Environmental toxicology is the scientific study of the harmful effects of chemical, physical, and biological agents on living organisms present in the environment, including humans, animals, plants, and microorganisms. It focuses on understanding how toxic substances enter the environment, how they move through ecosystems, how they transform chemically or biologically, and how they affect biological systems. The primary aim of environmental toxicology is to protect environmental quality and public health by identifying toxic hazards and evaluating risks associated with exposure. Environmental toxicology examines contamination in air, water, soil, and food chains and studies both short-term and long-term effects of exposure to pollutants. It also considers how toxic substances accumulate in organisms, magnify through food chains, and interact with environmental factors such as temperature, pH, and sunlight. Ecotoxicology is a related but broader field that specifically studies the effects of toxic substances on ecosystems as a whole rather than focusing only on individual organisms. It examines how pollutants affect populations, communities, and ecosystem functions such as nutrient cycling, energy flow, and biodiversity. Ecotoxicology considers interactions among organisms and their environment, analyzing how toxic chemicals influence ecological balance. For example, ecotoxicologists study how pesticides affect insect populations, how heavy metals influence aquatic ecosystems, and how industrial waste affects soil microbial communities. While environmental toxicology often emphasizes human health impacts, ecotoxicology primarily focuses on ecological health, though both fields overlap significantly. Together, they help in environmental risk assessment, pollution control, and sustainable development planning. Toxicants are harmful substances that can cause adverse health effects when humans or other organisms are exposed to them. These toxicants can originate from natural sources or human activities. One of