Isopropylcyclohexane

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-10-04 to 2011-11-21

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:

2009

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

2008

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Version / remarks:

1998

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Isopropylcyclohexane

EC Number:

211-792-4

EC Name:

Isopropylcyclohexane

Cas Number:

696-29-7

Molecular formula:

C9H18

IUPAC Name:

(propan-2-yl)cyclohexane

Test material form:

liquid

Details on test material:

isopropylcyclohexane of Sasol Germany, batch 3347/27372 of 17 August 2011
purity 99.93 % w/w, impurities 0.07 % unidentified substances

Test animals

Species:

rat

Strain:

other: Rattus norvegicus

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ORGANISMS: 
- Strain: Rattus norvegicus) / CD / Crl: CD(SD)
- Source: Charles River Laboratories, 97633 Sulzfeld, Germany
- Age: males: approx. 7 weeks, females: approx. 9 weeks
- Weight at study initiation: males: 241 - 245 g, females: 220 - 255 g
- Number of animals: 3 males and 3 females
- Fasting period before study: 16 hours
- Housing: groups of two or three
- Diet: ad libitum, ssniff R/m-H V 1534
- Water: ad libitum, tab water
- Acclimatisation period: at least 5 days
ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22°C +/- 3 °C
- Humidity (%): 55 + / - 15 %
- Photoperiod (hrs dark / hrs light): 12 hours darkness, 12 hours artifical light

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: compressed filtered air

Mass median aerodynamic diameter (MMAD):

2.268 µm

Geometric standard deviation (GSD):

2.64

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Type of exposure: nose-only, using a dynamic inhalation apparatus, air changes >/= 12/h
- Method of holding animals in test chamber (volume 40 l): separatley in Pyrex tubes at the edge of the chamber in radial position
- Source of air: compressed filtered air
- Method of conditioning air: manometer and air-flow meter (ROTA Yokogawa), flow rates checked once per hour and corrected if necessary
- Oxygen content: 21 %, determined at beginning and end of exposure, Carbon dioxide concentration did not exceed 1 %
- Type or preparation of particles: The aerosol of the test item was obtained using a spray-jet. The spray-jet was fed with compressed air (5.0 bar)
from a compressor and with the test item using a TSE infusion pump. At the bottom of the exposure chamber, the air was sucked off at a lower rate than created by the spray-jet in order to produce a homogenous distribution and a positive pressure in the exposure chamber (inflow 900 L/h,
outflow 800 L/h).
- Analysis of the aerosol concentration: The actual aerosol concentration in the inhalation chamber was measured gravimetrically with an air sample
filter (Minisart SM 17598 0.45 µm) and pump (Vacuubrand, MZ 2C ) controlled by a rotameter. Dust samples were taken once every hour during the exposure
- Method of particle size distribution: An analysis of the particle size distribution was carried out twice during the exposure period using a cascade
impactor according to MAY . The impactor is a device that classifies particles present in a sample of air or gas into known size ranges. It does this by drawing the air sample through a cascade of progressively finer nozzles. The air jets from these nozzles impact on pre-weighed plane sampling
surfaces (slides). The aerosol from the exposure chamber was drawn through the cascade impactor for 5 minutes at a constant flow rate of 5 L/min. The slides were removed from the impactor and weighed on an analytical balance (SARTORIUS, type 1601 004, precision 0.1 mg). The mass median aerodynamic diameter (MMAD) was determined as 2.268 µm. The Geometric Standard Deviation (GSD) of the MMAD was calculated as 2.64.
- Temperature, humidity: T: 20.4 +/- 0.08°C, H: 60.9 % +/- 0.15 %, measured once every hour
TEST ATMOSPHERE
- Concentrations: 5.04 mg/l 
Air flow entrance (L/h): 900
Air flow exit (L/h): 800
Air change (changes per hour): 22.5

Analytical verification of test atmosphere concentrations:

yes

Remarks:

Gravimetric determination of aerosol concentrations with an air sample filter. Dust samples were taken once every hour during the exposure.

Duration of exposure:

4 h

Concentrations:

gravimetric aerosol concentration of 5.04±0.11 mg Isopropylcyclohexane/L air was measured at the animals’ nose.

No. of animals per sex per dose:

3

Control animals:

no

Details on study design:

EXAMINATIONS: 
- Post dose observation period: 14 days
- body weights: before,  7 and 14 days after treatment   
- mortality: once per hour during, and once after treatment on day of  exposure;  thereafter twice daily
- clinical signs: during and following exposure, observations were made and recorded systematicallye,  at least twice daily until all symptoms
subsided, thereafter each working day
- Necropsy: all animals (macroscopic) when found dead or at terminal  sacrifice. In addition, the weight of the lungs was determined.

Statistics:

not necessary

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.04 mg/L air

Based on:

act. ingr.

Exp. duration:

4 h

Mortality:

No animal died prematurely.

Clinical signs:

other: slight ataxia, slightly reduced muscle tone and slight dyspnoea immediately until 60 minutes or 3 hours after end of exposure

Body weight:

All animals gained the expected body weight.

Gross pathology:

None findings

Other findings:

no other findings

Any other information on results incl. tables

The mean actual exposure concentration, MMAD and GSD of Isopropylcyclohexane were as follows:

nominal concentration	gravimetric concentration (actual)	mass median aerodynamic diameter (MMAD)	geometric standard deviation (GSD)
[µL/L air]	[mg/L air]	[µm]
11.11	5.04	2.268	2.64

Applicant's summary and conclusion

Conclusions:

Under the present test conditions, LC50-value for CD rats following inhalation of Isopropylcyclohexane for 4 hours was determined as follows
(actual concentration): LC50: exceeding 5.04 mg Isopropylcyclohexane/L air.

Executive summary:

The aim of the present experiment was to obtain information on the acute toxicity and LC₅₀, following a single 4-hour inhalation exposure in an acute inhalation study in rats.

Rats were exposed to isopropylcyclohexane at a concentration of 5.04±0.11 mg isopropylcyclohexane/L air for 4 hours by inhalation using a dynamic nose-only exposure chamber. The aerosol was generated with the aid of a spray-jet.

In the inhalation chamber, close to the animals' noses, the generated aerosol particulates had a mass median aerodynamic diameter (MMAD) of 2.268 µm as deter­mined with a cascade impactor. The Geometric Standard Deviation (GSD) of the MMAD was calculated as 2.64.

Under the present test conditions, a 4-hour inhalation of 5.04 mg isopropylcyclohexane/L air revealed slight ataxia, slightly reduced muscle tone and slight dyspnoea immediately until 60 minutes or 3 hours after end of exposure. No animal died prematurely. No pathological findings were noted at necropsy. All animals gained the expected body weight.

LC₅₀:     >5.04 mg/L air for both sexes combined

According to the EC Regulation 1272/2008 and subsequent regulationson classification, labelling and packaging of substances and mixtures, isopropylcyclohexane does not require classification for acute inhalation toxicity.