The present review encapsulates the burgeoning literature on the ecological toxicity from nanoparticles as well nanomaterials, followed by an elucidation of the underlying physico-chemistry that dictates particle behaviour within an eco-toxicological framework. Methods for quantifying nanoparticles in diverse biological and chemical matrices are also delineated. The burgeoning eco-toxicological literature indicates toxic effects on fish and invertebrates, often at low milligram per litter concentrations of nanoparticles. Currently, there is a notable deficiency of data about microbes, plants, and terrestrial species. Preliminary results indicate that some produced nanoparticles might react with other pollutants, hence affecting their environmentally harmful effects. The behaviour of particulates is affected by their dimensions, form, charge on the surface, along with their proximity to of other elements in their surroundings. Nanoparticles have a propensity to congregate in hard water as well saltwater, significantly impacted by the particular sort of organic material or other natural colloids found in clean water. The condition of dispersion will affect ecological toxicity; however, other abiotic factors influencing this, including pH, salinity, along with organic matters present, need comprehensive investigation within eco-toxicological investigations. Concentrations of engineered nanoparticles have seldom been quantified in the environment so far. Numerous methodologies exist to characterize nanoparticles for exposure and dosimetry, each presenting distinct benefits and drawbacks for the eco-toxicologist. We end by examining the consequences for the ecological safety evaluation of engineered nanoparticles.