Registration Dossier

Administrative data

Endpoint:
acute toxicity: inhalation
Type of information:
experimental study
Adequacy of study:
key study
Study period:
14 September 2012 - 2 October 2012
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Study conducted to GLP in compliance with agreed protocols, with no or minor deviations from standard test guidelines and/or minor methodological deficiencies, which do not affect the quality of the relevant results.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2012
Report Date:
2012

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Test type:
acute toxic class 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:
- Appearance: pale pink powder
- Storage conditions: Room temperature, in the dark

Test animals

Species:
rat
Strain:
Wistar
Sex:
male/female
Details on test animals and environmental conditions:
TEST ANIMALS
- Strain: RccHan:WIST
- Age at study initiation: approximately 8 - 12 weeks
- Weight at study initiation: 200 - 350 g
- Fasting period before study: no
- Housing: The animals were housed in groups of up to three by sex in solid-floor polypropylene cages with stainless steel lids, furnished with softwood flakes and provided with environmental enrichment items: wooden chew blocks and cardboard “fun tunnels”.
- Diet (e.g. ad libitum): With the exception of the exposure period, free access to food was allowed.
- Water (e.g. ad libitum): ad libitum with the exception of the exposure period.
- Acclimation period: at least 5 days

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 19 - 25 °C
- Humidity (%): 30 - 70 %
- Air changes (per hr): at least 15 per hour
- Photoperiod (hrs dark / hrs light): the lighting was controlled to give twelve hours continuous light and twelve hours darkness.

IN-LIFE DATES: From: 14 September 2012 To: 2 October 2012

Administration / exposure

Route of administration:
inhalation: dust
Type of inhalation exposure:
nose only
Vehicle:
clean air
Details on inhalation exposure:
ATMOSPHERE GENERATION
A dust atmosphere was produced from the test material using an SAG 410 Solid Aerosol Generator located adjacent to the exposure chamber. The SAG 410 was connected to a metered compressed air supply.
A particle separator was introduced before the aerosol entered the exposure chamber in order to remove large particles and thereby increase the inhalable portion of the generated aerosol.
Compressed air was supplied by means of an oil free compressor and passed through a water trap and respiratory quality filters before it was introduced to the SAG 410.
The cylindrical exposure chamber had a volume of approximately 30 litres (dimensions: 28 cm diameter x 50 cm high). The concentration within the chamber was controlled by adjusting the test material feed rate from the SAG 410. The extract from the exposure chamber passed through a ‘scrubber’ trap and was connected with a high efficiency filter to a metered exhaust system. The chamber was maintained under negative pressure.

Prior to the start of the study, test material atmospheres were generated within the exposure chamber. During this characterisation period test material input rates and the generation system were varied in order to achieve the required atmospheric conditions.

EXPOSURE PROCEDURE
Prior to the day of exposure each rat was acclimatised (for approximately 2 hours) to a tapered polycarbonate restraining tube. During the day of exposure, each rat was individually held in a tapered, polycarbonate restraining tube fitted onto a single tier of the exposure chamber and sealed by means of a rubber ‘O’ ring.
A target concentration of 5.0 mg/L was used for the exposure. The mean achieved concentration was 111 % of target.

EXPOSURE CHAMBER TEMPERATURE AND RELATIVE HUMIDITY
The temperature and relative humidity inside the exposure chamber were measured by an electronic thermometer/humidity meter located in a vacant port in the animals’ breathing zone of the chamber and recorded every thirty minutes.

EXPOSURE CHAMBER OXYGEN CONCENTRATION
Oxygen levels within the exposure chamber were measured by an electronic oxygen analyser located in a port in the animals' breathing zone. The test atmosphere was generated to contain at least 19 % oxygen.
The MMAD was 2.04 µm, resulting in an inhalable fraction (% <4 µm) of 82.3. The geometric standard deviation was 2.08.

EXPOSURE CHAMBER ATMOSPHERE CONCENTRATION
The actual chamber concentration was measured at regular intervals during the exposure period. The gravimetric method used glass fibre filters placed in a filter holder. The holder was temporarily sealed in a vacant port in the exposure chamber in the animals’ breathing zone and a suitable, known volume of exposure chamber air was drawn through the filter using a vacuum pump.
Each filter was weighed before and after sampling in order to calculate the weight of collected test material. The difference in the two weights, divided by the volume of atmosphere sampled, gave the actual chamber concentration.
The nominal chamber concentration was calculated by dividing the mass of test material used by the total volume of air passed through the chamber.
The nominal concentration is 257 % of the actual mean achieved atmosphere concentration and shows that keeping the aerosol airborne was relatively simplistic.

PARTICLE SIZE DISTRIBUTION
The particle size of the generated atmosphere inside the exposure chamber was determined three times during the exposure period using a Marple Personal Cascade Impactor. This device consisted of six impactor stages (8.6, 5.5, 3.8, 1.7, 0.86 and 0.41 µm cut points) with stainless steel collection substrates and a back up glass fibre filter, housed in an aluminium sampler. The sampler was temporarily sealed in a sampling port in the animals’ breathing zone and a suitable, known volume of exposure chamber air was drawn through it using a vacuum pump.
The collection substrates and backup filter were weighed before and after sampling and the weight of the test material, collected at each stage, calculated by the difference.
The mean amount for each stage was used to determine the cumulative amount below each cut-off point size. In this way, the proportion (%) of aerosol less than 8.6, 5.5, 3.8, 1.7, 0.86 and 0.41 µm was calculated.
The resulting values were converted to probits and plotted against Log10 cut-point size. From this plot, the Mass Median Aerodynamic Diameter (MMAD) was determined (as the 50 % point) and the geometric standard deviation was calculated. In addition the proportion (%) of aerosol less than 4 µm (considered to be the inhalable fraction) was determined.
Analytical verification of test atmosphere concentrations:
yes
Remarks:
The test atmosphere was sampled seventeen times during the exposure period and the actual concentration of the test material calculated.
Duration of exposure:
4 h
Concentrations:
5.53 mg/L
No. of animals per sex per dose:
3 animals per sex per dose
Control animals:
no
Details on study design:
- Duration of observation period following administration: all animals were observed for clinical signs at hourly intervals during exposure, immediately on removal from the restraining tubes at the end of exposure, one hour after termination of exposure and subsequently once daily for up to 14 days. Any evidence of overt toxicity was recorded at each observation.
- Frequency of observations and weighing: Individual bodyweights were recorded on arrival, prior to treatment on the day of exposure and on Days 1, 3, 7 and 14.
- Necropsy of survivors performed: yes. At the end of the 14 day observation period the animals were killed by intravenous overdose of sodium pentobarbitone. All animals were subjected to a full external and internal examination, and any macroscopic abnormalities were recorded. The respiratory tract was subjected to a detailed macroscopic examination for signs of irritancy or local toxicity.

Results and discussion

Effect levels
Sex:
male/female
Dose descriptor:
LC50
Effect level:
> 5.53 mg/L air (analytical)
Based on:
test mat.
Exp. duration:
4 h
Mortality:
There was no mortality during the study.
Clinical signs:
In addition to the observations considered to be due to the restraint procedure (such as hunched posture, pilo-erection, wet fur), increased respiratory rate was noted in all animals during exposure, on removal from the chamber and one hour post-exposure.
One day after exposure, all animals exhibited increased respiratory rate and hunched posture. In addition, two male animals also exhibited pilo-erection. Animals recovered to appear normal from Days 6 to 9 post-exposure.
Body weight:
One male and one female animal exhibited a slight bodyweight loss or showed no bodyweight gain on the first day post-exposure.
All male animals exhibited reasonable bodyweight gains during the remainder of the observation period.
In contrast, all female animals exhibited bodyweight losses or showed no bodyweight gain from Days 1 to 3; no bodyweight gain was noted in one female from Days 3 to 7.
Bodyweight gains were noted in all females during the final week of observation.
Gross pathology:
No macroscopic abnormalities were detected at necropsy.

Any other information on results incl. tables

Table 1: Exposure Chamber Atmosphere Concentrations

Duration of Exposure (minutes)

Net Weight of Sample (mg)

Volume of Air Sampled (L)

Chamber Flow Rate (L/min)

Atmosphere Concentration (mg/L)

5

10.09

2

60

5.05

15

9.49

2

60

4.75

30

10.04

2

60

5.02

45

10.23

2

60

5.12

60

12.33

2

60

6.17

75

10.52

2

60

5.26

90

11.95

2

60

5.98

105

11.32

2

60

5.66

120

9.78

2

60

4.89

135

12.74

2

60

6.37

150

11.50

2

60

5.75

165

11.11

2

60

5.56

180

10.97

2

60

5.49

198

11.13

2

60

5.57

210

11.95

2

60

5.98

225

11.42

2

60

5.71

237

11.28

2

60

5.64

Mean achieved atmosphere concentration: 5.53 mg/L (standard deviation 0.46)

 

Nominal Concentration

-Test material used: 216 g

-Air flow: 60 L/min

-Total generation time: 254 minutes*

-Nominal concentration: 14.2 mg/L

 

*Test atmospheres were generated for a total of 14 minutes prior to animal insertion to ensure that the test material concentration was being achieved.

 

Table 2: Particle Size Distribution - Cascade Impactor Data

Impactor Stage Number

Cut Point (µm)

Amount Collected (mg) Per Sample Number

Mean Amount Collected (mg)

1

2

3

3

8.6

0.08

0.06

0.05

0.06

4

5.5

0.10

0.35

0.08

0.18

5

3.8

1.03

1.40

0.97

1.13

6

1.7

1.47

2.00

1.21

1.56

7

0.86

0.64

0.53

0.61

0.59

8

0.41

0.44

0.20

0.28

0.31

Back-up filter

<0.41

0.28

0.10

0.09

0.16

Total mean amount of test material collected: 3.99 mg

 

Table 3: Particle Size Distribution - Calculation

Cut Point (µm)

Log10 Cut Point

Mean Cumulative Amount Less Than Cut Point

(mg)

(%)

Probit

8.6

0.935

3.93

98.5

7.17

5.5

0.740

3.75

94.0

6.55

3.8

0.580

2.62

65.7

5.40

1.7

0.230

1.06

26.6

4.37

0.86

-0.066

0.47

11.8

3.81

0.41

-0.387

0.16

4.01

3.25

MMAD: 2.04 µm

Geometric standard deviation: 2.08

Predicted amount <4 µm: 82.3 %

 

Table 4: Individual Bodyweights

Animal Number and Sex

Bodyweight (g) on Day:

Increment (g) During Days:

-6

0

1

3

7

14

-6 to 0

0 to 1

1 to 3

3 to 7

7 to 14

1 Male

237

269

270

276

295

321

32

1

6

19

26

2 Male

226

266

267

277

299

337

40

1

10

22

38

3 Male

220

258

256

264

280

306

38

-2

8

16

26

4 Female

215

243

245

238

243

254

28

2

-7

5

11

5 Female

196

215

215

210

219

231

19

0

-5

9

12

6 Female

191

206

208

208

208

210

15

2

0

0

2

Applicant's summary and conclusion

Interpretation of results:
not classified
Remarks:
Migrated information Criteria used for interpretation of results: EU
Conclusions:
The 4 hour LC50 was determined to be >5.53 mg/L, therefore the test material requires no classification under the conditions of this study in accordance with EU criteria.
Executive summary:

An acute inhalation study was conducted to assess the toxicity potential of the test material in accordance with the standardised guideline OECD 436.

Male and female RccHan:WIST strain rats (3 per sex) were exposed (nose only) for 4 hours to a dust atmosphere containing the test material at a mean concentration of 5.53 mg/L, with a MMAD of 2.04 µm.

Following exposure, the animals were observed for 14 days for signs of mortality and toxicity. At the end of the observation period, all animals were subjected to necropsy.

No deaths occurred throughout the study and the 4 hour LC50 was therefore determined to be >5.53 mg/L. The test material requires no classification under the conditions of this study in accordance with EU criteria.