Food safety authorities and the food industry are focused on uses of perfluoroalkyl substances (PFAS) in various food-contact packaging applications. Not widely known until recently, certain PFAS occur in paper-based packaging materials typically at parts-per-billion to parts-per-million concentrations. These substances are nonintentionally added substances (NIAS) and are attributed to residues from recycled fiber and paperboard used in the manufacture of new food packaging products. Low concentration PFAS detection has generated debate in the food industry and among scientific and governmental organizations about understanding their significance in food-contact products because certain PFAS are intentionally added to some food packaging materials. Distinguishing between both sources of PFAS in food packaging is essential for regulatory compliance purposes. In this paper, we describe ongoing research using contact angle measurement analysis to determine limits of performance (LOP) for perfluorocarboxylic acids (PFCAs) (C4, C6, C8, and C10) on the surface of recycled paper packaging materials. We find that the LOP concentrations for PFCAs ranged from 37 ppm (C10) to higher than 1238 ppm (C4). Because there is no economic justification for the presence of PFAS that do not provide functional performance, these LOP concentrations can reliably be considered as NIAS thresholds. This analytical method and the resulting test data are able to differentiate the source of PFAS in food packaging. Future research will broaden the test method to include measurements of fluorotelomer, sulfonamide, and fluoropolymer substances to develop a more comprehensive understanding of PFAS performance and NIAS concentration thresholds. Integr Environ Assess Manag 2021;17:7-12. © 2020 SETAC.