black copper, copper smelting

Endpoint summary

Additional information

The hazard assessment of inorganic UVCBs for the purpose of classification and derivation of fate properties and safe effect thresholds (e.g. PNEC) is a cumbersome and complex process. Due to the intrinsic variability of the composition of an UVCB, it is difficult to select a sample that would unambiguously be representative for the (eco)toxicological hazard profile of the UVCB and could subsequently be used for testing. Instead of direct testing, a precautionary approach is taken where the UVCB is treated as a complex metal containing substance containing a number of discrete constituents (metals, metal compounds, non-metal inorganic compounds etc.). For each of these constituents, the fate and hazard profile is used for deriving the proper classification of the UVCB (using the mixture rules) and/or for the derivation of the PNECs of the constituent (forwarded to the risk assessment). Using the fate of all individual constituents circumvents indirectly the issue of varying composition of an UVCB as it implicitly assumes that each time the UVCB substance consists of the pure substance, i.e. that each constituent would be present and bioavailable at a 100% concentration in the UVCB substance. This can be considered a conservative approach. A main outcome of the constituents’ based assessment is the selection of all the constituents for which any environmental hazard is identified. This selection defines the scope of the further exposure and risk assessment (CSR, Ch. 9&10).

 

The actual hazard profile and environmental fate properties of the inorganic UVCB substance and the individual constituents are dependent on the speciation of each and every constituent andhence this information needs to be collected and the correspondinginformation for the environmental fate properties will be used. Different scenarios can be encountered.

·      When the speciation of a constituent is known, this is used as such for the environmental fate properties assessment.

·      When the speciation is unknown or few metal species co-exist, the worst-case speciation for the purpose of environmental fate assessment and environmental hazard assessment is selected, i.e. the speciation that would lead to the most severe effects.

 

4.0. Introduction to environmental fate and pathways

The UVCB is a complex inorganic metals containing substance. The physico-chemical characterization of the UVCB (see relevant section in IUCLID) demonstrates the presense of different metal species; intermetallic and metal sulphides.Black copper remains molten through its whole life cycle (with the exception of routine process sampling). Black Copper may however be cooled down to ambient temperature and solidified for the purpose of transporting over longer distance (eg import into Europe or transport between different legal entities). In the later cases, black copper is as granules with typicallyD80 >3000µm and fraction of particle size smaller than 0.01mm is below 0.2%. This results inrelatively low solubilisation potential in water for most of the metals present in the UVCB (e.g. Cu, Pb, As) when crushed materials were tested (see Liipo, 2010).

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.

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 (adsoprtion/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 bio accumulation 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.