Tetrasodium enneatitanium icosaoxide hydrate

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 VIII, 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 is highly insoluble in water (Cross-reference to Endpoint Water solubility: water solubility below the detection limit, <0.51 µg/L (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 sodium ions are exchangeable, but the titanate structure of the substance is very stable. The function of the substance as an ion exchanger 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 which comprises only about 1-2 % of the total substance will be rinsed out. 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: 1.01 - 2.92 % (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: 1.01 - 2.92 % (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 2,83-2,97 x 10^3 kg/m3; Cross-reference to Endpoint Density: relative density 2.83 - 2.97 (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

Flask method: water solubility <0.51 µg/L at 20 °C (EU Method A6 and OECD 105 with slight deviations, GLP) 

Water solubility:

0.51 µg/L

at the temperature of:

20 °C

During the preliminary study the water solubility of the sodium form test item was estimated to be < 0.005 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 sample solution signals in the main test with the sodium form were below the limit of detection (LOD = 5.10 x 10^-7 g/L). Similarly, the water solubility of the sodium/hydrogen form was determined to be less than or equal to 7.43 x 10^-6 g/L. The substance is therefore very poorly soluble in water.

Cross-reference 2

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Mass based distribution (100 μm sieve): particle size of less than 100 μm: 1.01 - 2.92 % (EC EUR 20268, GLP)

A screening test consisting of sieving a known amount of test item with a 100 μm mesh concluded that only 2.92 % of the sodium form test item passed through the sieve and are inhalable. Only 1.01 % of the sodium/hydrogen form test item passed through the sieve and are 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.

Cross-reference 3

Reason / purpose for cross-reference:

data waiving: supporting information

Reference

Gas comparison pycnometer: relative density 2.83 - 2.97 (OECD 109, EU Method A3 with slight deviations, GLP)

Relative density at 20C:

2.83

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 in the case of a solid substance. With the exception of the test temperature, the method was followed and the density of the sodium form test item was determined to be 2.83 x 10^3 kg/m^3 at 22.4 ± 0.5 °C and to have a relative density of 2.83. The density of the sodium/hydrogen form was determined to be 2.97 x 10^3 kg/m^3 at 22.3 ± 0.5 °C and to have a relative density of 2.97.