Ferrosilicon - reaction mass of iron and iron disilicide and iron silicide and silicon

Endpoint summary

Additional information

The scope of the terrestrial effect assessment under the REACH regulation is restricted to soil organisms in a narrow sense, i.e. on non-vertebrate organisms living the majority of their lifetime within the soil and being exposed to substances via the soil pathway.

Exposure based adaptation rules have been given for testing requirements for terrestrial compartment under REACH Annex IX. These studies do not need to be conducted if direct and indirect exposure of the soil compartment is unlikely. For FeSi grades current manufacture and use categories indicate no direct exposure to soil compartment (SU3, 14, 15, PC 7 & 14).

Annex XI adaptation rules offer the possibility to apply weight of evidence approach. In estimation of hazard involved in metal constituents and impurities in FeSi, the read across method may be utilized in the first hand (case by case approach) by applying the already existing hazard data and PNEC_soilvalues applicable these metals and other elements. Based on already existing information, it is currently not seen necessary to have any targeted ecotoxicological testing of FeSi in soil.

A more conservative approach in PNEC derivation is to apply total concentrations of metals in FeSi in combination to PNECsoil values already derived for these metals in the context of e. g EU ERA (EC 793/93). Highly variable composition of FeSi alloys and grades means also that there should be several PNECs, depending on grade. Individual metals (and highest concentrations (ref ID card)) that could have most influence on PNEC soil would be: Barium conc. in FeSi is up to 12 %, Zinc (1.2%), Chromium (0.5%) and Copper (0.2%). The ranges of Predicted No Effect Concentrations in soil for these metals is given below. The values are taken from risk assessments made for these metals under the ERA program.

Zinc PNECin wet soil containing 60% solids (density 2,500 kg/m3), 20% water and 20% air by volume, i. e. 88% solids by weight, the PNECadd, terrestrialof 26 mg/kg dry soil is equivalent to a

PNECadd, terrestrialof 23 mg/kg wet soil (Zinc ERA 2008).

Copper NOEC values (HC5 at 50th % confidence limit (mg/kg)) are in the range of 18 mg/kg (sandy soil) -118 mg/kg (clay soil). According to the CSA guidance and TGD (2003) the PNEC should be derived from theadded HC5at 50^th% confidence limit and considering the application of an additional assessment factor.

Chromium (III), a PNECsoil = 3.3 mg/kg wet weight for acid conditions and 62 mg/kg wet weight for other conditions has been derived. It should be noted that the PNEC for chromium (III) is derived from experiments where a highly soluble (and hence bio available) form of chromium (III) has been tested. (Chromium ERA).

For barium the dataset is scarce, but there are chronic test results data available for three taxonomic group and lowest reported NOECs in soil are 82 mg/kg and maximum permissible addition (MPA) 180 mg/kg (RIVM 1992) (RIVM 2001).

Taken the values above into account a coarse PNECsoil for FeSi can be derived by applying above mentioned PNEC/NOEC values as ecotox reference values for the FeSi alloy materials.

These values would give PNEC soil values as follows: Ba: 100/12 x 82 mg/kg = 683 mg/kg, Zn: 100/1.2 x 23 mg/kg= 1916 mg/kg, Cu; 100/0.12 x 18 mg/kg= 15000 mg/kg. Cr: 100/0.5 x 3.3 mg/kg = 660 mg/kg (acidic soil) and 12400 mg/kg. The calculation method is coarse and considers only one metal at a time and does not account for combined effect and effects caused by Si, Fe, Mn, Mg, Ca.

The intention is just to give a coarse quantitative PNEC indicator for soil compartment. Chromium (in acid soil) and Barium gave quite similar values 660 and 683 mg/kg values and the barium (FeSi-Ba) value will be selected to represent all of the FeSi grades.