Zirconium acetate

Endpoint summary

Description of key information

Skin corrosion / irritation:
Four K1 studies are used in weight of evidence approach: 
- 2 in vitro studies performed with an aqueous solution containing 40.7% zirconium acetate anhydrous (Corvaro, 2013b and Bisini, 2013a; skin corrosion test according to OECD guideline 435 and skin irritation test according to OECD guideline 439, respectively)
- 1 in vivo study performed with an aqueous solution containing 40.7% zirconium acetate anhydrous (Longobardi, 2013b; according to OECD guideline 404) 
- 1 in vitro study with zirconium acetate powder (Corvaro, 2013a; according to OECD guideline 435). 
All these studies indicated that there are no corrosive/irritating effects on the skin.
Eye corrosion / irritation:
In a K1 study (Bisini, 2013b; according to OECD guideline 437) investigating the potential of the test item to be severely irritant or corrosive to the eye, zirconium acetate solution (40.7 % of anhydrous zirconium acetate) was observed to have corrosive or severe irritant properties towards the eye.

Key value for chemical safety assessment

Skin irritation / corrosion

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed (not irritating)

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Type of information:

experimental study

Adequacy of study:

key study

Study period:

3 January 2013

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Well documented GLP study conducted according to OECD guideline 437.

Qualifier:

according to guideline

Guideline:

OECD Guideline 437 (Bovine Corneal Opacity and Permeability Test Method for Identifying Ocular Corrosives and Severe Irritants)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Species:

other: Bovine corneas

Details on test animals or tissues and environmental conditions:

TEST ANIMALS
- Source: Butcher Service s.r.l.- Mattatoio no. 2067 M
- Age at study initiation: 6-12 months of age at collection of eyes

ENVIRONMENTAL CONDITIONS
- Temperature (°C): 32 ± 1°C

Vehicle:

unchanged (no vehicle)

Controls:

yes

Amount / concentration applied:

TEST MATERIAL
- Amount(s) applied (volume or weight with unit): 0.75 mL

Duration of treatment / exposure:

Corneas were exposed in horizontal position for 10 ± 1 minutes

Observation period (in vivo):

Corneas were observed through chamber glasses and pertinent observation recorded (e.g. tissue peeling/exfoliation, residual test substance, non-uniform opacity pattern etc.). During the post-exposure period, corneas were maintained in horizontal position, for futher 2 hours ± 10 minutes, incubated in a liquid bath at 32 ± 1°C.

Number of animals or in vitro replicates:

Three corneas per treatment (test item, negative and positive control).

Details on study design:

The test item was used in the form supplied, without any further dilution.
Positive control: 1% (w/v) sodium hydroxide in water
Negative control: Physiological saline (0.9% NaCl)

After 10 ± 1 minutes of exposure the corneas were rinsed thoroughly with complete Minimum Essential Medium Eagle's (MEM) EMEM with phenol red. A final wash with prewarmed complete EMEM without phenol red was carried out. After the incubation the opacity of all corneas was determined. On completion of the opacity measurements, EMEM was removed from both chambers (anterior first). The posterior chamber was re-filled with fresh complete EMEM without phenol red maintained at approximately 32°C. The anterior chamber was treated with 1 mL aliquot of 4 mg/mL sodium fluorescein solution in DPBS. The corneas were horizontally incubated in a liquid bath at 32 ± 1 °C for approximately 90 minutes. After the incubation, the medium was removed from the posterior chamber and the optical density of each sample was measured using a verified spectrophotometer at 490 nm. The linear range of a reference curve 0-20 µg/mL is carried out at RTC approximately once a year.
Quality controls of the same fluorescein solutions were prepared in complete EMEM without phenol red at concentrations of 2 and 10 µg/mL and were assayed in order to ensure that the fluorescein calibration curve was still acceptable at the time of the experiment.

Irritation parameter:

other: opacity

Basis:

mean

Score:

67.3

Max. score:

79

Remarks on result:

other: Standard Deviation 11.5

Irritation parameter:

other: permeability

Basis:

mean

Score:

0.023

Max. score:

0.037

Remarks on result:

other: Standard Deviation 0.0125

Irritation parameter:

other: in vitro irritancy score

Score:

67.6

Irritant / corrosive response data:

Alterations of cornea opacity were recorded during the study when compared to those of negative control. No significant alterations of cornea permeability were noted.

The negative and positive controls gave the expected results. The test is therefore considered as valid.

Interpretation of results:

Category 1 (irreversible effects on the eye)

Remarks:

Migrated information Criteria used for interpretation of results: EU

Conclusions:

According to the OECD Guideline No. 437, the test material should be classified as corrosive or severely irritant to the eye.

Endpoint conclusion

Endpoint conclusion:

adverse effect observed (irritating)

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Skin irritation / corrosion

Four K1 studies are used in a weight of evidence approach:

- 2 in vitro studies performed with an aqueous solution containing 40.7% zirconium acetate anhydrous (Corvaro, 2013b and Bisini, 2013a; skin corrosion test according to OECD guideline 435 and skin irritation test according to OECD guideline 439, respectively) - 1 in vivo study performed with an aqueous solution containing 40.7% zirconium acetate anhydrous (Longobardi, 2013b; according to OECD guideline 404)

- 1 in vitro study with zirconium acetate powder (Corvaro, 2013a; according to OECD guideline 435).

No irritation or corrosion was observed in these tests. Therefore it can be concluded that zirconium acetate is not irritating to the skin. This is also supported by the results of an acute dermal toxicity study (Longobardi, 2013a) where a solution containing 40.7 % of zirconium acetate anhydrous was applied to rats at a dose level of 2000 mg/kg bw (expressed as anhydrous zirconium acetate). No skin irritation/corrosion was observed 24 hours after exposure during the 14-day observation period.

Further, in a K3 in vitro study using the Transcutaneous Electrical Resistance method (TER), the test material (aqueous solution) was considered to have the potential to cause corrosion in vivo (Bradshaw, 2009). No details on visual observations of damage to the tissues were however included, therefore, the study is considered not reliable. This study is therefore also disregarded as the results are contradictory to the recent (reliable) in vitro and in vivo skin irritation/corrosion tests.

Eye irritation / corrosion

Bisini (2013b) investigated the potential of the test item (40.7% anhydrous zirconium acetate in aqueous solution) to cause corrosion/severe irritation by using the Bovine Corneal Opacity and Permeability (BCOP) assay, according to OECD guideline 437. The test item was tested as supplied on the epithelial surface of three idoneous bovine corneas, for an exposure period of 10 minutes plus a post incubation period of 2 hours. Positive and negative controls [a 1% (w/v) sodium hydroxide solution in water and physiological saline alone, respectively] were concurrently tested in the same number of replicates. The mean opacity of the corneas treated with the test item, detected with an opacitometer at the end of the test item exposure period, was 67.3. This was confirmed at the macroscopic observation in which the three corneas showed visible opacity. After the determination of opacity, the epithelial surface was treated with a 0.5% solution of sodium fluorescein in DPBS for 90 minutes, to investigate alteration in cornea permeability. Mean OD490 value of the corneas treated with the test item was unaffected by treatment. The results obtained indicate that the test item induced changes in cornea opacity, but not in permeability under the reported experimental conditions. The calculated in vitro irritancy score (IVIS) for the test item is 67.6.

Classification of the test item was performed according to the in vitro irritancy score:

Substances with an IVIS value > 55.1 should be classified as corrosive or severe irritant to the eyes.

Based on the results obtained, the test item should be classified as corrosive or severely irritant to the eye, which corresponds to GHS category 1 and EU category 1.

The assay is considered valid if the following criteria are met:

- The positive control yields an IVIS within the range defined by the historical control data (mean value ± 2 standard deviations).

- The negative control yields opacity and permeability values that are less than the established upper limits defined by the historical control data (mean value + 2 standard deviations).

Based on the results obtained the test is considered as valid.

Justification for selection of skin irritation / corrosion endpoint:
No key study is selected. Three in vitro studies and one in vivo study were used in weight of evidence approach.

Justification for selection of eye irritation endpoint:
There is only one reliable study available. Further studies are not scientifically requiered as the substance is corrosive to eyes.

Effects on eye irritation: corrosive

Justification for classification or non-classification

Based on the available data and according to the criteria of the DSD and the CLP Regulation an aqueous solution containing 40.7% zirconium acetate anhydrous as well as zirconium acetate as active ingredient should not be classified for skin corrosion/irritation.

According to the OECD Guideline 437, the test item should be classified as corrosive or severely irritant to the eye, which corresponds to Category 1, according to the Globally Harmonized System of Classification and Labelling of Chemicals (GHS) of the United Nations (2011) and Regulation (EC) No. 1272/2008 of the European Parliament and of the Council of 16 December 2008 on classification, labelling and packaging of substances and mixtures including all amendments.