Background: Stone wool is an inorganic mineral insulation material increasingly used to reduce the climate impact of buildings. The acute and chronic ecotoxicological potential of stone wool eluates have been studied in a battery of standardized laboratory ecotoxicological tests. The experiments were conducted with stone wool test materials in fibrous and milled form, with and without the presence of organic binder. For the preparation of eluates, the OECD protocol on the transformation/dissolution of metals and metal compounds was applied. The resulting eluates were used in acute tests, i.e., bioluminescence test with Aliivibrio fischeri (DIN EN ISO 11348-1:2009), algae growth test with Desmodesmus subspicatus (OECD No. 201) and immobilization test with Daphnia magna (OECD No. 202), as well as chronic tests, i.e., the Daphnia magna reproduction test (OECD No. 211) and the nematode growth and reproduction test with Caenorhabditis elegans (ISO 10872:2010).

Results: While no acute or chronic ecotoxicological effects of the eluates were observed for fibrous stone wool material, the milled test materials showed some chronic effects on aquatic invertebrates. Depending on the test materials and concentrations of milled stone wool used in the eluate preparation, these chronic effects included significant stimulation or inhibition of daphnid reproduction and nematode growth. The chemical analysis conducted in parallel to the ecotoxicological assessment indicated no leaching of organic substances from the applied binder or mineral oils and no formation of nanoparticles by the milling of stone wool. Furthermore, ICP-MS and ICP-OES analysis of eighteen elements revealed that only aluminum and nickel could be quantified in the eluates, at concentrations of approximately 750 µg/L and 7 µg/L, respectively.

Conclusions: Based on the present ecotoxicological assessment, eluates from stone wool fibers cannot be considered as chemically hazardous to the aquatic environment. However, additional investigations of the ecotoxicological potential of the milled material and the environmental exposure of stone wool products are necessary for a complete evaluation of potentially negative effects of stone wool insulation materials.