Our group is investigating the effects of waste incineration on the release of harmful organic additives from polystyrene plastic wastes. Open pit burning is a widely used waste management practice in some isolated and underserved Native American and rural communities. The burning of plastic waste is known to produce harmful airborne contaminants and emissions. However, the generation of partially incinerated plastics and microplastics (MPs) in the bottom ash and release of toxic additives in these polymers are often overlooked. Relevant burning temperatures for PS MPs were determined based on mass loss curves obtained from thermogravimetric analysis (TGA). Analyses using high resolution C 1s x-ray photoelectron spectroscopy (XPS) show an increase in oxygenated carbon functional groups in the near surface of burnt compared to unburned polystyrene MPs. However, bulk functional group chemistry, observed using Fourier Transform Infrared spectroscopy (FTIR), remained similar between burned and unburned polystyrene. Ongoing experiments are being conducted to identify specific compounds in burnt polystyrene leachates using gas chromatography- mass spectrometry (GC-MS). The relationships between leached compounds and material composition are used to inform the mechanisms of organic contaminant release. Investigating these mechanisms will aid in the understanding of health hazards presented by environmental polystyrene MPs generated through uncontrolled burning.