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Description of key information

The UVCB is a complex inorganic metals containing substance. The physico-chemical characterization of the UVCB (see relevant section in IUCLID) demonstrates the presence of different metal species.

More particularly the following needs to be taken into account when considering information on environmental fate of this UCVB:

Stability and biodegradation: The classic standard testing protocols on hydrolysis, photo-transformation and biodegradation are not applicable to inorganic substances such as this UVCB. This was recognized in the Guidance to Regulation (EC) No 1272/2008 Classification, Labelling and Packaging of substances and mixtures (metal annex): “Environmental transformation of one species of a metal to another species of the same does not constitute degradation as applied to organic compounds and may increase or decrease the availability and bioavailability of the toxic species. However as a result of naturally occurring geochemical processes metal ions can partition from the water column. Data on water column residence time, the processes involved at the water – sediment interface (i. e. deposition and re-mobilisation) are fairly extensive, but have not been integrated into a meaningful database. Nevertheless, using the principles and assumptions discussed above in Section IV.1, it may be possible to incorporate this approach into classification.

As outlined in CLP guidance (2009), understanding of the rate and extent of transformation/dissolution of sparingly soluble inorganic substances to soluble, potentially available metal species is relevant to the environmental hazard assessment.

Attenuation of the released metal ions: once released from the UVCB, the metal-ions will be sorbed to mineral and particulate organic matter surfaces in the water, sediment and soil and will bind to the dissolved organic and sulphide materials present in water, soil and sediment compartments. Binding, precipitation and partitioning allows for a reduction of "bio-available metal species" and thus potential metal toxicity as a function of time.

Transport and distribution: assessing transport and distribution of the UVCB substance has no meaning. The mechanisms of distribution over liquid/solid phase (adsorption/desorption, precipitation and removal from water column) of the metals contained in the UVCB have been assessed in the respective risk assessments and/or Chemical Safety reports. Partition coefficients for soil/water, sediment/water and suspended matter/water are available for different metals contained in the UVCB and further used for environmental exposure assessment, if relevant.

Bioaccumulation and secondary poisoning: the assessment of the bioaccumulation and secondary poisoning potential of this UVCB as no meaning. Accumulation data (BCF and BAF values) are available for relevant metal constituents of this UVCB. Metals like Cu, Zn for example are essential and well regulated in all living organisms and therefore the bioaccumulation criterion is not applicable. While some metals do not magnify in aquatic and terrestrial systems, for other metals secondary poisoning is to be considered relevant based on their known bioaccumulation potential.

According to the CLP Guidance for complex substances (section III 3.2) it is not recommended to estimate an average or weighted BCF value but identify one or more constituents for further consideration. Therefore, secondary poisoning of some constituents contained in the UVCB was further taken into account in the environmental exposure assessment.

 

Summary of the information on environmental fate and pathways for the purpose of classification:

The UVCB environmental hazard assessment fate and pathway of the UVCB is driven by the hazard assessment characteristics of the individual UVCB constituents. For the purpose of the hazard assessment, the fate and pathway of the UVCB is treated as a complex metal containing substance and therefore assessed from the fate and pathways of the discrete constituting compounds (metals, metal compounds, non-metal inorganic compounds). The hazard classifications of each compound are then factored into a combined classification of the UVCB as a whole. For environmental endpoints, additivity and/or summation algorithms are applied to quantitatively estimate the mixture’s toxicity to aquatic organisms. More information can be found in the MECLAS output (see AnnexI of the CSR).

 

Summary of the information on environmental fate and pathways for the purpose of risk assessment:

The environmental (risk) assessment is based onmeasured releases of relevant elements to air and receiving waters for all constituents of the UVCB that are hazardous to the environment. For the environment, most often, it is the metal ion that is the toxic driver (ECHA, 2008, R.7.13-2). Considering the composition and physico-chemical characterisation of this UVCB, only partial release and solubilisation of the various constituting species should be assumed in the aquatic environment. Assuming 100% solubilization into metal ion is therefore conservative as aquatic toxicity is driven by the metal ion.

To assess environmental risks for the various environmental compartments, information on the fate and pathways of the individual components are needed as described in below.

Table 21. Overview of the information on aquatic environmental fate and pathways for the purpose of risk assessment.

UVCB constituent

Transport/ distribution

Bio accumulation

Secondary poisoning

Silver

Metal ion (Ag+)

Partitioning coefficient available(silver IUCLID files)

BCF available (silver IUCLID files)

Secondary poisoning assessment not required(silver IUCLID files)

Nickel

Metal ion (Ni2+)

Partitioning coefficient available(nickel IUCLID files)

BCF available(nickel IUCLID files)

PNEC available(nickelIUCLID files)

Lead

Metal ion (Pb2+)

Partitioning coefficient available(lead IUCLID files)

BCF available(lead IUCLID files)

PNEC available(lead IUCLID files)

Zinc

Metal ion (Zn2+)

Partitioning coefficient available(zinc IUCLID files)

Not applicable as it is an essential element(zinc IUCLID files)

Secondary poisoning assessment not required(zinc IUCLID files)

Arsenic

Metal ion (As3+and As5+)

Partitioning coefficient available(diarsenic trioxide IUCLID files)

BCF available (diarsenic trioxide IUCLID files)

PNEC available(diarsenic trioxide IUCLID files)

Copper

Metal ion (Cu2+)

Partitioning coefficient available(copper IUCLID files)

Not applicable as it is an essential element(copper IUCLID files)

Secondary poisoning assessment not required(copper IUCLID files)

 

When quantitative exposure and risk assessment were conducted on a metal constituent, the environmental fate information on this individual metal is reported in the respective IUCLID endpointsummary sheet. The information is taken from the respective metal REACH IUCLID dossiers (seeseparate Annextothis CSR) and is summarizedin the table below.

Table 22. Overview of solid water partition coefficients (Kd), bioaccumulation factors and the fraction of emission directed to water by STP

Endpoint

Silver (Ag+)

Nickel (Ni2+)

Lead (Pb2+)

Zinc (Zn2+)

Arsenic (As3+, As5+)

Copper (Cu2+)

Kd Suspended matter (freshwater)

L/kg

190546

26303

295121

110000

10000

30246

Kd Suspended matter (marine)

L/kg

190546

6310

1518099

6010

ND

131826

Kd Sediment (freshwater)

L/kg

11092

7079

153848

73000

158

24409

Soil

L/kg

4023

724

6400

158.5

2512

2120

BCF/BAF (aquatic)

L/kg

70

270

1553

NA

270

NA

BCF/BAF (terrestrial)

kg/kg dw

0.62

0.3

0.39

NA

NA

NA

Removal rate STP to sludge

80.1

40

ND

ND

ND

ND

Reference

Silver IUCLID

Nickel IUCLID

Lead IUCLID

Zinc IUCLID

Diarsenic trioxide IUCLID

Copper IUCLID

ND: data not available

NA: data not applicable

Additional information

The UVCB environmental assessment is driven by the assessment of the individual UVCB constituents. The environmental assessment is based on selected ‘driving constituents’. For the environment, it is considered that it is the metal ion that is the toxic driver and that this will be the dominant form in emissions to the aquatic environment (ECHA, 2008, R.7.13-2). The parent compound of each driving constituent present in refinable substances is therefore typically not considered or relevant. Environmental fate information on the individual UVCB constituents is reported in the respective summary sheets for each constituent for which a quantitative exposure and risk assessment is conducted. The information is taken from the respective constituent IUCLID dossiers. More information on the scope of assessment for each constituent can be found in the introductions to Section 4 and Section 7 of this CSR.

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