Reaction mass of 2-ethyl-2-(methoxymethyl)-propane-1,3-diol and 2-ethylpropane-1,3-diol

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 April - 24 April 2018

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2018

Report date:

2018

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 433 draft (Acute Inhalation Toxicity: Fixed Concentration Procedure) (not officially approved)

Version / remarks:

9 October 2017

Deviations:

no

GLP compliance:

yes

Test type:

fixed concentration procedure

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2-ethyl-2-(methoxymethyl)propane-1,3-diol

EC Number:

231-621-7

EC Name:

2-ethyl-2-(methoxymethyl)propane-1,3-diol

Cas Number:

7658-03-9

Molecular formula:

C7H16O3

IUPAC Name:

2-ethyl-2-(methoxymethyl)propane-1,3-diol

Constituent 2

Reference substance name:

2-ethylpropane-1,3-diol

EC Number:

220-038-3

EC Name:

2-ethylpropane-1,3-diol

Cas Number:

2612-29-5

Molecular formula:

C5H12O2

IUPAC Name:

2-ethylpropane-1,3-diol

Test material form:

liquid

Test animals

Species:

rat

Strain:

Sprague-Dawley

Sex:

male

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Envigo RMS Spain
- Age at study initiation: 10 weeks
- Fasting period before study: Not applicable
- Housing: Group housing except during exposure
- Diet: ad libitum) except during exposure
- Water: except during exposure
- Acclimation period: 19 days; rats were also acclimated to the restraining tubes for 30 minutes

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 18.1-25.6
- Humidity (%): 29-50
- Photoperiod (hrs dark / hrs light): 12/12

IN-LIFE DATES: From: 09 April 2018 To: 23 April 2018

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Mass median aerodynamic diameter (MMAD):

2.25 µm

Geometric standard deviation (GSD):

> 1.88 - < 2.12

Remark on MMAD/GSD:

MMAD was measured at two sampling points during the study and gave values of 2.10 µm (GSD 1.88) and 2.40 µm (GSD (2.12). The proportion of respirable particles (<4 µm) was calculated to be 87.10 and 77.91% respectively.

Details on inhalation exposure:

Inhalation exposure was performed using a flow-past, nose-only exposure system. The animals were confined separately in restraint tubes which were positioned radially around the exposure chamber. The exposure system ensured a uniform distribution and provided a constant flow of test material to each exposure tube. The mean flow of air at each tube was approximately 1.137 L/min, which was sufficient to minimize rebreathing of the test aerosol. Exposure chambers type EC-FPC-232 (anodised aluminium, volume inside compartment: approximately 3 L), equipped with glass exposure tubes were used. The rats were individually exposed in glass tubes matching their size. Before treatment started, the homogeneity for the different levels of the exposure chamber was confirmed. The temperature and relative humidity of the test atmosphere in the exposure chamber were maintained as required by experimental conditions. Air flow was monitored regularly.

A liquid aerosol was generated from the test material using a nebulizer. The aerosol was diluted with filtered air from a compressor and conveyed via glass tubing, from the generator to the exposure chamber. The flow rate through the exposure chamber was adjusted as necessary. The test material usage was determined during exposure by weighing before and after exposure to determine the quantity used. The weight used was then divided by the total air-flow volume to give the nominal concentration. These data were used for the purpose of monitoring the performance of the generation system. Gravimetric determination of the aerosol concentration was performed twice each hour of exposure. Aerosol samples were collected using a filter sampling device for a sampling duration of 10 minutes. The filters were weighed before and immediately after sampling using a calibrated balance. The gravimetric aerosol concentration was calculated from the amount of test material present on the filter and the sample volume. The particle size distribution was determined gravimetrically twice during exposure; cumulative particle size distribution of the test aerosol was determined using a cascade impactor. The particle size distribution of the test material in the generated aerosol was measured by gravimetry analyzing the test item deposited on each stage of the cascade impactor. The mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD) were calculated on the basis of the results from the impactor.

Temperature in the chamber was measured continuously during exposure; the target range was 19-25 ºC. The results were reported approximately hourly from the start of the inhalation exposure. Relative humidity in the chamber was measured continuously during exposure. The results were reported approximately hourly from the start of the inhalation exposure. The oxygen and CO2 concentration of the test atmosphere were measured during the exposure period using a portable gas detector. These concentrations were maintained above 19% and below 1% respectively. The results were reported approximately hourly from the start of the inhalation exposure. The exposure airflow rate was adjusted as appropriate before the start of the exposure using the pressure difference over a Venturi tube. The actual airflow rate was monitored at least hourly during exposure. The target range was 1.0 ± 0.5 L/min through each inhalation tube.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Remarks on duration:

4 hour (nose-only); standard expsosure conditions

Concentrations:

4.701 mg/L

No. of animals per sex per dose:

Five males

Control animals:

no

Results and discussion

Preliminary study:

Not relevant.

Effect levels

Key result

Sex:

male

Dose descriptor:

LC50

Effect level:

> 4.701 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No deaths occurred, either during the 4-hour exposure period or during the 14-day observation period.

Clinical signs:

other: Immediately after exposure, wet fur, chromorrhinorrhoea and/or chromodacryorrhoea were observed in all animals. These transient signs were considered to be related to the exposure procedure rather than to a direct effect of the test material. All signs

Body weight:

A decrease in mean bodyweight of approximately 5% was observed in all animals between Day 1-2. Bodyweight increased thereafter and had recoverd by Day 8. Total mean body weight gain of approximately 10% was recorded during the 14 day observation period (from Day 1-15).

Gross pathology:

No macroscopic findings were present in any of the animals at necropsy.

Other findings:

None.

Any other information on results incl. tables

Summary of findings

Exposed (#)	Mortality (#)	Clinical signs (#)	Bodyweight (g)
			Day 1	Day 2	Day 8	Day 15
5	0/5	5/5	317.3	302.7	325.9	348.6

Exposure data

Analytical concentration (mg/L)	MMAD (µm)	GSD	% particles <4 µm
4.701	2.10, 2.40 (mean 2.25)	1.88, 2.12	87.10, 77.91 (mean 82.51)

Applicant's summary and conclusion

Interpretation of results:

Category 5 based on GHS criteria

Conclusions:

The acute (4 -hour, nose-only) inhalation LC50 of DMP Tech was found to be >4.701 mg/L under the conditions of this study. In the absence of any mortality at this concentration, it can reliably be predicted that the LC50 will be >5 mg/L. DMP Tech does not therefore require classification for acute inhalation toxicity according to CLP criteria.

Executive summary:

The acute inhalation toxicity of DMP Tech. (reaction mass of 2-ethyl-2 -(methoxymethyl)-propane-1,3-diol and 2 -ethylpropane-1,3 -diol) was investigated in a Fixed Concentration Procedure study performed according to OECD 433. A single group of five male Sprague-Dawley rats was exposed for four hours (nose-only) to an atmosphere containing liquid aerosols of DMP Tech. at a gravimetric concentration of 4.701 mg/L and observed for 14 days. No deaths occurred, either during the 4-hour exposure period or during the 14-day observation period. Immediately after exposure, wet fur, chromorrhinorrhoea and/or chromodacryorrhoea were observed in all animals.  These transient signs were considered to be related to the exposure procedure rather than to a direct effect of the test material.  All signs had resolved by one hour after exposure.  From Day 2 (24 hours after exposure) until sacrifice at Day 15, no clinical signs were recorded in any animals and all of them exhibited normal behaviour. A decrease in mean bodyweight of approximately 5% was observed in all animals between Day 1-2.  Bodyweight increased thereafter and had recoverd by Day 8.  Total mean body weight gain of approximately 10% was recorded during the 14 day observation period (from Day 1-15). No macroscopic findings were present in any of the animals at necropsy. The acute (4 -hour, nose-only) inhalation LC50 of DMP Tech was found to be >4.701 mg/L under the conditions of this study.  DMP Tech does not therefore require classification for acute inhalation toxicity according to CLP criteria.