Chronic Toxicity of Lithium to the Water Flea Daphnia pulex and Fingernail Clam Pisidium dubium

Abstract

Lithium (Li), a metal used in batteries and pharmaceuticals, is increasingly in demand as part of a greener economy. However, its extraction, use, and disposal may elevate environmental concentrations, raising concerns about aquatic ecosystems. This study assessed Li chronic toxicity and bioaccumulation in two freshwater invertebrates: Pisidium dubium (28-day exposure) and Daphnia pulex (21-day exposure). Organisms were exposed to environmentally relevant Li concentrations (0.05-10 mg/L for P. dubium; 0.5-3 mg/L for D. pulex). Results showed reduced survival (EC₅₀ = 1.37 mg/L) and impaired burrowing behavior (EC₅₀ = 1.59 mg/L) in P. dubium, with tissue analysis suggesting internal Li regulation. In D. pulex, reproduction (EC₅₀ = 1.77 mg/L) and growth (EC₅₀ = 3.01 mg/L) were significantly affected. While natural Li levels in surface waters are usually below these thresholds, elevated concentrations near mining and urban areas could harm aquatic invertebrates, highlighting the need for improved waste management strategies.