Towards an environmental quality standard (EQS) for lithium in fresh water.

Lithium (Li), because of its widespread and increasing use in Li-ion batteries, is an element of vital importance to the energy transition away from fossil fuels and toward clean, renewable energy (green energy). Extraction and refining operations, as well as utilisation in a growing number of applications, are expanding and thus increasing the environmental releases of Li. In order to evaluate consequences of such releases, and to risk assess the accumulation of Li in aquatic ecosystems, environmental quality standards (EQS) are needed so that measured concentrations can be evaluated. Satisfactory EQS for Li are yet to be established and therefore derivation of Predicted No Effect Concentrations (PNECs), or interim EQS, are vital for environmental protection. This study compiled Li freshwater ecotoxicology data from global literature, screened and evaluated it, and then employed it to derive PNECs for short term exposures (i.e. concentrations unlikely to cause harm if their duration is short) and PNECs for standard condition exposures (i.e. concentrations unlikely to cause harm if their duration is continuous) in freshwater ecosystems. The generated dataset comprised 194 individual ecotox endpoints from 31 reference sources, spanning 28 species from 10 separate taxonomic groups (broad organism types). The derived PNECs recommended for consideration in environmental regulation are 0.622 mg/L for short term exposures and 15.2 μg/L for standard condition exposures, but with potential adjustment for site specific water conditions incorporating water hardness, dissolved organic carbon concentration and pH.