Dichlobenil

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 August 1984 to 02 May 1986

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1986

Report date:

1984

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

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

Deviations:

yes

Remarks:

(only two test concentrations)

Test guideline 2

Qualifier:

according to guideline

Guideline:

EPA OPP 81-3 (Acute inhalation toxicity)

Deviations:

no

GLP compliance:

yes

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Dichlobenil

EC Number:

214-787-5

EC Name:

Dichlobenil

Cas Number:

1194-65-6

Molecular formula:

C7H3Cl2N

IUPAC Name:

2,6-dichlorobenzonitrile

Test material form:

solid: particulate/powder

Details on test material:

- Physical state: solid
- Storage condition of test material: room temperature

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Housing: stainless steel wire mesh cages
- Diet: ad libitum
- Water: tap water ad libitum
- Acclimation period: 6-8 days

ENVIRONMENTAL CONDITIONS
- Temperature: 20-25 °C
- Humidity: 48-77 %
- Air changes: 26 times per hour
- Photoperiod: 12 hours light / 12 hours dark

Administration / exposure

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure chamber volume: 40 L
- System of generating particulates/aerosols: Rehma type 504104 nebulizer
- Method of particle size determination: measured using a Marple personal cascade impactor, model 296. Samples were taken through the inlet adaptor at nose level at 1.5 L/min at 105 and 165 minutes after the start of exposure. Directly after sampling, the filters were extracted with methanol and the test material measured spectrophotometrically.
- Temperature, humidity, pressure in air chamber: 23.4-23.8 °C; 60.1-65.0 %

TEST ATMOSPHERE
- Brief description of analytical method used: samples of test atmosphere were taken through a 6cm plastic tube at 2 L/min for 2 minutes. After sampling, filters and the silica were extracted with dichloromethane and amounts of test material measured spectrophotometrically.
- Samples taken from breathing zone: yes

TEST ATMOSPHERE (if not tabulated)
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 2.11-2.57 µm (105 minutes); 2.00-2.61 µm (165 minutes) / 2.89-3.13 (105 minutes); 2.90-3.14 (165 minutes)

Analytical verification of test atmosphere concentrations:

not specified

Duration of exposure:

240 min

Concentrations:

0, 540 and 700 mg/m^3 (nominal)
133-233 mg/m^3 (lowest dose) - 250-326 mg/m^3 (highest dose)

No. of animals per sex per dose:

Five

Control animals:

yes

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: during exposure, respiratory frequencies if two males and two females were recorded; At 1.5, 18, 24 and 48 hours after exposure each animal was checked for toxic symptoms and then observed daily
- Necropsy of survivors performed: yes
- Other examinations performed: organ weights (lungs and trachea) and organ histopathology

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 250 mg/m³ air (analytical)

Based on:

test mat.

Remarks on result:

other: maximum attainable concentration (limit dose)

Mortality:

No deaths were reported during the study.

Clinical signs:

other: A temporarily decreased reactivity and locomotor activity of the rats suggested a slight effect on the nervous system when compared to controls.

Body weight:

No effects were observed.

Gross pathology:

All animals appeared normal. No macro- or microscopic abnormalities were detected which could be attributed to the test material.

Other findings:

- Organ weights: no changes in lung weights were observed.
- Histopathology: minor changes, not attributable to the test material, were observed.
- Other observations: respiratory frequencies were depressed in the test groups when compared to the controls.

Applicant's summary and conclusion

Interpretation of results:

other: Not classified in accordance with EU Criteria

Conclusions:

Under the conditions of the test, the LC50 of the test material was >250 mg/m³. A decreased respiratory frequency, observed during the exposure period, indicates an irritating action of the test material on the respiratory system. Further observations at 1.5 hours after exposure suggest a slight depression of the test material on the behaviour of the treated animals.

Executive summary:

In a GLP compliant acute inhalation study conducted in line with standardised guidelines EPA OPP 81-3 and partly in line with EU Method B.2, the acute inhalation toxicity of the test material was determined.

Under the conditions of the test the LC₅₀ of the test material in rats was determined to be >250 mg/m³. A decreased respiratory frequency, observed during the exposure period, indicates an irritating action of the test material on the respiratory system. Further observations at 1.5 hours after exposure suggest a slight depression of the test material on the behaviour of the treated animals.