This review provides an overview of nanomaterials and nanoparticles, their sources, and their potential toxicity. It aims to inform scientists and the public about the risks associated with nanoparticles, while highlighting the importance of understanding their biological effects. The review discusses the long history of human exposure to nanoparticles through natural processes such as dust storms, volcanic ash, and ocean evaporation. It also addresses the increased anthropogenic production of nanoparticles due to industrial and transportation activities, which has led to higher levels of nanoparticle pollution. Nanoparticles are defined as particles with at least one dimension smaller than 1 micrometer. They can be classified based on their dimensionality, morphology, composition, uniformity, and agglomeration. The review emphasizes that the toxicity of nanoparticles depends on various factors, including their size, shape, composition, surface properties, and the individual's genetic makeup. Nanoparticles can enter the body through various routes, such as inhalation, ingestion, and skin contact, and can translocate through the circulatory and lymphatic systems to reach various organs and tissues, potentially causing damage. The review discusses the health effects of nanoparticles, including respiratory and cardiovascular diseases, various cancers, and neurodegenerative disorders such as Alzheimer's and Parkinson's. It also highlights the potential benefits of nanoparticles in medical applications, such as their use as antioxidants and antimicrobial agents. The review stresses the need for a rational, science-based approach to minimize the risks associated with nanoparticles while supporting their continued development and use. It concludes with a call for further research and study to better understand the toxicological effects of nanoparticles and to develop strategies to mitigate their potential health impacts.This review provides an overview of nanomaterials and nanoparticles, their sources, and their potential toxicity. It aims to inform scientists and the public about the risks associated with nanoparticles, while highlighting the importance of understanding their biological effects. The review discusses the long history of human exposure to nanoparticles through natural processes such as dust storms, volcanic ash, and ocean evaporation. It also addresses the increased anthropogenic production of nanoparticles due to industrial and transportation activities, which has led to higher levels of nanoparticle pollution. Nanoparticles are defined as particles with at least one dimension smaller than 1 micrometer. They can be classified based on their dimensionality, morphology, composition, uniformity, and agglomeration. The review emphasizes that the toxicity of nanoparticles depends on various factors, including their size, shape, composition, surface properties, and the individual's genetic makeup. Nanoparticles can enter the body through various routes, such as inhalation, ingestion, and skin contact, and can translocate through the circulatory and lymphatic systems to reach various organs and tissues, potentially causing damage. The review discusses the health effects of nanoparticles, including respiratory and cardiovascular diseases, various cancers, and neurodegenerative disorders such as Alzheimer's and Parkinson's. It also highlights the potential benefits of nanoparticles in medical applications, such as their use as antioxidants and antimicrobial agents. The review stresses the need for a rational, science-based approach to minimize the risks associated with nanoparticles while supporting their continued development and use. It concludes with a call for further research and study to better understand the toxicological effects of nanoparticles and to develop strategies to mitigate their potential health impacts.