Per- and Polyfluoroalkyl Substances (PFAS) in mixtures show additive effects on transcriptomic points of departure in human liver spheroids

Per- and polyfluoroalkyl substances (PFAS) are a diverse group of compounds used in a variety of consumer and industrial products that expose humans directly. Numerous PFAS are chemically inert and persistent in the environment, resulting in increased exposure from water, soil, and food. Despite the fact that some PFAS have been linked to adverse health effects, data on simultaneous exposures to multiple PFAS (PFAS mixtures) are insufficient for making informed risk assessment decisions. Using data from our group's previous work using Templated Oligo-Sequencing (TempO-Seq™) for high-throughput transcriptomic analysis of PFAS-exposed primary human liver cell spheroids, we determine the transcriptomic potency of PFAS mixtures in the present study. The benchmark concentration (BMC) analysis was conducted on gene expression data from solitary PFAS and mixture exposures of liver cell spheroids. Comparing the potencies of single PFAS to PFAS compounds of varying complexity and composition, we utilized the 25th lowest gene BMC as a starting point. In particular, the empirical potency of eight PFAS mixtures was compared with predicted mixture potencies calculated using the principle of concentration addition (i.e., dose addition), in which mixture component potencies are added proportionally to predict mixture potency. In this investigation, empirical mixture potencies were comparable to concentration addition potencies for the majority of mixtures. This study provides evidence that the effects of PFAS mixtures on gene expression mainly follow the addition-predicted response to concentration and suggests that the effects of these individual PFAS in mixtures are neither strongly synergistic nor antagonistic.