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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Bioaccumulation of trace elements released from slag, is negligible in the environment 

Key value for chemical safety assessment

BCF (aquatic species):
10 dimensionless

Additional information

Ferrous slags are inorganic UVCB similar to natural rock. These materials contain trace elements of toxicological or environmental relevance. The accumulation of these elements was tested in field studies. For several elements tested, there was a high scattering of their concentrations in animals and algae, including controls, but it could not be shown that a significant accumulation of these trace elements occurred.

The BCF 10 was taken as the worst case for heavy metals in aquatic environments to cover for the influence of slags in comparison to natural rock material

Since slags are inorganic UVCB similar to natural rock, there is no need to perform any study on bioaccumulation.

Rejected Study

To elucidate the possible bioaccumulation of trace metals released from slag stones used in hydraulic engineering, slags were exposed to Rhine water. Dikerogammarus villosus (Amphipoda, Crustaceae), Bithynia tentaculata (Gastropoda), the mussels Corbicula fluminea and Dreissena polymorpha (Bivalvia), and the macrozoobenthos (sessile heterotrophes) were used to monitor bioaccumulation of trace elements which were assumed to be derived from slags. Basalt was used as control.

There were no data available for Dikerogammarus villosus, and there were in approximately 60 % of the measurements higher concentrations of trace metals (Cu, Pb, Cr and Ni) in slag-exposed organisms than in basalt-exposed organisms.

The author interpreted the data as evidence for relevant bioaccumulation:

Cu: As the control animals in contact with basalt had much higher Cu concentrations than the animals in the BOS (5-50 mm) baskets, it was assumed that there was an analytical error and the data were not taken into account for the overall assessment.

Pb, Cr, Ni: It was assumed that there was a relevant bioaccumulation in the bodies of the animals and in the sessile organisms on the slag-exposed organisms.

The interpretation of the author is not followed:

There was a large scattering in the concentrations of the 4 elements examined (Cu, Pb, Cr, and Ni). The concentrations of these metals in slag-exposed organisms were less than 1 % to up to 70 times the value of basalt-exposed organisms. The highest values were obtained in Bithynia tentaculata for Cr and in Corbicula fluminea for Ni. In both cases the bioaccumulation, as calculated from the ratio of concentrations in slag versus basalt-exposed concentrations, was high because the basalt controls were approximately one order of magnitude lower than in the other organisms. Taking into account that 40 % of the values of slags are lower than the control values, the data suggest that there was no significant bioaccumulation and there were no relevant differences between organisms exposed to slag and basalt.