Slags, ferronickel-manufg.

Endpoint summary

Additional information

Data on the terrestrial toxicity for slags, ferronickel-manufg. is not available for the whole substance. In order to avoid unnecessary testing to live organisms, it was attempted to identify possible adverse effects based on data for its recognised constituents, even though the results cannot be applied directly, due to the way the constituents are bound in the matrix of the substance and are not as bioavailable as the free substances that are examined. So, the results must be taken into consideration with care.

Data on studies on earthworms (macroorganisms) is available on some of the constituents of slags, ferronickel-manufg. The tests that were performed with these studies were with their more soluble species, in order to have a good understanding of their toxicological effects. From these studies, it was concluded that aluminium oxide (a constituent of the slag) showed no toxic effects even at the highest concentration of 5000mg/kg dw (at a range of pH values). On the other hand, Nickel (in the form of nickel chloride) was more toxic and produced some adverse effects but at higher concentrations.

Data on studies on microorganisms is available on some of the constituents of slags, ferronickel-manufg, mainly nickel. The tests were performed with the more soluble species of Nickel chloride, in order to have a good understanding of their toxicological effects. From these studies, it was concluded that nickel (in the form of nickel chloride) was more toxic and produced adverse effects but at relatively high concentrations.

Short-term exposure of wheat saplings to metalic ions (Al, Ni, Fe, Cr, Mg, Mn) resulted in growth inhibition of the roots and shoots of the tested species for Al(3+), Ni(2+) and Cr(2+), while no significant effects were observed for Fe(2+), Mg(2+) and Mn(2+). The effects for aluminium were observed at a pH of around 4, while for the other elements in neutral pH. Cr(2+) showed the more severe effects, followed by Nickel. However, it is in a form different than the one observed in Ferronickel slags, so these results must be carefully considered. Additionally, Nickel in ferronickel slags is in a very insoluble form and thus not much bioavailable, so it is unlikely that it will produce such inhibitory effects on terrestrial plants.

Terrestrial arthropod toxicity is mainly secondary and is closely related to the toxicity to terrestrial plants and microorganisms. Available studies on Nickel have shown some toxicity potential at relatively higher concentrations.

A large amount of data on mammals was collected during the course of the chemical safety assessment for slags, ferronickel-manufg. on a wide range of toxicological and ecotoxicological endpoints. According to Column 2 of Annex IX of REACH there is no need for testing to collect further data on bird toxicity.

The available data on terrestrial toxicity for the individual constituents of ferronickel slags does not justify an environmental classification, due to the very high NOAECs that were identified for slags, after extrapolation for the Nickel content.

In general, it can be said that Slags, ferronickel manufg. do not contain substances that are toxic to the terrestrial environment. Iron, Calcium, Aluminium and Magnesium are common elements that have no toxicity towards terrestrial organisms.Chromiumexistsin its less toxic formofCr(III). 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(NTUA 2011c).

The read-across approach for the available studies has shown that Nickel is the constituent of highest concern, but its toxicity for terrestrial organisms is much lower than its aquatic toxicity.

Additionally, the substance has very low solubility in water (ref.), therefore it poses no risk for plant life and soil microorganisms. Its most soluble components, Calcium and Magnesium, are common nutrients. Other terrestrial organisms that feed directly from the ground are more exposed, but the lack of solubility of the slags in water does not allow them to pass to tissues and cause toxicity. The coarse form of the material’s particles (see granulometry studies) decrease the bioavailability (and the solubility) of the substance to other soil macroorganisms (such as earthworms).

The various constituents of the slags are chemically bound in the mineral matrix of the substance and they do not dissociate readily into ionic form. Ionic forms of elements are more water soluble and, in general, more toxic (locally or systemically) to living organisms. Very low concentrations of nickel and chromium in ionic form indicate that toxicity is highly unlikely.