Tin

Acute Toxicity: inhalation

Administrative data

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 September 2008 to 8 October 2008

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The information obtained is relevant to to hazard assessment of metallic tin and all efforts were made to determine as accurately as feasiblly possible, the likely inhalation or respiratory effects of exposure to tin metal.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2009

Report date:

2009

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

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

Deviations:

no

Test guideline 3

Qualifier:

according to guideline

Guideline:

EPA OPPTS 870.1300 (Acute inhalation toxicity)

Deviations:

no

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Test material

Test material information

Constituent 1

Reference substance name:

Tin

EC Number:

231-141-8

EC Name:

Tin

Cas Number:

7440-31-5

Molecular formula:

Sn

IUPAC Name:

tin

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): Tin Metal Powder
- Physical state: grey metallic powder
- Analytical purity: 99.99 %
- Lot/batch No.: 814461
- Expiration date of the lot/batch: Not stated
- Stability under test conditions:
- Storage condition of test material: room temperature

Test animals

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Limited, Margate, Kent UK
- Age at study initiation: 57 days (males) and 78 days (females)
- Weight at study initiation: 230-251g (males) and 199-221g (females)
- Fasting period before study: no
- Housing: in groups of five in standard laboratory caging
- Diet: ad libitum, SQC Rat and Mouse Maintenance Diet No 1, Expanded, (Special Diets Services Ltd, Witham, UK)
- Water: ad libitum, mains water via water bottles
- Acclimation period: one week

ENVIRONMENTAL CONDITIONS
- Temperature: 19-25 °C
- Humidity: 40-70% RH
- Air changes: 15 per hr
- Photoperiod:12/12 (hrs dark / hrs light)

IN-LIFE DATES: From: 17 September 2008 To: 1 October 2008

Administration / exposure

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

not specified

Mass median aerodynamic diameter (MMAD):

3.34 µm

Geometric standard deviation (GSD):

2.38

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Rotating brush generator and flow through chamber
- Exposure chamber volume: 40 L
- Method of holding animals in test chamber: Standard holding tubes (polycarbonate type restraining tubes) attached to chamber walls to give nose-only exposure
- Source and rate of air: Generator, 20.1 L/min flow rate to achieve 12 air changes per hour
- System of generating particulates/aerosols: Rotating brush generator
- Method of particle size determination: Supplied test material was ground to produce a powder with particle size of 1-5 µm. Samples were returned for analysis and confirmation of particle size range. Particle sizes in the test aerosol were measured gravimetrically using a Marple 298 cascade impactor, from which the MMAD and GSD were determined. During the aerosol characterisation phase of the study, samples of the generated tin metal powder were sent to the Sponsor for examination under a microscope to check that agglomeration of the particles had not occurred during generation. The tin metal particles were collected from a port representative of the animals breathing zone. The duration of collection was 5 minutes. The tin particles were collected on Vaseline smeared glass slides. The slides were not directly analysed by scanning electron microscope (SEM) as it was expected that the Vaseline would degas in the SEM machine. Carbon tape was pressed onto the glass slide and then lifted off to collect a sample of tin powder and was then gold coated before being viewed by SEM.
- Treatment of exhaust air: The chamber was exhausted from the bottom of the chamber to ensure a dynamic flow of fresh aerosol through the chamber during exposure. Treatment of exhaust air was not reported.
- Temperature, humidity, pressure in air chamber: Measured continuously within the chamber along with oxygen content with targets of 20-24 °C; 30-70 % RH and 19 % v/v oxygen.

TEST ATMOSPHERE
- Brief description of analytical method used: Nominal test atmosphere concentration determined and achieved concentration determined by gravimetric analysis at half hourly intervals throughout the exposure period
- Samples taken from breathing zone: yes

VEHICLE
No vehicle employed

TEST ATMOSPHERE (if not tabulated)
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): 3.34 µm and 2.38 respectively

Analytical verification of test atmosphere concentrations:

yes

Duration of exposure:

>= 4 h

Concentrations:

4.75 mg/L measured (5 mg/L target)

No. of animals per sex per dose:

Five males and five females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Hourly observations during exposure and at daily intervals from day 2 to 15. Bodyweights recorded on daily.
- Necropsy of survivors performed: yes
- Other examinations performed: clinical signs, body weight, histopathology.

At necropsy the respiratory tract tissues were preserved for histopathology. The tissues included trachea, lung including main stem bronchi and bronchioles, tracheal bifurcation (bronchial), larynx, and nasopharynx.

Histopathological examinations included trachea, mainstem bronchi, bronchioles and lung for two animals per group

Results and discussion

Effect levels

Key result

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 4.75 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

not determinable due to absence of adverse toxic effects

Mortality:

No mortalities during the study

Clinical signs:

other: Treatment-related clinical signs observed on Day 1, during exposure to 4.75 mg/L tin metal powder were limited to tachypnoea (abnormally fast breathing). This observation was seen in all animals (both sexes) from 3 hours onwards during exposure. Wet fur w

Body weight:

All animals lost weight during exposure. The mean post exposure body weight loss (14 g) was considered to be due to removal of food and water during the exposure period and not due to the effects of the test article. This weight loss is considered to be a common phenomenon observed in acute inhalation studies. All animals gained weight on Day 2, however, females took longer on average to recover their pre-exposure body weight.

Gross pathology:

Dark lung was noted in all animals at necropsy. This observation is consistent with inhalation exposure to respirable particulate material. There were no other macroscopic findings due to effects of the test article. Most tissues were macroscopically unremarkable and the findings seen were generally consistent with the usual pattern of findings in animals of this strain and age.

Other findings:

- Histopathology:Microscopic evaluation of the trachea, mainstem bronchi, bronchioles and lung was performed on two animals of each sex. In addition, representative photomicrographs of intra-alveolar particles in the lung, and intra epithelial particles in the trachea were taken using a digital camera attached to a microscope.
Test article was noted in the lung in all treated animals examined which generally correlated with findings seen macroscopically of heavy staining in the lungs. In one male, sub-epithelial particles were noted in the trachea.
Test article in the lung was characterised by multiple dark particles in the alveolar spaces, generally associated with pale eosinophilic homogenous material, and occasionally within alveolar macrophages. Particles were located in all lung sections and distributed from alveoli in the deep lung parenchyma to sub-pleural alveoli, with no clear anatomic localisation. In addition, there were occasional very minor foci of mucus-associated particles adherent to the bronchial and/or bronchiolar epithelium.
Sub-epithelial particles in the trachea were characterised by a few dark particles associated with minor lymphoid foci localised beneath the epithelium of the carina of the tracheal bifurcation.
There were no other microscopic findings due to effects of the test article.

Any other information on results incl. tables

Table1

Group summary clinical signs

Group/Sex		Clinical sign	Number of animals in group showing signs during exposure on Day 1 (hours):		Number of animals in group showing signs post-exposure on Day 1 (hours):
			3	4	Imm	1	2	3	4
1M		Number examined:	5	5	5	5	5	5	5
		Tachypnoea	5	5
		Wet fur	5	5	5
		Unkempt				5	5	5	5
		Staining - head			5
		Staining*				3	2	1	2
		Vocalisation			1
1F		Number examined:	5	5	5	5	5	5	5
		Tachypnoea	5	5
		Wet fur	5	5	5
		Unkempt				5	5	5	5
		Staining - head			5
		Staining*				5	3	2	1
		Vocalisation			3

Imm = Immediately on return to cage
* where no area has been specified, this indicates that staining was seen across the whole of the animal's body

Table2
Group mean body weights

Group/ Sex	Animal number	Group mean body weights (g) for Day:
		1 (Pre-exposure)	1 Post-exposure	2	3	4	5
1M	Mean	239	225	239	245	246	249
	SD	8.5	7.3	9.7	9.4	8.8	11.5
1F	Mean	211    9.8	197	210	210	209	211
	SD		8.2	9.5	11.5	9.6	10.4

 

Group/ Sex	Animal number	Group mean body weights (g) for Day:
		6	7	8	9	10	11
1M	Mean	256	258	260	263	266	268
	SD	8.5	9.5	8.9	9.6	10.8	11.5
1F	Mean	213	213	214	214	216	216
	SD	9.8	10.4	9.0	9.1	10.2	13.3

 

Group/ Sex	Animal number	Group mean body weights (g) for Day:
		12	13	14	15
1M	Mean	271	274	279	279
	SD	12.6	11.8	12.8	12.6
1F	Mean	213	215	217	220
	SD	10.7	11.5	12.4	12.7

 

Table3
Group mean body weightgains

Group/ Sex	Animal         number			Pre-exposure body weight (g)	Body weight gain relative to pre-exposure(g)
					Day 1 post-exposure		Day 2	Day 8	Day 15
1M	Mean			239		-14	0	21	40
	SD			8.5		3.6	1.7	5.4	8.4
1F	Mean			211		-14	-1	3	9
	SD			9.8		3.9	3.4	7.4	5.5

 

Table 4
Particle Size

	% Mass of total
Cut point (µm)	100	21.3	14.8	9.8	6.0	3.5	1.55	0.93	0.52	MMAD (µm)		GSD
Stage	1	2	3	4	5	6	7	8	Filter
Gravimetric
PSD 1	100	100	100	98.43	35.08	19.37	14.14	11.52	5.76		3.82	2.76
PSD 2	100	99.32	99.32	99.32	40.54	20.27	12.16	9.46	6.08		3.06	2.21
PSD 3	100	100	99.29	99.29	43.26	19.86	12.77	7.80	4.26		3.15	2.17
Mean											3.34	2.38

MMAD = Mass median aerodynamic diameter

GSD = Geometric standard deviation

Applicant's summary and conclusion

Interpretation of results:

other: Not classified in accordance with EU criteria

Conclusions:

All animals survived a single 4-hour (nose only) inhalation exposure to tin metal powder. The mean achieved aerosol concentration during the 4 hour exposure was slightly below the OECD target dose level however, this concentration is considered to be the maximum practical achievable in order to maintain a respirable aerosol.
The mass median aerodynamic diameter (MMAD) was below 4 microns and therefore the particle size distribution was within the respirable range for rats.
No treatment related adverse effects were noted during the study. Macroscopic findings were consistent with exposure to dark material within the respirable range. Microscopic evaluation demonstrated that the test article had penetrated the deep lung.
The maximum practically achievable, respirable concentration of tin metal powder was 4.75 mg/L. In the absence of adverse clinical signs or pathology findings it is considered that the LC50 is in excess of 5 mg/L. The European Union (EU) classification of inhalation risk for test articles with an LC50 of greater than 5 mg/L is ‘unclassified’.

Executive summary:

A group of male and female rats was dosed with the maximum practical dose concentration of particulate tin metal, prepared as a dust in size range of 1 -5 µm. Nose only exposure for 4 hours was followed by 14 days observation, macroscopic and microscopic investigations were completed after necropsy. The LC50 for metallic tin dust was greater than 4.75 mg/L. No signs of a toxic response were evident following inhalation exposure.