diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

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:

1991

Report date:

1991

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:

EPA OPP 81-3 (Acute inhalation toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

EC Number:

603-923-2

Cas Number:

135590-91-9

Molecular formula:

C16H18Cl2N2O4

IUPAC Name:

diethyl 1-(2,4-dichlorophenyl)-5-methyl-4,5-dihydro-1H-pyrazole-3,5-dicarboxylate

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: HOECHST AG, Kastengrund, SPF breeding colony
- Age at study initiation: 8-10 weeks
- Weight at study initiation: mean males 192 g, females 188 g
- Housing: in fully air-conditioned rooms in Makrolon cages (Type 4) on soft wood granulate, in groups of 5 animals
- Diet: Altromin 1324 rat diet (Altromin GmbH, Lage/Lippe), ad libitum
- Water: tap water in plastic bottles, ad libitum
- Acclimation period: at least 5 days


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 22 ± 2
- Humidity (%): 50 ± 20
- Photoperiod (hrs dark / hrs light): 12/12

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

other: polyethylene glycol/ethanol

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Stainless-steel and glass cylinder, standing in a vent pipe with a volume of approx. 4 m³. The chambers have proved to yield a uniform distribution of aerosols at the different breathing zones of the animals.
- Exposure chamber volume: 60 L
- Method of holding animals in test chamber: individually in cylindrical plastic cages
- Source and rate of air: air was pumped at a pressure of 4 bar into a special nozzle with a welded-in supply tube for the test substance. The air supply at the nozzle was maintained at 800 L/h by means of an air-calibrated rotameter (Rota, Wehr). A suction device at the bottom of the exposure chamber drew off the aerosol at a rate of 1100 L/h through a cotton-wool filter, a Buehler filter, a washing flask filled with 10% sodium hydroxide solution and a calcium chloride flask. The difference in rate between the introduction of air at 800 L/h through the nozzle and its extraction at 1100 L/h is necessary to maintain the kinetic energy of the aerosol particles and to ensure a laminar flow of the aerosol from the top to the bottom of the exposure chamber.
- Method of conditioning air: passing through an oil separation filter and an absolute filter. In order to ensure the higher atmospheric humidity required by the current guidelines, air was passed via a porous stone at a rate of 100 L/h through a 1000 ml vacuum filter flask filled with water. The moisturised air was then conducted straight into the exposure chamber.
- System of generating particulates/aerosols: Hoe 107892 00 ZC97 0001 was injected into a nozzle at a constant speed by means of a continuous infusion apparatus. The primary aerosol was formed in a separator. Smaller aerosol particles (secondary aerosol) passed through a rising tube into the exposure chamber.
- Method of particle size determination:
- Treatment of exhaust air: Particles of test substance escaping from the exposure chamber into the vent pipe were drawn off and neutralised by gas-cleaning equipment.
- Temperature, humidity, pressure in air chamber: 20 - 22°C, 58.6 - 63.7%, no data on pressure


TEST ATMOSPHERE
- Brief description of analytical method used: Gravimetric analysis of the aerosol-concentration in the breathing zone of the animals was performed at intervalls of about 15 minutes. For this purpose, the test atmosphere was drawn off through a rotary gas counter, then through a glass fiber filter and a membrane filter with a pore width of 0.65 µm. The extraction rate was 3 L/minute, resulting in a flow rate of 1.25 m/sec. Before use, the filters were stored in an exsiccator filled with calcium chloride for 24 hours. The filters were weighed before and after sampling by means of an electronic balance. In order to determine the exact quantity of Hoe 107892 00 ZC97 0001 in the exposure chamber, chemical-analytical examinations were carried out. For this purpose, 31 L were drawn from the inhalation chamber over a period of 60 minutes and passed successively through three gas-washing flasks filled with Acetonitril and kept standing in a cold bath. Sampling was carried out within the breathing zone of the animals. Additionally two of the filters used for gravimetric measurements were floated with 30 ml Acetonitril and also analysed. Hoe 107892 00 ZC97 0001 was isolated by HPLC and determined spectrophotometrically.
Determination of the aerosol particle size distribution was performed with an Anderson 7 stage cascade impactor (Model Mark III, Anderson Samples Inc., Atlanta, U.S.A.). The test atmosphere was impacted at each stage onto steel discs which were weighed before and after sampling. Sampling was performed at a volume rate of 9.5 L/minute, resulting in a flow velocity of 1.25 m/s. Mass median aerodynamic diameter, standard deviation and other parameters of the particle size distribution were calculated using linear regression (probit values versus the logarithm of the particle size).
- Samples taken from breathing zone: yes


VEHICLE
- Composition of vehicle (if applicable): Hoe 107892 00 ZC97 0001 was tested as solution in polyethylene glycol 400/ Ethanol p.a.
- Concentration of test material in vehicle (if applicable): 15%
- Justification of choice of vehicle: substance could not be dispersed in its original form, stability and homogeneity of the solution for a period of 6 hours was verified before start of the study.


TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: < 0.6 to > 10.3 µm
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 1.18 µm/3.36 µm (1st measurement), 1.02 µm/2.65 µm (2nd measurement)

Analytical verification of test atmosphere concentrations:

yes

Remarks:

gravimetric and chemical-analytical

Duration of exposure:

4 h

Concentrations:

1.32 mg/L air

No. of animals per sex per dose:

5

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: behaviour continuously during exposure, thereafter twice daily; weighing on day 8 and day 15
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight

Statistics:

Means and standard deviations of body weights and body weight gains, linear regression and probit analysis for calculation of particle size distribution parameters.

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 1.32 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: Highest technically administrable dose.

Mortality:

No deaths occurred.

Clinical signs:

other: Irregular breathing, stilted gait, uncoordinated gait, ataxic gait and squatting posture. Additionally, ruffled coat was observed. The animals treated with the vehicle alone also showed irregular breathing, uncoordinated gait, ataxic gait and squatting p

Body weight:

Body weight development was not impaired.

Gross pathology:

The animals killed at the end of the observation period showed no macroscopically visible abnormalities.

Applicant's summary and conclusion

Interpretation of results:

other: CLP/EU GHS criteria not met, no classification required according to Regulation (EC) No. 1272/2008

Conclusions:

CLP: Not classified