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Water solubility

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Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
from 06 DEC 2005 to 15 JAN 2007
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 105 (Water Solubility)
Version / remarks:
and EU method A6 (water solubility) (in the report : EEC directive 92/69, A6)
Deviations:
no
GLP compliance:
yes (incl. certificate)
Type of method:
column elution method
Key result
Water solubility:
< 0.123 µg/L
Temp.:
20 °C
pH:
6.01 - 6.41
Details on results:
The measured results differ by less than 30%. Therefore, the study is considered to be valid.The water solubility was calculated including the content of the test item given in the certificate of analysis.

Table 1: Results of the water solubility of cerium dioxide

Experiment No.

Flow rate

(mL/h)

Sample No.

Concentration analysed (µg Cerium/L)

Mean (µg Cerium/L)

Water solubility calculated * (µg Test item/L)

Water solubility calculated (µg Test item/L)

pH

1

31

1.1

1.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.41

1

31

2.1

2.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.12

1

31

3.1

3.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.08

1

31

4.1

4.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.01

1

31

5.1

5.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.26

1

31

6.1

6.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.17

2

16

7.1

7.2

< 0.1

< 0.1

< 0.1

< 0.123

< 0.123 ± 0.0

6.34

2

16

8.1

8.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.21

2

16

9.1

9.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.20

2

16

10.1

10.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.30

2

16

11.1

11.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.35

2

16

12.1

12.2

< 0.1

< 0.1

< 0.1

< 0.123

 

6.15

SD = Standard deviation

* calculated with a content of cerium = 81.2455%

 

Conclusions:
Interpretation of results (migrated information): insoluble (< 0.1 mg/L)
The water solubility of cerium dioxide is < 0.123 µg/L at 20°C .
Executive summary:

The determination of the water solubility of cerium dioxide was performed according to the EEC Directive 92/69, A.6 “Water Solubility” (1992) and the OECD guideline No. 105, “Water Solubility” (adopted July 27, 1995), using the column elution method.

During the pre-tests, the water solubility of the test item at room temperature was estimated to be < 10 mg/L by visual judgement. Therefore, the column elution method was used for the performance of the main test.

During the main test six samples have been analysed in the first run (0.52 mL/min) and six samples during the second run (0.26 mL/min), each with a sampling interval of one hour. Total elution time was 94 hours.

The water solubility calculated on the basis of cerium content and purity of the test item is < 0.123 µg/L at 20°C .

The pH of the solution was between 6.01 and 6.41.

Description of key information

Water solubility < 0.123 µg/L at 20°C

Key value for chemical safety assessment

Additional information

Micrometric cerium dioxide (key result reported in "short description of key information")

An experimental study, scored as Klimisch 1, was selected as a key study and revealed very low water solubility (< 0.123 µg/L). Three other references, all selected as supporting studies, confirmed the insoluble nature of cerium dioxide without giving quantitative value of water solubility.

Nanometric cerium dioxide

Based on the only data available, scored as Klimisch 4, nanometric cerium dioxide should also be insoluble into water.