Cyclohexanecarboxylic acid, 1-(2-ethylbutyl)-

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

January 24, 2011 - April 21, 2011

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: This study has been performed according to OECD and/or EC guidelines and according to GLP principles.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2011

Report date:

2011

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

yes

Remarks:

a temporary deviation from the minimum level of relative humidity occurred

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

a temporary deviation from the minimum level of relative humidity occurred

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Deviations:

yes

Remarks:

a temporary deviation from the minimum level of relative humidity occurred

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: Japanese Ministry of Agriculture, Forestry and Fisheries (JMAFF), 12 Nousan, Notification No 8147, November 2000, including the most recent partial revisions.

Deviations:

yes

Remarks:

a temporary deviation from the minimum level of relative humidity occurred

GLP compliance:

yes

Test type:

acute toxic class method

Limit test:

no

Test material

Test material information

Constituent 1

Reference substance name:

1-(2-ethylbutyl)cyclohexane-1-carboxylic acid

EC Number:

619-508-4

Cas Number:

381209-09-2

Molecular formula:

C13 H24 O2

IUPAC Name:

1-(2-ethylbutyl)cyclohexane-1-carboxylic acid

Details on test material:

- Name of test material (as cited in study report): CAT-Acid
- Stability under test conditions: stable
- Storage condition of test material: at room temperature in the dark
- Density: 0.98 g/mL
- pH (1% in water, indicative range): 5.4-5.2

Test animals

Species:

rat

Strain:

other: Crl:WI (Han) (outbred, SPF-Quality)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Deutschland, Sulzfeld, Germany
- Age at study initiation: approximately 10 weeks
- Weight at study initiation (pre-administration): males: 297-311 g; females: 193-217 g
- Fasting period before study: not applicable
- Housing: group housing of five animals per sex per cage in labelled Macrolon cages (type IV; height 18 cm)
- Diet (e.g. ad libitum): pelleted rodent diet (SM R/M-Z from SSNIFF® Spezialdiäten GmbH, Soest, Germany), ad libitum, except during exposure period
- Water (e.g. ad libitum): tap water, ad libitum, except during exposure period
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.6 – 22.2 °C
- Humidity (%): 40 - 64%, except for 1 day on which the relative humidity dropped down to 26%. As laboratory historical data do not indicate an effect of this deviation, the study integrity was not adversely affected.
- Air changes (per hr): approximately 15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12 hours artificial fluorescent light and 12 hours darkness per day

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: no vehicle used

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: dynamic (continuous flow) system, based on the flow past nose-only inhalation chamber (Am. Ind. Hyg Assoc. J. 44(12): 923-928, 1983). The chamber consisted of three animal sections with eight animal ports each. Each animal port had its own atmosphere inlet and exhaust outlet. All components of the exposure chamber in contact with the test material were made of stainless steel, glass, rubber or plastic. To avoid exposure of the personnel and contamination of the laboratory the exposure chamber was placed in a fume hood, which maintained at a slight negative pressure.
- Method of holding animals in test chamber: the animals were placed in restraining tubes and connected to the animal ports.
- Source and rate of air: the number of animal sections and number of open inlets were adapted to the air flow in such a way that at each animal port the theoretical air flow was at least 1 L/min, which ensures an adequate oxygen supply to the animals.
- Method of conditioning air: the main inlet of the test atmosphere was located at the top section and the main outlet was located at the bottom section. The direction of the flow of the test atmosphere guaranteed a freshly generated atmosphere for each individual animal.
- System of generating particulates/aerosols: during the generation, the test substance was stirred with a magnetic stirrer and in order to reduce the
viscosity of the test substance, the magnetic stirrer was heated up to 50 ºC. The heated test substance was transferred to a nebulizer (type 950, Hospitak Inc., Lindenhurst, NY, USA) by means of a rotating pump (type VL500 digit, VERDER Lab Tec GmbH & Co. KG, Haan, Germany). The nebulizer was placed in a water bath of 50 ºC and the tube for the pressurized air used for nebulization was led through the same water bath. The primary aerosol was initially diluted with humidified pressurized air, and during the last hour with dry air, before it entered the exposure chamber. The mean total airflow was 16.9 L/min.
- Treatment of exhaust air: from the exposure chamber the test atmosphere was passed through a filter before it was released to the exhaust of the fume hood.
- Temperature, humidity, pressure in air chamber: the temperature and relative humidity were measured with a humidity and temperature indicator (E+E Elektronik, Engerwitzdorf, Austria) and were recorded after the animals were placed in the experimental set-up and at 30 minute intervals after initiation of the exposure. The probe was inserted in a tube mounted in one of the free animal ports of the middle section of the exposure chamber. The temperature of the atmosphere was between 22.4 and 23.3 degrees C and relative humidity was between 36 and 60% during the first 3 hours of exposure and between 16 and 19% during the last hour. These conditions were considered appropriate for this relatively short 4 hours exposure duration. The study integrity was not adversely affected by this temporary deviation.

TEST ATMOSPHERE
- Method of droplet size distribution: the droplet size distribution was characterized twice during the exposure period. The samples were drawn (2 L/min) from the test atmosphere through a tube mounted in one of the free animal ports of the middle section of the exposure chamber. The samples were collected with an 8 stage Marple personal cascade impactor containing fiber glass filters (SKC 225-713, fiber glass, SKC Omega Specialty Division, Chelmsford, MA, USA) and a fiber glass back-up filter (SEC-290-F1, Westech, Upper Stondon, Bedfordshire, England). Amounts of test substance collected were measured gravimetrically. Subsequently the Mass Median Aerodynamic Diameter (MMAD) and the Geometric Standard Deviation (GSD) were determined, twice:
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.):
The MMAD was 1.8 µm (gsd 2.1) and 2.8 µm (gsd 2.1) respectively.

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

The target concentration was based on the cut off concentration value specified in the UN and EC classification guidelines. One group of five animals of each sex were exposed for 4 hours to a target concentration of the test substance of 5.5 mg/L (the limit of the guideline was increased with 10% in order to avoid the mean actual concentration to fall below the cut off value due to experimental variation).

No. of animals per sex per dose:

5

Control animals:

other: not required

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of weighing: days 1 (pre-administration), 2, 4, 8 and 15.
- Necropsy of survivors performed: yes, all animals were subjected to necropsy and descriptions of all internal macroscopic abnormalities were recorded. Particular attention was given to any changes in the respiratory tract
- Other examinations performed:
During exposure: three times during exposure for mortality, behavioural signs of distress and effects on respiration.
After exposure: on Day 1, one and three hours after exposure and once daily thereafter until Day 15. The symptoms were graded according to fixed scales and the time of onset, degree and duration were recorded:
Maximum grade 4: grading slight (1) to very severe (4)
Maximum grade 3: grading slight (1) to severe (3)
Maximum grade 1: presence is scored (1).

Statistics:

No statistical analysis was performed

Results and discussion

Preliminary study:

Not applicable

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 4.7 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: No mortalities occurred.

Mortality:

No mortalities occurred

Clinical signs:

other: During exposure, shallow respiration was seen in one male and one female. After exposure, hunched posture was seen in all animals on Days 1 and 2. On Day 1, lethargy was seen in two females and piloerection was seen in two males. Rales were noted in one f

Body weight:

Overall body weight gain in males and females was within the range expected for rats of this strain and age used in this type of study.

Gross pathology:

No abnormalities were found.

Any other information on results incl. tables

- The mean actual concentration was 4.7 ± 1.4 mg/L. The nominal concentration was 18.9 mg/L. The generation efficiency (ratio of actual and nominal concentration) was 25%

- The concentration measurements distributed over time showed that the substance was sufficiently stable

Applicant's summary and conclusion

Interpretation of results:

not classified

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

In an acute inhalation study conducted in accordance with OECD 403 and GLP, the substance was administered as an aerosol by inhalation for 4 hours to one group of five animals of each sex to a target concentration of 5.5 mg/L.Animals were subjected to daily observations and determination of body weights on Days 1, 2, 4, 8 and 15. Macroscopic examination was performed on the day of death or after terminal sacrifice (day 15). The mean actual concentration was 4.7 ± 1.4 mg/L. No mortality occurred during the study. During exposure, shallow respiration was seen in one male and one female. After exposure, hunched posture was seen in all animals on Days 1 and 2. On Day 1, lethargy was seen in two females and piloerection was seen in two males. Rales were noted in one female on Day 2. Autopsy revealed no abnormalities. Therefore the 4h-LC50 is determined to be >4.7 mg/L. Since no mortality was seen and symptoms of treatment without necropsy findings were observed, for classification purpose the LC50 is considered to be >5 mg/L. Based on this result, classification of the substance for acute inhalation toxicity is therefore not needed in accordance with the CLP Regulation.