2-nitroaniline

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

27.10.1992 - 10.11.1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study conducted in compliance with GLP regulations

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1996

Report date:

1996

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

2-nitroaniline

EC Number:

201-855-4

EC Name:

2-nitroaniline

Cas Number:

88-74-4

Molecular formula:

C6H6N2O2

IUPAC Name:

2-nitroaniline

Details on test material:

- Name of test material (as cited in study report): o-nitroaniline feucht
- Analytical purity: 65 % o-nitroaniline, approx. 30 % water
- Impurities: 0.63 % 2-Nitrochlorobenzene (GC/IS), 0.4 % ammonium, 1.8 % chloride
- Purity test date: 01 June 1989
- Lot/batch No.: 1-8

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Strain SPF bred Wistar rats, strain BOR: WISW (Spf-Cpb)
- Source: Winkelmann, Borchen, Germany
- Age at study initiation: 2 - 3 months old
- Mean weight at study initiation: males 183.6 g (control), 194.0 g (test group); females 183.2 g (control), 190.8 g (test group)
- Fasting period before study: no
- Housing: one/cage
- Diet (ad libitum): Altromin 1324 pellets maintenance diet
- Water (ad libitum): tap water
- Acclimation period: at least 5 days

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

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 apparatus/Exposure chamber volume:
The baffle consisted of a glass flask with a diameter of approx. 12 cm and a volume of approx. 1 litre.
The modular inhalation chamber made of anodized aluminum consisted of two concentric cylinders (Dimensions: diameter and volume of inner cylinder = 14 cm and 3.84 L, total outer diameter and volume = 35 cm and 24.05 L, segment height = 25 cm.
- Method of holding animals in test chamber: Animals were exposed to the aerosolized test substance in restrainers made of Plexiglas.
- Source and rate of air: Compressed air was supplied by Boge compressors and was conditioned (i.e. freed from water, dust, and oil) automatically by a VIA compressed air dryer.
The test atmosphere generation conditions provide an adequate number of air exchanges per hour (> 300). Under such test conditions steady state is attained within the first 1.5 minutes of exposure.
- System of generating aerosols:
Under dynamic conditions the test substance-vehicle mixture was nebulized into a baffle (pre-chamber) which entrained the substance into the intake of the cylindrical inhalation chamber. The test substance, diluted in the vehicle, was nebulized using a two-component nozzle with conditioned compressed air (15 Litres of air/min; dispersion pressure approximately 600 kPa). A homogeneous mixture of the solution was ensured by continuous stirring. This solution was pumped directly into the nozzle using an infusion pump (Braun, Melsungen, Germany) equipped with a 50 mL glass syringe.
- Method of particle size determination: low-pressure Aeras stainless stecl cascade impactor LP1 4/0.06/9 stages
- Treatment of exhaust air: The exhaust air was purified via cotton-wool aerosol and HEPA filters.
- Temperature, humidity: 24 °C, 52 %

TEST ATMOSPHERE
- Brief description of analytical method used: GC
- Samples taken from breathing zone: yes

VEHICLE
- Composition of vehicle: PEG (Fluka Chemicals, no. 81170) / aceton (Merck, no. 14.1000), mixing ratio 1:1 (v/v)
- Concentration of test material in vehicle: 40 %
- Justification of choice of vehicle: Technical reasons


TEST ATMOSPHERE
- Particle size distribution: areosol mass < 3 µm = 70 %
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 2.1 µm / 1.9

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

4 h

Concentrations:

Nominal: 26.667 mg/L
Measured: 2.529 mg/L
All analytical concentrations reported refer to mg of test substance/L air and were calculated based on a o-Nitroanilin content of 65 %.

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:
The appearance and behaviour of each rat was examined carefully several times on the day of exposure, twice daily (morning and evening) on the first post-exposure day, and once daily thereafter. Body weights were measured before exposure, on days 3 and 7, and weekly thereafter. Individualweights were also recorded at death.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, gross pathology, other: methemoglobin formation, Functional Observational Battery (FOB), rectal temperature.

Statistics:

ANOVA, Chi-square-test

Results and discussion

Effect levels

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.529 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Mortality:

No lethalities occurred.

Clinical signs:

other: Vehicle control: reduced motility, piloerection, sluggishness Test substance group: reduced motility, piloerection, ungroomed coat, bradypnea, sluggishnes, high-stepping gait, distinct yellow discoloration of urine. Concerning the reflex measurements, com

Body weight:

A depression in body weight gain was observed.

Gross pathology:

Except for a fibrinous content in the urinary bladder of one animal in the test goup, macroscopical alterations were not observed.

Other findings:

An increase of the methemoglobin concentration was not measured in the treated animals.

Any other information on results incl. tables

The highly respirable aerosol of the test substance induced up to the technically maximum attainable concentration of 2529 mg/m3 air a low acute inhalation toxicity to the rat.

From the signs observed in the vehicle control group it may be concluded that the high concentrations of the vehicle constituent acetone, which has a well-known depressant action on the central nervous system, contributed, at least in part, to the observed clinical findings. Evidcnce for methemoglobin formation was not found. Observations such as hypothermia and bradypnea, observed exclusively in treated animals, are consistent with an assessment that this test substance induced sensory irrtation of the upper respiratory tract. The discoloration of the urine was most likely caused by the yellow color of the compound excreted renally.