Pesticides are a hidden threat to humans, animals, insects, as well as to all ecosystems. They control pests and play an important role in crop productivity and prevent vector borne-diseases in humans, but they also extremely pollute our surroundings. These toxic substances are found in soil, water, air, plants, food and feed. Their residues enter plants and animal products and accumulate in humans and animals by the food chain. They endanger our lives and put down our health, as well as demolish beneficial organisms in the environment. This paper expresses a piece of information that has been obtained from reviewing academic papers, books and other sources. People take these toxic chemicals from water, air, and agricultural products, as well as their surroundings. They are stored in humans and animals’ tissues or excreted by different routes, but their adverse effects have no end. Brain, kidneys, skin, gastrointestinal, liver, lungs, spleen and every organ of humans are suppressed by them. They cause various diseases, cancers, mutations, as well as lead to death. These chemicals destroy honeybees’ colonies and decrease pollinator’s populations. Additionally, birds, wildlife and soil organisms are extremely suppressed by the heavy application of pesticides. They damage human beings, animals, pollinators, honeybees, and soil microorganisms. Increasing the application of pesticides decreases the population of pollinators, honeybees, and other beneficial organisms, as well as impacts human health. If these living organisms are diminished, our lives are threatened by food shortage, a collapsed economy, and increased food and feed demand, therefore new crises including famine and diseases put down our prosperity. All pesticides should be used cautiously and need to develop a new type of pesticides that do not harm seriously our environment.