Registration Dossier

Administrative data

Endpoint:
adsorption / desorption: screening
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the physicochemical properties of the substance indicate that it can be expected to have a low potential for adsorption
Justification for type of information:
JUSTIFICATION FOR DATA WAIVING
see attached justification
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Reason / purpose:
data waiving: supporting information
Reason / purpose:
data waiving: supporting information
Reference
Endpoint:
water solubility
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
OECD Guideline 105 (Water Solubility)
Version / remarks:
and ETAD method
GLP compliance:
no
Type of method:
flask method
Key result
Water solubility:
< 10 µg/L
Conc. based on:
test mat. (total fraction)
Incubation duration:
72 h
Temp.:
23 °C
Remarks on result:
other: below LoQ of the method
Remarks:
no data on pH
Details on results:
3 independent vials from each solubility test were injected and measured. Each result given in the table below is the average of these 3 measurements.
Water solubility test: 10 µg/L*
n-Octanol solubility test: 10 µg/L*

* Limit of quantification of the method.
Conclusions:
The water solubility of test substance was determined to be below the LoQ which is 10 µg/L at 23°C.
Reason / purpose:
data waiving: supporting information
Reference
Endpoint:
partition coefficient
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2011
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
comparable to guideline study with acceptable restrictions
Qualifier:
equivalent or similar to
Guideline:
other: OECD Guideline 105 and ETAD method
Principles of method if other than guideline:
The partition coefficient was estimated based on the ratio of the solubilities in n-octanol and in water. The individual solubilities were determined by flask method based on OECD Guideline 105 and the ETAD method.
GLP compliance:
no
Type of method:
estimation method (solubility ratio)
Partition coefficient type:
octanol-water
Analytical method:
high-performance liquid chromatography
Key result
Type:
log Pow
Partition coefficient:
0
Temp.:
23 °C
Remarks on result:
other: no data on pH
Details on results:
3 independent vials from each solubility test were injected and measured. Each result given in the table below is the average of these 3 measurements.
Water solubility test: 10 µg/L*
n-Octanol solubility test: 10 µg/L*

* Limit of quantification of the method.

Estimation based on solubility ratio:

Pow= C(n-octanol) / C(water)= 10 µg/L / 10 µg/L = 1

log Pow= 0

Conclusions:
The partition coefficient of test substance was estimated to be log Pow= 0 at 23°C based on solubility ratio.
Reason / purpose:
data waiving: supporting information
Reference
Endpoint:
additional information on environmental fate and behaviour
Remarks:
Dispersion stability in simulated environmental media
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2020
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
other: OECD 318
GLP compliance:
no

At any of the time points mentioned in the TG-318, the influence of Ca is critical. Regardless of pH, the pigment is categorized at the 24h-sampling time as “unstable” in 10 mM Ca, representing high water hardness.

After 6h, at pH 7 and 9 the samples showed high dispersion stability in 0 and 1 mM Ca. Stability at all other conditions was on the lower end of intermediate level

After 24 hours the stability for samples at pH 7 and 9 in 0 and 1 mM Ca became intermediate. For the samples at pH 4 and/or in 10 mM the stability was low.

Table 1: full results of the dispersion stability in the presence of NOM

Ca(NO3)2

Stability after 6h

Standard deviation

Stability after 15h

Standard deviation

Stability after 24h

Standard deviation

[mM]

[%]

[%]

[%]

[%]

[%]

[%]

 

 

 

 

pH 4

0

16.9

1.0

6.0

0.4

4.0

0.3

pH 4

1

10.3

1.1

4.4

0.9

3.3

0.7

pH 4

10

10.7

1.6

4.2

0.5

3.2

1.0

.

 

 

 

 

 

 

pH 7

0

93.7

1.6

86.0

4.2

76.8

1.9

pH 7

1

98.7

0.5

93.1

1.9

83.7

5.3

pH 7

10

13.9

1.4

6.6

1.2

3.7

0.1

.

 

 

 

 

 

 

pH 9

0

99.2

0.5

92.7

2.1

86.6

3.4

pH 9

1

98.0

0.7

81.3

0.8

48.9

0.9

pH 9

10

11.2

0.4

5.6

0.8

4.4

0.7

 

 

Cross-check the apparent stability by a fractionating method that physically separates particles from dissolved matter, and centrifugation results

 

To rationalize the observed dispersion stability, we finally checked the particle size distribution directly in the environmental medium (exact same sample preparation as for the UV/VIS measurements). We applied the NanoDefine method of Analytical Ultracentrifugation (SOP AUC-RI).

 

The observed size distributions confirm the moderate agglomeration at 1 mM Ca, pH7, with NOM. If the particles would have been significantly dissolved, no size distribution would be observable at all by this method, which relies on the detection of the movement of particles during centrifugal separation.

 

Additionally, the centrifugation methods include a determination of the remaining absorption after centrifugation, fully consistent with the conventional determination of the dissolved fraction after centrifugation as recommended by the TG-318. The remaining absorption was measured at c.a 0.014.This is a fraction of 0.7% of the initial absorption, but actually is close to the LOD of the built-in UV/Vis detector. Considering the LOD, between 0% and 0.7% of the sample may have been dissolved.

 

All evidence combined, the results after centrifugation confirm that at least 99.3% of the observed dispersion stability has to be attributed to the particles, not to dissolution.

Executive summary:

The dispersion stability of Pigment Yellow 93 depends especially on pH and water hardness. At pH 7 and 9 in 0 and 1 mM Ca stability is intermediate, at all other conditions (pH 4 and/or 10 mM Ca) the stability is low.

Data source

Materials and methods

Results and discussion

Applicant's summary and conclusion