Ecological and Toxicological Impacts of Titanium Dioxide Nanoparticles on the Freshwater Clam Caelatura nilotica and Recovering Role of Dimercaptosuccinic Acid, Gizay Village, Menoufia Governorate, Egypt

Abstract

The increasing release of titanium dioxide nanoparticles (TiO₂ NPs) into aquatic environments raises concerns about their ecological and hydrological implications. This study investigated the impact of TiO₂ NPs on the freshwater clam Caelatura nilotica, a bioindicators for water pollution in the Nile ecosystem, focusing on genetic, immunological and histological responses of exposed clams that influence water quality and ecosystem stability. Parameters assessed include DNA damage in gills, haemocyte dynamics, neutral red uptake, and histological and ultrastructural changes in gills’ tissues. Clams were continuously exposed to 25 and 150 μg/L of TiO₂ NPs, with and without 200 μg/L of dimercaptosuccinic acid (DMSA), over 28 days. The high TiO₂ NP concentrations (150 μg/L) resulted in significant DNA damage (p < 0.05), reduced haemocyte counts and altered granulocyte dynamics, all of which can impair natural filtration processes critical to hydrological balance. Severe histological damage, such as cilia erosion and blood deprivation in gills, was observed at the high TiO₂ NP concentration, as confirmed by TEM analysis. Addition of DMSA alongside TiO₂ NPs during clam exposure mitigated these harmful effects, improving gills structure and function. These findings highlight the potential risks of TiO₂ NP contamination on aquatic ecosystems and underscore the protective role of DMSA in maintaining ecological and hydrological integrity.