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Physical & Chemical properties

Water solubility

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Administrative data

Endpoint:
transformation / dissolution of metals and inorganic metal compounds
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: This is a well designed and reported study conducted in accordance with sound scientific principles.

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2008

Materials and methods

Test guidelineopen allclose all
Qualifier:
according to
Guideline:
other: OECD Guideline for testing of chemicals - draft proposal - February 2001. Transformation dissolution of metals and metal compounds in aqueous media.
Qualifier:
according to
Guideline:
other: The Standard Operating Procedure for the Transformation/Dissolution of Metals and Sparingly Soluble Metal Compounds, Version February 2004.
Principles of method if other than guideline:
The transformation / dissolution of cupric oxide powder was tested in accordance to the draft OECD Transformation/Dissolution protocol. The experimental design includes refinements, agreed by the ad hoc OECD Validation Management Group (VMG), as described in the Standard Operating Procedures prepared by CANMET and LISEC. Samples of a commercially available cupric oxide powder were tested at pH 6, 7 and 8, at three loadings (1, 10 and 100 mg/L) for up to 28 days at a stirring rate of 100 rpm. The results can be compared with existing ecotoxicity data to establish the hazard identification and classification of the test substance.
GLP compliance:
no
Type of method:
flask method

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid: particulate/powder
Remarks:
migrated information: powder
Details on test material:
- Name of test material (as cited in study report): Cupric oxide.
- Physical state: Powder.
- Analytical purity: 97% min.
- Other: Particle size through 200 mesh sieve typically >98% (75µ).

Results and discussion

Solubility of metal ions in aqueous mediaopen allclose all
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
49 µg/L
Element analysed:
Cu
Loading of aqueous phase:
1 mg/L
Incubation duration:
7 d
Test conditions:
pH 6
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
5 µg/L
Element analysed:
Cu
Loading of aqueous phase:
1 mg/L
Incubation duration:
7 d
Test conditions:
pH 7
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
0 µg/L
Element analysed:
Cu
Loading of aqueous phase:
1 mg/L
Incubation duration:
7 d
Test conditions:
pH 8
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
221 µg/L
Element analysed:
Cu
Loading of aqueous phase:
10 mg/L
Incubation duration:
7 d
Test conditions:
pH 6
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
22 µg/L
Element analysed:
Cu
Loading of aqueous phase:
10 mg/L
Incubation duration:
7 d
Test conditions:
pH 7
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
0 µg/L
Element analysed:
Cu
Loading of aqueous phase:
10 mg/L
Incubation duration:
7 d
Test conditions:
pH 8
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
980 µg/L
Element analysed:
Cu
Loading of aqueous phase:
100 mg/L
Incubation duration:
7 d
Test conditions:
pH 6
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
64 µg/L
Element analysed:
Cu
Loading of aqueous phase:
100 mg/L
Incubation duration:
7 d
Test conditions:
pH 7
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
10 µg/L
Element analysed:
Cu
Loading of aqueous phase:
100 mg/L
Incubation duration:
7 d
Test conditions:
pH 8
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
210 µg/L
Element analysed:
Cu
Loading of aqueous phase:
1 mg/L
Incubation duration:
28 d
Test conditions:
pH 6
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
9 µg/L
Element analysed:
Cu
Loading of aqueous phase:
1 mg/L
Incubation duration:
28 d
Test conditions:
pH 7
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
1 µg/L
Element analysed:
Cu
Loading of aqueous phase:
1 mg/L
Incubation duration:
28 d
Test conditions:
pH 8
Details on results:
For all test designs, dissolved copper concentrations increased with time and the highest dissolved copper concentrations were observed at the end of the test periods. The curve fittings show that, after some initial equilibration time, transformation/dissolution of CuO resulted in a rather constant dissolved copper concentration in the test media. In several of the tests (all pH 7 tests and at 100mg/l for pH 6 and pH 8 tests), such apparent equilibrium was nearly reached at the end of the test periods for pH 7 and 8 media.

The rate and extent of the transformation/dissolution of CuO was related to the loading rate and inversely related to the pH of the test media. The lowest extent of transformation/dissolution of CuO was observed for the 1 mg CuO/L loading rate at pH 8; the amount of copper dissolved after 7 days remained within the range of the blank values (0.5 µg Cu/L). The highest extent of CuO transformation/dissolution was reached at pH 6 and a loading of 100 mg CuO/L; 980 µg Cu/L was detected in the solution after 7 days transformation/dissolution.

A tabulated summary of the short term (7 days) and long term (28 days) transformation/dissolution data obtained for CuO at different loadings and pHs are shown in Overall remarks, attachments (blank values have been subtracted). Detailed results are shown in Tables 1 - 3 and Figures 1 - 6 of the attached document.

Any other information on results incl. tables

Validity criteria were considered to have been met (Temperature between 20 & 25°C; dissolved oxygen concentration above 70% of its saturation in air;  pH around 0.2 units difference from the desired pH).

The temperature of the test media varied between 20 and 24 °C. The O2 concentrations of the test media varied between 6.76 and 8.42 mg O2/L. The pH of the media varied between 5.92 and 6.35 (pH 6 media), 6.88 and 7.25 (pH 7 media), 7.82 and 8.15 (pH 8 media).  A small and short term deviation in desired pH was only noted for the pH 6 media after 24 hours stirring: pH of 6.35 instead of 6 +/- 0.2.

Applicant's summary and conclusion

Conclusions:
The results of this transformation/dissolution test are suitable for comparison with existing ecotoxicity data to establish the environmental hazard identification and classification of the test substance.
Executive summary:

A transformation/dissolution test was carried out with copper oxide in accordance with OECD guidelines and standard operating procedures proposed by CANMET and LISEC. For the acute classification, tests were performed in modified OECD 203 media at pH , 6, 7 and 8 over a period of 7 days. The loading rates were 1, 10 and 100 mg/L loading ad the stirring rate was 100 rpm.  The long term (chronic) assays were performed at 1 mg/L loading for 28 days, in the same type of media and pHs.

 Three vessels were used for each loading rate (total 9 vessels), plus 3 blank vessels per pH. The same orbital shaker was used for all 12 vessels under the same CO2 atmosphere (pH 6.0 and 7.0). A 13th proxy vessel was also added to account for the possibility of metal contamination from the electrodes. At each time interval, 3 replicates were taken from each test vessel and the dissolved copper concentration was measured using ICP-MS. Validity criteria were considered to have been met.

It was found that dissolved copper concentrations increased with time, with the highest dissolved copper concentrations observed at the end of the test periods. The rate and extent of transformation/dissolution of CuO was related to loading rate and inversely related to pH of the test media. The lowest extent of transformation/dissolution was observed for the 1 mg CuO/L loading rate at pH 8. The highest extent of CuO transformation/dissolution was reached at pH 6 and a loading of 100 mg CuO/L.

A tabulated summary of the short term (7 days) and long term (28 days) transformation/dissolution data obtained for CuO at different loadings and pHs are shown in Overall remarks, attachments.