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Environmental fate & pathways

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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 speciation; intermetallic, metal sulphates and metal oxides that are formed as a by-product from refining and smelting of lead containing materials. This resulted in relatively high solubilisation potential in water for most of the metals present in the UVCB (e. g. Cu, Ag, As).

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

Stability and bio degradation: 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.

Given the dominant presence of metal sulphates and oxides in this complex UVCB and the high solubilization potential observed for several metals, no transformation/dissolution data was carried out and a conservative approach was adopted by considering the UVCB as fully soluble in water.

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 has 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 is driven by the hazard assessment of the individual UVCB constituents. For the purpose of the hazard assessment, the UVCB is treated as a complex metal containing substance with a number of 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 Annex I of the CSR). No further specific environmental fate information on the constituents is required to directly derive the hazard of the UVCB. Since the removal from the water column behaviour of the individual constituents can have an indirect impact on their respective environmental classification, an overview is given in the table below.

 

Table17:Summary of the information on environmental fate and pathways for the purpose ofclassification

UVCB constituent

 

Attenuation/ removal from water column

Element

Speciation used for classification (see IUCLID/CSR section 1.2 composition and IUCLID 4.23 additional Physico-chemical Information)

As

As2O3/ AsO3

No

see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)

Cd

CdSO4

Yes

see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)

Cu

CuSO4

Yes

see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)

Ni

NiSO4

Yes

see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)

Pb

Lead compounds with the exception of

those specified elsewhere in Annex VI

Yes

see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)

S

Metal sulfides/sulphates

See metal specific entry

Sb

Sb compounds

Yes

see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)

Zn

ZnSO4

Yes

see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)

Cr, Se

Cr2O3, Se compounds

No

Minors

Sulphide/compounds or metal

Below 0.1% and/or the speciation not impacting classification, see MECLAS report in CSR Annex I

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

The environmental (risk) assessment is based on all classified 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, full solubilisation of the various constituting species is assumed in the aquatic environment.

 

Table18:Summary of the information on aquatic environmental fate and pathways for thepurpose of risk assessment

UVCB constituent

Transport/ distribution

Bio accumulation

Secondary poisoning

Element

Speciation used for environmental fate

 

 

 

Cu

Metal ion

Partitioning coeff. available

No

See McGeer et al., 2013

Not needed

Ni

Metal ion

Partitioning coeff. Available

BCF value available

270 L/kg ww

Quantitative assessment conducted

Pb

Metal ion

Partitioning coeff. Available

BCF value available

1,553 L/kg ww

Quantitative assessment conducted

As

Metal ion

Partitioning coeff. Available

BCF value available

270 L/kg ww

Quantitative assessment conducted

Zn

Metal ion

Partitioning coeff. Available

No

See McGeer et al., 2013

Not needed

Ag

Metal ion

Partitioning coeff. Available

BCF value available

70 L/kg ww

 

Not needed

Cd

Metal ion

Partitioning coeff. Available

No

See McGeer et al., 2013

Quantitative assessment conducted for secondary poisoning soil

Sb

Metal ion

Partitioning coeff. Available

BCF value available

40 L/kg ww

Not needed

Se

Metal ion

Partitioning coeff. Available

BCF value available

944 L/kg ww

Quantitative assessment conducted

Mo

Metal ion

Partitioning coeff. Available

Negligible

Not needed

Mn

Metal ion

Partitioning coeff. Available

Not environmentally classified and no concern for environment

Not needed

Co

Metal ion

Partitioning coeff. Available

Cobalt does not biomagnify

Not needed

When quantitative exposure and risk assessment were conducted on a metal constituent (either because part of the UVCB composition and/or relevant at site), the environmental fate information on this individual metal is reported in the respective IUCLID endpoint summary sheet. The information is taken from the respective metal REACH IUCLID dossiers (see Annex II of this CSR) and is summarized in the table below.

 

Table19:Overview of solid water partition coefficients (Kd) and the fraction of emission directed to water by STP for the Lead intermediates.

 

Unit

Cu

Pb

As

Ni

Cd

Zn

Suspended matter (freshwater)

L/Kg

30,246

295,121

10,000

26,303

130,000

110,000

Suspended matter (marine)

L/Kg

131,826

1,518,099

10,000

6,290

130,000

6,010

Sediment (freshwater)

L/Kg

24,409

153,848

6,607

7,079

130,000

73,000

Soil

L/Kg

2,120

6,400

191

724

280

158.5

Removal rate STP to sludge

%

92

84

26*

40

81

82

Reference

Cu CSR (2010)

Pb CSR (2010)

Crommentuyn et al. (1997)

Ni CSR (2010)

Cd CSR (2010)

Zn CSR (2010)

*The fraction of Arsenic removed by a biological STP was calculated by means of EUSES 2.1.

 

Unit

Sb

Se

Ag

Mo

Mn

Co

Cr

Suspended matter (freshwater)

L/Kg

4466.84

3,090

190,546

2,793

(0)

38,905

30,000

Suspended matter (marine)

L/Kg

4466.84

3,090

(0)

2,793

(0)

97,096

30,000

Sediment (freshwater)

L/Kg

2511.87

316.23

(0)

1,778

(0)

871

1,100

Soil

L/Kg

117.5

53.7

4,023

871

994

2951.21

800

Removal rate STP to sludge

%

79.1

50*

80.1

50*

(0)

40

80

Reference

Ag CSR (2010)

Sb CSR update (2011)

Se CSR (2010)

Mo CSR (2010)

Mn CSR (2010)

Co CSR (2010)

Cr CSR (2010)

* If removal rate STP to sludge is unknown, the default value of 50% is used