2-Pyridinecarboxylic acid, 4-amino-3,6-dichloro-

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

16 May 2001 to 13 June 2001

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:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 4

Qualifier:

according to guideline

Guideline:

other: JMAFF, Nousan No. 4200

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-amino-3,6-dichloropyridine-2-carboxylic acid

EC Number:

604-721-7

Cas Number:

150114-71-9

Molecular formula:

C6H4Cl2N2O2

IUPAC Name:

4-amino-3,6-dichloropyridine-2-carboxylic acid

Test material form:

solid: particulate/powder

Details on test material:

- Appearance: light brown powder
- Storage condition of test material: sealed container at ambient temperature

Specific details on test material used for the study:

Purity: 94.5%

Test animals

Species:

rat

Strain:

Fischer 344

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Age at study initiation: Approximately 7 and 9 weeks for males and females, respectively
- Weight at study initiation: 142 - 162 g (on the day of exposure)
- Housing: individually in suspended wire mesh cages
- Diet: ad libitum
- Water: reverse osmosis-treated municipal water, ad libitum
- Acclimation period: The animals were acclimated to laboratory conditions for a minimum of seven days prior to initiation of exposure. The animals for use on study were acclimated to nose-only restraint tubes for a single two-hour period prior to exposure.

ENVIRONMENTAL CONDITIONS
- Temperature: 70 - 73 F
- Humidity: 42 - 49 %
- Photoperiod: 12 hours of darkness / 12 hours of light

Administration / exposure

Route of administration:

other: inhalation: dust aerosol

Type of inhalation exposure:

nose only

Vehicle:

air

Details on inhalation exposure:

CHAMBER DESCRIPTION
The exposure was conducted in an 8.6-L conventional nose-only exposure system (designed and fabricated by the testing facility). Animals were restrained in nose-only tubes during exposure. Food and water were withheld during the exposure.

TEST ATMOSPHERE GENERATION
The test material was metered at 1.1 g/min by an auger-type dust feeder (AccuRate, Inc., Whitewater, WI) to a jet mill air micronizer (Model 00 Jet-O-Mizer, Fluid Energy Aljet, Plumsteadville, PA) operating as a dispersion device. The dust feeder was equipped with a magnetic vibrator (Syntron Model V-2-8, FMC Corp., Homer City, PA) to facilitate delivery of the test material. The aerosol from the jet mill was piped to the exposure system inlet via ¾-inch Tygon® tubing. Humidified dilution air was added to maintain the protocol-specified humidity range and to further dilute the atmosphere as necessary. Exhaust aerosol was filtered (particulate) prior to entering the in-house exhaust system.

CHARACTERISATION OF EXPOSURE ATMOSPHERES
- Mean temperature: 21 °C
- Mean relative humidity: 30 %

TEST ATMOSPHERE
- Nominal concentrations: The nominal exposure concentration was calculated as the total amount of test material used during the exposure divided by the total volume of air that passed through the system during the exposure.
- Actual concentrations: Actual exposure concentrations were determined by standard gravimetric methods. Samples were collected on pre-weighed 25-mm glass-fibre filters (Type A/E, Gelman Sciences, Ann Arbor, MI) held in an open-face filter holder positioned in the sampling port of the nose-only system. Following sample collection, the filters were re-weighed and the concentration calculated as the filter weight difference (post-sample minus pre-sample) divided by the sample volume.

TEST ATMOSPHERE (if not tabulated)
- Particle size determination: Two aerosol particle size determinations were conducted using a seven-stage cascade impactor (In-Tox Products, Albuquerque, NM). Pre-weighed 25-mm glass-fibre filters (Gelman Sciences) were used as the collection substrates. The samples were collected at 1.8 LPM for 1.5 minutes. One sample was collected during the first two hours and one sample was collected during the last two hours. The filters were reweighed and the particle size calculated based on the impactor stage cut-offs. The aerosol size was expressed as the mass median aerodynamic diameter (MMAD) and the geometric standard deviation (GSD).
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): The exposure aerosol was characterised by a mass median aerodynamic diameter of 2.5 µm with a geometric standard deviation of 2.45.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

by standard gravimetric methods

Duration of exposure:

4 h

Concentrations:

5.5 mg/L

No. of animals per sex per dose:

5 males and 5 females per dose

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing:
> Mortality: Each rat was observed for mortality approximately hourly during exposure, immediately following exposure on day 0 and twice daily thereafter for 14 days.
> Clinical Observations: Each rat was observed immediately following exposure on day 0 and once daily thereafter for 14 days. Due to the limited visibility of the animals in the restraint tubes, observations during exposure were limited to evaluations for mortality.
> Body Weights: Body weights were obtained prior to exposure on day 0 and on post-exposure days 1, 3, 7, 10 and 14.
- Necropsy of survivors performed: Yes. Animals were euthanised by Isoflurane® anaesthesia following by exsanguination. The major organ systems of the cranial, thoracic and abdominal cavities were examined for all animals.

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.5 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

None of the animals died during exposure or the 14-day observation period.

Clinical signs:

other: Immediately following exposure, gasping was observed for one male and bilateral ptosis (partial closure of the eye) was noted for four males and five females. There were no other toxicologically significant clinical observations. Wet tan material on the e

Body weight:

Slight body weight losses (2 to 7 g) were noted for four males and three females from day 0 to 1. All animals surpassed their initial (day 0) body weight by day 3 and were considered normal.

Gross pathology:

There were no gross findings at the scheduled necropsy.

Any other information on results incl. tables

Table 1: Mean body weights (g)

Sex	Pre-exposure	Day 1	Day 3	Day 7	Day 10	Day 14
Male	159	156	171	193	203	221
Female	146	145	152	155	157	163

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

Under the conditions of the study, the LC50 of the test material was found to be greater than 5.5 mg/L when male and female rats were exposed to the test material as a dust aerosol for four hours.

Executive summary:

The acute inhalation toxicity of the test material was investigated in a study which was conducted under GLP conditions and in accordance with the standardised guidelines OECD 403, EPA OPPTS 870.1300, EU Method B.2 and JMAFF Nousan 4200.

During the study test material was administered to a single group of five male and five female albino rats, over a period of 4 hours, via nose-only exposure as a dust aerosol at a concentration of 5.5 mg/L. The exposure aerosol was characterised by a mass median aerodynamic diameter of 2.5 µm with a geometric standard deviation of 2.45. Following exposure, all animals were maintained for a 14-day observation period. Parameters evaluated were mortality, clinical observations, body weights and gross necropsy.

None of the animals died during exposure or the 14-day observation period. Gasping was observed for one male and bilateral ptosis was noted for nine animals (four males, five females) immediately following exposure. There were no other toxicologically significant clinical observations immediately following exposure. Dried red material around the nose, ptosis or complete closure of the eyes and/or yellow material on the urogenital area were noted for one female during the first week. There were no other toxicologically significant clinical observations during the 14-day observation period. Nine of the 10 animals had slight body weight losses from day 0 to 1. All animals surpassed their initial (day 0) body weight by day 3 and were considered normal. There were no gross findings at the scheduled necropsy.

Under the conditions of the study, the LC50 of the test material was found to be greater than 5.5 mg/L when male and female rats were exposed to the test article as a dust aerosol for four hours.