potassium (oxido-NNO-azoxy)cyclohexane; cyclohexylhydroxydiazene 1-oxide, potassium salt; [K-HDO]

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Cyclohexylhydroxydiazene 1-oxide, potassium salt

EC Number:

613-953-8

Cas Number:

66603-10-9

Molecular formula:

C6H11KN2O2

IUPAC Name:

Cyclohexylhydroxydiazene 1-oxide, potassium salt

Test material form:

liquid

Details on test material:

Xyligen 30F is a 30% aqueous solution of K-HDO.

Specific details on test material used for the study:

Name of test substance: Xyligen 30 F
Substance No.: 01/0069-1
Composition/Purity: 30.4 % in aqueous solution
Batch No.: U 8380
Date of production: Jan. 25 2001

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Male and female Wistar rats (strain: ClrGlxBrlHan:WI)
- Source: Charles River Deutschland GmbH, Sandhofer Weg 7, 97633 Sulzfeld
- Females: nulliparous and non-pregnant
- Age at study initiation: approx. 8 - 12 weeks for males and approx. 14 - 18 weeks for females
- Weight at study initiation: males: 246.74 g; females: 228.36 g
- Housing: animals were housed single in cages type DK Ill (Becker, Germany) without bedding
- Diet (e.g. ad libitum): KUBA rat/mouse/hamster laboratory diet 10 mm pellets, Provimi Kliba SA, Kaiseraugst, Switzerland ad libitum
- Water (e.g. ad libitum): drinking water ad libitum
- Acclimation period: The animals were subjected to an acclimatization period of at least 1 week in which they were adapted to the surroundings.

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 20 - 24°C
- Humidity (%): 30 - 70%
- Air changes (per hr): The animals were kept in fully air-conditioned rooms
- Photoperiod (hrs dark / hrs light): light/dark cycle of 12 hours (6 a.m. - 6 p.m. light on, 6 p.m. - 6 a.m. light off).

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose/head only

Vehicle:

air

Remark on MMAD/GSD:

Cascade impactor measurements resulted in particle size distributions with mass median aerodynamic diameters (MMADs) of < 1.2 µm in the low concentration and 1.4 µm in the high concentration, which are well within the respirable range.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Head-nose inhalation systems
- Exposure chamber volume: ca. 55 L
- Method of holding animals in test chamber: the animals were restrained in glass tubes and their snouts projected into the inhalation system.
- Source and rate of air: Supply air flows (compressed air) of 1.5 m³/h were used for the exposures
- Method of conditioning air: Supply air flows (compressed air) of 1.5 m³/h were used for the exposures. The exhaust air flows were set to 1 .35 m³/h. Air changes of about 27 times per hour
- System of generating particulates/aerosols: Liquid aerosols were generated. For each test group the aerosols were produced by continuously pumping amounts of the test substance to a two-component atomizer. In test group 1, the aerosol was produced with the atomizer inside the aerosol mixing vessel using compressed air and was passed via the cyclonic separator into the exposure system. In test group 2, the aerosol was produced with the atomizer inside the exposure system using compressed air
- Method of particle size determination: The calculation of the particle size distribution was carried out in the inhalation laboratory on the basis of mathematical methods for evaluating particle measurements (DIN 66141: Darstellung von Komgrößenverteilungen, DIN 66161: Partikelgrößenanalyse
- Treatment of exhaust air: The exhaust air flows were set to 1.35 m³/h. The lower amounts of exhaust air, which were adjusted by means of a separate exhaust air system, achieved positive pressures inside the exposure systems. This ensured that the mixtures of test substance and air were not diluted with laboratory air in the breathing zones of the animals.
- Temperature, humidity, pressure in air chamber: 22.5 / 22.7 °C (group 1 / group 2); 57.9% / 56.6% (group 1 / group 2); 1.8 bar

TEST ATMOSPHERE
- Brief description of analytical method used: The homogenous distribution of atmospheres in the inhalation system has been proven in technical tests with model aerosols.
- Samples taken from breathing zone: yes

VEHICLE
- Composition of vehicle (if applicable): The samples obtained were taken up in a suitable amount of solvent in a 50 ml calibrated flask. The flask was filled up to the calibration mark after 5 ml 1 M HCL and 0.5 % FeCl3 solution had been added using a pipette. Some of the sample preparations were diluted with doubly distilled water at a ratio of 1:1 in order to reach a suitable measuring range.
- Concentration of test material in vehicle (if applicable): Nominal concentration: 13.2 [mg/ml] (test group 1); 20.7 [mg/ml] (test group 2)
Analytical concentration: 1.12 [mg/l] (test group 1); 7.8 [mg/l] (test group 2)
- Justification of choice of vehicle:
- Lot/batch no. (if required):
- Purity:

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

CLASS METHOD (if applicable)
- Rationale for the selection of the starting concentration:

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

Nominal concentration: 13.2 [mg/ml] (test group 1); 20.7 [mg/ml] (test group 2)
Analytical concentration: 1.12 [mg/l] (test group 1); 7.8 [mg/l] (test group 2)

No. of animals per sex per dose:

5 animals per sex and dose

Control animals:

not specified

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight,gross-pathological examination

Statistics:

The statistical evaluation of the concentration-response relationship was carried out using a computer program. Depending on the data of the concentration-response relationship obtained by way of experiment, this program is used to estimate the LC50 or to perform a Probit analysis. Estimation of the LC50 will produce types "LC50 greater than", "LC50 approx.", or "LC50 smaller than". If the results are type "LC50 greater than" or "LC50 smaller than", an additional binomial test is carried out, in order to verify these statements statistically.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 7.8 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No mortality occurred at both test concentrations.

Clinical signs:

other: Clinical signs of toxicity in animals exposed to 1.12 mg/L comprised visually accelerated and slower respiration, apathy and squatting posture. Findings were observed until including study day 2. Clinical signs of toxicity in animals exposed to 7.8 mg/L

Body weight:

The mean body weights of the female animals exposed to the low concentration did not increase adequately during the first post exposure observation week but increased during the second week. The mean body weights of the other animals increased throughout the study period.

Gross pathology:

No gross pathological abnormalities were noted in the animals necropsied at termination of the post exposure observation periods.

Other findings:

None observed.

Any other information on results incl. tables

Maximum incidence of clinical findings

Male animals

Test group / Concentration (mg/L)	1 / 1.12	2 / 7.8
Total number of animals	5	5
Lethality (number of animals)	0	0
Respiration, visually accelerated	5	5
Respiration, visually slower	5	-
Salivation, red	-	1
Attempts to escape	-	5
Apathy	5	-
Squatting posture	5	5
Lateral position	-	1
Reduced general state	-	1
Fur, smeared	-	5

 - = not detected

Female animals

Test group / Concentration (mg/L)	1 / 1.12	2 / 7.8
Total number of animals	5	5
Lethality (number of animals)	0	0
Respiration, visually accelerated	5	5
Respiration, visually slower	5	-
Attempts to escape	-	5
Apathy	5	-
Squatting posture	5	5
Fur, smeared	-	5

 

Applicant's summary and conclusion

Conclusions:

No lethality occurred at the tested concentrations of 1.12 and 7.8 mg K-HDO/L during the study period of 14 days. Therefore, the study satisfies the criteria of a limit test.
LC50 values, 4-hour exposure:
LC50 (both sexes combined): > 7.8 mg/L
LC50 (male rats): > 7.8 mg/L
LC50 (female rats): > 7.8 mg/L

Executive summary:

For determination of the acute inhalation toxicity (single 4-hour-exposure) of Xyligen 30 F as a liquid aerosol, a study in male and female Wistar rats was performed according to CECO-Guideline method 403, as well as EEC and EPA guidelines. The following measured concentrations were tested: 1.12 and 7.8 mg/L.

Cascade impactor measurements resulted in particle size distributions with mass median aerodynamic diameters (MMADs) of< 1.2μm in the low concentration and 1.4μm in the high concentration, which are well within the respirable range. No mortality occurred at both concentrations.

Clinical signs of toxicity in animals exposed to 1.12 mg/L comprised visually accelerated and slower respiration, apathy and squatting posture. Findings were observed until including study day 2. Clinical signs of toxicity in animals exposed to 7.8 mg/L comprised attempts to escape, visually accelerated respiration, squatting posture and smeared fur. Red salivation, reduced general condition and lateral position was observed additionally in 1 male animal. Findings were generally observed until including study day 2 except in the male animal mentioned above, in which some persisted until day 9. The mean body weights of the female animals exposed to the low concentration did not increase adequately during the first post exposure observation week but increased during the second week. The mean body weights of the other animals increased throughout the study period. No gross pathological abnormalities were noted in the animals necropsied at termination of the post exposure observation periods.

Under the conditions of this study the LC50 for male and female rats after liquid aerosol inhalation was > 7.8 mg K-HDO/L.