Characterizing the presence of polychlorinated biphenyls within Biota Found in New Mexico

Polychlorinated biphenyls (PCBs) are a group of industrial chemicals that were widely used in the United States before being banned by the Toxic Substances Control Act in 1976. Concerns regarding PCBs arose in the 1960s due to their toxicity, classification as a carcinogenic compound, and longevity in the environment. Although the production of PCBs in the United States is currently banned, PCBs can still be found in legacy equipment, and the environment and PCBs are still unintentionally produced in common building materials. To document the concentration of PCBs in biota predominantly found in northern New Mexico, biota (mammalian, avian, and reptilian) were opportunistically collected from 2009 to 2025. We grouped biota species into feeding guilds (carnivore, herbivore, and omnivore) to examine whether different feeding guilds had higher or lower proportions of total PCBs, PCB homologs, dioxin-like PCB congeners, and toxic equivalents. When we examined the concentrations of PCB homologs and total PCBs, we found the highest abundance of PCBs in the carnivore feeding guild compared with both herbivores and omnivores. We also observed differences of dioxin-like PCB congeners among feeding guilds, examined in this study. Toxic equivalents were also observed at higher values in carnivores. Furthermore, we demonstrate the biomagnification of PCBs across trophic levels, with higher concentrations observed in mountain lions relative to their primary ungulate prey (mule deer and elk). A comparison of biota revealed a significant difference in concentrations of PCBs found in samples (mule deer and elk) collected in developed areas when compared with rural locations, with the developed areas having higher concentrations. Our investigation provides significant insight into the distribution, composition, and biomagnification of PCB in terrestrial animals in New Mexico, including the biomagnification of PCBs within the carnivore feeding guild, which could be at a higher risk of adverse effects from PCB exposure.