Cobalt chromite green spinel

Eye irritation

Administrative data

Endpoint:

eye irritation, other

Remarks:

in vivo study

Type of information:

read-across based on grouping of substances (category approach)

Adequacy of study:

key study

Study period:

2012-04-05 to 2012-04-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Read-across category approach:
Cobalt chromite green spinel is a spinel-type oxide/pigment with the general structural element AB2O4 which forms a strong and inert matrix. Co and Cr are the main components with percentages of ~12.7% w/w and 44.3% w/w respectively. The amount of Zn as component is about 14.9% w/w.

The read-across substance Cobalt chromite blue green spinel is a spinel-type pigment as well with an identical crystallographic structure and a very similar composition. Co content is ~14.8% w/w and the Cr content is ca. 30% w/w. Al is present in about 9.4% w/w. Contents of Zn is about 15.1% w/w.

Besides the obvious structural analogy the solubility of both pigments in aqueous and physilogical media are as follows (determination of Co and Cr):

Solubility of Co from the pigment Cobalt chromite green spinel in physiological media was in a range of 17.2 µg/L (GMB) and 99.1 µg/L (ALF) after 2 hours. After 24 hours a dissolution range from 12.8 µg/L (GMB) - 108 µg/L (ALF) was measured.

Solubility of Cr from the pigment Cobalt chromite green spinel in physiological media was in a range of 0.264 µg/L (GMB) and 5.95 µg/L (GST) after 2 hours. After 24 hours a dissolution range from 0.452 µg/L (GMB) - 6.80 µg/L (GST) was measured.

The read-across substance Cobalt chromite blue green spinel afforded after 2 hours a solubility for the element Co in range of 0.34 µg/L (PBS) and 6.45 µg/L (ALF) and after 24 hours a solubility of 0.37 µg/L (GMB) to 9.89 µg/L (GST).

Solubility of Cr from the pigment Cobalt chromite blue green spinel in physiological media was in a range of below LOD and 1.11 µg/L (ALF) after 2 hours. After 24 hours a dissolution range from 0.18 µg/L (PBS) - 0.99 µg/L (ALF) was measured.

T/D testing of the pigment Cobalt chromite green spinel afforded the following solubility at 1mg loading after 28 days:
Cobalt: 2.038 ± 0.008 and 0.790 ± 0.039 μg/L at pH 8 and pH 6, respectively
Chromium: 1.489 ± 0.008 μg/L and Zinc: 1.840 ± 0.378 μg/L and
T/D testing of the read-across substance Cobalt chromite blue green spinel afforded the following solubility at 1mg loading after 28 days:
Cobalt: below LOD at pH 8 and pH 6, respectively
Chromium: below LOD at pH 8 and pH 6, respectively

In sum, the two spinel type pigments are structurally identical with similar composition. Both show a very low solubility in different artificial and aqueous media. In fact, the read-across substance Cobalt chromite blue green spinel shows slightly lower dissolution and bioaccessibility without showing any signs of systemic or local toxicity in various studies (acute inhalation, skin/eye irritation, sensitisation).

Based on the information summarised above, read-across to Cobalt chromite blue green spinel is fully justified.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2012

Report date:

2012

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 405 (Acute Eye Irritation / Corrosion)

Version / remarks:

2002-04-24

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2009-11-12

Test material

Test material information

Constituent 1

Reference substance name:

Cobalt chromite blue green spinel

EC Number:

269-072-0

EC Name:

Cobalt chromite blue green spinel

Cas Number:

68187-11-1

Molecular formula:

ZnxCo(1-x)Cr(2-y-z)AlyO(4[3/2]z)

Test material form:

solid: particulate/powder

Details on test material:

- Name of test material (as cited in study report): Cobalt chromite blue green spinel (Pigment Blue 36; C.I. 77343)
- Physical state: solid, blue green powder, odourless
- Melting point: >1000°C
- Water solubility: practically insoluble
- Relative density: 4.96

Specific details on test material used for the study:

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: at room temperature, kept dry in closed container

Test animals / tissue source

Species:

rabbit

Strain:

Himalayan

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: LPT Laboratory of Pharmacology and Toxicology GmbH & Co. KG, Branch Löhndorf, 24601 Löhndorf/Post Wankendorf, Germany
- Age at study initiation: approx. 4.5 - 5.5 months
- Weight at study initiation: 2.7 to 3.0 kg
- Housing: for 8 hours following test item application, the animals were kept singly in restrainers which allowed free movement of the head but prevented a complete body turn, wiping of the eyes with the paws and excluded irritation of the eye by excrements and urine. During the acclimatisation period and after the 8-hour period in restrainers, the animals were kept singly in cages with dimensions of 380 mm x 425 mm x 600 mm (manufacturer: Dipl.Ing. W. EHRET GmbH, 16352 Schönwalde, Germany)
- Diet (ad libitumbefore and after the exposure period ): commercial diet, ssniff® K-H V2333 (ssniff Spezialdiäten GmbH, 59494 Soest, Germany)
- Water (ad libitum before and after the exposure period): tap water
- Acclimation period: at least 20 adaptation days

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

Test system

Vehicle:

unchanged (no vehicle)

Controls:

no

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 100 mg of the test item were administered into one eye each of three animals. The volume of particulates was measured after gently compacting them, e.g. by tapping the measuring container.
The test item was placed into the conjunctival sac of the right 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 in order to prevent loss of the material. The left eye, which remained untreated, served as a control.

Duration of treatment / exposure:

1 hour

Observation period (in vivo):

1, 24, 48 and 72 hours after the administration

Number of animals or in vitro replicates:

3 male rabbits

Details on study design:

The test was performed initially using one animal. As no corrosive or severe irritant effects were observed in this animal, 2 further animals were employed 24 hours after start of the initial test.

REMOVAL OF TEST SUBSTANCE
- Washing: the eyes were rinsed with portions of 20 mL 0.9% aqueous NaCl solution, each.
- Time after start of exposure: 1 hour after administration

SCORING SYSTEM: according to the Draize scale
Any further lesions are listed.

TOOL USED TO ASSESS SCORE:
The eyes were examined ophthalmoscopically with a slit lamp prior to the administration and 1, 24, 48 and 72 hours after the administration. The eye reactions were observed and registered.
24 hours after administration, fluorescein (Fluorescein SE Thilo drops (ALCON PHARMA GmbH, 79108 Freiburg, Germany)) was applied to the eyes before being examined to aid evaluation of the cornea for possible lesions.

OBSERVATIONS:
Body weight of all animals was measured at the beginning and the end of the study. Behaviour and food consumption were monitored.

Results and discussion

In vivo

Results

Results 1

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 2

Irritation parameter:

iris score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

2

Results 3

Irritation parameter:

conjunctivae score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

3

Results 4

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

animal #1

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 5

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 6

Irritation parameter:

iris score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

2

Results 7

Irritation parameter:

conjunctivae score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0.33

Max. score:

3

Reversibility:

fully reversible within: 48 hours

Results 8

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

animal #2

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 9

Irritation parameter:

cornea opacity score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Results 10

Irritation parameter:

iris score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

2

Results 11

Irritation parameter:

conjunctivae score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

3

Results 12

Irritation parameter:

chemosis score

Basis:

mean

Remarks:

animal #3

Time point:

24/48/72 h

Score:

0

Max. score:

4

Irritant / corrosive response data:

Under the present test conditions, a single instillation of 100 mg cobalt chromite blue green spinel (Pigment Blue 36) per animal into the conjunctival sac of the right eye of three rabbits caused following change:
Conjunctival redness (grade 1) was observed in one animal 24 hours after instillation.
The corneae and irises were not affected by instillation of the test item.
24 hours fluoresscein test: all animals: no pathological findings.

Other effects:

There were no systemic intolerance reactions.

Applicant's summary and conclusion

Interpretation of results:

GHS criteria not met

Conclusions:

The substance is not irritating to the eyes.
According to Regulation (EC) No 1272/2008 and subsequent adaptations, the substance does not require classification as eye irritant.