This review aim to covers the toxicity impact of chemical Pesticides, Mechanism of action, its ecological risk impact on plant, soil, animals, water air and microorganisms. Pesticides are chemical substance designed to kill or retard the growth of pests that damage or interfere with the growth of crops, shrubs, trees, timber and other vegetation desired by humans. Practically all chemical pesticides, however, are poisons and pose long-term danger to the environment and humans through their persistence in nature or body tissue. Synthetic pesticides increases heavy metals in the soil which is then transferred to plant, consumed by human and thereby accumulate in the food chain since they are not biodegradable. Most of the pesticides are non-specific and may kill life forms that are harmless or useful. Exposure occurs through ingestion of food and water as well as skin respiratory absorption. Pesticides can contaminate soil, water, turf, and other vegetation and cause harm to animals and humans. In addition to killing insects or weeds, pesticides can be toxic to a host of other organisms including birds, fish, beneficial insects, and non-target plants. Exposure to chemical pesticides can lead to Asthma, Birth Defects, Neurological Effects, Cancer and Hormone Disruptions. Effects of pesticides on soil micro-organisms can cause a ripple effect that can last for years. Microorganisms are essential to healthy soil. Unfortunately, many pesticides can kill more than just their intended targets, namely the necessary microorganisms in the soil. Pesticides are found as common contaminants in soil, air, water and on non-target organisms in our urban landscapes. Pesticides can reach surface water and ground water through runoff from treated plants and soil. Contamination of water by pesticides is widespread.