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Toxicity to aquatic algae and cyanobacteria

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Description of key information

According to the results of a short term aquatic toxicity test of slags, ferronickel-manufg. on aquatic algae the EC50 (48 h) the EC50-values for the test item Slags, ferronickel-manufg. could not be determined and they were estimated to be > 100 mg/L (nominal). The LOEC was estimated to be >100 mg/L (nominal), the NOEC was determined to be 100 mg slag/L (nominal).
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 studies on the aquatic toxicity of the slags which showed no mortality or toxicity up to the measured concentration for algae (Dengler, 2010). 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.

Key value for chemical safety assessment

Additional information

Ferronickel Slags

The aim of the study was the assessment of the effects of the test item on single cell green algae within the framework of laws for registration according to OECD Guideline 201.

According to the results of a short term aquatic toxicity test of slags, ferronickel-manufg. on aquatic algae the EC50 (48 h) the EC50-values for the test item Slags, ferronickel-manufg. /Electric Furnace Slag/Converter Slag could not be determined and they were estimated to be > 100 mg/L (nominal). The LOEC was estimated to be > 100 mg/L (nominal), the NOEC was determined to be 100 mg/L (nominal).

The test was performed within the solubility limit of the test item. The maximum water solubility of the test item determined under test conditions for the nominal used concentration of 100 mg/L wasfound below the LOQ for Aland Crin all samples and was0.16 mg/L for Fe and 0.009 mg/L for Ni. Since the NOEC and the EC50was found to be equal or above the maximum water solubility limit, the toxicological endpoints were evaluated using nominal concentrations of the test item.

For the range-finding test: Inhibitory effects were observed at all test item concentrations.

For the definitive test: The results of the range-finding test were not verified by the definitive test: there were no statistically significant inhibitory effects in all concentration rates up to 100 mg/L (nominal) at day 3. The validity criteria were fulfilled.

Individual Constituents

I. 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.

II. 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.

III. Chromium (III)

No studies on toxicity of Cr(III) to algae and aquatic plants was found. However, this is expected due to the low toxic and genotoxic potential of Cr(III) species.A study on the speciation of Chromium in Ferronickel slags using alkaline digestion and colorimetric analysis (EPA 3060A and EPA 7196A respectively) showed that no hexavalent Chromium species were present up to the limit of detection of the analytical method (20mg/kg) so all Cr in the substance is considered to be in trivalent form.

IV. 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.

Deleebeeck et al. (2004) examined the toxicity of Nickel Chloride on freshwater algaePseudokirchnerella subcapitatain a static test with concentrations that ranged from 10 to 1000μg Ni/L, in accordance with OECD 201 method. The test was performed in multiple pH values. The results gave an EC50 range between 81.5 and 148μg dissolved Ni/L.

Deleebeeck et al. (2006/2009) also performed a series of examinations on various algal species on both soft and hard water, to compare their responses after exposure to Nickel Chloride, following OECD method 201. The EC10 values that were determined varied among the various species and were between 12.6 and 59.4μg/L.

Parametrix Inc (2007) determined significantly higher EC10 values after testing the effects of exposure to Nickel Chloride on a marine algae species (Skeletonema costatum), with a static set-up, based on OECD method 201. The lowest EC10 was 122.7μg dissolved Ni/L at 72h, while the highest EC10 at 72h was 773.4μg/L.

Another study by Parametrix Inc (2007b) onDunaliella tertiolectain various marine environmentsproduced even higher EC10 values, which produced a NOEC (72h) of 5.48mg/L.

V. Rest of the 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.