Occurrence of C6 And C8 Per/Polyfluoroalkyl Substances (Pfas) In Surface Waters in the Philippines

Date of Award

5-1-2023

Document Type

Thesis

Degree Name

Master of Science in Chemistry

First Advisor

Ian Ken D. Dimzon, PhD

Abstract

Per/Polyfluoroalkyl substances or PFAS, defines a specific group of aliphatic organic compounds that are either fully (per) or partially (poly) fluorinated. PFAS are compounds with numerous properties, such as chemical inertness, hydrophobicity, lipophobicity, and thermodynamic stability, which make them very useful for various applications in industries. However, it is also because of this, that PFAS is very persistent and easily bioaccumulated in humans and the environment. The recalcitrant nature of PFAS, is hazardous due to its toxicity, with evidence of immunotoxic effects in humans. With water contamination as one of the major sources of PFAS exposure in humans, it is vital to trace PFAS contaminations from their possible sources to the surface waters that eventually lead to drinking waters.

This research aimed to determine the occurrence of four PFAS species: Perfluorooctanoic acid (PFOA), Perfluorooctanesulfonic acid (PFOS), Perfluorohexanoic acid (PFHxA), Perfluorohexane sulfonic acid (PFHxS), in surface waters, in the Philippines along with their possible sources of contamination. Surface water samples were collected from Laguna Lake, and two water dams and analyzed using LC-MS/MS to determine PFAS concentrations in surface waters with varying exposures to sources of PFAS contamination.

Results show surface waters having PFOA concentrations ranging from 7.42- 29.7 ng/L, and PFHxA concentrations ranging from 7.52-43.4 ng/L. All samples also showed PFOS and PFHxS concentrations below the limit of detection of < 0.1. Soil samples near Laguna Lake, on the other hand, showed concentrations ranging from 0.02-0.17 mg/L for PFOA, 0.02-0.40 mg/L for PFHxA. PFOS and PFHxS were again, below the detection limit. These findings show that PFAS is significantly present in the Philippines, with the short chain PFAS (PFHxA) showing greater concentration than the long-chain one (PFOA).

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