# PFAS: The Journey from Wonder Chemicals to Environmental Nightmares and the Search for Solutions
## 2 Applications and Environmental Ubiquity of PFAS
### Environmental Exposure and Ubiquity
PFAS enters to the WWTPs from various pathways like domestic, industrial and landfill and making these facilities one of the primary sources of PFAS contamination in surface water. Some studies have shown that perfluorobutanesulfonic acid (PFBS), a short-chain PFAS molecule used in food packaging, floor wax and carpets was detected in wastewater, drinking water, and surface water compared to perfluorooctane sulfonic acid (PFOS), a long-chain PFAS molecule [38]. Table 4 summarizes the PFAS concentration in the global aquatic environment. A study by Skaggs and Logue analyzed the residential tap water in Brookings, South Dakota (USA) and found PFHxA and PFOA in 268 ng/L and 213 ng/L concentrations respectively [63] where a different study found PFHxA, PFOS, PFOA, and PFBS PFAS molecules in residence and public drinking water facilities in Gustavus and Alaska (USA). Groundwater samples in North Carolina (USA) show 20-4773 ng/L of total PFAS concentration [64] and in Hurlburt Field AFB, Florida detected PFOA, PFOS, and PFBS substances in 109 ng/L, 830 ng/L, and 9250 ng/L concentrations respectively [65]. Many PFAS-related products with different fields of applications are routinely released to the aquatic systems. As most PFAS compounds transport readily in water due to their high-water solubility and comparatively low molecular weight, they are more likely to rapidly spread in aquatic systems. Perfluorobutanoic acid (PFBA) and PFBS are the most common short-chain PFAS compounds found in drinking water, sewage sludge and sediments in a large quantity. As PFAS is distributed from the primary manufacturer to the commercial user to final disposal, it can be released to the environment in both controlled and unrolled pathways and since the degradation methods have not been well characterized, PFAS are ubiquitous environmental contaminant and incredibly resilient in typical environmental conditions [66; 67]. PFAS has been detected in _groundwater_ globally with different concentration levels. Among different groundwater contamination pathways, the release AFFs from fireight training facilities has been recognized as the major cause [68; 69; 70]. \begin{table}
\begin{tabular}{p{113.8 pt} p{113.8 pt} p{113.8 pt} p{113.8 pt}} \hline \hline
**Water Source** & **PFAS** & \multicolumn{2}{c}{**Concentration (ng/L)**} & **Location/Region** \\ \hline \multirow{8}{*}{Sea Water} & PFBS & 0.02875 & \\ \cline{2-4}  & PFOS & 0.22675 & \\ \cline{2-4}  & PFOA & 0.2155 & Northwestern Atlantic Margin [71] \\ \cline{2-4}  & br-PFOS & 0.14275 & \\ \cline{2-4}  & PFHxS & 0.065 & \\ \hline \multirow{8}{*}{Groundwater} & PFOA & 58 & \\ \cline{2-4}  & PFBA & 25 & A US Department of Defense site near a fire training area where AFF was used [72] \\ \cline{2-4}  & PFOS & 25 & \\ \cline{2-4}  & PFHxS & 160 & \\ \cline{2-4}  & PFBS & 45 & \\ \cline{2-4}  & PFOA & 90.8 & \\ \cline{2-4}  & PFBA & 33.1 & \\ \cline{2-4}  & PFOS & 19.2 & \\ \cline{2-4}  & PFHxS & 0.9 & \\ \cline{2-4}  & PFBS & 4.8 & \\ \cline{2-4}  & PFNA & 4.7 & \\ \hline \hline \end{tabular}
\end{table} 
Table 4: PFAS occurrence in water bodies in different locations. Agricultural uses of contaminated irrigation water and landfills are among other reasons for groundwater contamination. Groundwater contamination is also directly impacted for the PFAS contamination of _drinking water_. Drinking water is an important source for humans, and PFAS in drinking water leads to a significant burden in human blood serum over a lifetime [69; 70].