Registration Dossier

Environmental fate & pathways

Additional information on environmental fate and behaviour

Administrative data

Endpoint:
additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
key study
Study period:
29 October 2018 to 04 December 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference
Reference Type:
study report
Title:
Unnamed
Year:
2018
Report Date:
2019

Materials and methods

Test guideline
Qualifier:
according to
Guideline:
other:
Version / remarks:
OECD 29: Transformation/Dissolution of Metals and Metal Compounds in Aqueous Media, adopted
on 23 July 2001.
Deviations:
not specified
GLP compliance:
yes

Test material

Reference
Name:
Unnamed
Type:
Constituent
Test material form:
solid

Results and discussion

Any other information on results incl. tables

Screening test

The results showed the lowest solubility of test item in the buffering solution with pH 8.5. As there were no observable deviation between the solutions with pH 6 and pH 7 it was decided to use the buff

ering solution with pH 6 for the full transformation/ dissolution test. The diluted cadmium contents of the test vessels with pH 6 varied between 88 μg / L and 110 μg / L.

All oxygen levels were within the recommended range of the OECD Test Guideline 29.

Main test

The results of the transformation/ dissolution of "Cadmium selenide" in dissolution medium with a pH of approximately 6 with different loading rates at 22 ± 2°C are listed in sections 6.2.2 and 6.2.3.

The temperatures during the whole experiment were between 20.8 and 23.5 °C.

The pH values of the solutions were between 6.1 and 6.3 at all loading rates and therefore remained constant during the whole experiment.

The following results were obtained at the different loading rates:

1 mg test item / L: 23 μg Cd / L after 7 days (short term test)

Solubility equilibrium of 43.7 ± 4.6 μg Cd / L has been reached between 336 h (14 days) and 672 h (28 days) because three subsequent total dissolved metal concentration data points vary no more

than 15 % according to the OECD Test Guideline 29. 10 mg test item / L: 171 μg Cd / L after 7 days (short term test)

No solubility equilibrium have been reached during the test period of seven days.

100 mg test item / L: 551 μg Cd / L after 7 days (short term test)

No solubility equilibrium have been reached during the test period of seven days.

All oxygen levels were within the recommended range of the OECD Test Guideline 29.

The numerical data in the tables have been rounded for presentation, a manual recalculation therefore may yield slightly different results to those given in the tables.       

Screening test

Buffering solution with pH 6

Equilibration time

Concentration of dissolved µg Cd / L

pH

1streplicate

2ndreplicate

3rdreplicate

Mean

Vessel 1

110

106

109

108

6.0

Vessel 2

105

101

103

103

6.0

Vessel 3

91

88

91

90

5.9

Overall mean

100

6.0

Overall standard deviation

8

0.0

Buffering solution with pH 7

Equilibration time

Concentration of dissolved µg Cd / L

pH

1streplicate

2ndreplicate

3rdreplicate

Mean

Vessel 1

81

81

81

81

7.0

Vessel 2

111

111

112

111

7.0

Vessel 3

105

105

105

105

7.1

Overall mean

99

7.0

Overall standard deviation

14

0.1

Buffering solution with pH 8.5

Equilibration time

Concentration of dissolved µg Cd / L

pH

1streplicate

2ndreplicate

3rdreplicate

Mean

Vessel 1

56

56

58

57

8.4

Vessel 2

53

53

54

53

8.4

Vessel 3

74

74

74

74

8.5

Overall mean

61

8.4

Overall standard deviation

10

0.1


 

Short term dissolution tests

Transformation / dissolution - initial loading rate of 10 mg test item / L

Equilibration time

Concentration of dissolved µg Cd / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

< 3.1

< 3.1

< 3.1

< 3.1

2 h

3.9

5.5

3.7

4.4

6 h

11

19

12

14

24 h (=1 d)

18

33

21

24

72 h (=3 d)

72

140

92

102

168 h (=7 d)

140

185

188

171

Equilibration time

Concentration in µg test item / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

< 5.2

< 5.2

< 5.2

< 5.2

2 h

6.6

9.4

6.3

7.4

6 h

19

32

21

24

24 h (=1 d)

31

56

36

41

72 h (=3 d)

123

239

157

173

168 h (=7 d)

238

315

320

291

 

Equilibration time

pH

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

6.3

6.3

6.3

6.3

2 h

6.1

6.2

6.2

6.2

6 h

6.2

6.2

6.2

6.2

24 h (=1 d)

6.2

6.2

6.1

6.2

72 h (=3 d)

6.3

6.3

6.3

6.3

168 h (=7 d)

6.3

6.3

6.2

6.2

Transformation / dissolution - initial loading rate of 100 mg test item / L

Equilibration time

Concentration of dissolved µg Cd / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

< 3.1

< 3.1

< 3.1

< 3.1

2 h

29

30

23

28

6 h

80

90

72

80

24 h (=1 d)

117

136

111

121

72 h (=3 d)

323

406

332

354

168 h (=7 d)

529

587

537

551

Equilibration time

Concentration in µg test item / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

< 5.2

< 5.2

< 5.2

< 5.2

2 h

50

52

40

47

6 h

137

152

122

137

24 h (=1 d)

199

232

189

207

72 h (=3 d)

550

691

565

602

168 h (=7 d)

900

999

913

937

Equilibration time

pH

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

6.3

6.3

6.3

6.3

2 h

6.1

6.1

6.1

6.1

6 h

6.1

6.2

6.1

6.1

24 h (=1 d)

6.2

6.2

6.1

6.2

72 h (=3 d)

6.3

6.2

6.2

6.2

168 h (=7 d)

6.2

6.3

6.2

6.3

Long term dissolution test

Transformation / dissolution - initial loading rate of 1 mg test item / L

Equilibration time

Concentration of dissolved µg Cd / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

< 3.1

< 3.1

< 3.1

< 3.1

2 h

< 3.1

< 3.1

< 3.1

< 3.1

6 h

< 3.1

< 3.1

< 3.1

< 3.1

24 h (=1 d)

3.5

3.8

3.1

3.5

72 h (=3 d)

14

14

11

13

168 h (=7 d)

26

24

19

23

336 h (=14 d)

41

42

33

39

504 h (=21 d)

44

46

44

44

672 h (=28 d)

44

52

48

48

Equilibration time

Concentration in µg test item / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

< 5.2

< 5.2

< 5.2

< 5.2

2 h

< 5.2

< 5.2

< 5.2

< 5.2

6 h

< 5.2

< 5.2

< 5.2

< 5.2

24 h (=1 d)

5.9

6.5

5.3

5.9

72 h (=3 d)

24

23

18

22

168 h (=7 d)

44

41

33

39

336 h (=14 d)

71

71

57

66

504 h (=21 d)

75

78

75

76

672 h (=28 d)

75

88

82

82


 

Equilibration time

pH

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

6.2

6.3

6.3

6.3

2 h

6.1

6.2

6.1

6.1

6 h

6.2

6.2

6.2

6.2

24 h (=1 d)

6.2

6.1

6.1

6.1

72 h (=3 d)

6.2

6.3

6.3

6.2

168 h (=7 d)

6.1

6.2

6.2

6.2

336 h (=14 d)

6.2

6.2

6.2

6.2

504 h (=21 d)

6.3

6.3

6.2

6.3

672 h (=28 d)

6.3

6.2

6.3

6.3


Blank solutions for short and long term dissolution test

Equilibration time

Concentration of dissolved µg Cd / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

< 3.1

< 3.1

< 3.1

< 3.1

2 h

< 3.1

< 3.1

< 3.1

< 3.1

6 h

< 3.1

< 3.1

< 3.1

< 3.1

24 h (=1 d)

< 3.1

< 3.1

< 3.1

< 3.1

72 h (=3 d)

< 3.1

< 3.1

< 3.1

< 3.1

168 h (=7 d)

< 3.1

< 3.1

< 3.1

< 3.1

336 h (=14 d)

< 3.1

< 3.1

< 3.1

< 3.1

504 h (=21 d)

< 3.1

< 3.1

< 3.1

< 3.1

672 h (=28 d)

< 3.1

< 3.1

< 3.1

< 3.1

Equilibration time

Concentration in µg test item / L

1streplicate

2ndreplicate

3rdreplicate

Mean

Start = 0 h

< 5.2

< 5.2

< 5.2

< 5.2

2 h

< 5.2

< 5.2

< 5.2

< 5.2

6 h

< 5.2

< 5.2

< 5.2

< 5.2

24 h (=1 d)

< 5.2

< 5.2

< 5.2

< 5.2

72 h (=3 d)

< 5.2

< 5.2

< 5.2

< 5.2

168 h (=7 d)

< 5.2

< 5.2

< 5.2

< 5.2

336 h (=14 d)

< 5.2

< 5.2

< 5.2

< 5.2

504 h (=21 d)

< 5.2

< 5.2

< 5.2

< 5.2

672 h (=28 d)

< 5.2

< 5.2

< 5.2

< 5.2


Equilibration time

pH

Start = 0 h

6.3

2 h

6.2

6 h

6.2

24 h (=1 d)

6.2

72 h (=3 d)

6.2

168 h (=7 d)

6.2

336 h (=14 d)

6.2

504 h (=21 d)

6.2

672 h (=28 d)

6.3


Validation Results

Linearity

The calibration curve was linear from the quantification limit up to the highest concentration of 100 µg Cd / L. The coefficient of determination (R2) was 0.99996.

The following functions were received:

y [cps] = 94.01893 [cps/(µg / L)] * x [µg / L] + 79.45502 [cps]

where
x = nominal concentration of cadmium in µg / L
y = signal in counts per second (cps)

with the following ranges respectively confidence intervals for slope and intercept of the linear function:

Slope: 93.83990 – 94.19796 = 94.01893±0.17903
Intercept: 70.15852 – 88.75152 = 79.45502±9.29650

Detection limit

0.17 µg Cd / L in the diluted samples, which corresponds to 1.4 µg test item / L calculated with a dilution factor of 5 (rounded to two significant digits).

Quantification limit

0.61 µg Cd / L in the diluted samples, which corresponds to 5.2 µg test item / L calculated with a dilution factor of 5 (rounded to two significant digits).

Residual standard deviation

The residual standard deviation was 20 counts per second (cps) in the diluted samples.

Method standard deviation

The method standard deviation was 0.22 µg Cd / L in the diluted samples.

Relative method standard deviation

The relative method standard deviation was 0.57 %.

Accuracy

Sample

Measured concentration
without addition
(µg Cd / L)

Added concentration
calculated
(µg Cd / L)

Measured concentration
with addition
(µg Cd / L)

Added concentration
measured
(µg Cd / L)

Recovery (%)

Measurement 1

14.21

15

29.45

15.24

102

Measurement 2

14.45

15

29.47

15.02

100

Measurement 3

14.63

15

29.54

14.91

99

 

 

 

 

Mean

100

The mean recovery of the standard addition experiment was 100 %.

 

Reproducibility

 

Concentration of dissolved µg Cd / L

1streplicate

2ndreplicate

3rdreplicate

Within- vessel

Mean

Standard deviation

Relative Standard deviation
[%]

Vessel 1

110

106

109

108

2

2

Vessel 2

105

101

103

103

2

2

Vessel 3

91

88

91

90

2

2

Vessel 4

117

117

117

117

0

0

Vessel 5

137

135

137

136

1

1

Vessel 6

111

111

110

111

1

0

Mean between-vessel

111

---

---

Standard deviation between-vessel

15

---

---

Relative standard deviation between-vessel [%]

14

---

---

The calculated relative standard deviations (RSD) of the results were lower than the recommended values (< 20 % between-vessel and < 10% within- vessel) and therefore prove the reproducibility of the analysis.

Specificity / Selectivity

The specificity of the element cadmium was proved by using two different wavelengths which are characteristic and specific for cadmium. The specificity was calculated from the measurements of the spiked samples from the accuracy experiments.

Sample

Measured concentration
(µg Cd / L)

214.400 nm

228.802 nm

Measurement 1

15.24

15.22

Measurement 2

15.02

14.92

Measurement 3

14.91

15.11

Mean

15.06

15.08

The deviation between the two wavelengths was lower than 1 % relative and prove the specificity of the used wavelengths.  

Applicant's summary and conclusion

Conclusions:
At a loading of 1 mg test item / L, the dissolved mean concentration was 23 μg Cd / L (39 μg test it em / L) after the 7 days transformation / dissolution test and the equilibrium concentration observed within the test period of 28 days was 43.7 μg Cd / L (74 μg test item / L).

At a loading of 10 mg test item / L, the dissolved mean concentration was 171 μg Cd / L (291 μg test item / L) after the 7 days transformation / dissolution test. Within the test period of 7 days no equilibrium was observed.

At a loading of 100 mg test item / L, the dissolved mean concentration was 551 μg Cd / L (937 μg test item / L) after the 7 days transformation / dissolution test. Within the test period of 7 days no equilibrium was observed.
Executive summary:

The objective of the study was to determine the transformation / dissolution of the test substance"Cadmiumselenide". For the complete test substance no single analytical method is available. The transformation / dissolution was therefore estimated by analysis of the element cadmium.

The screening test showed that at pH of 6 maximises the dissolution of cadmium selenide. Therefore the full transformation/ dissolution tests were performed with a dissolution media with this pH value.

Main experiments

Short term transformation / dissolution at 22±2 °C per loading rate:

1 mg test item / L:                23 µg Cd / L after 7 days
                                             pH range: 6.1 to 6.3

10 mg test item / L:              171 µg Cd / L after 7 days
                                             pH range: 6.1 to 6.3

100 mg test item / L:            551 µg Cd / L after 7 days
                                             pH range: 6.1 to 6.3

 

Long term transformation / dissolution at 22±2 °C per loading rate:

1 mg test item / L:                Solubility equilibrium of 43.7 ± 4.6 µg                                             Cd / L has been reached between                                             336 h (14 days) and 672 h (28 days)
                                             pH range: 6.1 to 6.3

In each of the blank vessels without test item the content of diluted test item was less than the limit of quantification (< 5.2 µg / L) of the analytical method.

The observed levels and variations in temperature, pH and oxygen concentrations were in compliance with the test guideline OECD 29.

The transformation curves can be found in Appendix 3 as plots of time and measured cadmium concentrations.


Conclusion

At a loading of 1 mg test item / L, the dissolved mean concentration was 23 µg Cd / L (39 µg test item / L) after the 7 days transformation / dissolution test and the equilibrium concentration observed within the test period of 28 days was 43.7 µg Cd / L (74 µg test item / L).

 

At a loading of 10 mg test item / L, the dissolved mean concentration was 171 µg Cd / L (291 µg test item / L) after the 7 days transformation / dissolution test. Within the test period of 7 days no equilibrium was observed.

 

At a loading of 100 mg test item / L, the dissolved mean concentration was 551 µg Cd / L (937 µg test item / L) after the 7 days transformation / dissolution test. Within the test period of 7 days no equilibrium was observed.