Flue dust, copper-refining

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

7.8 µg/L

Assessment factor:

1

Extrapolation method:

sensitivity distribution

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

5.2 µg/L

Assessment factor:

1

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

230 µg/L

Assessment factor:

1

Extrapolation method:

sensitivity distribution

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

87 mg/kg sediment dw

Assessment factor:

1

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

676 mg/kg sediment dw

Assessment factor:

1

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

65 mg/kg soil dw

Assessment factor:

1

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Additional information

Justification for absence of bioaccumulation potential and no-concern for secondary poisoning, is summarized below 

The copper Risk Assessment Report (2008) and REACH Chemical Safety Report (2010) have provided detailed information on (1) the essentiality of copper; (2) the homeostatic control of copper; (3) the mechanisms of action of copper-ions; (4) the comparison between copper toxicity from dietary versus waterborne exposures.

The data clearly demonstrate that:

-         Copper is an essential nutrient for all living organisms

-         Copper ions are homeostatically controlled in all organisms and the control efficiencies increase with trophic chain. As a consequence,

o  copper BCF/BAF values  decrease with increasing exposure concentrations (water and food), vary depending on nutritional needs (seasonal, life stage, species dependent),  vary pending on “internal detoxification” mechanisms

o  Copper BMFs values are < 1

-         Water-borne exposure (not diet borne exposure) is the exposure route critical to copper toxicity

Essential trace element : Copper is an essential micronutrient, needed for optimal growth and development of micro-organisms, plants, animals and humans. It plays a vital role in the physiology of animals: for foetal growth and early post-natal development, for haemoglobin synthesis, connective tissue maturation especially in the cardiovascular system and in bones, for proper nerve function and bone development, and inflammatory processes. Copper acts as an active cofactor in over 20 enzymes and proteins, notably the respiratory enzymes haemocyanin and cytochrome oxidase and the anti-oxidant superoxide dismutase (WHO, 1998).   Copper deficiency has been observed in intensive cultures of fish, crops and farm animals. The most striking examples of copper deficiency come from farming practices. Insufficient bioavailable copper in soils has been shown to reduce agricultural yields and to produce metabolic copper deficiencies in animals. Copper deficiency was first recognised in Europe in the 1930s and its incidence increased with the intensification of arable farming over the last 50 years. Copper deficiency has also been noted in a wide variety of soils world-wide (IPCS 1998).  Depending on the organism’s metabolic need, different copper levels are found in tissues from different strains, species and life stages. 

Differences among species and strains:Aquatic invertebrates such as gastropods, some crustacea and bivalves, relying on haemoocyanin as respiratory pigment, have typically higher copper levels than invertebrates relying on haemoglobin as respiratory pigment (e.g. Timmermans et al, 1989).  In higher organisms (vertebrates), homeostatic control of copper supply is achieved mainly by storage in the liver and biliary secretion (Underwood and Suttle, 1999). Copper is bound to proteins such as ceruloplasmin and metallothionenin, functioning as copper storage and mobilised as needed.

Differences within species: Of all factors that affect the physiology of animals, body size exerts the major effect and provides an integrated value of all physiological processes (Marsden and Rainbow, 2004). In aquatic environments, several investigators demonstrated an inverse relation between copper tissue levels and the length or weight of the organisms (e.g. Timmermans et al, 1989).  Different copper needs are of relevance to both agricultural and medical practices: Copper supplements are provided to piglets and pigs to enhance growth. Considering the high needs during the fast growth stages, copper levels given to piglets are much higher than those given to adult pigs. The copper concentration in the liver of a mammalian and human foetus is much higher during the last term of pregnancy than in an adult. This is because of the high copper need during this period, as well as during the first months after birth, and because breast milk contains little copper. Consequently, the milk formulae for premature babies contain higher copper levels than those for newborns.

In summary, as an essential element, all organisms will naturally accumulate copper without deleterious effects. Different levels of accumulation in tissue reflect differences in nutritional needs.    

Homeostatic control, uptake and depuration of copper ions The natural copper levels, available for plants, micro-organisms and animals, living in a specific environment, depend on the natural geological and physico-chemical characteristics of the water, sediments and soils. Homeostatic regulation of copper allows organisms, within certain limits, to maintain the physiologically required levels of copper in their various tissues, both at low and high copper intakes.  The molecular mechanism of copper homeostasis is related to 2 key elements: P-type ATPases that can pump copper across biological membranes in either direction or copper chaperones, important for intracellular copper homeostasis (Odermatt et al, 1992). The latter is considered to be universal as the sequences of copper chaperones are highly conserved between species (Wunderli et al. 1999). Besides these active cellular regulation mechanisms, some groups of organisms have developed additional mechanisms (molecular binding to e.g. metallo-thioneins and sequestration in granules) to prevent copper excess (Borgmann, 1993 and Rainbow, 1980, 1985, 1989; Marsden and Rainbow, 2004). Vertebrate dietary copper exposure studies (fish, mammals, birds and humans) demonstrate additional organ-related homeostasis. Intestinal adsorption/biliary excretion of copper is regulated with varying dietary intakes (WHO, 1998).  Due to the homeostatic regulation of copper (and other metals),/BAFs are not independent of exposure concentration (e.g. Mc Geer et al., 2003). Increased/decreased copper intakes/eliminations, lead to BCFs and BAFs that are inversely related to exposure concentration (i. e. decreasing/BAFs with increasing exposure concentration (water and diet). For copper, this inverse relationship was clearly demonstrated for BCFs, BAFs and biota-sediment accumulation factors (BSAFs) (Adams et al., 2003). The observed inverse relationship has been explained by homeostatic regulations of internal tissue concentrations At low metal concentrations, organisms are actively accumulating metals in order to meet their metabolic requirements, while at high ambient metal concentrations, organisms are able to excrete excess metals or limit uptake. Additionally, different BCFs for different species, life stages and seasons have been observed, depending on the organism’s metabolic need (in e.g. Cu-enzymes). Further complicating the application of BCF and BAF to metals is that many aquatic organisms store metals in detoxified forms, such as in inorganic granules or bound to metallothionein-like proteins. The use of granules is of particular note in the context of BCFs, because high body burdens are often associated with this storage mechanism, but there is a lack of adverse effects. Using BCF and BAF for essential metals and their compounds to assess ecotoxicity therefore ignores fundamental physicochemical and toxicological properties associated with these substances.

Compared with the diffusional uptake of neutral organics, metal uptake is complex. It includes a diversity of mechanisms, accumulation of both essential and non-essential elements from the natural background, homeostatic control of accumulation, as well as internal detoxification, storage and elimination.[1]  

Mechanism of action of copper toxicity/deficiency

Freshwater From the copper risk assessment, it was clearly concluded that the most sensitive uptake route for acute and chronic copper toxicity is directly from the water with free Cu-ions as most potent Cu-species. The key indicator of copper toxicity is disturbance of the sodium homeostasis (e.g. Paquin et al., 2002; De Schamphelaere and Janssen, 2003; Kamunde et al., 2001 & 2005). The key target tissue for copper toxicity is therefore the water/organism interface, with cell wall and gill-like surfaces acting as target biotic ligands in all species investigated. The importance of water-borne exposure was confirmed from the freshwater chronic ecotoxicity database, demonstrating: ·           The influence of water chemistry on chronic copper toxicities (influence of DOC, pH,... on chronic NOECs)

·           The small inter-species variability in observed NOECs (after BLM normalisation) (max/min NOEC ratio of 23 for 27 species),

·           Small acute to chronic ratios (typically a factor of 1 to 3)

·           Higher sensitivity of smaller compared to larger organisms (Grosel et al., 2007).

·           No concern of secondary poisoning from copper mesocosm studies:

·           Roussel (2007) reported for a lentic mesosocm study a low sensitivity of the predating fish compared to the invertebrates and algae.

·           The freshwater pond mesocosms (Schaefers et al, 2002 and Rousel (2007) and the marine pond mesocosm (Foekema et al 2010) did not show a concern from copper secondary poisoning.       

Marine     Freshwater and marine organisms face very different ion- and osmo-regulatory problems related to living in either a very dilute or concentrated salt environment. These differences in ion- and osmo-regulatory physiology may also lead to differences in metal accumulation and metal toxicity (Prosser, 1991; Wright 1995; Rainbow, 2002). Marine organisms are, as freshwater organisms, also exposed via the gills. But in addition, they take in water via the gut exposing an additional series of epithelial structures to the metals (Wang and Fisher 1998; Glover et al 2003; Mouneyrac et al 2003). Both the epithelia of gills and gut are thus important and potentially sensitive targets because they provide a variety of essential physiological functions such as the energy dependent transport of nutrients across the interface and the maintenance of homeostatic balance. Despite these apparent physiological differences, it has been shown that marine fish also suffer from osmo-regulatory disturbances under metal exposure.  The importance of waterborne exposure was confirmed from marine ecotoxicity databases, demonstrating:

·           The mitigating effect of DOC on the marine NOECs/EC10s.

·           The absence of a higher copper sensitivity with increasing trophic chain level.

·           For the bivalve Mytilus edulis, the short term (48 hrs) early life stage NOEC was similar to the 10 days growth inhibition NOEC. The 83 days marine mesocosm study (Foekema et al., 2010), furthermore showed that the safe level in the mesocosm could be predicted from the single-species SSD and DOC correction, developed for water-only exposure.

The interaction between free copper-ions and “gill-like structures” induce osmo-regulatory stress. Osmo-regulatory disturbance from waterborne exposure is recognised as the primary symptom of copper toxicity to aquatic organisms.    

Copper toxicity from dietary versus waterborne exposures 

Invertebrates:A few key studies are available:

- De Schamphelaere and Janssen (2003) demonstrated the influence of water characteristics on the chronic toxicity of D. magna and showed that, for D. magna, waterborne copper and not dietary copper uptake is responsible for copper toxicity (De Schamphelaere and Janssen, 2004).

- Similarly, Allinson (2002) investigated the bioaccumulation of copper through a simple food chain (Lemna minor – C. destructor) and observed regulation of copper by the crayfish, C. destructor, with the gills being the main site for absorption and depuration of copper to and from the water column. C. destructor does not appear to be sensitive to dietary copper.

Fish: 

- Kamunde, 2001 observed that dietary copper pre-exposure decreased the uptake of copper across the gills, providing further evidence of homeostatic interaction between the two routes of uptake. Rainbow trout regulated dietary copper at the level of the gut by increasing clearance to other tissues, at the liver by increasing biliary copper excretion, and at the gill by reducing waterborne copper uptake in response to dietary exposure. The modest morphological changes in the intestinal tract suggested high cell and organelle turnover and local regulation of copper. In spite of possible increased energy demand for regulation and tissue repair, there was no significant growth inhibitory effect following dietary exposure.

- Blust et al., 2007, reviewed the literature on copper toxicity after dietary copper exposures of fish and compared waterborne versus diet borne toxicity of copper to fish. After detailed evaluation of the Clearwater et al., 2002 review paper, Blust derived critical diet borne toxicity effects value for Atlantic salmon and Rainbow trout of respectively 15.5 and 44 mg Cu/kg fresh weight/day. Blust et al, 2007 further assessed if the waterborne exposures, PNEC of 7.8 µg Cu//l, as derived in the copper risk assessment, would result in a dietary copper dose or copper food concentration exceeding a critical level. The concentrations in food were calculated from the regressions presented in McGeer et al. (2003) which allow the estimation of the whole body copper concentration, for different types of aquatic organisms, as a function of the copper waterborne concentration. The results of the simulations show that aquatic invertebrates exposed to 8µg Cu/l waterborne copper reach mean Cu body levels of 53-84 mg Cu/kg dry weight (depending on the diet). The resulting daily uptake by fish at 7.8 µg Cu/L was < 4.20 mg Cu/kg fresh weight/day. These results lead to the conclusion that the copper concentrations in food items and daily dietary copper dose in fish are unlikely to cause negative effects at the threshold waterborne copper concentration of 7.8 µg/l.

Comparison of the dietary copper levels and “normal” background Cu levels in live food items Cu is a naturally occurring element and is essential to all living organisms. Naturally, a background Cu burden is present in all organisms to fulfil their biochemical requirements. Table 1 presents a summary of a few ‘background’ Cu concentrations in freshwater biota that may serve as food items for fish.

 

Table: Background Cu burdens of selected freshwater biota that may be considered food items for fish. Species

Species	CuH2O (µg/L)	Cufood (mg/kg dry wt)	Reference
Daphnia magna(adults)	1	10.2 - 22.1	Bossuyt et al. (2005a,b)^a
Daphnia magna(juveniles)	1	20 - 120	Bossuyt et al. (2005a,b)^a
Hyalella azteca	3.5	79	Borgmann et al. (1993)

    ^aFifth or 6^thgeneration daphnids taken from a multi-generation exposure; 1µg/L was sufficient to avoid deficiency  

Bossuyt et al. (2005a, b) reported background body burdens of 40d-old D. magna at 1 µg Cu/L between 10.2 and 22.1 mg Cu ∙ kg-1 dry wt. Juvenile daphnids of up to 2 days old seemed to have higher copper body burdens between 20 and 120 mg Cu ∙ kg-1 dry wt.

 Borgmann et al. (1993) report a Cu burden in Hyalella. azteca of 79 mg Cu ∙ kg-1 dry wt in organisms exposed to control conditions, i.e. 3.5 µg Cu/L.

The background copper burdens (10 - 120 mg Cu/kg dry weight) as determined above, furthermore encompass the simulated Cu body levels of 53 - 84 mg Cu/kg dry weight calculated for aquatic invertebrates exposed to 8 µg Cu/l waterborne copper and therefore provide additional evidence that the Cu concentrations in food items and daily dietary Cu dose in fish are unlikely to cause negative effects at the threshold waterborne Cu concentration of 8 µg/l.   

Waterborne Cu is therefore recognised as the critical copper exposure route for invertebrates and fish.

Critical papers of relevance to bio-magnification   The absence of copper bio-magnification, with consistent BMFs < 1, was shown from several papers:

- Barwick and Maher (2003), compared trace metal levels in a contaminated seagrass ecosystem in Lake Macquire, the largest estuary in New South Wales (Australia). The structure of the estuarine food web was studied in detail and all organisms (algae, invertebrates, fish) were categorised as autotrophs, herbivores, planktivores, detrivores, omnivores and carnivores. The results of the analysis showed the absence of copper bio-magnificationin this estuarine system. Copper concentrations ranged between 0.27 µg Cu/g dw (Omnivore: Monacanthus and 88 µg Cu/g dw (Herbivore: Bembicum auratum (gastropod with haemocyanin)). The higher levels (e.g. B. auratum) were associated with species with active accumulation of copper into the respiratory pigment haemocyanin.

- Farag et al., 1998, studied copper concentration in benthic invertebrates that represent various functional groups and sizes from de Coeur d’Alene river,, influenced by mining activities. The copper concentrations noted across the trophic chain, demonstrated the absence of bio-magnification from the sediment to herbivores, omnivores, detrivores and carnivores.

- Wang (2002) noted the bio-diminution of metals in the classical marine planktonic food chain (phytoplankton to copepods to fish) and explained the phenomenon as the result of the effective efflux of metals by copepods and the low assimilation of metals by marine fish.

- Quinn et al., 2003, evaluated trophic chain transfer of metals in insects (35 species) from a stream food web influenced by acid mine drainage with copper levels up to 100 µg Cu/L. They demonstrated that metal concentrations were higher in water and insects closer to the mining sites and taxa richness increased with distance away from the site. The relation between the trophic positions, determined from15N radio isotope determination, indicated that the trophic chain had no effect on copper levels in the insects.

Copper is therefore not bio-magnified across the trophic chain.  

Conclusion There is a substantial amount of information available on copper. The data clearly demonstrate that:

·           Copper is an essential nutrient for all living organisms

·           Copper ions are homeostatically controlled in all organisms and the control efficiencies increase with trophic chain. As a consequence, copper BCF/BAF values ·           decrease with increasing exposure concentrations (water and food), vary depending on the nutritional needs (seasonal, life stage, species dependent), vary pending on “internal detoxification” mechanisms

·          Copper BMFs values are < 1

·           Copper waterborne exposure (and not diet borne exposure) is the exposure route critical to copper toxicity  
[1]Mc Geer et al, 2010. From : http://www.icmm.com/page/1321/environmental-fact-sheet-8-the-use-of-bioaccumulation-criteria-for-hazard-identification-of-metals

Conclusion on classification

The classification of the various copper forms for environmental hazards is summarized below. It is explained in detail in the attached reports:

"Environmental hazard classification of copper";

"Derivation of acute ERVs for copper" + excel database;

"Derivation of chronic ERVs for copper" + excel database.

All reports and excel sheets are attached to the IUCLID (to the endpoint summary "Ecotoxicological information").

The environmental classification of the various copper forms, discussed below, follow the European CLP Regulation and its ATPs (adaptations to technical progress). They are based on acute and chronic toxicity thresholds, transformation-dissolution data in relevant environmental media, and taking into account the degradability potential. Special guidance is available for the environmental classification of metals and metal compounds.

 

In accordance with the CLP guidance (version 4.1, 2015), ecotoxicity data of soluble inorganic compounds are combined to define the toxicity of the dissolved metal. Classification of metals is based on comparing the soluble metal concentration, measured after Transformation/Dissolution (T/D) testing, with the ecotoxicity reference values (ERVs) of the corresponding metal ion. The CLP guidance recognizes that, for inorganic compounds and metals, the concept of degradability, as commonly applied to organic substances, has limited or no meaning. Some discussions and guidance on “metal removal”, as equivalent to the “degradation of organic substances”, is available fromthe Annex IV.3 - CLP guidance v4.1 (2015) and v2009.

 

For the classification of copper for environmental hazards, the following overall strategy was therefore adopted:

1. The potential for ‘rapid removal from the water column’ of copper ions has been evaluated in accordance with the CLP guidance (version 4.1 (2015) and version 2009), by assessing the removal rates of copper ions through partitioning and their subsequent potential for sediment mineralization/remobilization.
2. The acute and chronic ERVs for copper ions were derived. All high-quality data from tests performed with soluble copper compounds were combined and expressed as dissolved Cu concentration (μg dissolved Cu/L).
3. Transformation/dissolution tests were performed using a surface-based concept. This implies that the release of copper from a material depends on the exposed surface area. The copper release in transformation-dissolution tests was therefore expressed per unit surface area.

 

Finally, the environmental hazard of each copper form is derived. The specific surface area of the finest particles of each form was used to convert the release per unit surface to the release in transformation-dissolution test at a mass loading of 1 mg/L (as prescribed by the CLP and its guidance). These release values are finally compared to the acute and chronic ERVs, and environmental classifications are derived in accordance with the CLP.

1       Degradation and rapid removal from the water column

The information on “rapid removal from the water-column and absence of remobilization”, as equivalent to ‘degradation of organic substances”, was assessed, following the CLP guidance, version 4.1 (2015) and the version 2009^[1]. The CLP guidance (metal section) mentionsthat “naturally occurring geochemical processesof partitioning/precipitation and speciation may remove metal ions from the water column” and that it may be possible to incorporate this approach into the classification for chronic environmental hazard. This metal ion removal concept for metals and its application for chronic environmental classification was discussed at ECHA workshops (Feb 2012 and August 2016).

 

During discussions on the harmonized classification of coated copper flakes and copper compounds by ECHA’s Risk Assessment Committee (RAC) (December 2014), the rapid removal concept was not recognized for copper. RAC acknowledged the evidence provided but mentioned the uncertainty related to some parameters of the Unit World Model, did not consider the MELIMEX system as worst-case, and pointed at the lack of data on specific aquatic systems (e.g. systems with little sediment, high turbulence, great depth, oxic sediment, or sediments with existing metal contamination).

 

During the August 2016 “Metals framework workshop” by Eurometaux and ECHA, ECHA confirmed that “no follow‐up of the 2012 workshop was organised. However, there is interest to re‐start the discussion. A couple of aspects should however be clarified first. ECHA will discuss internally timings/ways forward related to planning and resources.”

 

During and after the consideration by RAC, additional evidence on the rapid removal of copper has been gathered, and new data have emerged. For copper, the large weight of evidence obtained from laboratory experiments, field data and fate modelling exercises demonstrate that under most environmentally relevant conditions, copper ions are rapidly removed from the water column through partitioning and settling to sediments. Further processes at the water-sediment interface ensure the continuous formation of insoluble, unavailable Cu-species (e.g. copper sulphides). Experimental data further demonstrate that remobilisation of copper ions from lake and river sediments to aqueous phases is not expected, not even during re-suspension and long-term oxygenation of sediments. All available evidence, including the newly added studies, is presented in the report “Environmental hazard classification of copper” which is attached to the IUCLID dossier (endpoint summary “ecotoxicological information”). The assessment is based on the following lines of evidence:

•        the intrinsic properties that drive partitioning and speciation to nontoxic copper species;

•        quantification of the removal rates from laboratory and field experiments and monitoring data relevant to partitioning under a range of environmentally relevant conditions and

•        quantification of the irreversible changes in speciation in sediments (to less soluble, non-available forms), under a range of environmentally relevant conditions.

A major part of the evidence is also presented in section 4 of the CSR, because it is also relevant with regards to the environmental fate properties of copper.

 

In summary, the combined scientific data support the view that that under “environmentally relevant” conditions, copper-ions are rapidly removed from the water-column andthe processes involved at the water – sediment interface result in“irreversible” change in speciation to insoluble/non-available forms. This allows to conclude that copper ions are rapidly removed from the water-column, equivalent to the “biodegradability” of organic substances, and consistent with the metal-specific guidance and the conclusions from the Feb 2012 ECHA workshop.

 

2   Derivation of ecotoxicity reference values of copper ions

 

The effects of copper in the aquatic environment are determined by the release of soluble copper ions. Therefore, the copper ecotoxicity reference values (ERVs) are expressed as dissolved copper concentrations. The derivation of copper ERVs is described extensively in two separate reports (titled “Derivation of acute Ecotoxicity Reference Values (ERVs) for copper” and “Derivation of chronic Ecotoxicity Reference Values (ERVs) for copper”). Both reports are attached to the IUCLID file (endpoint summary “ecotoxicological information”), and the ecotoxicity studies mentioned therein are added as entries in the IUCLID file. The main points are summarized here.

 

The ecotoxicity database from the Copper Voluntary Risk Assessment, which included studies up to 2005 and which was agreed by SCHER and TCNES, was used as a starting point. For reasons of consistency, this database was maintained and supplemented with additional data. New studies from 2006 onwards were identified through dedicated searches in the scientific literature. All available ecotoxicity data on soluble copper compounds were compiled, and the results (EC₅₀for acute ERV derivation, NOEC or EC₁₀values for chronic ERV derivation) were expressed as dissolved Cu. After a data quality assessment and applying relevance criteria (e.g. standard OECD species, endpoints, test durations and test media), the high quality acute L(E)C₅₀values and chronic NOEC/EC₁₀values were retained.

 

The updated acute ecotoxicity database contains 785 high quality data points; the updated chronic ecotoxicity database contains 190 high quality data points. Acute data are available for 3 algal species, 2 invertebrate species, and 5 fish species. Chronic data are available for 4 algal/aquatic plant species, 2 invertebrate species, and 3 fish species.

 

Given the data-richness of the copper dataset, the data were split according to pH as described in the CLP guidance. The lowest species-specific acute L(E)C₅₀and chronic NOEC/EC₁₀values at each pH were selected as final ERV. Data-summaries were carried out in accordance with the CLP guidance. Due to the extensive copper ecotoxicity dataset, geometric mean values were calculated if more than 4 data-points were available for the same species across all pH bands and endpoints.The derived acute and chronic ERVs for dissolved copper are provided in the table below

 

Acute and chronic reference values for soluble copper ions

 

pH 6	pH 7	pH 8		pH 6	pH 7	pH 8
12.1	14.0	40.0		11.4	6.3	12.6

 

It must be noted that the chronic ERV at pH 7 was based on data for C. dubia (a nonstandard species in the EU) and on tests that did not meet the validity criterion of the protocol. However, for reasons of consistency with the Copper Voluntary Risk Assessment, this value was kept. Further information is available in the report “Derivation of chronic Ecotoxicity Reference Values (ERVs) for copper”, which is attached to the IUCLID file (endpoint summary “ecotoxicological information”).

 

3   Transformation-dissolution of copper

 

Copper metal (Cu°) is insoluble and needs to be transformed to solubilised (dissolved) species in order to be available to the aquatic environment. Therefore, transformation-dissolution tests were conducted according to the GHS protocol (GHS, 6^thedition, Annex 10) and are subsequently used for assessing the environmental hazard of copper.

 

The available studies on transformation-dissolution of copper are discussed in the report “Environmental hazard classification of copper” which is attached to the IUCLID dossier (endpoint summary “ecotoxicological information”).Given the relevance to the environmental fate properties of copper, they are also discussed in section 4 of the CSR. The individual transformation-dissolution studies are attached to the IUCLID dossier under “Additional information on environmental fate and behaviour”, and they are summarized in the table in section 4 of the Chemical Safety Report (CSR).

 

The various transformation-dissolution experiments have different pH (6, 7, or 8), duration (7 or 28 days), copper forms tested (massive copper, coarse powders, or fine powders), experimental set-ups (materials testedas suchor embedded in epoxy resin), and loadings (expressed per unit mass or per unit exposed surface area). The results show that the release of copper depends on the exposed surface area. Therefore, all results are expressed as a release per unit surface area. Guiding principles have been established to determine how to select the most reliable transformation-dissolution data for each form of copper, and the selection of appropriate transformation-dissolution data is discussed separately for each copper form.

 

4   Classification of copper for environmental hazards

 

The classification of copper for environmental hazards is discussed in detail in the report “The environmental hazard classification of copper” which is attached to the IUCLID dossier(endpoint summary “ecotoxicological information”). The information is summarized here.

 

Evaluation of the acute and long term aquatic toxicity for the various forms of copper is accomplished by comparison of:

•        The concentrations of the metal ions in solution, produced during transformation-dissolution in a standard aqueous medium, with

•        Appropriate ecotoxicity reference values (ERVs) as determined from tests carried out with the soluble metal species (acute and chronic values), and

•        Taking into account the information on rapid removal from the water column.

 

The transformation-dissolution and the ecotoxicity of copper metal depend on pH. Therefore, in accordance with the CLP guidance (v. 4.1, Annex IV.4.2, p. 586), ERVs and transformation-dissolution data are always compared at the same pH. This implies that the transformation-dissolution at pH 6 is compared to the ERV at pH 6, the transformation-dissolution at pH 7 is compared to the ERV at pH 7, and the transformation-dissolution at pH 8 is compared to the ERV at pH 8. The worst-case classification entry across pHs is then finally used for classification.

 

4.1   Forms of copperconsidered for environmental classification

 

As discussed in section 1, four forms of copper are considered for environmental classification.

 

Copper massive is defined as having a specific surface area (SSA) below 0.67 mm²/mg. This definition is based on previous discussions on the environmental classification of metals, which originate from a 1995 debate on zinc. The concept of different classification entries for different forms of the same substance was then accepted, based on the recognition that the release per surface in transformation-dissolution is a physical constant and therefore an intrinsic property that could be used for classification. The policy debate at EU, but later also at UN level, indicated that separate classification entries for metals substances were justified. A default value of 1 mm was assumed to distinguish between two forms (powders and massives). The 1 mm was defined based on an ISO recommendation as the lower limit for massive, but had no other meaning than being a default for the purposes of classification. Assuming spherical particles of pure copper (density 8.96 mg/mm³), this corresponds to a specific surface area of 0.67 mm²/mg. The environmental classification of copper massive is therefore derived assuming a worst-case SSA equal to 0.67 mm²/mg.

 

Copper powders span a wide range of specific surface areas (SSA) and particle sizes. Since a wealth of transformation-dissolution data is available to demonstrate copper release from various forms of copper powders (coarse versus fine powders, seeTable25), it is appropriate to assess the environmental hazard of coarse and fine copper powder forms separately. It is increasingly realized that different environmental classifications for different forms of the same substance may be necessary (for example, see guidance on nanoforms by ECHA, JRC and RIVM, 2016). For copper, ample data are available on release in transformation-dissolution tests, measured at various surface loadings and using a surface area dependent concept. Therefore, we propose to use the critical surface area concept to distinguish the classifications of coarse and fine powders.Copper powder A is defined here as fine copper powder having a SSA above 9.1 mm²/mg, which corresponds to spherical particles with diameters of 10 µm. A reasonable worst case, very fine powder with particle size of 10 µm diameter is used as the basis for the environmental classification of copper powder A. Assuming spherical particles, this value corresponds to a SSA of 67 mm²/mg. This SSA is in line with the measurements for a very fine copper powder by different techniques (47—107 mm²/mg, depending on the analytical technique, Skeaff & Hardy, 2005) and is therefore a reasonable worst case value. Copper powder B is defined as coarse copper powder with SSA between 0.67 and 9.1 mm²/mg. This corresponds to spherical particles with diameters between 1 mm and 74 µm. The environmental classification of copper powder B is based on transformation-dissolution tests and assumes a worst-case SSA of 9.1 mm²/mg. The 9.1 mm²/mg cut-off between both powder forms was selected based on the critical surface area for copper powder to obtain classification for acute environmental hazards (Acute 1). The critical surface area concept is further explained in section 4.2.

 

Coated copper flakes are produced by a very specific production process, which yields fine flakes, characterized by a high surface area and organic coating. The normal handling and use of copper massive and powder does not produce such flakes. Coated copper flakes have received a harmonized classification through the 9^thAdaptation to Technical Progress (ATP). The CLH entry does not contain the CAS and EC numbers of copper. This recognizes that, in fact, the coated copper flakes are a separate substance due to their coating with aliphatic acid. It seems evident, therefore, that coated copper flakes from should be removed from the copper REACH dossier. The removal of coated copper flakes from the copper REACH dossier is currently being evaluated and may be implemented through the next update of the CSR.

 

4.2   The critical surface area for environmental hazard classification

 

The copper release from various copper forms, as measured in transformation-dissolution tests, depends on the exposed surface area. This release is then compared to the copper ERVs to derive an environmental classification for acute and long-term hazards. From the above, if follows that a specific surface area (SSA) can be calculated which constitutes the threshold between different classifications for environmental hazards. In other words, a copper form with a SSA above the threshold would merit a certain classification, whereas a copper form with SSA below the threshold would not merit that classification. This threshold is termed the “critical surface area”. The use of the transformation-dissolution data for environmental classification, and for deriving critical surface area thresholds, is outlined below in detail.

 

1.         We know how much copper is released (in transformation-dissolution tests at a mass loading of 1 mg/L) per unit of surface area of metallic copper (expressed as μg/mm²).

2.         For any copper object, its surface area, volume, mass and specific surface (surface area per unit of mass) can be calculated.

3.         From 1 and 2, the total copper released from any copper shape in transformation-dissolution can be predicted (in µg copper).

4.         Since the loading is fixed at 1 mg/L, the volume of the virtual assay (in litre, L) is also known (one litre for each milligram of copper). Obviously, for large copper forms (low specific surface area) the transformation-dissolution test cannot be practically executed, since extremely large assay volumes would be required. However, this is not necessary since we can use the copper release per unit surface area to predict the total release for any size and shape of known dimensions.

5.         From 3 and 4, the final copper concentration can be derived (in µg Cu/L). This is the value to be compared with the corresponding ERV to determine whether the metal classifies or not.

6.         This methodological approach allows to predict, for any given ERV, at what level of specific surface area (in mm²/mg) the copper concentration released in transformation-dissolution tests would reach the ERV. Thus, one can set critical thresholds of specific surface area which are the boundaries between two different classifications for environmental hazards.

 

This approach is followed to define different copper forms with different environmental classification. For the distinction between copper powder A and copper powder B, the limit of 9.1 mm²/mg has been derived based on this critical surface area approach (see section 4.4). It is the limit above which copper powders merit Acute 1 classification, but below which they do not merit classification for acute environmental hazard.

 

The critical surface area between “no classification for environmental hazard” and “Chronic 3 classification; no acute classification”, according to the above approach, is 1.3 mm²/mg for copper (see details in section 4.3). This is fairly close to the default limit between copper massive and copper powder B (0.67 mm²/mg, equivalent to spheres with 1 mm diameter). For reasons of consistency, the “default” limit has been used to distinguish between copper massive and copper powder B.

 

4.3   Classification of copper massive for environmental hazards

 

Transformation-dissolution data

 

The following transformation-dissolution data were identified as the most reliable data for classification of copper massive (specific surface area 0.67 mm²/mg) for environmental hazards (see section 4 of the CSR and attached report “The environmental hazard classification of copper”):

 

At pH 6 after 7 days: 1.5 µg Cu/mm²* 0.67 mm²/mg * 1 mg/L = 1.0 µg dissolved Cu/L released

At pH 6 after 28 days: 5.0 µg Cu/mm²* 0.67 mm²/mg * 1 mg/L = 3.4 µg dissolved Cu/L released

 

These data assume a mass loading of 1 mg/L and a worst case (finest) copper massive particle of 0.67 mm²/mg.

 

Acute environmental hazard classification for copper massive

 

At pH 6, the copper release after 7 days transformation-dissolution at a mass loading of 1 mg/L (1.0 µg Cu/L) is below the acute ERV at pH 6 (12.1 µg Cu/L). The copper release at pH 6 is, as worst-case assumption, also compared to the acute ERVs at pH 7 (14.0 µg/L) and at pH 8 (40.0 µg/L). The copper release is in both cases lower than the corresponding ERV.

 

Therefore, copper massive does not merit classification for acute environmental hazard.

 

Chronic environmental hazard classification for copper massive

 

At pH 6, the copper release after 28 days transformation-dissolution at a mass loading of 1 mg/L (3.4 µg Cu/L) is below the chronic ERV at pH 6 (11.4 µg Cu/L). The copper release at pH 6 can, as worst-case assumption, also be compared to the chronic ERVs at pH 7 (6.3 µg/L) and at pH 8 (12.6 µg/L). The copper release is in both cases lower than the ERV.

 

Therefore, copper massive does not merit classification for long-term environmental hazard.

 

From the information in section 1, copper can be considered as rapidly removed from the water column, but this does not affect the conclusions.

 

It must be noted that, from the available transformation-dissolution data for copper massive, the critical surface area for “no environmental classification” can be derived. The 28-day transformation-dissolution release from a copper form would equal the chronic ERV at pH 7 if that copper form had a SSA equal to (6.3 µg/L) / (5.0 µg/mm²) / (1 mg/L) = 1.3 mm²/mg. A similar calculation at other pH values, and comparing 7-day releases to acute ERVs, shows that the above SSA is the lowest SSA to trigger any classification. Therefore, the critical surface area for no classification for environmental hazards is 1.3 mm²/mg. Copper forms with SSA above this value would obtain Chronic 3 classification.

 

4.4   Classification of copper powders A and B for environmental hazards

 

Transformation-dissolution data selection

 

Copper powder A (fine)

 

The following transformation-dissolution data were identified as the most reliable data for classification ofcopper powder A (specific surface area above 9.1mm²/mg)for environmental hazards (details: see section 4 of the CSR and attached report “The environmental hazard classification of copper”).

 

These data assume a mass loading of 1 mg/L and the specific surface area of a very fine representative powder (67 mm2/mg).

At pH 6, after 7 days: 0.41 µg Cu/mm²* 67 mm²/mg * 1 mg/L = 27.5 µg Cu/L released

• At pH 7, after 7 days: 0.19 µg Cu/mm²* 67 mm²/mg * 1 mg/L = 12.7 µg Cu/L released
• At pH 8, after 7 days: 0.13 µg Cu/mm²* 67 mm²/mg * 1 mg/L = 8.7 µg Cu/L released
• At pH 6, after 28 days: 27.5 µg/L * 4 = 110 µg Cu/L released
• At pH 7, after 28 days: 12.7 µg/L * 4 = 50.8 µg Cu/L released
• At pH 8, after 28 days: 8.7 µg/L * 4 = 34.8 µg Cu/L released

 

Copper powder B (coarse)

 

The following transformation-dissolution data were identified as the most reliable data for classification ofcopper powder B (specific surface area 0.67—9.1 mm²/mg)for environmental hazards (details: see section 4 of the CSR and attached report “The environmental hazard classification of copper”).

 

These data assume a mass loading of 1 mg/L and a worst case (finest) copper powder B particle of 9.1 mm²/mg.

• At pH 6, after 7 days: 1.3 µg Cu/mm²* 9.1 mm²/mg * 1 mg/L = 11.8 µg Cu/L released
• At pH 7, after 7 days: 0.88 µg Cu/mm²* 9.1 mm²/mg * 1 mg/L = 8.0 µg Cu/L released
• At pH 8, after 7 days: 0.45 µg Cu/mm²* 9.1 mm²/mg * 1 mg/L = 4.1 µg Cu/L released
• At pH 6, after 28 days: 5.0 µg Cu/mm²* 9.1 mm²/mg * 1 mg/L = 45.5 µg Cu/L released
• At pH 7, after 28 days: 3.3 µg Cu/mm²* 9.1 mm²/mg * 1 mg/L = 30.0 µg Cu/L released
• At pH 8, after 28 days: 1.9 µg Cu/mm²* 9.1 mm²/mg * 1 mg/L = 17.3 µg Cu/L released

 

Acute environmental hazard classification for copper powder A

 

At pH 6, the copper release after 7 days transformation-dissolution at a mass loading of 1 mg/L (27.5 µg Cu/L) is above the acute ERV at pH 6 (12.1 µg Cu/L). The ratio of copper release divided by the corresponding ERV equals 2.3. At pH 7 and 8, the copper release is below the corresponding acute ERV. In accordance with the CLP guidance v4.1, the worst case classification entry is used.

 

Therefore, copper powder A merits acute 1 classification. The M-factor is 1, since the ratio of copper release at pH 6 divided by the corresponding ERV is below 10.

 

Long-term environmental hazard classification for copper powder A

 

At all pH values, the copper release after 28 days transformation-dissolution at a mass loading of 1 mg/L are above the corresponding chronic ERV. According to the CLP guidance, Annex IV.5.2.2.1, the copper release at a mass loading of 0.1 mg/L must then be compared to the corresponding ERV. The copper release at 0.1 mg/L mass loading can be calculated by dividing the copper release at 1 mg/L mass loading by ten. This results in copper releases of 11 µg/L at pH 6; 5.1 at pH 7; and 3.5 at pH 8. All these values are below the corresponding chronic ERVs.

 

From the information in section 1, copper can be considered as rapidly removed from the water column.

 

Therefore, according to the classification scheme in the CLP guidance, Annex IV.5.2.2.1, it can be concluded that copper powder A merits Chronic 3 classification. Without “rapid removal from the water column”, Chronic 2 classification would be derived.

 

Acute environmental hazard classification for copper powder B

 

At pH 6, the copper release after 7 days transformation-dissolution at a mass loading of 1 mg/L (11.8 µg Cu/L) is below the acute ERV at pH 6 (12.1 µg Cu/L). Likewise, the copper releases at pH 7 (8.0 µg Cu/L) and 8 (4.1 µg Cu/L) are also below the corresponding acute ERV.

 

Therefore, copper powder B does not merit acute classification.

 

It must be noted that the copper release at pH 6 (11.8 µg/L) isonly just belowthe acute ERV (12.1 µg/L). This shows that, as discussed in section 4.2, 9.1 mm²/mg is the critical surface area for Acute 1 classification of copper powders. If a copper powder would have SSA above 9.1 mm²/mg, then the copper release at pH 6 would exceed the acute ERV of 12.1 µg/L, and the powder would then merit Acute 1 classification. For this reason, the critical surface area of 9.1 mm²/mg has been used as the limit between copper powder A and copper powder B.

 

Long-term environmental hazard classification for copper powder B

 

At pH 6 and 7, the copper release after 28 days transformation-dissolution at a mass loading of 1 mg/L (45.5 and 30.0 µg Cu/L) are above the corresponding chronic ERV. At pH 8, the copper release is below the corresponding chronic ERV. According to the CLP guidance, Annex IV.5.2.2.1, the copper release at a mass loading of 0.1 mg/L must then be compared to the corresponding ERV. The copper release at 0.1 mg/L mass loading can be calculated by dividing the copper release at 1 mg/L mass loading by ten. This results in copper releases of 4.55 µg/L at pH 6; 3.0 at pH 7; and 1.7 at pH 8. All these values are below the corresponding chronic ERVs.

 

From the information in section 1, copper can be considered as rapidly removed from the water column.

 

Therefore, according to the classification scheme in the CLP guidance, Annex IV.5.2.2.1, it can be concluded that copper powder B merits Chronic 3 classification. Without “rapid removal from the water column”, Chronic 2 classification would be derived.

 

4.5   Classification of coated copper flakesfor environmental hazards

 

Coated copper flakes have received a harmonized classification through the 9^thAdaptation to Technical Progress (ATP), which will enter into force on March 1st, 2018. The CLH entry does not contain the CAS and EC numbers of copper. This recognizes that, in fact, the coated copper flakes are a separate substance due to their coating with aliphatic acid. However, including coated copper flakes in the REACH dossier automatically links it with the CAS and EC numbers of copper. It seems therefore that the removal of coated copper flakes from the copper REACH dossier may need to be considered. The copper REACH dossier will be brought in line with the 9^thATP in this respect up front of its entry into force (March 1, 2018).

 

4.6   Conclusions on classification of copper for environmental hazards

 

For the detailed overview of the rationale for these classifications, please refer to the report “The environmental hazard classification of copper” which is attached to the IUCLID file (endpoint summary “ecotoxicological information”).

 

	Classification for acute environmental hazard	Classification for long-term environmental hazard
Copper massive (SSA below 0.67 mm^2/mg)	none	none
Copper powder B (SSA 0.67—9.1 mm^2/mg)	none	Chronic 3
Copper powder A (SSA above 9.1 mm^2/mg)	Acute 1 (M = 1)	Chronic 3

SSA: specific surface area