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Water solubility

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Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
28 May 2010- 5 August 2010
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
This study has been performed according to OECD and EC guidelines and according to GLP principles. The test substance is adequately characterised. Therefore full validation applies.
Qualifier:
according to guideline
Guideline:
OECD Guideline 105 (Water Solubility)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EU Method A.6 (Water Solubility)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Type of method:
flask method
Remarks:
visual observation
Water solubility:
>= 1 000 g/L
Loading of aqueous phase:
1 000 g/L
Temp.:
19.9 °C
pH:
3.3

After the stirring period, the test sample was clear and no undissolved test substance was observed. From this, it was concluded that the water solubility of 202240/A at 20°C was > 1 x 10E3 g/l (pH 3.3).

Conclusions:
Interpretation of results (migrated information): very soluble (> 10000 mg/L)
Totally dissolved at 1000 g/L, pH acidic.
Executive summary:

The water solubility of dialuminium chloride pentahydroxide was investigated according to OECD/EC guidelines, flask method. A limit test was conducted at the nominal concentration of 1000 g/L. The substance was totally dissolved after 24 hours.

Endpoint:
transformation / dissolution of metals and inorganic metal compounds
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Reason / purpose for cross-reference:
read-across source
Reason / purpose for cross-reference:
read-across source
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
ca. 12 µg/L
Element analysed:
element as Al2+
Loading of aqueous phase:
1 mg/L
Incubation duration:
28 d
Test conditions:
21.5°C, pH ca 6.0
Type of test:
screening transformation/dissolution test - sparingly soluble metal compounds
Mean dissolved conc.:
7 471 µg/L
Element analysed:
result as μg Al/L
Loading of aqueous phase:
100 mg/L
Incubation duration:
24 h
Test conditions:
21.9°C, pH=4.75
Type of test:
screening transformation/dissolution test - sparingly soluble metal compounds
Mean dissolved conc.:
359 µg/L
Element analysed:
result as μg Al/L
Loading of aqueous phase:
100 mg/L
Incubation duration:
24 h
Test conditions:
21.9°C, pH=5.27
Conclusions:
From analogue, solubility of monomeric Al is expected to be ca 12 μg/L at pH 6.
Executive summary:

Elemental Aluminium solubility is pH dependent. pH drift was observed in the 24h study. The 28-d TDp study was considered more realistic regarding environmental conditions.

Endpoint:
transformation / dissolution of metals and inorganic metal compounds
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17/10/2014 to 24/10/2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
comparable to guideline study
Remarks:
Study following TDp method as laid down in GHS.
Reason / purpose for cross-reference:
reference to other 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
Qualifier:
according to guideline
Guideline:
other: GHS Annex 10
Deviations:
no
GLP compliance:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
other: transformation/dissolution
Type of test:
full transformation/dissolution test - metals and sparingly soluble metal compounds
Mean dissolved conc.:
ca. 12 µg/L
Element analysed:
as Al2+
Loading of aqueous phase:
1 mg/L
Incubation duration:
28 d
Test conditions:
21.5°C, pH ca 6.0
Details on results:
The temperature of the test solutions fluctuated between 21.4 and 21.9°C which was in line with the test conditions of 20 – 23°C.
The pH measured in the medium at the start of the test, and in the blank and test item vessels during the test varied from 5.98 to 6.05. All measured data were within the specifications of pH 6 ± 0.2
The measured TOC of the media were <1.0 mg/L C, and below the required level of 2.0 mg/L C as laid down in the OECD Test Guidance no.29
The test media at the start of the test and the blank control vessels during the test showed no concentrations above the reporting limit of 5 μg/L aluminium
The dissolved oxygen concentration measured in the blank and test item vessels at pH 6 varied from 8.42 to 8.51 mg/L O2. These values were higher than the required value of ± 6 mg/L O2 at 22°C corresponding with a minimal saturation level in air of 70%.

1 mg/L loading

aluminium (µg/L Al)

 

 

Time (h)

0

2

6

24

48

96

168

336

504

672

 

Accred. Report Limit

5

5

5

5

5

5

5

5

5

5

 

Detection limit

1

1

1

1

1

1

1

1

1

1

 

replica1

spl1

78

45

31

24

19

17

16

15

13

14

 

 

spl2

75

45

31

24

19

17

17

14

14

14

 

 

xavg,1

76

45

31

24

19

17

17

14

14

14

 

 

swithin,1

2

0

0

0

0

0

0

0

0

0

 

 

CVwithin,1(%)

2

0

0

1

0

2

1

2

1

0

 

 

T (°C)

 

 

 

 

 

 

21.4

 

 

21.7

 

 

pH

 

 

 

 

 

 

6.04

 

 

6.03

 

 

DO (mg/L O2)

 

 

 

 

 

 

8.45

 

 

8.42

 

replica2

spl1

60

28

20

15

13

13

13

12

12

11

 

 

spl2

59

30

20

16

13

14

13

12

12

11

 

 

xavg,2

60

29

20

15

13

13

13

12

12

11

 

 

swithin,2

1

1

1

0

0

1

0

0

0

0

 

 

CVwithin,2(%)

1

4

3

3

3

4

0

1

1

1

 

 

T (°C)

 

 

 

 

 

 

21.4

 

 

21.7

 

 

pH

 

 

 

 

 

 

6.03

 

 

6.02

 

 

DO (mg/L O2)

 

 

 

 

 

 

8.46

 

 

8.47

 

replica3

spl1

67

43

31

24

19

16

15

13

12

12

 

 

spl2

69

47

30

29

19

16

15

13

12

12

 

 

xavg,3

68

45

30

27

19

16

15

13

12

12

 

 

swithin,3

1

3

1

4

0

0

0

0

0

0

 

 

CVwithin,3(%)

2

7

3

15

1

1

2

0

1

1

 

 

T (°C)

 

 

 

 

 

 

21.4

 

 

21.6

 

 

pH

 

 

 

 

 

 

6.04

 

 

6.03

 

 

DO (mg/L O2)

 

 

 

 

 

 

8.47

 

 

8.45

 

 

xavg

68

40

27

22

17

16

16

13

12

12

 

 

sbetween

8

9

6

6

3

2

2

1

1

1

 

 

CVbetween(%)

12

24

23

27

19

13

12

9

8

11

 

 

S

7

8

5

6

3

2

2

1

1

1

 

 

CV (%)

11

21

20

25

17

11

11

8

7

10

 

xavg,v

within vessel averageof 2 samples where v is the replica blank control vessel number (N=2)

swithin,v

within vessel standard deviation where v is the replica blank control vessel number (N=2)

CVwithin,v

within vessel Coefficient of Variation where v is the replica blank control vessel number (N=2)

xavg

averageof 3 test vessels (2 samples per test vessel; blank corrected) (N=6)

sbetween

between vessel standard deviation (N=3)

CVbetween

between vessel Coefficient of Variation (N=3)

s

overall standard deviation (N=6)

CV

overall Coefficient of Variation (N=6)

Conclusions:
Interpretation of results (migrated information): insoluble (< 0.1 mg/L)
At a loading of 1 mg/L Kemira ALG using the modified ISO 6341 (OECD 203) standard medium at pH 6, an initial nominal concentration of 88 µg/L Al decreased to average values of 16 µg/L Al (CV=11%) and 12 µg/L Al (CV=10%) at the 7 days sample point and 28 days endpoint, respectively.
Executive summary:

The objective of this study was to obtain information about the dissolution characteristics of Kemira ALG, the product name for aluminium sulphate 14 -hydrate containing 9% (8.8 -9.2) elemental aluminium. The long-term (chronic) transformation/dissolution endpoint was based on the dissolved aluminium concentrations obtained after 28 days. With these results the sponsor is able to compare them with the chronic ecological reference value (ERV) at the corresponding pH of the element(s) tested in order to get information about the toxicity of the test item in aqueous medium and to classify the test item according to the EU-CLP and UN-Globally Harmonized System.

This study has been performed according to UN GHS Annex 10.

The set-up of this study, including the choice of the test system (modified ISO 6341 test medium at pH 6) was designed by the Study monitor on behalf of the Sponsor in order to obtain information about the dissolution characteristics (“removal from the water column”) and was based on the results of study X01-195 (24 hours Transformation/Dissolution Screening Study of Kemira ALG at a 100 mg/L loading in a standard aqueous medium at pH 6 and pH 8).

The pH-dependent extent of dissolution of Kemira ALG was tested in standard aqueous solutions at pH 6 (CO2-buffering) for 28 days (1 mg/L loading) at an agitation speed of 100 rpm.

All test parameter conditions were fully in accordance with the GHS Annex 10 Test Guidance requirements:

·       The pH measured in the medium at the start of the test, and in the blank and test item vessels during the test varied from 5.98 to 6.05. All measured data were within the specifications of pH 6 ± 0.2.

·       The measured TOC of the media were <1.0 mg/L C, and below the required level of 2.0 mg/L C.

·       The temperature of the test solutions fluctuated between 21.4 and 21.9°C and corresponded to the required test conditions of 20 – 23°C.

·       The dissolved oxygen concentration measured in the blank and test item vessels at pH 6 varied from 8.42 to 8.51 mg/L O2. These values were higher than the required value of ± 6 mg/L O2at 22°C corresponding with a minimal saturation level in air of 70%.

The test medium and blank control were analysed for background aluminium concentrations over a 28-day study period and these were found to be negligible (close to or below limit of detection). At a loading of 1 mg/L Kemira ALG using the modified ISO 6341 (OECD 203) standard medium at pH 6, an initial nominal concentration of 88 µg/L Al decreased to average values of 16 µg/L Al (CV=11%)and 12 µg/L Al (CV=10%) at the 7 days sample point and 28 days endpoint, respectively. Based on the aluminium content in the test item (8.8%)and the average dissolved aluminium concentration in the test solutions, an aluminium recovery of 18% and 14% could be calculated at the7 days sampling point and 28 days extraction endpoint.

Endpoint:
transformation / dissolution of metals and inorganic metal compounds
Type of information:
experimental study
Adequacy of study:
key study
Study period:
17/10/2014 to 24/10/2014
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Remarks:
Study following TDp method as laid down in GHS.
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:
no
Other quality assurance:
ISO/IEC 17025 (General requirements for the competence of testing and calibration laboratories)
Type of method:
other: transformation/dissolution
Type of test:
screening transformation/dissolution test - sparingly soluble metal compounds
Mean dissolved conc.:
7 471 µg/L
Element analysed:
result as μg Al/L
Loading of aqueous phase:
100 mg/L
Incubation duration:
24 h
Test conditions:
21.9°C, pH=4.75
Type of test:
screening transformation/dissolution test - sparingly soluble metal compounds
Mean dissolved conc.:
359 µg/L
Element analysed:
result as μg Al/L
Loading of aqueous phase:
100 mg/L
Incubation duration:
24 h
Test conditions:
21.9°C, pH=5.27
Details on results:
The temperature of the test solutions fluctuated between 21.5 and 21.9°C which was in line with the test conditions of 20 – 23°C.
The test item has an immediate influence on the pH of the test systems. The pH measured in the medium at the start of the test, and in the blank and test item vessels during the test at pH 6 and pH 8 dropped from 6.05 to 4.75 and from 8.01 to 5.27, respectively. So, the measured data at pH 6 and at pH 8 were not within the specifications of ± 0.2.
The measured TOC of the media were <1.0 mg/L C, and below the required level of 2.0 mg/L C as laid down in the OECD Test Guidelines no.29
The test media at the start of the test and the blank control vessels during the test showed no concentrations above the reporting limit of 5 μg/L aluminium

Solution at pH6
When the test item and the test medium were mixed, the pH of the test medium decreased from pH 6.05 to 4.75 within a couple of minutes. The pH remained stable at about 4.75 during test and could not be corrected to pH 6.0 ± 0.2 by means of the used CO2/air buffer system within the 24 hours test period.
An average dissolved concentration of 7471 ± 16 μg/L Al was found at the 24 hours endpoint with a between-vessel coefficient of variation of 0%.
An average dissolved concentration of 7579 ± 46 μg/L Al was found at the 24 hours endpoint with a between-vessel coefficient of variation of 1% for samples which were centrifugated (30 minutes at 3000g) before 0.2 μm filtration.

Solution at pH8
When the test item and the test medium were mixed, the pH of the test medium decreased from pH 8.01 to 5.27 within a couple of minutes. The pH remained stable at about 5.27 during test and could not be corrected to pH 8.0 ± 0.2 by natural air buffering within the 24 hours test period.
An average dissolved concentration of 359 ± 37 μg/L Al was found at the 24 hours endpoint with a between-vessel coefficient of variation of 10%. The within-vessel coefficients of variation met the <10% quality criteria for all test vessels. Based on the aluminium content in the test item (8.8%, annex 7) and the average dissolved aluminium concentration, a remaining dissolved aluminium content of approximately 4.1% could be calculated at the 24 hours endpoint.
An average dissolved concentration of 346 ± 33 μg/L Al was found at the 24 hours endpoint with a between-vessel coefficient of variation of 9% for samples which were centrifugated (30 minutes at 3000g) before 0.2 μm filtration.
Executive summary:

During this study on Kemira ALG at a loading of 100 mg/L, it was shown that significant concentrations of aluminium 7471 μg/L Al (CV=1%) at nominal pH 6 (actual pH was 4.75) and 359 μg/L Al (CV=9%) at nominal pH 8 (actual pH was 5.27) were measured, using the standard protocol corresponding with a dissolved aluminium content of 85% and 4.1% respectively. However, it was not possible to maintain the pHs at the designated levels of 6 and 8 as the high concentration (100 mg/L) of the test substance used in the assay influenced the pH and the pH influenced the solubility.

Based on the rounded results, this study identified “pH 6” as the pH where the highest dissolved aluminium concentrations were found.

This dissolution result may be important in the design of the standard 7 days and/or 28 days transformation/dissolution test to enable appropriate hazard classification categories under EU-CLP and UN-Globally Harmonized System. Based on the results of this study a long-term TDp study was performed at a more environmentally realistic concentration to reduce pH drift.

Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
study well documented, meets generally accepted scientific principles, acceptable for assessment
Remarks:
The experiment was not conducted according to guideline, and shows weakness regarding equilibration and separation of forms. However scientific reasoning was used and investigations regarding pH-dependency were considered suitable for purpose. Test substance is adequately characterised. Therefore the study is considered reliable with restrictions.
Principles of method if other than guideline:
Equilibration for 90 min, pH adjustment and measurement of dissolved aluminium.
Water solubility:
101 µg/L
Conc. based on:
element
Remarks:
µg/L as Al; minimum solubility
Temp.:
20 °C
pH:
6.7

Measured concentrations (as log) were plotted against pH.

The aluminium chlorohydrate data do not show good agreement with the theoretical Al137 + line. For pH less than the pH of minimum solubility, the slope is less than expected for the polymer, and the measured soluble Al was higher than predicted by theory. These deviations may be due to the presence of Al-species other than those examined here.

Above pH8, the measured soluble Al showed good agreement with the theoretical solubility line for Al(OH)41-.

Conclusions:
Interpretation of results (migrated information): moderately soluble (100-1000 mg/L) (as salt)
Concentration of dissolved monomeric Al is related to speciation, and pH-dependent.
Executive summary:

Aluminium chlorohydrate was added to deionised water, and pH was adjusted between 4 and 9. After 90 min equilibration, and filtration to remove particulate and colloidal forms, dissolved Aluminium was measured by colorimetric method. Solubility was found to be pH-dependent, with speciation matching the theoretical predictions only above 8. Minimum free (monomeric) aluminium was measured at pH=6.7 with a concentration of 101 µg Al/L.

Description of key information

Very soluble salt (>> 100 g/L).

However, aluminium speciation rapidly leads to salting out to various degrees which are highly pH dependent. Solubility of monomeric Al can descend as low as 101 µg Al/L within a 90-minute experiment in pure water, and 12 µg/L after 28 days in reconstituted natural medium.

Key value for chemical safety assessment

Additional information

A fully reliable experimental study, conducted according to a recognized OECD/EC method and under GLP, is available. Therefore, it is considered as a key study, but the limit value (> 1000 g/L) is not retained as key data.

Additionally, two valid transformation/dissolution studies were conducted with an analogue (aluminium sulphate), the first a 24h study at nominal pH 6 and 8, in ISO 6341 reconstituted test medium 10x diluted (pH6) or undiluted (pH8), and aluminium concentrations dropped from 8.8 to 7.5 mg Al/L and 0.36 mg Al/L, respectively. This drop was less than expected due to the considerable reduction from the target pH (especially at pH6, which descended to 4.75 within a couple of minutes) caused by the capacity of aluminium to consume the alkalinity of the test medium (approximately 0.5 mg/L of alkalinity as CaCO3 per mg/L of alum according to Pernitsky and Edzwald, 2003). For this reason a 28-day TDp study was performed at a more environmentally realistic concentration of 1 mg/L at pH 6 (in diluted ISO 6341). In this case pH 6 was selected as the solubility was found to be the higher of the 2 pHs tested. In this study the original nominal concentration of 1 mg/L as aluminium sulphate (88 µg as elemental aluminium) dropped to 16 µg/L as elemental aluminium within 7 days and just 12 µg/L after 28 days and can therefore be considered as insoluble when added to environmental media within a few hours.

A supporting publication reports consistent information on significant pH- and speciation-dependency, in deionised water, with a minimum solubility of 101 µg Al/L (pH=6.7) for aluminium chlorohydrate.

Moreover, in both experiments, solutions were filtered (0.2 µm) before analysis, in order to remove polymeric and colloidal species, as it is generally assumed that only dissolved metal ions will pass through such a filter.

This explains the variability between experiments observed.

Speciation is detailed under Section 5 on Environmental fate and pathways.