Chromium iron oxide

Water solubility

Link to relevant study record(s)

Reference

Endpoint:

transformation / dissolution of metals and inorganic metal compounds

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009-09-07 to 2010-02-10

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Series on Testing and Assessment No. 29 (23-Jul-2001): Guidance document on transformation/dissolution of metals and metal compounds in aqueous media

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

signed 2009-06-19

Type of method:

flask method

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Chromium

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

24 h

Test conditions:

T = 22.4 - 22.5 °C ; pH = 6.06 - 6.13

Remarks on result:

other: < LOD

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Iron

Loading of aqueous phase:

100 other: mg test item /L

Incubation duration:

24 h

Test conditions:

T = 22.4 - 22.5 °C, pH = 6.06 - 6.13

Remarks on result:

other: < LOD

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Chromium

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

24 h

Test conditions:

T = 22.4 - 22.5 °C, pH = 8.02 - 8.11

Remarks on result:

other: < LOD

Type of test:

screening transformation/dissolution test - sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Iron

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

24 h

Test conditions:

T = 22.4 - 22.5 °C, pH = 8.02 - 8.11

Remarks on result:

other: < LOD

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Chromium

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

7 d

Test conditions:

T = 22.4 - 22.5 °C, pH = 6.02 - 6.1 (6.9 in one sample at 0 h)

Remarks on result:

other: < LOD

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Iron

Loading of aqueous phase:

100 other: mg test item / L

Incubation duration:

7 d

Test conditions:

T = 22.4 - 22.5 °C, pH = 6.02 - 6.1 (6.9 in one sample at 0 h)

Remarks on result:

other: < LOD

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Chromium

Loading of aqueous phase:

1 other: mg test item /L

Incubation duration:

28 d

Test conditions:

T = 22.4 - 22.6 °C, pH = 6.03 - 6.11

Remarks on result:

other: < LOD

Type of test:

full transformation/dissolution test - metals and sparingly soluble metal compounds

Mean dissolved conc.:

< 0.5 µg/L

Element analysed:

Iron

Loading of aqueous phase:

1 other: mg test item /L

Incubation duration:

28 d

Test conditions:

T = 22.4 - 22.6 °C, pH = 6.03 - 6.11

Remarks on result:

other: < LOD

Screening Test at 0.1 g/L		^52Cr(µg/L)	^56Fe(µg/L)
AA76579 pH 6 T24h	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-
AA76579 pH 8 T24h	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-

Conclusion of the screening test:

Dissolved Fe or Cr concentrations were below the LOD at both pH levels. Therefore, pH 6 was selected for the full test assuming that the dissolution of metal oxides (i.e. this pigment) is maximized at the lower pH (in acidic medium).

Full Test 7 days at 0.1 g/L pH6		^52Cr(µg/L)	^56Fe(µg/L)
AA76579 T1 day	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-
AA76579 T4 days	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-
AA76579 T7 days	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-

Full Test 28 days at 1 mg/L pH6		^52Cr(µg/L)	^56Fe(µg/L)
AA76579 T1 day	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-
AA76579 T7 days	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-
AA76579 T14 days	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-
AA76579 T28 days	Mean	n.d.	n.d.
	S.D.	-	-
	RSD%	-	-

Test conditions:

- The pH was inside of the acceptable range (pH6 +0.2 units) in a range of 6.02 to 6.12

- The temperature was inside of the acceptable range (20 -25 +/- 2) in a range of 22.4 to 22.6

- The O2 -concentration was always above the accaptable limit of 70% in a range of 79.8% to 81.6%

- The within-vessel values and the between-vessel values could not be determined, because the concentrations of Cr and Fe were below the LOD (0.5µg/L for Cr and Fe).

Conclusions:

Transformation/dissolution of chromium iron oxide (24-screening test according to OECD Series 29, loading of 100 mg/L, pH 6 and 8) resulted in metal concentrations that are below the respective LODs for iron and chromium (< 0.5 µg/L). Dissolved metal concentrations were also below the respective LODs after the 7-d test with 100 mg/L at pH 6 and after the 28-d test with 1 mg/l at pH 6. Thus, chromium iron oxide is considered to be environmentally inert.

Description of key information

Chromium iron oxide is considered to be environmentally inert. Transformation/dissolution of chromium iron oxide (according to OECD Series 29: (i) 24 h, loading of 100 mg/L, pH 6 and 8; (ii) 7 d, loading of 100 mg/L, pH 6; and (iii) 28 d, loading of 1 mg/L, pH 6) resulted in metal concentrations that are below the respective LODs for iron and chromium (< 0.5 µg/L).