Slags, ferronickel-manufg.

Long-term toxicity to fish

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 but 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).
Long-term toxicity studies for fish on slags, ferronickel-manufg. show that there is no toxicity up to the measured concentration (Gonsior, 2011a). To further augment these findings and produce an as much as possible representative PNEC, a read-across approach was chosen to be followed, based on the individual constituents of the substance.
Nickel was found to be the most important critical constituent. Studies on its chronic toxicity to fish showed that this substance produces toxic effects on fish at concentrations much higher than its maximum water solubility from ferronickel slags that is usually observed in solubility or leachability tests. Calcium and Sulfur are the two most soluble elements in ferronickel slags, but their acute toxicity to fish is insignificant. Magnesium and iron are both of low solubility and ecotoxicological activity, therefore they will not affect the resolution.

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 fish (Gonsior, 2011). These results show that 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 and the following approach based on mixture rules is not recommendable. 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. Several long-term tests with soluble Nickel compounds produced EC10/20 and LOEC/NOEC values that are higher than the maximum solubility of Nickel that is observed in water solubility or leachability tests of ferronickel slags, so no adverse effects are expected because of it.

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 CS (see 4.2.1.1 and 4.2.1.2 respectively) as well as in the skin and eye irritation experiments (see 7.3.1 and 7.3.2 respectively). It is concluded that CaO is of negligible toxicity in ferronickel slags.

Chromium (III)

No studies of chronic toxicity of Cr(III) to fish were 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.Toxicity to aquatic organisms due to Cr(III) leaching from slags ferronickel manufg is therefore not expected.

Nickel

Nickel was found out to be the constituent with the highest potential for aquatic toxicity. From the species examined, it was also observed that marine species showed higher tolerance to Ni than freshwater species.

Brix et al. (2004) studied the chronic toxicity of Ni to rainbow trout (Oncorhynchus mykiss). Test solutions were prepared by diluting a stock solution of Nickel chloride. The authors found a substantially higher Ni chronic effects threshold for rainbow trout than reported in previous study and a NOEC of 0.466mg Ni/L.

Birge et al. (1984) studied the long term of soluble Ni compounds to embryo and sac fry stages of P.promelas in a flow-through setup for 32 days. A NOEC of 0.057mg Ni/L was derived, based on mortality, terata and length. A LOEC of 0.12mg Ni/L was based on mortality and terata.

Nebeker et al. (1985) derived a NOEC of 35μg Ni/L, based on survival and growth on freshwater fish O.mykiss after a flow-through test on early fish stages, after exposure to dissolved Nickel Chloride.

Dave and Xiu (1991) studied the freshwater fish D.rerio for 8 -day exposure to dissolved Nickel Chloride in a semi-static setup on early fish stages (embryo and sac-fry). A NOEC of 40μg Ni/L was derived, based on hatching time.

Studies on marine species showed much higher NOECs. More specifically, Hunt et al (2002) in a 40-day flow-through test on A.affinis (early life stage: reproduction) derived an EC10 of 4.2mg dissolved Ni/L based on survival. Additionally, Golder Associated Ltd (2007), derived a NOEC of 21.7mg Ni/L based on survival and growth of C.variegatus after an early life stage: reproduction flow-through test.

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.