- Exposure chamber volume: No data.
- 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.
- Source and rate of air: Flow of compressed air was at least 0.5 L/min.
- Method of conditioning air: Compressed air was supplied by means of an oil-free compressor passed through a suitable filter system prior to introduction to the nebulizer.
- System of generating particulates/aerosols: Stainless steel concentric jet nebulizer (TSE Systems GmbH, Bad Homburg, Germany)
- Method of particle size determination: The particle size of the test atmosphere was determined three times during the exposure period using a 7-stage Mercer style impactor (TSE Systems GmbH, Bad Homburg, Germany). Such devices employ an inertial separation technique to isolate patticles in the discrete aerodynamic size ranges. Samples were taken from an unoccupied exposure port (representing the animal's breathing zone). The collection substrates and the backup filter were analyzed using a validated HPLC-UV method after the sampling and the amount of test item collected at each stage was calculated. The total amount collected 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< 0.550, 0.550, 0.960, 1.550, 2.1 05, 3.555, 6.655 and 10.550 µm was calculated. From these data, using the software supplied with the impactor (TSE Systems GmbH, Bad Homburg, Germany), the Mass Median Aerodynamic Diameter (MMAD), and Geometric Standard Deviation (GSD) were calculated. In addition, the proportion (%) of aerosol less than 4µm (considered to be the inhalable portion) was determined.
- Treatment of exhaust air: No data.
- Temperature, humidity, pressure in air chamber: The chamber temperatures were recorded manually and hourly using a calibrated min-max thermometer. The relative humidity values in the inhalation chamber were not registered due to the malfunction of the built-in humidity sensor. Chamber airflow rates, test atmosphere carbon dioxide concentrations and oxygen concentrations were monitored continuously and recorded every minute during each exposure period.

TEST ATMOSPHERE
- Brief description of analytical method used: The test atmosphere was sampled at regular intervals during the exposure period. Samples were taken from an unoccupied exposure port (representing the animal's breathing zone) by pulling a suitable, known volume of test atmosphere through GF10 glass fiber filters (Type GF10, Whatman, Germany) and then the filters were analyzed using a validated HPLC-UV method. The amount of the depositions on the filters expressed in original test item, divided by the volume of atmosphere sampled, was equal to the actual achieved test atmosphere concentration. The nominal concentration was calculated by dividing the mass of test material disseminated into the chamber by the total volume of air that through the chamber during the same period.
- Samples taken from breathing zone: yes

TEST ATMOSPHERE
- Particle size distribution: Analysis of the particle size distribution of the aerosol at the animals' breathing zone demonstrated, that during both parts of the study (sighting exposure and main study) the test atmosphere was respirable to the animals.
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): The mean values of the particle size distribution parameters calculated from three samples of each exposure was 3.48 / 1.97.

SIGHTING EXPOSURES
The sighting study was performed in order to estimate the test substance inhalation toxicity, identity sex differences in susceptibility and assist in selecting exposure concentration levels for the main study.
One group of animals (1 male and 1 female) was exposed to a concentration of 5.25 mg/L. As no lethality occurred, therefore 5 mg/L target concentration was selected for the main study exposure.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

5 mg/L

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:
Morbidity/mortality: Animals were checked hourly during exposure, 1 hour after exposure and twice daily (early and late in the working day) during the 14-day observation period.
Clinical signs: All animals were observed for clinical signs at hourly intervals during exposure whilst the animals were still restrained. Following exposure, clinical observations were performed twice on the day of exposure (following removal from the restrainer and approximately one hour after completion of the exposure) and subsequently once daily for 14 days.
Body weight: Individual body weights were recorded prior to treatment on the day of exposure (before the exposure on Day 0) and on Days 1, 3, 7 and 14.
- Necropsy of survivors performed: Yes, at the end of the 14-day observation period, the surviving animals were sacrificed by exsanguination under anaesthesia and gross macroscopic examination was performed.

Statistics:

No statistical analysis was performed (the method used was not intended to calculate a LC50 value).

Results and discussion

Preliminary study:

One group of animals (using a single male and female rat) was exposed to a concentration of 5.25 mg/L (MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 3.33 / 1.91. As no lethality occurred, therefore 5 mg/L target concentration was selected for the main study exposure.

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No animals died during the study.

Clinical signs:

other: Slight laboured respiration was observed in all animals during the exposure and shortly thereafter when removed from the restraint tubes. Slight weak body condition was seen in a single male and a single female rat on Day 1-2. From Day 4 all animals were

Body weight:

Slight bodyweight loss (1-6%) or a reduction in bodyweight gain was recorded in all animals on Day 1. Both males and females gained back their initial bodyweight by Day 3 with exception of a single female where by Day 7.

Gross pathology:

No external or internal finding was recorded at necropsy.

Other findings:

Additionally, wet fur was generally recorded in all animals of the study on the day of exposure and red-brown staining was noted in a single male on Day1-3. These observations were considered to be related to the restraint and exposure procedures and were considered not to be of toxicological relevance.

Applicant's summary and conclusion

Interpretation of results:

other: Not classified.

Remarks:

According to Regulation (EC) No. 1272/2008.

Conclusions:

In an acute inhalation toxicity study with male and female rats, performed according OECD 403 test guideline and GLP principles, an LC50 >5 mg/L was determined for 3-methoxy-N,N-dimethylpropanamide.

Executive summary:

An acute inhalation toxicity study with nose-only exposure was performed according OECD 403 test guideline and GLP principles. Five male and five females per group were exposed for 4 hours to an aerosol concentration of 5.07 mg/L.

No animals died during the study. Slight laboured respiration was observed in all animals during the exposure and shortly thereafter when removed from the restraint tubes. Slight weak body condition was seen in a single male and a single female rat on Day 1-2. From Day 4 all animals were symptom-free. Slight bodyweight loss (1-6%) or a reduction in bodyweight gain was recorded in all animals on Day 1. Both males and females gained back their initial bodyweight by Day 3 with exception of a single female where by Day 7. No external or internal finding was recorded at necropsy.

Based on this result, an inhalation LC50 >5 mg/L was established for 3-methoxy-N,N-dimethylpropanamide, which implies that the test substance does not have to be classified for acute dermal toxicity according to Regulation (EC) No. 1272/2008.