Plastics are an integral part of modern life and are essential to agriculture and food packaging. “Plastics” refers to an immense number of materials that are created from different polymers and an estimated 13,000 chemical additives. While the presence of plastics in the environment has been a concern for decades, their breakdown products, micro- and nanoplastics (MNPs), are an emerging human health and environmental concern. Recent studies on microplastic contamination in our air, water, land, food, and bodies provide the data needed to begin evaluating the resultant health effects and creating exposure reduction strategies. In this work, we utilize a mixtures hazard index (HI) method to identify harmful additives found within plastics identified in agricultural products. We illustrate the relative potency of a few toxic substances within microplastics such as DEHP, which is possibly 2,000 times more toxic than available potential substitutes. Additionally, we demonstrate that a few toxic additives can result in an elevated hazard index for the amount of microplastics detected in crops. Thus, the hazard index method can be applied to aid in the development of a new generation of plastics with lower toxic potential.