Zirconium dichloride oxide

Endpoint summary

Description of key information

Zirconium dichoride oxide being very well water soluble, instantaneously releases hydrogen chloride in contact with water. At a nominal concentration of 10 g/L the pH becomes 1.83. The moisture on the skin / mucous layer of the eyes are considered to initiate this hydrolysis of zirconium dichloride oxide and the subsequent release of HCl. The substance should thus be considered corrosive to skin and eyes and no testing should be conducted. 

Key value for chemical safety assessment

Skin irritation / corrosion

Link to relevant study records

Reference

Endpoint:

skin corrosion: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no study available

Eye irritation

Link to relevant study records

Reference

Endpoint:

eye irritation: in vitro / ex vivo

Data waiving:

study scientifically not necessary / other information available

Justification for data waiving:

other:

Endpoint conclusion

Endpoint conclusion:

no study available

Respiratory irritation

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

When dissolving zirconium dichloride oxide into water rapid hydrolysis to the insoluble zirconium dioxide will occur. During this process hydrogen chloride is released. In a non-buffered environment (e.g., pure water) this hydrolysis is incomplete in the presence of hydrochloric acid due to the acidic nature of the solution. As an example, a sample solution prepared at a nominal concentration of 10 g/L resulted in stable acidic pH of 1.83 within 1 hour of preparation (O'Connor and Woolley, 2010). In a buffered environment the hydrogen ions will be absorbed and additional hydrogen chloride is released (as long as zirconium dichloride oxide is present in solution). This is expected to happen in physiologically relevant solutions such as the moisture on skin and eyes. Due to the pH decrease triggered by HCl formation zirconium dichloride oxide is assumed to be corrosive to both skin and eyes and no testing is considered necessary.

Effects on skin irritation/corrosion: corrosive

Effects on eye irritation: corrosive

Justification for classification or non-classification

Zirconium dichoride oxide releases hydrogen chloride in contact with water leading to a pH < 2. It is therefore proposed to follow the classification of hydrogen chloride dissolved in water (hydrochloric acid) for skin/eye corrosion/irritation. Zirconium dichloride oxide should thus be classified as Skin corrosive category 1B (H314) according to Annex 6 of the CLP regulation for harmonized classification of hydrochloric acid.

As the substance is classified as corrosive to the skin category 1B, it should be classified as Xi, R41 and Eye damage category 1 (H318) according to the criteria of the DSD and CLP Regulation, respectively.

Respiratory irritation may also be possible due to release of HCl.