Reaction Mass of (4R)-4-isopropenyl-1-methylcyclohexene and (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

06 July - 12 October 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study was conducted in accordance with international guidelines and in accordance with GLP. All guideline validity criteria were met.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

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:

(R)-p-mentha-1,8-diene

EC Number:

227-813-5

EC Name:

(R)-p-mentha-1,8-diene

Cas Number:

5989-27-5

Molecular formula:

C10H16

IUPAC Name:

(4R)-4-isopropenyl-1-methylcyclohexene

Constituent 2

Reference substance name:

(4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene

Cas Number:

30199-25-8

Molecular formula:

C11H20O

IUPAC Name:

(4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene

Test material form:

liquid

Specific details on test material used for the study:

RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity: n/a
- Specific activity: n/a
- Locations of the label: n/a
- Expiration date of radiochemical substance: n/a

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: ca. 2-8 ºC, in the dark and under nitrogen.
- Stability under test conditions: Stable - confirmed by HPLC.
- Solubility and stability of the test substance in the solvent/vehicle: Test item was aerosolised as supplied. For analysis, the collected test item was dissolved in methanol, in which it was stable and soluble.
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: n/a

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: The test item was aerosolized using a metal concentric jet nebulizer (Envigo CRS Limited, UK) located at the top of the exposure chamber.
- Preliminary purification step (if any): n/a
- Final dilution of a dissolved solid, stock liquid or gel: n/a
- Final preparation of a solid: n/a

FORM AS APPLIED IN THE TEST (if different from that of starting material): The test item was aerosolized using a metal concentric jet nebulizer (Envigo CRS Limited, UK) located at the top of the exposure chamber. The particle size analysis of the atmosphere drawn from the animals’ breathing zone concluded that the mean mass median aerodynamic diameter was 2.28 µm.

OTHER SPECIFICS: n/a

Test animals

Species:

rat

Strain:

other: RccHan™ : WIST

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 old
- Weight at study initiation: 200-350 g
- Fasting period before study: No
- 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. The animals were provided with environmental enrichment items which were considered not to contain any contaminant of a level that might have affected the purpose or integrity of the study.
- Diet (e.g. ad libitum): Ad libitum - 2014C Teklad Global Rodent diet supplied by Envigo RMS (UK) Limited, Oxon, UK
- Water (e.g. ad libitum): Ad libitum - mains drinking water
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-25 ºC
- Humidity (%): 30-70 %
- Air changes (per hr): At least 15/hour
- Photoperiod (hrs dark / hrs light): 12:12

IN-LIFE DATES: From: 06 July 2017 To: 12 October 2017

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

clean air

Mass median aerodynamic diameter (MMAD):

2.28 µm

Geometric standard deviation (GSD):

1.58

Remark on MMAD/GSD:

The results of the particle size distribution should be viewed with caution and are included only as a guide to the aerosol/vapor ratio of the generated atmosphere, as the volatility of a test item will be over-emphasized by the high air velocities and low pressures within a cascade impactor.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Nose only exposure apparatus.
- Exposure chamber volume: The cylindrical exposure chamber had a volume of approximately 30 liters (dimensions: 28 cm diameter x 50 cm high).
- Method of holding animals in test chamber: During the exposure period, 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.
- Source and rate of air: Compressed air was supplied by means of an oil free compressor at a rate of 40 L /minute
- Method of conditioning air: Air was passed through a water trap and respiratory quality filters before it was introduced to the nebulizer.
- System of generating particulates/aerosols: Metal concentric jet nebulizer (Envigo CRS Limited, UK) located at the top of the exposure chamber.
- 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 (Westech IS Ltd, Beds., UK). This device consisted of six impactor stages (10.4, 7.7, 4.1, 1.3, 0.90 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, 0.90 and 0.56 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. An impinger, set up as per atmosphere concentration determination was placed in series after the cascade impactor. Submission of these samples for chemical analysis allowed an estimate to be made of the amount of atmosphere present in the vapor phase. The sampling procedure involved 2 liters of test atmosphere being drawn through a glass impinger containing methanol (made up to 80mL). The samples were then submitted for chemical analysis.
- 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.
- Temperature, humidity, pressure in air chamber: The temperature and relative humidity inside the exposure chamber were measured by an electronic thermometer/humidity meter (Hanna Instruments Ltd, Beds., UK) located in a vacant port in the animals’ breathing zone of the chamber and recorded every 30 minutes throughout the 4-Hour exposure period. Oxygen levels within the exposure chamber were measured by an electronic oxygen analyzer (Servomex (UK) Ltd, Crowborough, East Sussex) located in a port in the animals breathing zone during the 4 Hour exposure period.

TEST ATMOSPHERE
- Brief description of analytical method used: The test atmosphere was sampled nine times during the exposure period. The sampling procedure involved 2 liters of test atmosphere being drawn through a glass impinger containing methanol (made up to 80mL). The samples were then submitted for chemical analysis (HPLC) using an external standard technique.
- Samples taken from breathing zone: yes

VEHICLE
- Composition of vehicle (if applicable): n/a
- Concentration of test material in vehicle (if applicable): n/a
- Justification of choice of vehicle: n/a
- Lot/batch no. (if required): n/a
- Purity: n/a

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: Tabulated
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): Tabulated

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration: Highest concentration stipulated for aerosols in OECD 436.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

Mean measured atmospheric concentration was 5.67 mg/L

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Individual body weights were recorded on arrival, prior to treatment on the day of exposure (Day 0) and on Days 1, 3, 7 and 14.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs

Statistics:

Not required

Results and discussion

Preliminary study:

During the characterization phase of the study, a group of two rats (one male, one female) were exposed to an atmosphere of the test item at a mean achieved atmosphere concentration of 1.82 mg/L for four hours. During exposure both animals exhibited decreased respiratory rate and wet fur. On removal from the chamber both animals decreased respiratory rate, hunched posture, pilo-erection, red/brown staining around the snout and wet fur. One hour post-exposure, decreased respiratory rate was no longer apparent. Both animals recovered to appear normal on Day 1 post-exposure.

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.67 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 mortality was observed.

Clinical signs:

other: Signs of hunched posture and pilo-erection are commonly seen in animals for short periods on removal from the chamber following 4-Hour inhalation studies. Wet fur is commonly recorded both during and for a short period after exposure. These observations a

Body weight:

With the exception of one female, all animals showed body weight loss on Day 1 post-exposure. Animals showed expected gains in body weight during the remainder of the recovery period with the exception of one female that showed no gain in body weight from Days 3 to 7 post-exposure.

Gross pathology:

With the exception of dark patches on the lungs of two females, no abnormalities were noted at necropsy.

Other findings:

Not examined

Any other information on results incl. tables

Table 2       Concentrations, exposure conditions and mortality per animals treated

Nominal Concentration (mg/L)	Analytical Concentration (mg/L)	MMAD (µm)	GSD	Mortality (# dead/total)
				Male	Female	Combined
11.91	5.67	2.28	1.58	0/3	0/3	0/6

Table 3       Individual clinical observations - (day of exposure)

Mean achieved atmospheric concentration (mg/L)	Animal number and sex	Effects noted during exposure			Effects noted on removal from chamber	Effects noted 1 hour post exposure
		1 hour	2 hours	3 hours
5.67	1 male	WfRd	WfRd	WfRd	WfRdHP	WfRdHP
	2 male	WfRd	WfRd	WfRd	WfRdHP	WfRdHP
	3 male	WfRd	WfRd	WfRd	WfRdHP	WfRdHP
	4 female	WfRd	WfRd	WfRd	WfRdHP	WfRdHP
	5 female	WfRd	WfRd	WfRd	WfRdHP	WfRdHP
	6 female	WfRd	WfRd	WfRd	WfRdHP	WfRdHP

H: hunched posture

P: pilo-erection

Rd: decreased respiratory rate

Wf: wet fur

Clinical signs were not observed in any of individuals beyond the completion of the exposure period.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The test item did not meet the criteria for classification according to Regulation (EC) No. 1272/2008 on the Classification, Labelling and Packaging of Substances and Mixtures.

Executive summary:

OECD 436 (2017) - In an acute inhalation toxicity study, groups of young adult rats (RccHan:WIST, 3 males and 3 females) were exposed by inhalation route to Reaction Mass of (4R)-4-isopropenyl-1-methylcyclohexene and (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene for 4 hours to nose only at a concentration of 5.67 mg/L (limit test).  Animals then were observed for 14 days.

In the absence of mortality during the observation period, the inhalation LC₅₀ was estimated to be greater than 5.67 mg/L.

In addition, with the exception of dark patches on the lungs of 2 female rats, there were no treatment related clinical signs, necropsy findings or changes in bodyweight observed in any of the individuals at the end of the observation period.

Reaction Mass of (4R)-4-isopropenyl-1-methylcyclohexene and (4R)-4-(2-methoxypropan-2-yl)-1-methylcyclohexene did not meet the criteria for classification according to Regulation (EC) No. 1272/2008 on the Classification, Labelling and Packaging of Substances and Mixture.