Dipotassium hexacyanocobalt(II)-ferrate(II)

Long-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

long-term toxicity to aquatic invertebrates

Data waiving:

exposure considerations

Justification for data waiving:

other:

Justification for type of information:

JUSTIFICATION FOR DATA WAIVING

In accordance with column 2 of REACH Annex VII, the long-term toxicity testing on aquatic invertebrates shall be considered if the substance is poorly soluble in water.

Based on the water solubility test the substance can be considered poorly soluble in water (water solubility below the 1 mg/L threshold or below the detection limit of the analytical method of the test substance), as its water solubility is 0.89 mg/L (Cross-reference to Endpoint Water solubility: water solubility less than or equal to 0.89 mg/L at 20 °C (EU Method A6, OECD 105 w. slight dev., GLP). However, as aquatic toxicity is unlikely to occur due to exposure considerations, the long-term toxicity testing on aquatic invertebrates is waived.

The substance is unreactive. The substance's potassium ions are exchangeable, but the backbone structure of the ion-exchange material formed by hexacyano cobalt and hexacyano ferrate is very stable. The function of the substance as an ion exchanger itself dictates that the substance needs to hold its form and remain stable under its use conditions in order to effectively exchange ions.

The substance is only used industrially in highly controlled industrial environments, mainly nuclear facilities and equivalent environments, where all necessary risk management measures are in place. The main function of the substance is to remove radioactive nuclides and other isotopes from waste water. It is not used professionally nor by consumers, nor in any context where its use could be considered as widely dispersive.

During manufacture of the substance, water that has been in contact with the substance undergoes ultrafiltration. The permeate is further pretreated with neutralization, flocculation and clarification before release into the sewage system. As such there is no emission of the substance to the aquatic compartment during manufacture.

The substance is only used very occasionally and batch-wise, in small amounts at a time. Before use the substance is rinsed. The amount of water used for rinsing is small, approximately 100 L per 10 L column. As the substance is highly granular, only the dusty fraction will be rinsed out, comprising only about 1-2 % of the total substance. The downstream users are further advised to treat the used rinsing waters through a filtering membrane or by means of settling in the rinsing vessel before release. The particle size of the substance is such that with the pretreatment of the rinsing waters in place, emissions of the substance from the rinsing step to the aquatic compartment can be considered negligible (Cross-reference to Endpoint Particle size distribution/granulometry: particle size of less than 100 μm: 1.05% (EC EUR 20268, GLP)). Any unused substance should be treated as hazardous waste.

The rinsed substance is packed into ion-exchange columns and can then be washed in the column using backwashing. The ion-exchange columns, where the substance is washed and used, have e.g. a 32 or a 40 µm filter at the column outlets, at both ends of the column to take into account backwash as well. The filter therefore prevents the granular substance from escaping the column into the washing waters or into the treated waters, as the particle size of the substance is larger than 100 µm (Cross-reference to Endpoint Particle size distribution/granulometry: particle size of less than 100 μm: 1.05% (EC EUR 20268, GLP)). As the function of the substance as an ion exchanger depends upon the stability of the substance and of the particles, any molecule-size emissions from the substance to the aquatic compartment can be considered negligible.

Furthermore, radioactive waters treated with the substance are directed from the ion-exchange column to a monitoring tank, where they stay at least for some days to even months. The relative density of the substance is larger than that of water (density 2.21 x 10^3 kg/m3; Cross-reference to Endpoint Density: relative density 2.21 (OECD 109, EU Method A3 w. slight dev., GLP)), meaning that any possible residual substance that may have passed through the column filter will sink to the bottom of the monitoring tank, and will therefore not be released to the aquatic compartment.

When treating radioactive water with the substance, the radioactivity and therefore also the substance use is closely monitored. Should the substance be released from the column during its use, this would also mean that radioactive matter is released from the column. In such a situation the process will immediately be stopped and the ion-exchange column replaced for a new one. Therefore, during the monitoring of the radioactive emissions also the particulate emissions from the substance are being monitored and minimized. As such, any emissions from the substance to the aquatic compartment can be regarded as negligible.

The spent ion-exchange columns containing the substance are handled either as radioactive waste and deposited into final disposal containers for radioactive waste, or when no radioactive nuclides are involved, are treated as hazardous waste and disposed of accordingly. No emissions therefore result from the spent ion-exchange column under normal use.

Therefore, considering both the manufacture and use of the substance, aquatic toxicity is unlikely to occur due to exposure considerations, as emissions of the substance to water are negligible.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

water solubility

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24.5.-11.9.2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study was performed by following the recommended methods (Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 105 of the OECD Guidelines for Testing of Chemicals, 27 July 1995) and GLP.

Qualifier:

according to guideline

Guideline:

EU Method A.6 (Water Solubility)

Deviations:

yes

Remarks:

The flask method was used even though the method recommends the column elution method for test items with a solubility < 10 mg/L.

Qualifier:

according to guideline

Guideline:

OECD Guideline 105 (Water Solubility)

Deviations:

yes

Remarks:

The flask method was used even though the method recommends the column elution method for test items with a solubility < 10 mg/L.

GLP compliance:

yes (incl. QA statement)

Remarks:

Certificate is included in the study report

Type of method:

flask method

Water solubility:

<= 0.89 mg/L

Temp.:

20 °C

pH:

>= 6.32 - <= 6.48

Remarks on result:

other: T = 20.0 ± 0.5 °C

Details on results:

The final concentration was calculated based on the iron and cobalt concentrations in the samples:
Concentration Range:
- 4.35 x 10^-4 to 8.90 x 10^-4 g/L based on cobalt solubility
- 1.93 x 10^-4 to 5.32 x 10^-4 g/L based on iron solubility.
Overall Result : ≤ 8.90 x 10^-4 g/L at 20.0 ± 0.5 ºC

The cobalt concentration (g/L) in the sample solutions is shown in the following table:

Sample Number	Time Shaken at ~ 30 ⁰C (hours)	Time Equilibrated at 20 ⁰C (hours)	Concentration (g/L)	Mean Concentration (g/L)	Test Item Mean Concentration (g/L)	Solution pH
1A	24	24	8.87 x 10^-5	8.90 x 10^-5	5.27 x 10^-4	6.32
1B	24	24	8.93 x 10^-5
2A	48	24	1.49 x 10^-4	1.50 x 10^-4	8.90 x 10^-4	6.48
2B	48	24	1.51 x 10^-4
3A 3B	72 72	24 24	7.34 x 10^-5 7.34 x 10^-5	7.34 x 10^-5	4.35 x 10^-4	6.33

The iron concentration (g/L) in the sample solutions is shown in the following table:

Sample Number	Time Shaken at ~ 30 ⁰C (hours)	Time Equilibrated at 20 ⁰C (hours)	Concentration (g/L)	Mean Concentration (g/L)	Test Item Mean Concentration (g/L)	Solution pH
1A	24	24	4.83 x 10^-5	4.83 x 10^-5	3.02 x 10^-4	6.32
1B	24	24	4.83 x 10^-5
2A	48	24	8.46 x 10^-4	8.52 x 10^-4	5.32 x 10^-4	6.48
2B	48	24	8.58 x 10^-4
3A 3B	72 72	24 24	3.03 x 10^-5 3.15 x 10^-5	3.09 x 10^-5	1.93 x 10^-4	6.33

Conclusions:

During the preliminary study the water solubility of the test item was estimated to be 0.558 mg/L. Method A6 Water solubility (440/2008/EC) recommends that the column elution method should be used if the water solubility is < 1x10^-2 g/L. However, since the substance is insoluble in organic solvents, the column elution method could not be applied.

Using the flask method, the water solubility of the test item has been determined to be less than or equal to 8.90 x 10-4 g/L of solution at 20.0 ± 0.5 °C. The substance is therefore poorly soluble in water.

Executive summary:

The water solubility of the substance was determined to be less than or equal to 8.90 x 10^-4 g/L of solution at 20.0 ± 0.5 °C, using the flask method, designed to be compatible with Method A6 Water Solubility of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 105 of the OECD Guidelines for Testing of Chemicals, 27 July 1995.

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

particle size distribution (granulometry)

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24.5.-11.9.2014

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

The determination was carried out using a procedure designed to be compatible with that given in European Commission Guidance Document EUR 20268 ‘Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances’, 2002 and the results can therefore be thought of as reliable with restrictions. A known amount of test item was sieved with a mesh of 100 μm and the percentage of test item to pass through the sieve was calculated. According to the Integrated testing strategy for granulometry (Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint specific guidance Version 3.0, August 2014) no further testing is necessary if there are virtually no particles with diameters below 100 μm. The study is GLP compliant.

Qualifier:

according to guideline

Guideline:

other: European Commission Guidance Document EUR 20268 ‘Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances’, 2002.

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Certificate included in the study report.

Type of method:

sieving

Type of distribution:

mass based distribution

Key result

Remarks on result:

other: The percentage of test item having an inhalable particle size of less than 100 μm was determined to be 1.05%. The test item has been considered to be essentially non-inhalable.

No.:

#1

Size:

ca. 100 µm

Distribution:

ca. 1.05 %

Remarks on result:

other: The percentage of test item having an inhalable particle size of less than 100 μm was determined to be 1.05%. The test item has been considered to be essentially non-inhalable.

Conclusions:

A screening test consisting of sieving a known amount of test item with a 100 μm mesh concluded that only 1.05 % of the test item passed through the sieve and is inhalable. According to the Integrated testing strategy for granulometry (Guidance on Information Requirements and Chemical Safety Assessment Chapter R.7a: Endpoint specific guidance Version 3.0, August 2014) no further testing is necessary. The test item is considered to be essentially non-inhalable.

Executive summary:

The proportion of test item having an inhalable particle size of less than 100 μm was determined by a sieve method to be 1.05%. Particle size data was acquired using a procedure designed to be compatible with that given in European Commission Guidance Document EUR 20268 ‘Determination of Particle Size Distribution, Fibre Length and Diameter Distribution of Chemical Substances’, 2002. The test item is considered to be essentially non-inhalable.

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Endpoint:

relative density

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24.5.-11.9.2014

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

A gas comparison pycnometer method designed to be compatible with Method A3 Relative Density of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 109 of the OECD Guidelines for Testing of Chemicals, 02 October 2012 was used for the determination of the density. The study is GLP compliant.

Qualifier:

according to guideline

Guideline:

EU Method A.3 (Relative Density)

Deviations:

yes

Remarks:

The density was determined at 22.6 Celsius and 22.0 Celsius.

Qualifier:

according to guideline

Guideline:

OECD Guideline 109 (Density of Liquids and Solids)

Deviations:

yes

Remarks:

The density was determined at 22.6 Celsius and 22.0 Celsius.

GLP compliance:

yes (incl. QA statement)

Remarks:

Certificate is included in the study report.

Type of method:

pycnometer method

Type:

relative density

Density:

ca. 2.21

Temp.:

22.3 °C

Remarks on result:

other: T = 22.3 ± 0.5 °C.

The density of the substance was determined with two samples (triplicate readings). However, because the reproducibility was not acceptable (not within ± 20 kg/m^3), the determination was repeated with two new samples (triplicate readings). The reproducibility between the pressure readings of three of the samples were acceptable (within ± 20 kg/m^3)

and therefore the density was calculated as the mean value of the 3 samples' triplicate readings.

Determination	Test	P1(sample) (psig)	P2(sample) (psig)	Volume (cm^3)	Density(kg/m^3)	Mean Density (kg/m^3)	T (°C)
1*	A	17.308	6.974	14.542	2.212x10^3	1.926x10^3	22.6
	B	17.431	7.124	17.719	1.815x10^3
	C	17.441	7.149	18.369	1.751x10^3
2	A	17.737	7.193	15.988	2.208x10^3	2.196x10^3	22.6
	B	17.301	7.020	16.109	2.191x10^3
	C	17.313	7.025	16.113	2.190x10^3
3	A	17.279	6.945	13.978	2.275x10^3	2.221x10^3	22.0
	B	17.120	6.896	14.467	2.198x10^3
	C	17.195	6.928	14.525	2.189x10^3
4	A	17.102	6.999	18.018	2.237x10^3	2.199 x10^3	22.0
	B	17.171	7.042	18.483	2.181x10^3
	C	17.126	7.024	18.498	2.179x10^3

* Neglected reading

P1(sample), P2(sample) = Pressure readings with the sample cell containing test item (psig)

Mean density (Determinations 2, 3 & 4) : 2.206x103 kg/m^3

Relative density : 2.206

Mean Temperature : 22.3 ± 0.5 °C

Conclusions:

Even though the test temperature deviated from the one determined in Method A3 (440/2008/EC), the effect on the final results can be neglected (see overall remarks). With the exception of the test temperature, the method was followed and the density of the test item was determined to be 2.21 x 10^3 kg/m^3 at 22.3 ± 0.5 °C and have a relative density of 2.21.

Executive summary:

The density of the test substance was determined to be 2.21 x 10^3 kg/m^3 at 22.3 ± 0.5 °C (relative density of 2.21), using a gas comparison pycnometer, designed to be compatible with Method A3 Relative Density of Commission Regulation (EC) No 440/2008 of 30 May 2008 and Method 109 of the OECD Guidelines for Testing of Chemicals, 02 October 2012.