Synthetic wollastonite

Endpoint summary

Description of key information

Testing has not been carried out on Synthetic Wollastonite however acute toxicity testing via the oral and inhalation routes has been conducted on the analogue substance Kieselghur soda ash flux calcined. Testing for dermal toxicity was not considered relevant.

 Acute oral toxicity study in rats (OECD TG 420) LD50 >2000 mg/kg.  Acute inhalation toxicity study in rats (OECD TG 403) LD50 >2.6 mg/L maximum attainable dose concentration.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

The study was performed between 11 May 2010 and 15 June 2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes (incl. QA statement)

Test type:

fixed dose procedure

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories U.K. Ltd., Oxon, UK
- Age at study initiation: Eight to twelve weeks of age
- Weight at study initiation:
- Fasting period before study: Overnight fast immediately before dosing
- Housing: Housed in groups of up to four in suspended solid floor polypropylene cages furnished with woodflakes
- Diet: 2014 Teklad Global Rodent diet supplied by Harlan Laboratories U.K. Ltd., Oxon, UK ad libitum
- Water: ad libitum
- Acclimation period: At least five days

ENVIRONMENTAL CONDITIONS
- Temperature: 19 to 25°C
- Humidity: 30 to 70%
- Air changes: At least fifteen changes per hour
- Photoperiod: Lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

All animals were dosed once only by gavage, using a metal cannula attached to a graduated syringe. The volume administered to each animal was calculated according to the fasted bodyweight at the time of dosing. Treatment of animals was sequential

Doses:

300 mg/kg (preliminary study)
2000 mg/kg (main study)

No. of animals per sex per dose:

One animal treated at a dose level of 300 mg/kg and a total of five animals were treated at a dose level of 2000 mg/kg in the study

Details on study design:

Clinical observations were made ½, 1, 2, and 4 hours after dosing and then daily for fourteen days. Morbidity and mortality checks were made twice daily. Individual bodyweights were recorded on day 0 (the day of dosing) and on days 7 and 14.

Preliminary study:

Individual clinical observations and mortality data are given in Table 1. There was no mortality. No signs of systemic toxicity were noted during the observation period. Individual bodyweights and bodyweight changes are given in Table 2. The animal showed expected gains in bodyweight over the observation period. Necropsy findings are given in Table 3. No abnormalities were noted at necropsy. Based on the results at a dose level of 300 mg/kg, a dose level of 2000 mg/kg bodyweight was investigated.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

There were no deaths

Clinical signs:

other: Hunched posture was noted in all animals. Ataxia was also noted in one animal. All animals appeared normal three days after dosing. Individual clinical observations and mortality data are given in Table 4

Gross pathology:

No abnormalities were noted at necropsy. Individual necropsy findings are given in Table 6

Table 1: Individual Clinical Observations and Mortality Data -300mg/kg

Dose Level mg/kg	Animal Number and Sex	Effects Noted After Dosing (Hours)				Effects Noted During Period After Dosing (Days)
		½	1	2	4	1	2	3	4	5	6	7	8	9	10	11	12	13	14
300	1-0 Female	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0

0=     No signs of systemic toxicity

Table 2: Individual Bodyweights and Bodyweight Changes -300mg/kg

Dose Level mg/kg	Animal Number and Sex	Bodyweight (g) at Day			Bodyweight Gain (g) During Week
		0	7	14	1	2
300	1-0 Female	166	186	198	20	12

Table 3: Necropsy Findings -300 mg/kg

Dose Level mg/kg	Animal Number and Sex	Time of Death	Macroscopic Observations
300	1-0 Female	Killed Day 14	No abnormalities detected

Table 4: Individual Clinical Observations and Mortality Data -2000mg/kg

Dose Level mg/kg	Animal Number and Sex	Effects Noted After Dosing (Hours)				Effects Noted During Period After Dosing (Days)
		½	1	2	4	1	2	3	4	5	6	7	8	9	10	11	12	13	14
2000	2-0 Female	0	HA	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0
	3-0 Female	0	H	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0
	3-1 Female	0	H	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0
	3-2 Female	0	H	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0
	3-3 Female	0	H	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

A =      Ataxia

H =      Hunched posture

Table 5: Individual Bodyweights and Bodyweight Changes -2000mg/kg

Dose Level mg/kg	Animal Number and Sex	Bodyweight (g) at Day			Bodyweight Gain (g) During Week
		0	7	14	1	2
2000	2-0 Female	178	199	204	21	5
	3-0 Female	187	192	212	5	20
	3-1 Female	196	203	216	7	13
	3-2 Female	186	195	213	9	18
	3-3 Female	189	195	203	6	8

Table 6: Individual Necropsy Findings -2000mg/kg

Dose Level mg/kg	Animal Number and Sex	Time of Death	Macroscopic Observations
2000	2-0 Female	Killed Day 14	No abnormalities detected
	3-0 Female	Killed Day 14	No abnormalities detected
	3-1 Female	Killed Day 14	No abnormalities detected
	3-2 Female	Killed Day 14	No abnormalities detected
	3-3 Female	Killed Day 14	No abnormalities detected

Interpretation of results:

not classified

Conclusions:

The acute oral median lethal dose (LD50) of kieselguhr soda ash flux calcined was >2000mg/kg and is therefore not classified in accordance with CLP Regulation (EC) no. 1272/2008

Reference 2

Endpoint:

acute toxicity: oral

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

The study was performed between 11 May 2010 and 15 June 2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

The use of data derived for Soda-ash flux calcined kieselghur are justified for read-across to
synthetic wollastonite. Justification for read-across is warranted given the similarities in toxicity profile and physico-chemical properties for Soda-ash flux calcined kieselghur and synthetic wollastonite.
Considering the available data:
The source substance show no concerns for the environment.
The source substance has low acute toxicity and low toxicity in repeated dose studies, is non-irritant (skin and eye), non-sensitizing, non-mutagenic to bacteria, non-cytogenic and has low toxicity for reproductive and developmental toxicity.
Please see RAAF attached in Section 13. for further details.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

GLP compliance:

yes (incl. QA statement)

Test type:

fixed dose procedure

Species:

rat

Strain:

Wistar

Sex:

female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories U.K. Ltd., Oxon, UK
- Age at study initiation: Eight to twelve weeks of age
- Weight at study initiation:
- Fasting period before study: Overnight fast immediately before dosing
- Housing: Housed in groups of up to four in suspended solid floor polypropylene cages furnished with woodflakes
- Diet: 2014 Teklad Global Rodent diet supplied by Harlan Laboratories U.K. Ltd., Oxon, UK ad libitum
- Water: ad libitum
- Acclimation period: At least five days

ENVIRONMENTAL CONDITIONS
- Temperature: 19 to 25°C
- Humidity: 30 to 70%
- Air changes: At least fifteen changes per hour
- Photoperiod: Lighting was controlled by a time switch to give twelve hours continuous light (06:00 to 18:00) and twelve hours darkness

Route of administration:

oral: gavage

Vehicle:

arachis oil

Details on oral exposure:

All animals were dosed once only by gavage, using a metal cannula attached to a graduated syringe. The volume administered to each animal was calculated according to the fasted bodyweight at the time of dosing. Treatment of animals was sequential

Doses:

300 mg/kg (preliminary study)
2000 mg/kg (main study)

No. of animals per sex per dose:

One animal treated at a dose level of 300 mg/kg and a total of five animals were treated at a dose level of 2000 mg/kg in the study

Details on study design:

Clinical observations were made ½, 1, 2, and 4 hours after dosing and then daily for fourteen days. Morbidity and mortality checks were made twice daily. Individual bodyweights were recorded on day 0 (the day of dosing) and on days 7 and 14.

Preliminary study:

Individual clinical observations and mortality data are given in Table 1. There was no mortality. No signs of systemic toxicity were noted during the observation period. Individual bodyweights and bodyweight changes are given in Table 2. The animal showed expected gains in bodyweight over the observation period. Necropsy findings are given in Table 3. No abnormalities were noted at necropsy. Based on the results at a dose level of 300 mg/kg, a dose level of 2000 mg/kg bodyweight was investigated.

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 2 000 mg/kg bw

Based on:

test mat.

Mortality:

There were no deaths

Clinical signs:

other: Hunched posture was noted in all animals. Ataxia was also noted in one animal. All animals appeared normal three days after dosing. Individual clinical observations and mortality data are given in Table 4

Gross pathology:

No abnormalities were noted at necropsy. Individual necropsy findings are given in Table 6

Table 1: Individual Clinical Observations and Mortality Data -300mg/kg

Dose Level mg/kg	Animal Number and Sex	Effects Noted After Dosing (Hours)				Effects Noted During Period After Dosing (Days)
		½	1	2	4	1	2	3	4	5	6	7	8	9	10	11	12	13	14
300	1-0 Female	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0

0=     No signs of systemic toxicity

Table 2: Individual Bodyweights and Bodyweight Changes -300mg/kg

Dose Level mg/kg	Animal Number and Sex	Bodyweight (g) at Day			Bodyweight Gain (g) During Week
		0	7	14	1	2
300	1-0 Female	166	186	198	20	12

Table 3: Necropsy Findings -300 mg/kg

Dose Level mg/kg	Animal Number and Sex	Time of Death	Macroscopic Observations
300	1-0 Female	Killed Day 14	No abnormalities detected

Table 4: Individual Clinical Observations and Mortality Data -2000mg/kg

Dose Level mg/kg	Animal Number and Sex	Effects Noted After Dosing (Hours)				Effects Noted During Period After Dosing (Days)
		½	1	2	4	1	2	3	4	5	6	7	8	9	10	11	12	13	14
2000	2-0 Female	0	HA	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0
	3-0 Female	0	H	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0
	3-1 Female	0	H	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0
	3-2 Female	0	H	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0
	3-3 Female	0	H	H	H	H	H	0	0	0	0	0	0	0	0	0	0	0	0

0=      No signs of systemic toxicity

A =      Ataxia

H =      Hunched posture

Table 5: Individual Bodyweights and Bodyweight Changes -2000mg/kg

Dose Level mg/kg	Animal Number and Sex	Bodyweight (g) at Day			Bodyweight Gain (g) During Week
		0	7	14	1	2
2000	2-0 Female	178	199	204	21	5
	3-0 Female	187	192	212	5	20
	3-1 Female	196	203	216	7	13
	3-2 Female	186	195	213	9	18
	3-3 Female	189	195	203	6	8

Table 6: Individual Necropsy Findings -2000mg/kg

Dose Level mg/kg	Animal Number and Sex	Time of Death	Macroscopic Observations
2000	2-0 Female	Killed Day 14	No abnormalities detected
	3-0 Female	Killed Day 14	No abnormalities detected
	3-1 Female	Killed Day 14	No abnormalities detected
	3-2 Female	Killed Day 14	No abnormalities detected
	3-3 Female	Killed Day 14	No abnormalities detected

Interpretation of results:

not classified

Conclusions:

The acute oral median lethal dose (LD50) of the analogue substance kieselguhr soda ash flux calcined was >2000mg/kg and is therefore not classified in accordance with CLP Regulation (EC) no. 1272/2008.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Reference 1

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12-Apr-2010 - 26-Apr-2010

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes (incl. QA statement)

Test type:

fixed concentration procedure

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories B.V. Kreuzelweg 53 5961 NM Horst / Netherlands
- Age at study initiation: Males: 8 weeks; Females: 9 weeks
- Weight at study initiation: Males: 263.9 to 284.3 g ;Females: 182.6 to 198.0 g
- Fasting period before study:
- Housing: Animals were housed in groups of 5 of the same sex in Makrolon® type-IV cages with wire mesh tops and standard softwood bedding
- Diet: Animals had ad libitum access to a pelleted standard Harlan Teklad 2914C rat maintenance diet ( except during the period when the animalsand) batch no. were restrained in exposure tubes.
- Water: Community tap water from Füllinsdorf ad libitum in water bottles, except during the period when they were restrained in exposure tubes
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature : 22 ± 3 °C,
- Humidity: 30 - 70%
- Air changes: 10 - 15 air changes per hour
- Photoperiod 12 hour fluorescent light / 12 hour dark cycle:

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Inhalation exposure was performed using a flow-past, nose-only exposure system.
- Method of holding animals in test chamber: The animals were confined separately in restraint tubes which were positioned radially around the exposure chamber.
- Source and rate of air: The exposure system ensured a uniform distribution and provided a constant flow of test material to each exposure tube. The flow of air at each tube was 1.0 L/min.
- System of generating particulates/aerosols: A dust aerosol was generated from the test item using a CR 3020 rotating brush aerosol generator connected to a micronizing jet mill. The aerosol generated was then discharged into the exposure chamber through a 63Ni charge neutralizer
- Method of particle size determination: The particle size distribution of the test aerosol was determined three times during exposure using a 7 stage Mercer cascade Impactor (Model 02-130, In-Tox. Products Inc., Albuquerque, New Mexico, U.S.A.). The particle size distribution was measured by gravimetrically analyzing the test item deposited on each stage of the cascade impactor. Mass Median Aerodynamic Diameters (MMAD) and Geometric Standard Deviations (GSD) were calculated on the basis of the results from the impactor, using Microsoft Excel Software . The target range was 1 to 4 μm for the MMAD and between 1.5 and 3 for the GSD.
- Temperature, humidity, pressure in air chamber: The temperature and relative humidity of the test atmosphere was measured continuously during
exposure using a calibrated device. The results were recorded manually and are reported at 30 minute intervals from the start of exposure and additionally at the end of exposure The actual airflow rate through the exposure chamber was recorded at approximately 30 minute intervals from the start of the inhalation exposure.




TEST ATMOSPHERE
- Particle size distribution: Particle size distribution data are presented in table 4
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): MMAD and GSD data are presented in tables 2 and3

Duration of exposure:

4 h

Concentrations:

The mean gravimetric aerosol concentration determined was 2.7 mg/L air
The nominal aerosol concentration was 20.4 mg/L air.

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Observations for viability were recorded once before exposure on the day of exposure (test day
1), three times during exposure, immediately and 1 h after exposure on test day 1 and twice daily during the observation period. Observations for clinical signs was examined three times during exposure, immediately and 1 h after exposure on test day 1 and once daily during the observation period.The body weight of each animal was recorded on test days 1 (before exposure), 2, 4, 8 and 15 (before necropsy).
- Necropsy of survivors performed: yes

Statistics:

No statistical analysis was performed as only one group was allocated to the study

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.6 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

All animals survived the scheduled observation period

Clinical signs:

other: Moderately ruffled fur was noted in all animals on test day 1 after the end of the exposure and persisted with a reduced severity degree until test day 2. In addition, a slightly scabbed nose was recorded in all animals on test day 1 after the end of the

Body weight:

From test day 1 to test day 2, marginal to slight body weight loss was noted in five males and four females. Thereafter normal body weight development was recorded in these animals. Marginal body weight loss or stagnation of the body weight gain is not unusual in inhalation studies. Therefore, effects on the body weight were considered to be mainly due to the restraining of the animals in the tubes during the nose-only exposure procedure and not related to treatment with the test item. However, a contribution of a test-item related effect cannot be excluded completely.

Gross pathology:

No macroscopic findings were present at necropsy

Test atmosphere conditions:

Temperature, relative humidity and oxygen concentration during exposure were considered to be satisfactory for this type of study. Data on temperature, relative humidity and oxygen concentration are presented in table 1.

Table 1: Temperature, relative humidity and oxygen concentration

Recording time[hours:min]	O2 concentration [Vol %]	Temperature [°C]	Relative humidity [% RH]
06:30	20.6	22.2	9.2
07:00	20.6	22.3	5.6
07:30	20.7	22.4	5.4
08:00	20.6	22.3	5.7
08:30	20.7	22.3	5.5
09:00	20.6	22.3	5.5
09:30	20.6	22.4	7.2
10:00	20.6	22.3	5.0
10:30	20.7	22.3	5.2
10:39	20.6	22.3	5.1
Mean St. Dev N	20.6 0.0 10	22.3 0.1 10	5.9 1.3 10

Gravimetric determination of aerosol concentrations:

The mean gravimetric aerosol concentration determined was 2.7 mg/L air. The aerosol concentration was in general stable during the exposure period. Data on gravimetric aerosol concentrations are presented in table 2.

Table 2: Gravimetric determination of aerosol concentrations

Sampling time [hours:min]	Sampling volume [L]	Amount of test item on the filter [mg]	Gravimetric aerosol concentration [mg/L air]
06:40 – 06:45	4.9	9.592	2.0
06:50 – 06:55	4.9	14.728	3.0
07:40 – 07:45	4.9	14.220	2.9
08:40 – 08:45	4.9	13.151	2.7
09:43 – 09:48	4.9	14.605	3.0
Mean St. Dev N			2.7 0.4 5

Chemical determination of aerosol concentrations:

The chemically determined aerosol concentration was in general stable during the exposure period. Only one single value at the beginning of the aerosol generation was lower. The remainder of the values were close to the technical limit of approximately 3 mg/L as targeted. The chemical aerosol concentration compared favourably to the gravimetrically determined concentration. This was in accordance with the high purity of the test item. Details on chemically determined aerosol concentrations are presented in table 3.

Table 3: Chemical determination of aerosol concentrations

Sampling time [hours:min]	Sampling volume [L]	Amount of test item on the filter [mg]	Gravimetric aerosol concentration [mg/L air]
06:40 – 06:45	4.9	9.135	1.9
06:50 – 06:55	4.9	13.93	2.9
07:40 – 07:45	4.9	13.60	2.8
08:40 – 08:45	4.9	12.70	2.6
09:43 – 09:48	4.9	14.13	2.9
Mean St. Dev N			2.6 0.4 5

Particle size distribution:

The Mass Median Aerodynamic Diameters (MMAD) obtained from tree gravimetric measurements of particle size distribution during the exposure were similar (MMAD between 2.39 and 2.95 μm). This led to the conclusion that the particle size of the generated aerosol was fairly stable during the whole exposure period. The MMADs were well within the target range of 1 to 4 μm, thus deposition of the particles can be assumed to have occurred in both the upper and the lower respiratory tract. In addition, the Geometric Standard Deviations (GSD) were within the target range of 1.5 to 3. Hence, the particle size distributions obtained were considered to be appropriate for acute inhalation toxicity testing. Data on particle size distribution are presented in table 4.

Table 4: Particle size distribution

Time	Total amount collected [µg]									MMAD [µm]	GSD	Corr.Coeff (R )	% < 4 µm
		1 --	2 4.6	3 3.0	4 2.13	5 1.6	6 1.06	7 0.715	8 0.325
06:58	1487	19.4	30.3	16.6	13.4	9.8	7.5	0.8	2.2	2.75	2.32	0.964	67.2
07:42	1919	23.4	27.6	16.1	16.3	7.7	4.7	1.4	2.9	2.95	2.47	0.957	63.2
08:42	828	13.9	32.7	16.5	11.6	6.6	12.6	3.7	2.3	2.39	2.35	0.973	72.8

Interpretation of results:

not classified

Conclusions:

In conclusion, the LC50 of Soda-ash flux-calcined kieselguhr obtained in this study was estimated to be greater than 2.6 mg/L air (chemically determined mean aerosol concentration). As the study was conducted up to the maximum attainable concentration and in accordance with Regulation (EC) No. 1272/2008 (EU CLP) the substance is not considered to be classified.

Reference 2

Endpoint:

acute toxicity: inhalation

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

12-Apr-2010 - 26-Apr-2010

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

The use of data derived for Soda-ash flux calcined kieselghur are justified for read-across to
synthetic wollastonite. Justification for read-across is warranted given the similarities in toxicity profile and physico-chemical properties for Soda-ash flux calcined kieselghur and synthetic wollastonite.
Considering the available data:
The source substance show no concerns for the environment.
The source substance has low acute toxicity and low toxicity in repeated dose studies, is non-irritant (skin and eye), non-sensitizing, non-mutagenic to bacteria, non-cytogenic and has low toxicity for reproductive and developmental toxicity.
Please see RAAF attached in Section 13. for further details.

Reason / purpose for cross-reference:

read-across source

Qualifier:

according to guideline

Guideline:

OECD Guideline 403 (Acute Inhalation Toxicity)

GLP compliance:

yes (incl. QA statement)

Test type:

fixed concentration procedure

Species:

rat

Strain:

Wistar

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories B.V. Kreuzelweg 53 5961 NM Horst / Netherlands
- Age at study initiation: Males: 8 weeks; Females: 9 weeks
- Weight at study initiation: Males: 263.9 to 284.3 g ;Females: 182.6 to 198.0 g
- Fasting period before study:
- Housing: Animals were housed in groups of 5 of the same sex in Makrolon® type-IV cages with wire mesh tops and standard softwood bedding
- Diet: Animals had ad libitum access to a pelleted standard Harlan Teklad 2914C rat maintenance diet ( except during the period when the animalsand) batch no. were restrained in exposure tubes.
- Water: Community tap water from Füllinsdorf ad libitum in water bottles, except during the period when they were restrained in exposure tubes
- Acclimation period: 5 days

ENVIRONMENTAL CONDITIONS
- Temperature : 22 ± 3 °C,
- Humidity: 30 - 70%
- Air changes: 10 - 15 air changes per hour
- Photoperiod 12 hour fluorescent light / 12 hour dark cycle:

Route of administration:

inhalation: aerosol

Type of inhalation exposure:

nose only

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: Inhalation exposure was performed using a flow-past, nose-only exposure system.
- Method of holding animals in test chamber: The animals were confined separately in restraint tubes which were positioned radially around the exposure chamber.
- Source and rate of air: The exposure system ensured a uniform distribution and provided a constant flow of test material to each exposure tube. The flow of air at each tube was 1.0 L/min.
- System of generating particulates/aerosols: A dust aerosol was generated from the test item using a CR 3020 rotating brush aerosol generator connected to a micronizing jet mill. The aerosol generated was then discharged into the exposure chamber through a 63Ni charge neutralizer
- Method of particle size determination: The particle size distribution of the test aerosol was determined three times during exposure using a 7 stage Mercer cascade Impactor (Model 02-130, In-Tox. Products Inc., Albuquerque, New Mexico, U.S.A.). The particle size distribution was measured by gravimetrically analyzing the test item deposited on each stage of the cascade impactor. Mass Median Aerodynamic Diameters (MMAD) and Geometric Standard Deviations (GSD) were calculated on the basis of the results from the impactor, using Microsoft Excel Software . The target range was 1 to 4 μm for the MMAD and between 1.5 and 3 for the GSD.
- Temperature, humidity, pressure in air chamber: The temperature and relative humidity of the test atmosphere was measured continuously during
exposure using a calibrated device. The results were recorded manually and are reported at 30 minute intervals from the start of exposure and additionally at the end of exposure The actual airflow rate through the exposure chamber was recorded at approximately 30 minute intervals from the start of the inhalation exposure.




TEST ATMOSPHERE
- Particle size distribution: Particle size distribution data are presented in table 4
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): MMAD and GSD data are presented in tables 2 and3

Duration of exposure:

4 h

Concentrations:

The mean gravimetric aerosol concentration determined was 2.7 mg/L air
The nominal aerosol concentration was 20.4 mg/L air.

No. of animals per sex per dose:

5 males and 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations and weighing: Observations for viability were recorded once before exposure on the day of exposure (test day
1), three times during exposure, immediately and 1 h after exposure on test day 1 and twice daily during the observation period. Observations for clinical signs was examined three times during exposure, immediately and 1 h after exposure on test day 1 and once daily during the observation period.The body weight of each animal was recorded on test days 1 (before exposure), 2, 4, 8 and 15 (before necropsy).
- Necropsy of survivors performed: yes

Statistics:

No statistical analysis was performed as only one group was allocated to the study

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 2.6 mg/L air

Based on:

test mat.

Exp. duration:

4 h

Mortality:

All animals survived the scheduled observation period

Clinical signs:

other: Moderately ruffled fur was noted in all animals on test day 1 after the end of the exposure and persisted with a reduced severity degree until test day 2. In addition, a slightly scabbed nose was recorded in all animals on test day 1 after the end of the

Body weight:

From test day 1 to test day 2, marginal to slight body weight loss was noted in five males and four females. Thereafter normal body weight development was recorded in these animals. Marginal body weight loss or stagnation of the body weight gain is not unusual in inhalation studies. Therefore, effects on the body weight were considered to be mainly due to the restraining of the animals in the tubes during the nose-only exposure procedure and not related to treatment with the test item. However, a contribution of a test-item related effect cannot be excluded completely.

Gross pathology:

No macroscopic findings were present at necropsy

Test atmosphere conditions:

Temperature, relative humidity and oxygen concentration during exposure were considered to be satisfactory for this type of study. Data on temperature, relative humidity and oxygen concentration are presented in table 1.

Table 1: Temperature, relative humidity and oxygen concentration

Recording time[hours:min]	O2 concentration [Vol %]	Temperature [°C]	Relative humidity [% RH]
06:30	20.6	22.2	9.2
07:00	20.6	22.3	5.6
07:30	20.7	22.4	5.4
08:00	20.6	22.3	5.7
08:30	20.7	22.3	5.5
09:00	20.6	22.3	5.5
09:30	20.6	22.4	7.2
10:00	20.6	22.3	5.0
10:30	20.7	22.3	5.2
10:39	20.6	22.3	5.1
Mean St. Dev N	20.6 0.0 10	22.3 0.1 10	5.9 1.3 10

Gravimetric determination of aerosol concentrations:

The mean gravimetric aerosol concentration determined was 2.7 mg/L air. The aerosol concentration was in general stable during the exposure period. Data on gravimetric aerosol concentrations are presented in table 2.

Table 2: Gravimetric determination of aerosol concentrations

Sampling time [hours:min]	Sampling volume [L]	Amount of test item on the filter [mg]	Gravimetric aerosol concentration [mg/L air]
06:40 – 06:45	4.9	9.592	2.0
06:50 – 06:55	4.9	14.728	3.0
07:40 – 07:45	4.9	14.220	2.9
08:40 – 08:45	4.9	13.151	2.7
09:43 – 09:48	4.9	14.605	3.0
Mean St. Dev N			2.7 0.4 5

Chemical determination of aerosol concentrations:

The chemically determined aerosol concentration was in general stable during the exposure period. Only one single value at the beginning of the aerosol generation was lower. The remainder of the values were close to the technical limit of approximately 3 mg/L as targeted. The chemical aerosol concentration compared favourably to the gravimetrically determined concentration. This was in accordance with the high purity of the test item. Details on chemically determined aerosol concentrations are presented in table 3.

Table 3: Chemical determination of aerosol concentrations

Sampling time [hours:min]	Sampling volume [L]	Amount of test item on the filter [mg]	Gravimetric aerosol concentration [mg/L air]
06:40 – 06:45	4.9	9.135	1.9
06:50 – 06:55	4.9	13.93	2.9
07:40 – 07:45	4.9	13.60	2.8
08:40 – 08:45	4.9	12.70	2.6
09:43 – 09:48	4.9	14.13	2.9
Mean St. Dev N			2.6 0.4 5

Particle size distribution:

The Mass Median Aerodynamic Diameters (MMAD) obtained from tree gravimetric measurements of particle size distribution during the exposure were similar (MMAD between 2.39 and 2.95 μm). This led to the conclusion that the particle size of the generated aerosol was fairly stable during the whole exposure period. The MMADs were well within the target range of 1 to 4 μm, thus deposition of the particles can be assumed to have occurred in both the upper and the lower respiratory tract. In addition, the Geometric Standard Deviations (GSD) were within the target range of 1.5 to 3. Hence, the particle size distributions obtained were considered to be appropriate for acute inhalation toxicity testing. Data on particle size distribution are presented in table 4.

Table 4: Particle size distribution

Time	Total amount collected [µg]									MMAD [µm]	GSD	Corr.Coeff (R )	% < 4 µm
		1 --	2 4.6	3 3.0	4 2.13	5 1.6	6 1.06	7 0.715	8 0.325
06:58	1487	19.4	30.3	16.6	13.4	9.8	7.5	0.8	2.2	2.75	2.32	0.964	67.2
07:42	1919	23.4	27.6	16.1	16.3	7.7	4.7	1.4	2.9	2.95	2.47	0.957	63.2
08:42	828	13.9	32.7	16.5	11.6	6.6	12.6	3.7	2.3	2.39	2.35	0.973	72.8

Interpretation of results:

not classified

Conclusions:

In conclusion, the LC50 of of the analogue substance Soda-ash flux-calcined kieselguhr obtained in this study was estimated to be greater than 2.6 mg/L air (chemically determined mean aerosol concentration). As the study was conducted up to the maximum attainable concentration and in accordance with Regulation (EC) No. 1272/2008 (EU CLP) the substance is not considered to be classified.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

2.6 mg/m³ air

Acute toxicity: via dermal route

Link to relevant study records

Reference

Endpoint:

acute toxicity: dermal

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

the study does not need to be conducted because skin contact in production and/or use is not likely

the study does not need to be conducted because the substance does not meet the criteria for classification as acute toxicity or STOT SE by the oral route and no systemic effects have been observed in in vivo studies with dermal exposure (e.g. skin irritation, skin sensitisation)

Justification for type of information:

In accordance with column 2 of Annex VIII section 8.5.3 of REACH Regulation 1907/2006 testing by the dermal route is appropriate if 1) inhalation of the substance is unlikely, 2) skin contact in production and use is likely and 3) the physicochemical and toxicological properties suggest potential for a significant rate of absorption.

Inhalation of Synthetic wollastonite is expected to be the primary route of exposure. An acute inhalation study has been performed on the read-across material Kieselguhr soda ash flux-calcined. As Synthetic wollastonite and Kieselguhr soda ash flux-calcined follow the same exposure routes an acute dermal study was not considered to be necessary. The physiological properties of the substance do not suggest a significant rate of absorption through the skin and no systemic effects or other evidence of absorption were seen in the skin or eye irritation studies. Furthermore the test substance is poorly soluble in water and therefore a limited amount of potential substance is available for absorption via the dermal route. On this basis the short term toxicity test via the dermal route is considered to be scientifically unjustified

Reason / purpose for cross-reference:

data waiving: supporting information

Reason / purpose for cross-reference:

data waiving: supporting information

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Read-Across Justification of oral and inhalation routes

Synthetic wollastonite is a UVCB substance, the main constituents of which are amorphous in nature. It also contains crystalline silica. The percentage of crystalline silica may range up to 1.5% (<=0.21% respirable). The acute toxicity information has been read-across from the analogue substance Kieselguhr, soda ash flux-calcined. The analogue has been chosen for its similarity in structure and properties to Synthetic wollastonite. The main difference in structure between Synthetic wollastonite and Kieselguhr, soda ash flux-calcined is the presence of a calcium ion in Synthetic wollastonite. It is clear from a number of studies carried out on amorphous and crystalline silica and the analogue substance Silicic acid, calcium salt that results were consistent between the two substances and that there was no effect from the presence of the calcium ion. Moreover, it is well documented that these substances have a low potential for hazard to health and the environment. 

The toxicological properties via the oral and inhalation route of both forms are well described and may be used to predict the effects of exposure to Synthetic wollastonite via both the oral and inhalation routes, and to support the available data for this substance.

Acute oral:

In the key study (Bradshaw 2010) oral toxicity was assessed using the fixed dose procedure. Following a sighting test at dose levels of 300 mg/kg and 2000 mg/kg, a further group of four fasted females was given a single oral dose of test material, as a suspension in arachis oil BP, at a dose level of 2000 mg/kg bodyweight. Clinical signs and bodyweight development were monitored during the study. All animals were subjected to gross necropsy. The acute oral median lethal dose (LD₅₀) of the test material in the female Wistar strain rat was estimated to be greater than 2000mg/kg bodyweight.

 

Acute dermal:

No acute dermal toxicity studies have been performed.The physiological properties of the substance do not suggest a significant rate of absorption through the skin and no systemic effects or other evidence of absorption were seen in the skin or eye irritation studies. Furthermore the test substance is poorly soluble in water and therefore a limited amount of potential substance is available for absorption via the dermal route

 

Acute inhalation:

In the key study (Schuler 2010) a group of five male and five female albino rats was exposed by nose only, flow-past inhalation for four hours to the test item at a chemically determined mean concentration of 2.6 mg/L. All animals were observed for clinical signs and mortality and 14 days post exposure. The LC50 of soda-ash flux-calcined kieselguhr obtained in this study was estimated to be greater than 2.6 mg/L air (chemically determined mean aerosol concentration). This was the highest technically achievable concentration.

Justification for classification or non-classification

Acute toxicity: oral: The acute oral median dose (LD50) of kieselguhr soda ash flux calcined is greater than 2000 mg/kg bw and it is therefore not classified according to CLP Regulation (EC) No 1272/2008.

Acute toxicity: inhalation:The acute inhalation median concentration (LC50) of kieselguhr soda ash flux calcined was estimated to be greater than 2.7 mg/L. The result was achieved at the maximum attainable concentration and is considered to be equivalent to a limit test conducted at 5 mg/L and therefore kieselguhr soda ash flux calcined is not considered to be classified according to CLP Regulation (EC) No 1272/2008.

Based on the results of testing on the analogue substance Kieselghur soda ash fkux calcined, the test substance Synthetic Wollastonite can be considered to be not classified for acute toxicity via the oral and inhalation routes.