# PFAS: The Journey from Wonder Chemicals to Environmental Nightmares and the Search for Solutions
## 2 Applications and Environmental Ubiquity of PFAS  
### PFAS Applications from World War II to the AI Era  
Having a unique molecular structure, PFAS accounts for various properties including high thermal stability and amphiphilic properties as it can simultaneously show both hydrophobic and hydrophilic properties hence used in different applications including consumer products, industrial uses, medical and healthcare and construction, and automotive applications. This section overviews the previous and current applications of different PFASs and their ubiquitous presence after decades of manufacturing and consumption. Table 2 summarizes the applications and related properties and functions of PFAS employed. It also overviews the maximum and minimum PFAS concentrations used in each product category. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Application Category** & **Properties of PFAS Employed** & **Function of PFAS** & **Total PFAS Concentration max – min in ppm** \\ \hline Chemical Industry & Low surface tension, non-reactive, stable, bipolar character of some PFAS & Serves as optimal material for surfactants, coatings, and lubricants & \(3490.60-0.0005\)[32] \\ \hline Textile & Water and stain resistance, durability & Imparts water and stain resistance & \(295.20-0.0002\)[33] \\ \hline Medical uses & Biocompatibility, chemical resistance & Material for medical devices and implants & N/A *[34] \\ \hline Pesticides & Surfactant (reduces the surface tension of the solution) properties & Enhances spread and penetration of pesticides & \(19.20-3.92\)[35] \\ \hline Food package & Hydrophobic and, oleophobic properties, and grease resistance & Contaminant resistance preserves food safety and quality & \(25.2-0.0001\)[36] \\ \hline Building material & Weather resistance, high physical stability, and long durability & Serves as durable material for paints, sealants, and coatings & \(4300.28-0.0001\)[32] \\ \hline Cosmetics & Longevity, hydrophobic and oleophobic properties, extensive durability & Water resistance and spreadability serve shampoos, makeup, and conditioners & \(2425.08-0.0020\)[37] \\ \hline Electronic products & Thermal stability, low dielectric constant, thermal stability, and semiconducting potential & Stable material for photolithography, etching processes, and semiconductor manufacturing & \(0.03-0.0001\)[38] \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Applications and properties of the PFAS employed. The production cost of PFAS is 100-1000 times more expensive than conventional hydrocarbon surfactant per unit volume. Hence, used only when a smaller amount of PFAS can replace a larger quantity of non-fluorinated chemicals with the same performance or when there is no other substance that can deliver the required performance. PFAS has both hydrophobic and oleophobic perfluorocarbon moieties, so it can produce effective surfactants and surface protectors. PFAS-based fluor surfactants can lower the surface tension of water from 72 mNm\({}^{-1}\) to 16 mNm\({}^{-1}\), making them useful in a wide range of surfactants and repellants [32]. PFAS such as PTFE or Teflon have been used in cooking pans since the mid-20 th century. The first Teflon-coated non-stick frying pan was introduced to the market in the early 1960s and gained popularity ever since due to its convenience and ease of cleaning. Production expanded globally by producing non-stick frying and baking pans, and other kitchen utensils. Due to having resistance to heat, water, grease, and stain and extremely low friction coefficient, PFAS are used in various other industries such as food wrapping, pesticides, paints, drink can-lining materials, military, leather, aerospace, textile, surgical instruments, lubricant & oil, firefighting foams, cosmetics, plastics, etc.