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Long-term toxicity to aquatic invertebrates

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Description of key information

There is some (inconclusive) evidence for bioaccumulation of slags’ components which may affect long-term toxicity of the substance. Generally, experimental field studies in local environment indicate that the local environment is enriched with a variety of metals and these metals are accumulated by marine organisms. However, different species accumulate different metals to a different extent and assessments of the effects of pollution must be taken into account. A series of oceanographic studies available to the Lead Registrant has not found any evidence that chronic exposure of marine organisms to slags can be harmful to them.
Slags, ferronickel manufg. has no toxicity and it does not need to be classified as toxic to the aquatic environment based on available long-term studies on the aquatic toxicity of the slags (performed for potential disposal as waste) which showed no mortality or toxicity up to the measured concentration for the reproduction aquatic invertebrates (daphnia magna) (Weber, 2011). These results show that no classification for aquatic hazards is required for the slags, according to CLP. To further augment these findings and produce an as much as possible representative PNEC, a read-across approach was chosen to be followed, to assess the toxicity of the individual constituents of the substance.
From this read-across approach, Nickel was identified to be the constituent most dangerous to the aquatic environment and the only one that has a relevant classification (Aquatic Chronic 3). For that reason, the PNEC aquatic will be based on NOECs from studies on Nickel and more specifically the Nickel PNECs, that are available for use by the Lead Registrant.

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Additional information

Slags, ferronickel manufg. has no toxicity and it does not need to be classified as toxic to the aquaticenvironmentbased on available long-term studies on the aquatic toxicity of the slags (performed for potential disposal as waste) which showed no mortality or toxicity up to the measured concentration for the reproduction aquatic invertebrates (daphnia magna)(Weber, 2011). These resultsshowthat no classification for aquatic hazards is required for the slags, according to CLP.

There issome(inconclusive) evidence for bioaccumulation of slags’ components which may affect long-term toxicity of the substance. Generally, experimental field studies in local environment indicate that the local environment is enriched with a variety of metals and these metals are accumulated by marine organisms. However, different species accumulate different metals to a different extent and assessments of the effects of pollution must be taken into account.A series of oceanographic studies available to the Lead Registrant has not found any evidence that chronic exposure of marine organisms to slags can be harmful to thembut only large quantities of the material can cause disruption of the benthic ecosystem, as would happen with practically any element discarded in great volumes(ELKETHE, 2009).

The CLP Regulation puts priority on information that is available for the whole substance. Slags, ferronickel manufg. is not considered a mixture. Nickel is the only constituent of the substance that is considered toxic to the aquatic environment (Aquatic Chronic 3 in powder form) but its content in the slags is not high enough to characterise them as toxic as well, according to the mixture rules described in the CLP.

To further augment these findings and produce an as much as possible representative PNEC, a read-across approach was chosen to be followed, to assess the toxicity of the individual constituents of the substance.

Iron Oxides

Iron has no known toxic effects to the aquatic environment.Available data do suggest that iron salts are relatively non toxic and this was sufficient for the EU Classification and Labeling Committee to determine that there was no need for classification of iron salts. It was also concluded that iron massive and sparingly soluble forms of iron are highly insoluble and non-hazardous. The solubility of iron species of the slag is insignificant.

Calcium Oxide

CaO effect is mainly its contribution to water pH after its transformation to Ca(OH)2. However, in large dilutions (e.g. in sea or in rivers where constant current exists) this has insignificant effect. Furthermore, Calcium Oxide is bound in the mineral matrix of the slags which reduces significantly its reactivity.This has been verified in the acute oral and inhalation toxicity experiments of ferronickel slags (see relative endpoint information) as well as in the skin and eye irritation experiments. It is concluded that CaO is of negligible toxicity in ferronickel slags.

Chromium (III)

In a chronic toxicity test of Cr(III) on C.dubia, the following results were obtained: Test species: Ceriodaphnia dubia, duration: 7 days, endpoints: IC50= 3.428 mg CrIII /L (2.976-3.990 mg CrIII/L), NOAEC= 1.253 mg CrIII/L. The maximum solubility of trivalent chromium from Ferronickel slags is less than the EC50 value found in this study and very close to the NOAEC value. It can be assumed that the substance will pose no significant effects of chronic toxicity, in regards to Cr(III), for aquatic invertebrates.

Nickel

Various long-term studies on aquatic invertebrates on soluble Nickel compounds were examined for the purpose of this hazard assessment. Nickel has shown that, among the individual constituents of Ferronickel Slags, it is the most likely to cause aquatic toxicity, due to the lower NOECs that were derived through these studies. The NOECs and EC10 that were derived ranged broadly, depending on the examined species.

Keithly et al. studied the acute toxicity of Ni to cladoceran Ceriodaphnia dubia. Stocks solutions of Ni were prepared by Nickel chloride pentahydrate. Nickel, Ca, Mg, organic carbon, K, Na, sulfate, bicarbonate, carbonate, and chloride were measured at test initiation. Ceriodaphnia dubia was found to be significantly more sensitive in chronic exposures than other species reported in the literature (including other daphnids such as Daphnia magna). The test produced EC20 and LOEC/NOEC values that are significantly higher than the maximum solubility of Nickel that is present in ferronickel slags.

Deleebeeck et al. performed a series of long-term toxicity tests with Nickel Chloride on various freshwater Cladoceran species (e.g. C.quadrangula, P.truncata etc.) in a static renewal setup, equivalent to EPA 1002 guideline. Based on mortality, the EC10 (21days) that were observed ranged from 2.95μg dissolved Ni/L (C.quadrangular) to 113μg dissolved Ni/L (D.longispina).

Kuhn et al. (1999) produced a NOEC (21 days) of 90μg/L (nominal) based on survival and reproduction, with a static renewal setup on D.magna exposure to Nickel Acetate Tetrahydrate.

Munzinger (1990) examined the effects of nickel dichloride in a 42-day static renewal test on freshwater invertebrate D.magna. A NOEC of 40μg/L (measured) was determined based on reproduction (total number of offspring in untreated and two pre-exposed generations) and body length of primiparous individuals.The progeny of nickel pre-exposed generations exhibited no adaptation towards nickel except an altered reproduction pattern which induced an increase ofreproduction and they remained smaller than the progeny of an unaltered generation.

Munzinger (1994) also examined the toxicity of Nickel Chloride on D.magna in a flow-through setup for 8 weeks. The test resulted in a NOEC of 40μg/L (nominal) based on growth and of 120μg/L (nominal) based on reproduction.

Testing for long-term effects of dissolved Nickel Chloride on C.magnifica (8months) in a flow-through setup, Nebeker et al. (1984) derived a NOEC of 66μg/L based on mortality.

Nebeker et al. (1986) performed a 21-day flow-through study on the effects of nickel chloride on the mollusc J.plicifera and calculated a NOEC of 124μg/L (measured) based on mortality.

Hunt et al (2002) examined the toxicity of Nickel Chloride on two saltwater species (M.intii and H.rufescens) for 28 days in a static setup and derived NOECs of 22.1μg/L and 26.4μg/L respectively, based on mortality.

Gentile et al (1982) also examined a saltwater species (M.bahia) for 36 days in a flow-through environment and resulted in a NOEC of 61μg/L based on survival and reproduction.

Pagano (2007) studied the effects of Nickel Chloride Hexahydrate on the saltwater species P.lividus, using a static setup. The 24h EC10 for observed defects on embryogenesis was 217μg/L (nominal).

Rest of constituents

Of the other components, Magnesium has no known toxic effects to the aquatic environment. Aluminium is also supposed to be a benign metal, however it has been found to produce toxic effects in short-term exposure under very specific environmental conditions, due to colloidal formation. In Ferronickel Slag, its low water solubility prevents it from producing adverse effects to the aquatic environment.

From this read-across approach, Nickel was identified to be the constituent most dangerous to the aquatic environment and the only one that has a relevant classification (Aquatic Chronic 3). For that reason, the PNEC aquatic will be based on NOECs from studies on Nickel and more specifically the Nickel PNECs, that are available for use by the Lead Registrant.