# An Overview of Nanofiltration and Nanoadsorption Technologies to Emerging Pollutants Treatment
## 2 Emerging Pollutants  
The increase in the emerging pollutants in water resources has generated numerous concerns. The main implications are related to pollutants emerging in areas of water scarcity or poor management of effluent treatment plants [8]. These pollutants can modify the physical-chemical parameters of the water, considered essential for the maintenance of aquatic life. Problems with eutrophication in water bodies, death, and migration of species are possible interferences that these substances can cause in the ecosystem [3]. Furthermore, these pollutants are susceptible to bioaccumulation and biomagnification in aquatic organisms, contributing to toxicity at higher trophic levels. Bioaccumulation processes occur from the absorption of substances by aquatic organisms or ingestion of contaminated food. In biomagnification, there is a progressive accumulation of these substances along the food chain [3; 24]. When in contact with humans, these pollutants can be associated with cancer risks, hormonal changes, DNA changes, gastrointestinal toxicity, infertility, thyroid diseases, among other problems [25]. Pharmaceutical pollutants include drugs used to treat diseases. Pharmaceutical products such as antibiotics, contraceptives, antidepressants, analgesics, and antipyretics are examples of these substances commonly found in water resources [4]. After consumption, a part of these drugs is metabolized. The remainder is later released into the environment from human or animal excreta. These contaminants are introduced into the environment through direct release from effluent treatment plants, fields fertilized with animal waste, or landfill disposal [3; 8]. UV filters, insect repellants, and shampoos are examples of personal care products that can disrupt the aquatic ecosystem. Oxybenzene and octinoxate are found in sunscreens and other commonly used products, such as shampoos, body lotions, and fragrances, soaps, among others. These two compounds are responsible for bleaching coral reefs [26]. Oxybenzene has also been evaluated for toxicological effects on eukaryotic and prokaryotic microalgae [27]. Pesticides are another group of substances commonly found in water resources and are mainly associated with agricultural activities. These contaminants can reach water resources in different ways, persisting in the environment for days or years. The main forms of exposure occur through surface runoff, caused by rain, infiltration, or volatilization, depending on the characteristics of each compound [17; 28]. Plasticizers are also considered emerging pollutants [3; 29]. Flame retardants are identified in a variety of environmental matrices. This group of emerging contaminants is widely used to prevent the combustion of diverse materials (construction, furniture, textiles, and electronics) [9]. According to [PERSON] et al. [2], many emerging contaminants identified in water bodies exceed the reference values established by the European Union. In this sense, although there is a concern with these compounds in the environment, the regulations of emerging contaminants still need attention from environmental agencies. There are no laws to stipulate the limits of concentrations of pollutants in drinking water, the environment, or wastewater [30]. However, some emerging contaminants were included in lists of priority substances in several environmental bodies, such as The European Union Water Framework Directive, which listed 45 priority compounds with environmental quality standards [31]. Table 1 shows some quality reference values from different regulatory bodies for some commonly identified priority pollutants in water.