The effects of surfactant molecules involved in macro-, mini-, nano-, and microemulsions used in cosmetics and pharmaceuticals are related to their amphiphilic interactions with oil and water phases. Basic ideas on their behavior when they are put together in a system have resulted in the energy balance concept labeled the hydrophilic-lipophilic deviation (HLD) from optimum formulation. This semiempirical equation integrates in a simple linear relationship the effects of six to eight variables including surfactant head and tail, sometimes a cosurfactant, oil-phase nature, aqueous-phase salinity, temperature, and pressure. This is undoubtedly much more efficient than the hydrophilic-lipophilic balance (HLB) which has been used since 1950. The new HLD is quite important because it allows researchers to model and somehow predict the phase behavior, the interfacial tension between oil and water phases, their solubilization in single-phase microemulsion, as well as the corresponding properties for various kinds of macroemulsions. However, the HLD correlation, which has been developed and used in petroleum applications, is sometimes difficult to apply accurately in real cases involving ionic–nonionic surfactant mixtures and natural polar oils, as it is the case in cosmetics and pharmaceuticals. This review shows the confusion resulting from the multiple definitions of HLD and of the surfactant parameter, and proposes a “normalized” Hydrophilic-Lipophilic Deviation (HLD_N) equation with a surfactant contribution parameter (SCP), to handle more exactly the effects of formulation variables on the phase behavior and the micro/macroemulsion properties.

Public concern over per- and polyfluoroalkyl substances (PFAS) continues to grow as evidence highlights their persistence, bioaccumulation potential, and adverse health effects. Increasing detections in drinking water, consumer products, and industrial discharges have intensified regulatory scrutiny. This review examines the evolving PFAS regulatory landscape in the United States, focusing on the pulp, paper, and textiles industries, which contribute significantly to PFAS contamination through wastewater discharges, end-product disposal, and the absence of dedicated removal technologies. PFAS emissions from food packaging alone are estimated at 2,300 kg annually. Addressing contamination presents substantial economic challenges, with wastewater treatment costs projected to reach USD 3 billion annually and growing risks of legal liabilities exemplified by paper mill settlements reaching USD 11.9 million for historical pollution. Large-scale remediation of PFAS remains financially prohibitive, with estimates exceeding the global gross domestic product (GDP) of USD 106 trillion. Additionally, healthcare costs for PFAS-linked diseases exceed USD 62 billion and further emphasize the need for prevention. State-level restrictions on PFAS-containing consumer products are expanding, particularly in food packaging and textiles, which are now the most regulated across the United States. As PFAS-containing products face increasing market limitations and potential loss of sustainability certifications, which have already reduced sales growth by 70% in some cases, transitioning to non-fluorinated alternatives could significantly mitigate economic risks for paper and textiles companies. Within this context, this review highlights the urgency of integrating policy, technological innovation, and economic incentives to accelerate the transition away from PFAS and mitigate long-term environmental and financial liabilities.