Cobalt sulphide

Endpoint summary

Description of key information

Acute oral toxicity:
LD50(rat)> 5000 mg cobalt sulphide/kg bw

Acute inhalation toxicity:
LC50 (4h, rat)> 5.09 mg cobalt sulphide/L air

Acute dermal toxicity:
Conduct of an acute dermal toxicity study for cobalt sulphide is unjustified since dermal uptake is considered negligible.

Key value for chemical safety assessment

Acute toxicity: via oral route

Link to relevant study records

Reference

Endpoint:

acute toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Remarks:

- The purity and stability of the test material were not stated. Minor deviations with no effect on the study results: -According to the guideline, the volume administered to the animals should not exceed 1ml/100 g bw. The information on the volume administered was missing in the study report. -According to the guideline, the diet and environmental conditions shoud be stated in the test report. This information was missing in this report.

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 401 (Acute Oral Toxicity)

Deviations:

yes

Remarks:

see rationale for reliability

GLP compliance:

yes

Test type:

standard acute method

Limit test:

yes

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Breeding Laboratories, Inc., Wilmington, MA
- Weight at study initiation: Males 215- 253 g; females 182 - 219 g
- Fasting period before study: Food was withheld the night prior to dosing.
- Housing: Rats were individually housed in wire mesh bottom cages
- Diet: ad libitum
- Water: ad libitum
- Acclimation period: At least 5 days

ENVIRONMENTAL CONDITIONS
Rats were held in environmentally controlled rooms.
No further information on the test animals was stated.

Route of administration:

oral: gavage

Vehicle:

corn oil

Details on oral exposure:

VEHICLE
- Concentration prepared: 50 % suspension
PREPARATION PROCEDURE: Weighed 12.5 g test article Q.S. to 25 ml with corn oil (suspension). The test article was administered at a constant concentration.
No further information on the oral exposure was stated.

Doses:

5000 mg/kg

No. of animals per sex per dose:

5 males / 5 females

Control animals:

no

Details on study design:

- Duration of observation period following administration: 15 days
- Frequency of observations and weighing:Animals were observed frequently on the day of dosing and twice daily thereafter. Body weights were recorded initially (prior to dosing), on days 8 and 15 or at death.
- Necropsy of survivors performed: Yes
All animals that died during the study and those sacrificed at termination were subjected to a gross necropsy and abnormalities were noted.
No further information on the study design was stated.

Statistics:

not required

Sex:

male/female

Dose descriptor:

LD50

Effect level:

> 5 000 mg/kg bw

Based on:

test mat.

Mortality:

no mortalities occured

Clinical signs:

other: All animals appeared normal throughout the observation period.

Gross pathology:

No remarkable visceral findings were noted at necropsy.

Interpretation of results:

GHS criteria not met

Conclusions:

The LD50 (male and females rats) for cobalt sulfide is:
LD50 (male and females rats) > 5000 mg/kg
According to the EC Regulation No. 1272/2008 and subsequent regulations, the test item is not classified.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via inhalation route

Link to relevant study records

Reference

Endpoint:

acute toxicity: inhalation

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-01-25 to 2011-03-31

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The minor deviations from the guidline do not effect the reliability of the study.

Qualifier:

according to guideline

Guideline:

OECD Guideline 436 (Acute Inhalation Toxicity: Acute Toxic Class Method)

Version / remarks:

2009

Deviations:

yes

Remarks:

The demanded values of MMAD= 1-4 µm & GSD= 1.5-3.0 were slightly exceeded: MMAD: 4.004, 4.418; GSD: 3.51, 3.58. The rationale for selecting the test concentration was not stated.

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2009-11-17

Test type:

acute toxic class method

Limit test:

yes

Specific details on test material used for the study:

Particle size parameter were determined with a CILAS 715 (non-GLP determination): d(0.1) = 4.86 μm; d(0.5) = 33.85 μm (median); d(0.9) = 89.28 μm

Species:

rat

Strain:

Sprague-Dawley

Remarks:

Crl: CD(SD)

Sex:

male/female

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Charles River Laboratories, Research Models and Services, Germany GmbH, Sandhofer Weg 7, 97633 Sulzfeld, Germany
- Females nulliparous and non-pregnant: not specified
- Age at study initiation: males: approx. 8 weeks, females: approx. 9 weeks
- Weight at study initiation: males: 240 - 268 g, females: 217 - 236 g
- Fasting period before study: 16 h
- Housing: groups of 2 - 3 animals by sex in MAKROLON cages (type III plus); bedding material: granulated textured wood (Granulat A2, J. Brandenburg, 49424 Goldenstedt, Germany)
- Historical data: not stated
- Diet: ad libitum, ssniff® R/M-H V1534 (ssniff Spezialdiäten GmbH, 59494 Soest, Germany)
- Water: tap water ad libitum
- Acclimation period: at least 5 days. The animals were acclimatised to the test apparatus for approx. 1 hour on 2 days prior to testing. The restraining tubes did not impose undue physical, thermal or immobilization stress on the animals.


ENVIRONMENTAL CONDITIONS
- Temperature: 22 °C ± 3 °C
- Humidity: 55 % ± 15 %
- Air changes: 12/h
- Photoperiod (hrs dark / hrs light): 12/12 (150 lux at approx. 1.50 m room height)

Route of administration:

inhalation: dust

Type of inhalation exposure:

nose only

Vehicle:

clean air

Mass median aerodynamic diameter (MMAD):

>= 4.004 - <= 4.418 µm

Geometric standard deviation (GSD):

>= 3.51 - <= 3.58

Remark on MMAD/GSD:

The mass median aerodynamic diameter (MMAD) was determined as 4.004 μm (main study) or 4.418 μm (satellite animals). The Geometric Standard Deviations (GSD) of the MMAD were calculated as 3.51 (main study) or 3.58 (satellite animals). No smaller MMASs or GSDs could be obtained with the test item supplied.

Details on inhalation exposure:

GENERATION OF TEST ATMOSPHERE / CHAMBER DESCRIPTION
- Exposure apparatus: dynamic inhalation apparatus (RHEMA-LABORTECHNIK, 65719 Hofheim/Taunus, Germany) (air changes/h (≥ 12 times)) with a nose-only exposure of the animals according to KIMMERLE & TEPPER.
- Exposure chamber volume: 40 L
- Method of holding animals in test chamber: the animals were hold in pyrex tubes in a way that the animals’ noses were placed at the edge of the chamber in a radial position.
- Source and rate of air (airflow): entrance: 900 L/h; exit: 800 L/h; air changes: 22.5/h. At the bottom of the exposure chamber, the air was sucked off at a lower flow rate than it was created by the dust generator in order to produce a homogenous distribution and a positive pressure in the exposure chamber. A manometer and an air-flow meter (ROTA Yokogawa GmbH & Co. KG, 79664 Wehr/Baden, Germany) were used to control the constant supply of compressed air and the exhaust, respectively. Flow rates were checked hourly and corrected if necessary.
- Method of conditioning air: The generator was fed with compressed air (5.0 bar) from a compressor (ALUP Kompressorenfabrik, 73257 Köngen, Germany). The air was taken from the surrounding atmosphere of the laboratory room and filtered using an in-line disposable gas-filter.
- System of generating particulates/aerosols: rotating brush dust generator (RBG 1000, PALAS GmbH Partikel und Lasermesstechnik, 76229 Karlsruhe, Germany).
- Method of particle size determination: particle size distribution was determined twice daily by a cascade impactor according to MAY (MAY, K. R. Aerosol impaction jets, J.Aerosol Sci. U6U, 403 (1975), RESEARCH ENGINEERS Ltd., London N1 5RD, UK).
The dust from the exposure chamber was drawn through the cascade impactor for 5 minutes at a constant flow rate of 5 L/min. The slides were removed from the impactor and weighed on an analytical balance (SARTORIUS, type 1601 004, precision 0.1 mg). Deltas of slides’ weight were determined.
The mass median aerodynamic diameter (MMAD) was estimated by means of nonlinear regression analysis. The 32 μm particle size range and the filter (particle size range < 0.5 μm) were not included in the determination of the MMAD in order not to give undue weight to these values.
The Geometric Standard Deviation (GSD) of the MMAD was calculated from the quotient of the 84.1%- and the 50%-mass fractions, both obtained from the above mentioned non-linear regression analysis.
In addition, a sample of approx. 10 g test material was taken from the exposure chamber to determine the median physical particulate size with a CILAS 715 by My- Tec, 91325 Adelsdorf, Germany. This determination was non-GLP.
- Treatment of exhaust air: the exhaust air was drawn through gas wash-bottles.
- Temperature, humidity: Temperature (20.5°C ± 0.1°C (main study) or 20.1°C ± 0.1°C (satellite group)) and humidity (60.8% ± 0.1% (main study) or 60.5% ± 0.1% (satellite group)) were measured once every hour with a climate control monitor (testo 175-HZ data logger).
- Oxygen, carbon dioxide: The oxygen content in the inhalation chamber was 21%. It was determined at the beginning and at the end of the exposure with a DRÄGER Oxygen-analysis test set (DRÄGER Tube Oxygen 67 28 081). Carbon dioxide concentration did not exceed 1%.


TEST ATMOSPHERE
- Brief description of analytical method and equipment used: the actual dust concentration in the inhalation chamber was measured gravimetrically with an air sample filter (Minisart SM 17598 0.45 μm) and pump (Vacuubrand, MZ 2C7) controlled by a rotameter. A probe was placed close to the animals' noses and air was drawn through the air sample filter at a constant flow of air of 5 L/min for 1 minute. The filters were weighed before and after sampling (accuracy 0.1 mg).
- Samples taken from breathing zone: yes, once every hour during the exposure
- Time needed for equilibrium of exposure concentration before animal exposure: 15 min. (t95 approximately 8 min.)


TEST ATMOSPHERE (if not tabulated)
- Particle size distribution: d(0.1) = 4.86 μm; d(0.5) = 33.85 μm (median); d(0.9) = 89.28 μm
- MMAD (Mass median aerodynamic diameter) / GSD (Geometric st. dev.): main study: MMAD: 4.004 µm, GSD: 3.51; satellite study: MMAD: 4.418 µm, GSD: 3.58.

Analytical verification of test atmosphere concentrations:

yes

Remarks:

see above `Details on inhalation exposure´

Duration of exposure:

4 h

Remarks on duration:

Exposition started by locating the animals’ noses into the exposure chamber after equilibration of the chamber concentration for at least 15 minutes.

Concentrations:

5.09 mg/L (main study);
5.09 mg/L (satellite study)

No. of animals per sex per dose:

3 males and 3 females (main study); 3 males and 3 females (satellite study)

Control animals:

no

Details on study design:

- Duration of observation period following administration: 14 days
- Frequency of observations: During and following exposure, observations were made and recorded systematically; individual records were maintained for each animal. Careful clinical examinations were made at least twice daily until all symptoms subsided, thereafter each working day. Observations on mortality were made at least once daily (in the morning starting on test day 2).
- Frequency of weighing: Individual weights of animals were determined once during the acclimatisation period, before and after the exposure on test day 1, on test days 3, 8 and 15.
- Necropsy of survivors performed: yes
- Examinations performed:
Cageside observations included, but were not limited to: changes in the skin and fur, eyes, mucous membranes, respiratory, circulatory, autonomic and central nervous system, somatomotor activity and behaviour patter, observation of tremor, convulsions, salivation, diarrhoea, lethargy, sleep and coma and indications of respiratory irritation such as dyspnoea, rhinitis etc.

Changes in weight were calculated and recorded when survival exceeded one day.

Necropsy of all main study and satellite animals (3 + 3 males and 3+3 females) was carried out and all gross pathological changes were recorded.

Histophatology: All animals were subjected to the same level of histopathological examination. Attention was paid to alterations that might be indicative of respiratory irritation, such as hyperaemia, oedema, minimal inflammation, thickened mucous layer.
The following organs of all animals were fixed in 10% (nose, i.e. head without brain, eyes and lower jaw) or 7% (other organs) buffered formalin for histopathological examination:
- Nose (5 levels of the nasal turbinates): The tip and Level 1 of the nose were taken from a cut just anterior to the incisor teeth. With tip removed, Level 2 was taken approximately 2 mm posterior to free tip of the incisor teeth. Level 3 was cut through the incisive papilla. Level 4 was cut through the middle of the second palatal ridge, which is located just anterior to the molar teeth. Level 5 was cut through the middle of the molar teeth. All sections were embedded face down to yield a section from the anterior section, except the nose tip was embedded posterior surface down.
- Larynx
- Trachea
- Lungs (five levels)
Paraffin sections were prepared of all above mentioned organs and stained with haematoxylin-eosin.

Statistics:

Since no animal died prematurely, the calculation of an LC50 was not required.

Preliminary study:

not specified

Sex:

male/female

Dose descriptor:

LC50

Effect level:

> 5.09 mg/L air (analytical)

Based on:

test mat.

Exp. duration:

4 h

Remarks on result:

other: LC50 cut-off value is 'unclassified'.

Mortality:

No mortality occured.

Clinical signs:

other: Slight tremor (day 1, 0- 30 min. post exposure), slight ataxia, slight dyspnoea (reduced frequency of respiration with increased volume) (day 1 & 2), slightly reduced motility (day 2) in all male and female animals.

Body weight:

No influence in body weight gain was observed.

Gross pathology:

no pathologically noteworthy findings.

Other findings:

Histopathology: Macroscopic changes in the nasal cavity and lungs
- Nose level 1-5: mild congestion in 5/6 terminal sacrificed animals and all interim sacrificed animals.
- Nose level 1: respiratory epithelium with mild focal vacuolization in 1/6 subepithelial terminal sacrificed animals.
- Nose level 3-5: minimal to moderate focal lympho-histiocytic infiltration of respiratory epithelium in 3/6 terminal sacrificed animals and all interim sacrificed animals.
- Nose level 5: mild lymphocytic follicle in 5/6 terminal sacrificed animals and 4/6 interim sacrificed animals
- Nose level 3-5: minimal to moderate (focal) artefacts/degeneration of the olfactory epithelium was observed in all terminal and all interim sacrificed animals.
- Nose level 4-5: minimal to moderate (focal) mucus in the lumen in all terminal sacrificed animals and 5/6 interim sacrificed animals.
- Nose level 5: minimal to moderate (focal) vacuolization of the olfactory epithelium in 4/6 terminal sacrificed animals and 4/6 interim sacrificed animals.
- Trachea: minimal focal lympho-histiocytic infiltration in 2/6 terminal sacrificed and 1/6 interim sacrificed animals.
- Trachea: minimal to mild focal/multifocal loss of epithelial cells in 5/6 terminal sacrificed animals and 5/6 interim sacrificed animals.
- Lung: mild alveolar pulmonary oedema in 1/6 terminal sacrificed animals.
- Lung: minimal to mild (focal/multifocal) inflammatory perivascular oedema in all animals.
- Lung: minimal to mild pneumonic foci in 3/6 terminal sacrificed animals and 1/6 interim sacrificed animals.
- Lung: mild congestion in 5/6 terminal sacrificed animals and all interim sacrificed animals.
- Lung: mild focal haemorrhage in 1/6 terminal sacrificed animals.
- Lung: minimal to mild focal alveolar pulmonary emphysema in 1/6 terminal sacrificed animals and 3/6 interim sacrificed animals.
- Lung: minimal infiltration mixed cells, perivascular in 2/6 interim sacrificed animals)

Interpretation of results:

GHS criteria not met

Conclusions:

Under the present test conditions, the LC50 value for rats following inhalation of Cobalt sulphide for 4 hours was determined to be: LC50 > 5.09 mg Cobalt sulphide/L air (gravimetric concentration).
Based on the results of the histopathological and macroscopic investigations, Cobalt sulphide does not require classification for respiratory irritation.
According to the EC Regulation 1272/2008 and subsequent regulations, the test material does not require classification for `acute inhalation toxicity´ or `specific target organ toxicity - single exposure´.

Executive summary:

Rats were exposed to a dry aerosol of Cobalt sulphide at a gravimetrically determined concentration of 5.09 ± 0.06 mg/L air (main study – 14-day sacrifice) or 5.09 ± 0.05 mg/L air (satellite animals – 24-hour sacrifice) for 4 hours by inhalation using a dynamic nose-only exposure chamber. The aerosol was generated with the aid of a dry, rotating brush dust generator.

The generated aerosol particulates of the main study and satellite animals had a mass median aerodynamic diameter (MMAD) and a Geometric Standard Deviation (GSD) of MMAD: 4.004 μm (GDS: 3.51) and MMAD: 4.418 μm (GSD: 3.58), respectively as determined with a cascade impactor. No smaller MMADs and GSDs could be obtained with the test item supplied.

No premature death occurred.

Slight tremor (day 1, 0- 30 min. post exposure), slight ataxia, slight dyspnoea (reduced frequency of respiration with increased volume) (day 1 & 2), slightly reduced motility (day 2) in all male and female animals occurred. However, this effect is considered to be an overall clinical sign of general toxicity common to dust exposure, but not necessarily test item related.

Discoloration of the lungs were observed in 2/3 male and 3/3 female animals of the main study and in all animals of the satellite study.

The histomorphological examination of the satellite animals of the five lung localisations, the five levels of the nose, the trachea and the larynx revealed mild morphological changes in form of an inflammatory reaction in level 4 and 5 of the noses and in all five levels of the lungs which are considered to be test item related. The changes observed had almost normalised 14 days after exposure.

The minimal lympho-histological infiltration in the lungs, nose, trachea and larynx, and the pneumonic foci in the lungs were considered as coincidental findings or normal immunological reaction in healthy rats.

Since the detailed histopathology of the respiratory tract revealed no pathologically noteworthy findings, Cobalt sulphide is not considered to be irritating to the respiratory system.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LC50

Value:

> 5.09 mg/L air

Physical form:

inhalation: dust / mist

Quality of whole database:

The study is reliable without restrictions.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Additional information

Justification for selection of acute toxicity – oral endpoint
Key study

Justification for selection of acute toxicity – inhalation endpoint
Key study

Justification for selection of acute toxicity – dermal endpoint
Weight of evidence information

Justification for classification or non-classification

Acute oral toxicity

The reference Reagan (1984) is considered as the key study for acute oral toxicity of cobalt sulphide and will be used for classification. Male and female Sprague-Dawley rats were dosed 5000 mg/kg orally via gavage. During the observation period of 15 days no adverse effects or mortalities were observed, thus the LD50 is > 5000 mg cobalt sulphide/kg bw.

The classification criteria according to regulation (EC) 1272/2008 as acutely toxic are not met since the ATE is above 2000 mg/kg body-weight, hence no classification required.

Specific target organ toxicant (STOT) – single exposure: oral

The classification criteria acc. to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, oral are not met since no reversible or irreversible adverse health effects were observed immediately or delayed after exposure and no effects were observed at the guidance value, oral for a Category 1 classification of 300 mg/kg bw and at the guidance value, oral for a Category 2 classification of 2000 mg/kg bw. No classification required.

 

Acute dermal toxicity

Conduct of an acute dermal toxicity study for cobalt sulfide is unjustified since dermal uptake is considered negligible.

Specific target organ toxicant (STOT) – single exposure: dermal

Conduct of an acute dermal toxicity study for cobalt sulfide is unjustified since dermal uptake is considered negligible.

 

Acute inhalation toxicity

The reference Haferkorn (2013) is considered as key study for the endpoint acute inhalation toxicity and will be used for classification.

Under the conditions of this study, the 4-hour inhalation LC50 of cobalt sulphide is >5.09 mg/L air. According to the EC Regulation 1272/2008 and subsequent regulations, the test material is not classified for acute inhalation toxicity.

Specific target organ toxicant (STOT) – single exposure: inhalation

The classification criteria acc. to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, inhalation dust/mist/fume are not met since no reversible or irreversible severe or significant health effects were observed immediately or delayed after exposure and no effects were observed at the guidance value, inhalation dust/mist/fume for a Category 1 classification of 1.0 mg/L/4h and at the guidance value, inhalation dust/mist/fume for a Category 2 classification of 5.0 mg/L/4h. Therefore, no classification is required.

Finally, any category 3 classification should primarily be based on human data. However, such classification is also not warranted, since observations on respiratory irritation in test animals (rats) were not observed.