Cobalt dichloride

Endpoint summary

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2011-11-17 to 2011-11-25

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 404 (Acute Dermal Irritation / Corrosion)

Version / remarks:

2002-04-24

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or test system and environmental conditions:

TEST ANIMALS
- Source: Kuiper Rabbitry, Gary, Indiana
- Age at study initiation: approximately ten to twelve weeks old
- Weight at study initiation: 2.97 to 3.28 kg
- Housing: the rabbits were individually housed in stainless steel cages.
- Diet (ad libitum): Purina Laboratory Rabbit Chow
- Water (ad libitum): water
- Acclimation period: at least five days prior to study initiation

The rabbits were maintained according to the recommendations contained in the National Academy Press 1996: "Guide for the Care and Use of Laboratory Animals".
All animals used in this study were considered to be in good health at study initiation.

ENVIRONMENTAL CONDITIONS
- Temperature: 20 ± 3°C
- Humidity: 30 - 70%
- Photoperiod (hrs dark / hrs light): 12/12

Type of coverage:

semiocclusive

Preparation of test site:

shaved

Vehicle:

water

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.5 g aliquot of the test material

Duration of treatment / exposure:

4 hours

Observation period:

approximately 30 minutes after patches were removed, and 24, 48 and 72 and 168 hours after treatment

Number of animals:

3 male rabbits

Details on study design:

TEST SITE
- Area of exposure and type of wrap if used: the day before study initiation, electric clippers were used to remove the hair from the left side of the trunk, from the midline of the back to the abdomen. The following day an aliquot of the test material was then applied to an area approximately 6 square centimeters on the side of the test animal. The application site is slightly moistened with water to assure good skin contact, and is located approximately 5 - 7 centimeters down from the backbone. The test substance was then covered with a 2.5 cm^2 - 2 layer gauze patch held in place with non-irritating Kendall Curity Standard Porous Tape and the patch was then covered with a semi-occlusive plastic overwrap secured in place with Kendall Curity Standard Porous Tape for the duration of the exposure period.

REMOVAL OF TEST SUBSTANCE
- Washing (if done): excess material was removed from the site
- Time after start of exposure: at the end of the 4 hour contact period

SCORING SYSTEM: the site was observed and scored according to the Draize scale
Other adverse changes at the skin sites will be recorded if present.

Irritation parameter:

erythema score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

0.67

Max. score:

4

Reversibility:

fully reversible within: 72 hours

Irritation parameter:

edema score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritation parameter:

erythema score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

1.67

Max. score:

4

Reversibility:

fully reversible within: 7 days

Irritation parameter:

edema score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 48 hours

Irritation parameter:

erythema score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

1.33

Max. score:

4

Reversibility:

fully reversible within: 7 days

Irritation parameter:

edema score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

0.33

Max. score:

4

Reversibility:

fully reversible within: 48 hours

Irritant / corrosive response data:

There were mild irritation reactions in all of the test subjects which clreared by the 168 hour observation.

Interpretation of results:

GHS criteria not met

Conclusions:

The test material is non-irritating to the skin of rabbits.
According to the EC Regulation No. 1272/2008 and subsequent regulations, cobalt dichloride is not classified as a skin irritant.

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2010-10-28 to 2010-11-25

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Version / remarks:

2002-04-24

Deviations:

no

GLP compliance:

yes

Species:

rabbit

Strain:

New Zealand White

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Harlan Laboratories U.K. Ltd., Hillcrest, Dodgeford Lane, Belton, Loughborough, Leics, LE12 9TE / UK
- Age at study initiation: 12 - 13 weeks
- Weight at study initiation: 2603 - 2702 g
- Housing: individually in stainless steel cages equipped with feed hoppers and drinking water bowls. A piece of wood (batch no. 102240, imported by
Indulab AG, Gams / Switzerland from ABEDD® - LAB & VET GmbH, 1160 Vienna / Austria) and a haystick 4642 (batch no. 80/09, Provimi Kliba AG,
4303 Kaiseraugst / Switzerland) were provided for environmental enrichment.
- Diet (ad libitum): pelleted standard Teklad Global High Fiber Rabbit Diet 2031C (batch no. 25/10, Provimi Kliba AG, 4303 Kaiseraugst / Switzerland)
- Water (ad libitum): community tap water from Füllinsdorf
- Acclimation period: under laboratory conditions after health examination. Only animals without any visual signs of illness were used for the study.

ENVIRONMENTAL CONDITIONS - Standard Laboratory Conditions
- Temperature: 17-23 °C
- Relative humidity: 30-70%
- Air changes: air-conditioned with 10-15 air changes per hour
- Photoperiod (hrs dark / hrs light): 12/12 (music played during the daytime light period)

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): the test item was ground to a fine powder with a mortar and pestle. The test item was applied as a weight of 0.1 g/animal. The test item was applied with an eye glass to the conjunctival sac of the left eye of each animal after gently pulling the lower lid away from the eyeball. The lids were then gently held together for about one second to prevent loss of test item. The right eye remained untreated and served as the reference control.

Duration of treatment / exposure:

not applicable

Observation period (in vivo):

approximately 1, 24, 48 and 72 hours, as well as 7, 10, 14, 17 and 21 days after administration

Number of animals or in vitro replicates:

3 male rabbits

Details on study design:

The eyes of the animals were examined one day prior to test item administration.

One animal was treated first. As neither a corrosive effect nor a severe irritant effect was observed after the 1- and 24-hour examinations, the test was completed using the two remaining animals.

REMOVAL OF TEST SUBSTANCE
The treated eyes were not rinsed after instillation.

SCORING SYSTEM: according to the Draize scale
Scleral reddening and ocular discharge were also assessed (scale for assessment can be seen in the field "Any other information on materials and methods incl. tables" below).

TOOL USED TO ASSESS SCORE:
Eye examinations were made with a Varta Cliptrix diagnostic-lamp (Roth AG, 4153 Reinach / Switzerland).

OBSERVATIONS:
- Viability / Mortality: daily from acclimatization of the animals to termination of the test.
- Clinical Signs (systemic): daily from acclimatization of the animals to termination of the test.
- Body Weights: at start of acclimatization, on the day of application and at termination of observation. Body weights of two animals were additionally recorded on test day 16 and 18.
-Necropsy: no necropsy was performed on the animals sacrificed at termination of observation.

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

other: Moderate to marked reddening of the sclera and slight ocular discharge at 24, 48 and 72 hours after adminsitration.

Irritation parameter:

iris score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

2

Irritation parameter:

conjunctivae score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

2.67

Max. score:

3

Reversibility:

not fully reversible within: 21 days

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

2.67

Max. score:

4

Reversibility:

not fully reversible within: 21 days

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

other: Moderate reddening of the sclera and slight ocular discharge 24 hours after administration.

Irritation parameter:

iris score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

2

Irritation parameter:

conjunctivae score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

1.33

Max. score:

3

Reversibility:

not fully reversible within: 21 days

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0.67

Max. score:

4

Reversibility:

fully reversible within: 48 hours

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Remarks on result:

other: Moderate to marked reddening of the sclera at 48 and 72 hours after administration.Slight to moderate ocular discharge at 24, 48 and 72 hours after administration.

Irritation parameter:

iris score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

2

Irritation parameter:

conjunctivae score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

2.67

Max. score:

3

Reversibility:

not fully reversible within: 21 days

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

2.67

Max. score:

4

Reversibility:

not fully reversible within: 21 days

Irritant / corrosive response data:

Moderate reddening and moderate to marked chemosis as well as slight to moderate ocular discharge were noted 1 hour after instillation of the test item.
In one animal, these signs gradually reversed until the 48-hour reading, when only slight redness of the conjunctive was noted. However, slight redness of the conjunctivae was noted in this animal until test day 22, the end of the observation period.
In the other two animals, moderate to marked redness of conjunctivae and sclerae and slight to marked chemosis of the conjunctivae, as well as slight to moderate discharge was observed throughout the entire observation period of 21 days after test item instillation. Additionally, white deposits were noted 7, 10, 14, 17 and 21 days after test item instillation in one animal and 7 and 21 days after instillation of the test item in the other animal.
In all three animals, the signs of ocular irritation had not reversed 21 days after instillation of the test item.
No abnormal findings were observed in the cornea or for the iris light reflex of any animal at any of the measurement intervals.
No staining produced by the test item was observed in the treated eyes.
No test item remnants were observed in the treated eyes of any animal at any of the reading times.
No corrosion of the cornea was observed at any of the reading times.

Other effects:

- Viability / Mortality: no intercurrent deaths occurred during the course of the study.
- Clinical signs: no clinical signs were recorded throughout the entire observation period.
- Body weights: the body weight of the animals was within the range commonly recorded for this strain and age.
- Macroscopic findings: no necropsy was performed at the end of the study.

Interpretation of results:

Category 1 (irreversible effects on the eye)

Conclusions:

The instillation of cobalt dichloride into the eyes of three male young New Zealand white rabbits resulted in moderate to marked signs of eye irritation such as reddening and chemosis of the conjunctivae and reddening of the sclerae, as well as ocular discharge and white deposits in the eye. These signs of eye irritation were not reversible within 21 days after instillation of the test item.
According to the EC Regulation No. 1272/2008 and subsequent regulations, the test item is classified as Category 1.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Additional information

Justification for selection of skin irritation / corrosion endpoint:
Key study

Justification for selection of eye irritation endpoint:
Key study

Effects on eye irritation: corrosive

Justification for classification or non-classification

Skin corrosion

Reference Heppenheimer (2010) is considered as the key study for skin corrosion and will be used for classification. The overall irritation results are as follows:

Relative viability 3 min after treatment: 78.7 %

Relative viability 60 min after treatment: 63.8 %

The classification criteria according to regulation (EC) 1272/2008 as corrosive to skin are not met since the relative viability after 3 and 60 min was above 50 % and 15 % respectively, hence no classification required.

Skin irritation

Reference Kukulinski (2011) is considered as the key study for skin irritation and will be used for classification. The overall irritation results 24, 48 and 72 hours after application per animal are as follows (according to OECD 404):

- erythema: 0.67 1.67, 1.33

- oedema: 0.33, 0.33, 0.0

The classification criteria acc. to regulation (EC) 1272/2008 as irritating to skin are not met, since the values of erythema and oedema were below the threshold of ≥ 2.3 as well as the effects were fully reversible within 48 hours. No classification required.

In an initial testing programme cobalt dichloride was tested for skin corrosion in an in vitro system (according to OECD 431, Heppenheimer 2010). Following this test, cobalt dichloride needed to be classified as skin irritating category 2.

In another regulatory context a re-test with cobalt dichloride for in vivo skin irritation was required (according to US EPA TG OPPTS 870.2500 and OECD 404, Kukulinski 2011). The outcome did not show any skin corrosion or irritation potential of cobalt dichloride, thus no classification required.

Since in vivo test results should take precedence over in vitro test results, the results received from this in vivo test are taken forward for the chemical hazard assessment. The reference Heppenheimer 2010 on the in vitro test results was included for the sake of completeness as disregarded study.

Eye irritation

The references Heppenheimer (2010) and Sieber (2012) are considered as the key studies for eye irritation and will be used for classification.

According to Heppenheimer (2010) the mean in vitro score after 240 minutes incubation results of the in vitro bovine corneal opacity and permeability assay (BCOP, according to OECD TG 437) was 8.01. The value was below the threshold for severe eye irritants of 55.1. The classification criteria according to regulation (EC) 1272/2008 as severe eye irritation are not met, hence no classification required.

According to Sieber (2012) in the in vivo eye irritation test in rabbits (according to OECD 405) the overall irritation results 24, 48 and 72 hours after application per animal are as follows:

- Corneal opacity = 0.00 for all three animals

- Iris light reflex = 0.00 for all three animals

- Conjunctival redness = 2.67, 1.33, 2.67 individual mean scores

- Conjunctival oedema = 2.67, 0.67, 2.67 individual mean scores

The classification criteria acc. to regulation (EC) 1272/2008 as irritating to eyes are met, since conjunctival redness was above the threshold of ≥ 2 as well as the signs of eye irritation were not reversible within 21 days. Thus, cobalt dichloride will be classified as eye irritant category 1 (H318), Xi (R41).

Respiratory irritation

The justification for non classification as respiratory irritant is covered under the endpoint specific target organ toxicity- single exposure: inhalation as given in the acute toxicity section.