Lead, dross

Endpoint summary

Additional information

The UVCB is a complex inorganic metals containing substance. The physico-chemical characterisation of the UVCB demonstrates the presence of different metal speciation; intermetallic and metal oxides that forms on the surface of molten lead bullion during pyrometallurgical refining of either primary or secondary lead bullion or in the production of lead containing alloys.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 (ECHA, 2017), 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 oxides in this complex UVCB, 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
As	As2O3 / AsO3	No see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)
Cd	CdO	Yes see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)
Cu	covellite	Yes see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)
Ni	Ni massive	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 Pb massive	Yes see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)
S	Metal sulphides/sulphates	See metal specific entry
Sb	Sb compounds	Yes see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)
Zn	ZnO	Yes see Waeterschoot et al (2012) and MECLAS (Annex I of this CSR)
Cr, Se	Cr, Se	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 hysic-chemical hysicerization 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 the purpose 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 and is summarised 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 REACH Consortium iUVCBs.

	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 (2016)	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)	87,096	30,000
Sediment (freshwater)	L/Kg	2239.72	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

** Values checked 2018