Nanotechnology has revolutionized gene therapy, diagnostics and environmental remediation. Their bulk production, uses and disposal have posed threat to the environment. With the appearance of these nanoparticles in the environment, their toxicity assessment is an immediate concern. This review is an attempt to summarize the major techniques used in cytotoxity determination. The review also presents a detailed and elaborative discussion on the toxicity imposed by different types of nanoparticles including carbon nanotubes, gold nanoparticles, silver nanoparticles, quantum dots, fullerenes, aluminium nanoparticles, zinc nanoparticles, iron nanoparticles, titanium nanoparticles and silica nanoparticles. It discusses the in vitro and in vivo toxological effects of nanoparticles on bacteria, microalgae, zebrafish, crustacean, fish, rat, mouse, pig, guinea pig, human cell lines and human. It also discusses toxological effects on organs such as liver, kidney, spleen, sperm, neural tissues, liver lysosomes, spleen macrophages, glioblastoma cells, hematoma cells and various mammalian cell lines. It provides information about the effects of nanoparticles on the gene-expression, growth and reproduction of the organisms.

In the recent decades, development of new and innovative technology resulted in a very high amount of effluents. Industrial wastewaters originating from various industries contribute as a major source of water pollution. The pollutants in the wastewater include organic and inorganic pollutants, heavy metals, and non-disintegrating materials. This pollutant poses a severe threat to the environment. Therefore, novel and innovative methods and technologies need to adapt for their removal. Recent years saw nanomaterials as a potential candidate for pollutants removal. Nowadays, a range of cost-effective nanomaterials are available with unique properties. In this context, nano-absorbents are excellent materials. Heavy metal contamination is widespread in underground and surface waters. Recently, various studies focused on the removal of heavy metals. The presented review article here focused on removal of contaminants originated from industrial wastewater utilizing nanomaterials.

Owing to various industrial applications of mercury (Hg), its release into the environment at high concentration is becoming a great threat to living organisms on a global scale. Human exposure to Hg is greatly correlated with contamination in the food chain through cereal crops and sea foods. Since Hg is a non-essential component and does not possess a biological role and exhibits carcinogenic and genotoxic behaviour, biomonitoring with a focus on biomagnification of higher living animals and plants is the need of the hour. This review traces the plausible relationship between Hg concentration, chemical form, exposure, bioavailability, bioaccumulation, distribution, and ecotoxicology. The toxicity with molecular mechanisms, oxidative stress (OS), protein alteration, genomic change, and enzymatic disruptions are discussed. In addition, this review also elaborates advanced strategies for reducing Hg contamination such as algal and phytoremediation, biochar application, catalytical oxidation, and immobilization. Furthermore, there are challenges to overcome and future perspectives considering Hg concentrations, biomarkers, and identification through the nature of exposures are recommended.