Zirconium dichloride oxide

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Read across from a study performed with zirconium acetate. The read across justification document is attached to IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

>= 1 000 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks on result:

other:

Remarks:

The read across substance zirconium acetate is also a 'water soluble' zirconium compound which behaves similarly in the aquatic compartment as zirconium dichloride oxide. Based on the results of the study from Bayliss (2013), performed with zirconium acetate, it was concluded that zirconium dichloride oxide is not expected to present toxicity to aquatic micro-organisms either.

Description of key information

Following the read across strategy, it is considered appropriate to cover this endpoint by a key study performed with zirconium acetate, another 'water soluble' zirconium compound with similar behaviour as zirconium dichloride oxide. Zirconium acetate did not cause any adverse effects in aquatic microorganisms in an activated sludge respiration inhibition study performed according to OECD guideline 209 (Bayliss, 2013). The 3-h EC50 and NOEC for zirconium acetate were > 1000 mg/L and >= 1000 mg/L (based on anhydrous zirconium acetate), i.e., the highest test concentration used.

Additional information

Because no data on zirconium dichloride oxide are available, the endpoint was covered using a study performed with zirconium acetate, another 'water soluble' zirconium compound which behaves similarly in the aquatic compartment as zirconium dichloride oxide.

In the study under consideration (Bayliss, 2013), a relatively large increase in respiration rate was observed in the test vessels at 1000 mg/L (anhydrous zirconium acetate), which was considered to be due to metabolism of the acetate component of the test item. No statistically significant toxic effects were observed at any of the test concentrations. The 3-h EC50 for zirconium acetate was > 1000 mg/L, and the 3-h NOEC was >= 1000 mg/L (anhydrous zirconium acetate). These results can be used for read across purposes to indicate that zirconium dichloride oxide is not expected to be toxic to microorganisms at equivalent doses.