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Toxicological information

Acute Toxicity: inhalation

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Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
11 October 2000 to 31 October 2000
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 guidelineopen allclose all
Qualifier:
according to
Guideline:
OECD Guideline 403 (Acute Inhalation Toxicity)
Deviations:
yes
Remarks:
see "Principles of method if other than guideline"
Qualifier:
according to
Guideline:
EPA OPPTS 870.1300 (Acute inhalation toxicity)
Deviations:
yes
Remarks:
see "Principles of method if other than guideline"
Qualifier:
according to
Guideline:
other: J-MAFF test guidelines for acute inhalation studies
Deviations:
not specified
Principles of method if other than guideline:
The mass median aerodynamic diameter (MMAD) of the test aerosol was 4.6 µm. This volume is slightly in excess of the guideline maximum of 4.0 µm. However it is considered that the value obtained was the minimum practical at the concentration achieved given the nature of the test material.
GLP compliance:
yes
Test type:
standard acute method
Limit test:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Physical state: Grey powder
- Storage conditions: In the dark at ambient room temperature (approximately 20 °C) and in the original container

Test animals

Species:
rat
Strain:
Sprague-Dawley
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Age at study initiation: 7 and 8 weeks (males and females respectively)
- Housing: by sex, in groups of 5 in holding cages made of stainless steel sheet and wire mesh suspended on a movable rack
- Diet: SDS rat and mouse diet (RM1 (E) SQC expanded pellet) ad libitum.
- Water: Anglian tap water ad libitum.
- Acclimation period: 6 days
- Source: Charles River UK Limited, Manston Road, Margate, Kent, England.


ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19.5 - 20.5 ºC
- Humidity (%): 39 - 65 %
- Air changes (per hr): 15 air changes/ hour
- Photoperiod (hrs dark / hrs light): 12 hours dark / 12 hours light (06:00 - 18:00 GMT)

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: a Wright Dust Feed mechanism was used to produce and maintain atmospheres containing a particulate aerosol by suspending material scraped from the surface of a compressed powder in a stream of dry air. The concentration of particulate aerosol was altered by changing the rate at which the scraper blade is advanced into the compressed powder held in the test material canister. The Wright Dust Feed was mounted on a glass cylinder attached to the top of the exposure chamber. The conditioned test atmosphere entered through a port at the top centre of the chamber and passed out through a port at the base section below the level of the rats.
- Exposure chamber volume: 30 L
- Method of holding animals in test chamber: snout-only exposure chambers (animals held in moulded polycarbonate restraining tubes and held in a forward position by an adjustable foamed plastic stopper, which also provided a seal for the tube)
- Source and rate of air: clean, dry air was passed through an electronic neutraliser, connected to a generator and the supply pressure adjusted to give a flow rate of 16 litre/minute. An in-line flow meter was used to monitor the generator air supply throughout the exposure. The exhaust airflow was calibrated and adjusted to produce a slightly negative pressure.
- Method of particle size determination: particle size measured with a Marple cascade impactor. The volume of air sampled was measured using a wet-type gas meter. The amount of material collected on the stages of the sampler was determined gravimetrically. The particle size distribution of the test atmosphere was then assessed using linear regression analysis.
- Treatment of exhausted air: the exposure system was positioned inside a large cabinet equipped with an extract fan exhausting to atmosphere through an absolute filter.
- Temperature and humidity in air chamber: 20.0 - 20.1 °C, 42 - 58 % (mean values)

TEST ATMOSPHERE
- Brief description of analytical method used: five samples of air were removed from the test chamber following equilibration and hourly thereafter. Each air sample was withdrawn at a rate of 2 L/min through a pre-weighed glass fibre filter. The volume of air sampled was measured using a wet-type gas meter. The filters were reweighed following sampling for gravimetric analysis of the test aerosol.

TEST ATMOSPHERE
- MMAD (Mass median aerodynamic diameter): 4.6 µm (approximately 67 % of the aerosol generated consisted of particulate of size < 7 µm)

Analytical verification of test atmosphere concentrations:
yes
Duration of exposure:
4 h
Concentrations:
The nominal concentration was 92.2 mg/L. The mean chamber concentration was 5.6 % of the nominal concentration that reflects losses of the test material due to impaction, deposition and cohesion due to static within the exposure system. The mean chamber concentration of total particulate was 5.18 mg/L and was in good agreement with target (5 mg/L).
No. of animals per sex per dose:
5 animals per sex per dose.
Control animals:
yes
Details on study design:
- Duration of observation period following administration: 14 days.
- Environmental conditions in the exposure chamber: air temperature was measured using an alcohol-in-glass thermometer and relative humidity was measured using a Casella type T6900 relative humidity meter. The temperature and relative humidity were recorded at the start of exposure and then at 30 minute intervals during the 4 hour exposure.
- Frequency of observations and weighing: throughout the study, all cages were checked at least twice daily for dead or moribund animals. Rats were observed intermittently for signs of reaction to the test material during exposure and at least twice daily throughout the observation period. Clinical signs were recorded at the end of the chamber equilibration period, at 0.25, 0.5 and 1.0 hours then hourly during the exposure. Clinical signs were recorded immediately following exposure and then at 1.0 and 2.0 hours post-exposure. During the observation period, clinical signs were recorded twice daily. Bodyweights were recorded twice during the week prior to exposure (day 0) and then weekly during the observation period and on the day of death.
- Necropsy of survivors performed: yes.
- Other examinations performed: at the end of the 14-day observation period, the rats were killed by intraperitoneal injection of pentobarbitone sodium followed by exsanguinations from the brachial blood vessels and subjected to a detailed macroscopic examination. The lungs (including the larynx and trachea) were removed, dissected clear of surrounding tissue, weighed and the weights recorded.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5.18 mg/L air
Based on:
test mat.
Exp. duration:
4 h
Mortality:
There were no unscheduled deaths.
Clinical signs:
other: DURING EXPOSURE: - Exaggerated breathing was observed in a proportion of test rats from 15 minutes and in all test rats from 30 minutes into exposure. Grey staining of the fur was noted for all test rats from 3 hours into exposure. Soiling of the fur wit
Body weight:
There were no treatment-related effects.
Gross pathology:
There were no treatment-related effects at necropsy.
Incidental effects noted included: small dark foci noted on the lungs of two male test rats and a male control rat. Hair loss from head was noted for a male test rat.
Other findings:
Lung weight: there were no treatment-related effects.

Any other information on results incl. tables

Table 1: Chamber Concentration of Test Material

Sample Time taken (h:min) Gravimetric conc. (mg/L) Nominal conc. (mg/L)
1 0:10 4.95
2 1:00 5.00
3 2:00 5.48
4 2:58 5.04
5 3:54 5.41
Mean 5.18 92.2
SD 0.249

Table 2: Particle Size Distribution of Test Material

Sample Time taken (h:min) Stage Cut-off size (µm) Amount collected (mg)
PSD 1 1:31 1 21.30 0.06
2 14.80 0.07
3 9.80 0.35
4 6.00 0.63
5 3.50 0.34
6 1.55 0.26
7 0.93 0.01
8 0.52 0.00
Filter 0.00 0.08
Total 1.80
PSD 2 3:31 1 21.30 0.00
2 14.80 0.09
3 9.80 0.39
4 6.00 0.77
5 3.50 0.40
6 1.55 0.29
7 0.93 0.06
8 0.52 0.03
Filter 0.00 0.08
Total 2.11

Table 3: Individual and Group Mean Bodyweights

Group Rat Day of observation
-7 -4 -2 -1 0 7 14
1 M (Control) 101 215 246 268 278 331 377
102 221 253 277 284 331 368
103 223 245 274 280 332 349
104 235 265 288 298 350 386
105 228 265 292 295 359 404
Mean 224 255 280 287 341 377
2 M (Test) 81 219 239 258 306 352
82 220 239 257 297 332
83 228 243 261 299 335
84 228 249 263 300 343
85 218 235 253 300 343
Mean 223 241 258 300 341
1 F (Control) 106 204 223 234 237 256 265
107 189 199 199 204 209 205
108 208 220 228 229 243 252
109 204 222 225 233 255 255
110 209 222 231 236 245 247
Mean 203 217 223 228 242 245
2 F (Test) 86 199 215 222 238 242
87 205 211 212 227 235
88 203 207 216 233 237
89 208 212 219 222 211
90 196 205 209 218 229
Mean 202 210 216 228 231

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
Under the conditions of the test, the median lethal concentration of the test material was estimated to be in excess of 5.18 mg/L to male and female rats. The study is considered to be reliable, relevant and adequate for risk assessment and classification and labelling purposes.
Executive summary:

The acute inhalation toxicity of the test material was determined in accordance with the standardised guidelines OECD 403 and EPA OPPTS 870.1300. Five male and five female rats were exposed for a period of 4 hours to a particulate aerosol generated from the test material at a target concentration of 5 mg/L (5.18 mg/L measured). A further group, acting as a concurrent common control was exposed to clean air only.

During the 4 hour exposure period, and the 14 day post-exposure observation period, no unscheduled deaths occurred. Clinical signs during the exposure period were limited to exaggerated breathing in test rats 15 to 30 minutes into exposure and grey staining on the fur 3 hours into exposure. During the observation period, clinical signs were limited to exaggerated breathing in all test rats immediately post exposure, persisting to day 4 of the observation period. A black/grey substance on the fur of the snout and jaws was evident on all test animals, persisting to day 2 of the observation period and hair loss from head of a single male test rat on day 14 of the observation period. All animals gained weight during the study. There were no macroscopic abnormalities at examination post mortem.

The median lethal concentration of the test material was estimated to be in excess of 5.18 mg/L to male and female rats.