AN OVERVIEW ON THE APPLICATIONS AND ENVIRONMENTAL RISK ASSESSMENT OF NANOMATERIALS IN THE AQUATIC ORGANISMS

Nanomaterials are nano-scaled materials of 1-100 nm size, having at least one dimension with novel characteristics than the same material of large size. Nanomaterials are classified into several types based on the origin, dimensions, characteristics and formation. The small size of nanomaterial provides unique physico-chemical properties that are utilized for various purposes including aerospace, automobiles, construction industries, electrical and electronic goods, sports, cosmetics, food and medicines. The discharge of nanomaterials into the environment by anthropogenic activities exists in the form of ultrafine particles in air, and as colloids in soil and water. In general, nanomaterials enter into aquatic ecosystems through the wastewater discharge from the production site, spillage during transport, as untreated effluents from industries, rainwater run-off or by strong wind. The aquatic organisms adsorb the nanomaterials through the skin or mucous lining, oral engulpment, gills, operculum or by olfactory organs. Engineered nanomaterials induce toxic effects in aquatic organisms by the induction of oxidative stress, ionoregulatory disturbances, oxygen consumption, cytotoxicity, neurotoxicity, behavioural and histological modifications, haematological, developmental and reproductive changes, immune response, and modifications in gene expressions. The present review overviewed some key aspects on the applications of nanomaterials as well as its toxic impacts in aquatic organisms. Besides its advantages, the adverse effects of nanomaterials directly or indirectly target the health of humans; therefore, it is necessary to pay special attention to prevent the intentional discharge of nanomaterials into the environment.