Registration Dossier

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:
2012
Report Date:
2012

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
no
Qualifier:
according to
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Deviations:
no
Qualifier:
according to
Guideline:
other: JMAFF 12-Nousan-8147 (2000)
Deviations:
no
Qualifier:
according to
Guideline:
EU Method B.2 (Acute Toxicity (Inhalation))
Deviations:
no
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Details on test material:
Purity: 92.1%

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 9 weeks
- Weight at study initiation: males 231-252 grams and females 173-203 grams
- Fasting period before study: No
- Housing: individually housed in plastic solid bottom polycarbonate cages
- Diet: Harlan Teklad Global 16% Protein Rodent Diet® #2016. The diet was available ad libitum, except during the exposure.
- Water: Filtered tap water was supplied ad libitum by an automatic water dispensing system.
- Acclimation period: 6 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19-23ºC
- Humidity (%): 56-75%
- Air changes (per hr): 13
- Photoperiod (hrs dark / hrs light): 12-hour light/dark cycle

Administration / exposure

Route of administration:
inhalation: aerosol
Type of inhalation exposure:
nose only
Vehicle:
clean air
Details on inhalation exposure:
GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Mini-Nose-Only Inhalation Chamber, ADG Developments LTD
- Exposure chamber volume: 6.7 liters
- Method of holding animals in test chamber: Animals were individually housed in polycarbonate holding tubes which seal to the chamber with an “O” ring during exposure. The base unit terminates the chamber with a 0.5-inch diameter tube for discharged air.
- Source and rate of air: Approximately 30.0 liters per minute (Lpm) of filtered air was supplied by an air compressor to the dust generator. An additional 6.0 Lpm of compressed mixing air, supplied by an air compressor which was introduced into the chamber to help uniformly distribute the test atmosphere by creating a vortex at the chamber inlet.
- Method of conditioning air: The exposure tube temperature and relative humidity ranges during exposure were 24-25º C and 14-36%, respectively.
- System of generating particulates/aerosols: The test substance was aerosolized using a modified Wright Dust Generator driven by a variable speed motor D.C. speed control with 0-100 potentiometer. The test substance was packed into the dust container and compressed to 2000 lbs/in2 using a lab press. The container was then fitted with a stainless steel cutting head and cutting blade. Compressed/mixing air was supplied to the dust generator at 30 psi. The aerosolized dust was then fed directly into the chamber through the dust outlet assembly.
- Method of particle size determination: An eight-stage ACFM Andersen Ambient Particle Sizing Sampler was used to assess the particle size distribution of the test atmosphere. Samples were withdrawn from the breathing zone of the animals at two intervals during exposure. The filter paper collection stages were weighed before and after sampling to determine the mass collected upon each stage. The aerodynamic mass median diameter and geometric standard deviation were determined graphically using two-cycle logarithmic probit axes.
- Treatment of exhaust air: not reported
- Temperature, humidity, pressure in air chamber: The exposure tube temperature and relative humidity ranges during exposure were 24-25º C and 14-36%, respectively.

TEST ATMOSPHERE
- Brief description of analytical method used: Gravimetric samples were withdrawn at six intervals from the breathing zone of the animals. Samples were collected using 37 mm glass fibre filters in a filter holder attached by ¼ inch Tygon tubing to a vacuum pump. Filter papers were weighed before and after collection to determine the mass collected. This value was divided by the total volume of air sampled to determine the chamber concentration. The collections were carried out for 1 minute at airflows of 4 Lpm. Sample airflows were measured using a Mass Flowmeter.
- Samples taken from breathing zone: yes

VEHICLE
- Composition of vehicle (if applicable): Approximately 30.0 liters per minute (Lpm) of filtered air was supplied by an air compressor to the dust generator. An additional 6.0 Lpm of compressed mixing air, supplied by an air compressor which was introduced into the chamber to help uniformly distribute the test atmosphere by creating a vortex at the chamber inlet.

TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: see Table 1, Materials and Methods below
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 2.8 μm ± 2.0 (MMAD ± GSD).


Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
Nominal: 9.98 mg/L.
Measured: 5.06 ± 0.03 mg/L (mean ± SD).
No. of animals per sex per dose:
5
Control animals:
no
Details on study design:
- Duration of observation period following administration: 14 days
- Frequency of observations: The animals were observed for mortality, signs of gross toxicity, and behavioural changes at least once daily for 14 days following exposure. Body weights were recorded prior to exposure and again on Days 1, 3, 7 and 14 (termination). Necropsies were performed on all animals at terminal sacrifice.

Results and discussion

Effect levels
Key result
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5.06 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Mortality:
None
Clinical signs:
Following exposure, all animals exhibited irregular respiration. However, the animals recovered from this symptom by Day 2 and appeared active and healthy for the remainder of the 14-day observation period.
Body weight:
Although four males and two females lost and/or failed to gain body weight by Day 1, all animals showed a continued weight gain thereafter through Day 14.
Gross pathology:
No gross abnormalities were noted for any of the animals when necropsied at the conclusion of the 14-day observation period.

Applicant's summary and conclusion

Interpretation of results:
GHS criteria not met
Conclusions:
4-hour LC50 > 5.06 mg/L
Executive summary:

An acute inhalation toxicity test was conducted with rats to determine the potential for the test substance to produce toxicity from a single exposure via the inhalation (nose-only exposure) route. Ten healthy Sprague-Dawley derived, albino rats (5/sex) were exposed to 5.06 mg/L (measured) of the test atmosphere for 4 hours. Chamber concentration and particle size distributions of the test substance were determined periodically during the exposure period. The animals were observed for mortality, signs of gross toxicity, and behavioural changes at least once daily for 14 days following exposure. Body weights were recorded prior to exposure and again on Days 1, 3, 7 and 14 (termination). Necropsies were performed on all animals at terminal sacrifice.

All animals survived exposure to the test substance atmosphere. The mass median aerodynamic diameter (MMAD) and geometric standard deviation (GSD) of the atmosphere was 2.8 μm ± 2.0 (MMAD ± GSD). Following exposure, all animals exhibited irregular respiration. However, the animals recovered from this symptom by Day 2 and appeared active and healthy for the remainder of the 14-day observation period. Although four males and two females lost and/or failed to gain body weight by Day 1, all animals showed a continued weight gain thereafter through Day 14. No gross abnormalities were noted for any of the animals when necropsied at the conclusion of the 14-day recovery period. Under the conditions of this study, the single 4-hour inhalation medial lethal concentration (LC50) for the test substance is greater than 5.06 mg/L in male and female rats.