Pesticides are widely used in agriculture and are practical and economical to improve the quality of food safety for the permanent population around the world. Even though insecticides are beneficial to cropping views, their extensive use may result in severe consequences due to their biocompatible and permanent nature. Various pesticides can cause serious health risks of direct or indirectly contaminated air, water, soil, and the general ecosystem. The effect of pesticides on blood in the mammalian cell is significant because blood can act as a target and carrier for pesticides. However, the mechanism by which they bind to biopolymers, particularly blood proteins, is not clearly understood yet. This chapter investigates the molecular effects of pesticides on biomacromolecules, especially hemoglobin.