Plastic pollution, including microplastics, presents a significant threat to aquatic ecosystems and wildlife. [1] Experiments measuring microplastic toxicity often use microplastic particles recovered from the environment. In this seminar, I will discuss a controlled approach in which microplastics are produced with a known composition. This method was used to incorporate various additives into polyvinyl chloride (PVC) [2] and polystyrene [3] microplastics. The diffusion of the additives from the microplastics under various conditions (temperature, agitation, salinity, microplastic size) was studied to understand the effect of environmental factors on additive diffusion. [2-5] The implications of leaching on the marine environment will be discussed, and safer, more sustainable alternatives will be presented.[6]