Table of Contents
Background
Per- and polyfuoroalkyl substances (PFAS) belong to a group of synthetic chemicals that are also classified as emerging contaminants. These contaminants possess a highly persistent chemical nature due to strong C-F bonds and once released into the environment, they have the potential to accumulate environmental matrices including air, water, soil, and living organisms. Chemically, PFAS possess some unique characteristics such as recalcitrant, hydrophobic, oleophobic, and thermochemically stable due to this, these chemicals have diverse applications at domestic, industrial, and commercial levels, for example, surfactants, metal plating, aqueous films, paper, textile and a range of domestic products. Such wide-range applicability of PFAS makes them highly makes them potentially toxic to the environment during their whole life cycle from manufacturing to consumer use and disposal.
So far, thousands of PFAS congeners have been identified with more than 600 being widely used in the United States (US). Drinking water contamination from PFAS has gained global attention in recent years and has gained global attention because of the high risks associated with their exposure. The same is the condition in the US, where PFAS have been widely detected in drinking water from various states and areas of great concern. Water supply systems in the US mainly use surface water and underground aquifers. Water from these reservoirs is supplied to the households after treatment following the regulations of the EPA.
Various sources have been identified to be responsible for PFAS contamination of drinking water that may either be direct sources comprising industrial process and discharge and aqueous film forming foams (AFFFs) usages or indirect sources which include waste-related anthropogenic activities such as landfills leachates, and Wastewater treatment plants (WWTPs) discharges into the environment from where PFAS eventually contaminates the surface and groundwater reservoirs.
Although, the US government is very much concerned to ensure a PFAS-free drinking water supply to its residents and is continuously focusing to regulate PFAS through EPA in order to implement the US-SDWA. For this purpose, thousands of drinking water wells supply systems have been monitored for PFAS throughout the US. However, because of being classified as emerging contaminants, very limited background information exists related to their levels in drinking water and toxic potential among humans which implicates the PFAS regulations and due to this, no federal enforceable standards (MCLs) for PFAS have been set by EPA so far.
Although, various states have set local guidelines for PFAS in NYC water. For instance, New York was among the first to set a permissible limit of 10 parts per billion (ppb) for two main PFAS congeners i.e PFOA and PFOS whereas, in Minnesota, these limits are set to be 15 ppb. To date, these classes of contaminants lie under unregulated chemicals with no set MCL by US EPA although, the agency set non-enforceable lifetime health advisory levels (HALs) for a combined concentration limit of 70 ppt for PFOA and PFOS. In October 2021, EPA announced a strategic roadmap for PFAS regulation in drinking water that comprises setting timelines for taking specific actions to ensure the monitoring of PFAS in the US from the year 2021-2024. This was followed by the release of the final contaminant candidate list (CCL 5) by EPA in November 2022 which included PFAS in the list of individually listed chemicals to set the MCLs.
In the US, CDC, NCEH, and ATSDR are continuously helping local populations and have been continuously trying to address the public health concerns associated with PFAS exposure. There exist growing evidence of multiple adverse health impacts due to PFAS exposure from drinking water mainly including elevated serum cholesterol, and reduced antibody response to the vaccines. Despite various regulatory efforts in establishing federal limits for PFAS there exist research gaps to monitor PFAS contamination in drinking water, their removal strategies, and associated health impacts among humans and demands systematic investigation through integrated approaches.
PFAS occurrence in drinking water has been reported globally with the predominant detection of perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) (Domingo and Nadal 2019). This has raised serious public health concerns as the populations consuming PFAS-contaminated drinking water are at high risk of developing various health implications associated with exposure.
Notably, PFAS detection in human serum samples has been widely correlated with drinking water PFAS levels (Daly et al. 2018a). Much of the recently conducted epidemiological studies from the USA have focused to investigate PFOAs-contaminated drinking water and their correlation with human serum PFOA levels (Domingo and Nadal 2019). Further, it was revealed that tap water PFOA and PFNA were found statistically significant predictors of their occurrence in human plasma among individuals consuming PFAS-contaminated drinking water.
The study measured 15 PFAS congeners from tap water samples collected from 225 prospective women cohort of the US (Hu et al. 2019). Moreover, an epidemiological study conducted in New Hampshire found elevated PFOS, PFOA, and PFHxS levels in the serum of 1578 individuals consuming PFAS-contaminated drinking water compared to the general US population (Daly et al. 2018b). Interestingly, a recent study reported ultra-short chain and other PFAS in 39/101 bottled water samples from the USA.
The study detected 15/32 target PFAS analytes having concentrations above the instrumental detection limits. However, the majority of samples (97%) contained PFAS levels <5 ng/L. The study also reported that the water products treated with reverse-osmosis (RO) systems had significantly lower PFAS levels compared to the water without RO treatment (Chow et al. 2021). This suggests that federal agencies should also consider bottled water while setting permissible limits for PFAS in NYC water or ensure proper drinking water treatment using modern approaches such as RO systems.
Detection Methods and Removal Strategies
PFAS quantification in drinking water can be carried out through chromatographic separation techniques. These techniques notably comprise high-performance liquid chromatography (HPLC), gas chromatography (GC), and liquid chromatography (LC) systems. The sensitivity of these analytical platforms depends on various types of detection systems attached to the instrument and can quantify organics at ng/L levels. Various detectors have been developed over the years so far comprising ultraviolet (UV), Infrared (IR), and mass spectrometry (MS). Among these, LC coupled with MS, UHPLC-MS, or LCMS-QTOF has been recognized as a state-of-the-art analytical platform for the wide and quick detection of thousands of organics in a single run.
These analyses are further carried out using two different approaches i.e. targeted detection of PFAS which includes the detection of selected PFAS congeners having reference standards. The other most recently used approach uses non-targeted analysis of PFAS in drinking water. In non-targeted analysis, no reference standards are used and PFAS are measured using semi-quantification or suspect screening methods. Through these techniques, thousands of compounds can be measured and mapped using integrated statistical analysis approaches and are widely applied to report unknown compounds in environmental matrices.
Once detected in the drinking water, a serious challenge arises for their efficient removal. Various removal techniques and strategies have been developed so far to eliminate PFAS from drinking water and make it safe for consumption. Recently, the granular activated carbon (GAC) and Anion exchange (AE) column tests have shown high efficiency for PFASremoval from drinking water (McCleaf et al. 2017). Different treatment technologies have been recently reviewed and it was recommended that high-pressure membrane systems along with GAC, and AE be the most promising and applied treatment technologies for PFAS removal. Furthermore, amine-containing sorbents have also been used recently and it has been recommended that various chemical factors are responsible for their removal efficiency which mainly includes the electrostatic and hydrophobic interactions and sorbent morphology (Ateia et al. 2019).
Moreover, it has been found that AE resins show high removal efficiency for short-chain PFAS compounds which are not removed through carbon-based adsorption approaches (Dixit et al. 2021). More recently, water treatment technologies comprising electrochemical treatment processes have been proposed which can chemically convert highly toxic PFAS into less toxic inorganic products (CO2, F– etc.). These strategies mainly consist of electrocoagulation and electrooxidation methods (Ryan et al. 2021). However, these electrochemical-based findings are based on laboratory-level experiments and their application at a broader level should be investigated considering various chemical, biological and physical parameters along with economic costs related to the implementation of technologies.
Public Perspective
Following frequently asked questions (FAQs) try to address some general public concerns in the US, especially the NYC region.
If you are concerned about PFAS in your drinking water, EPA recommends you contact your local water utility to learn more about your drinking water and to see whether they have monitoring data for PFAS or can provide any specific recommendations for your community
Studies have shown that PFAS when entered inside the human body, it may cause adverse effects on the liver and immune systems. Furthermore, low birth weights, birth-related defects, and delayed development have also been found to correlate with PFAS exposure.
The granular activated carbon (GAC) and reverse osmosis filters (RO) have been shown to reduce/remove PFAS substances in drinking water. However, both these systems result in less water flow compared to a standard water faucet.
A blood test for PFAS can tell you how much PFAS levels are in your blood at the time of blood withdrawal. However, it does not predict whether the detected levels are safe or unsafe in your body.
Household items including fast food containers, microwave popcorn bags, pizza boxes, candy wrappers, stain-resistant coatings on carpets, cleaning products, water-resistant clothing, personal care products, and cosmetics may contain significant amounts of PFAS.
Exposure to PFAS can cause the progression of cancer when consumed for a longer time. These cancers include kidney, testicular, ovarian, endometrial, prostate, non-Hodgkin lymphoma, thyroid cancer, and childhood leukemia.
A recent review from the CDC outlines a host of health effects associated with PFAS exposure. This includes liver damage decreased fertility and increased risk of asthma and thyroid diseases.
Common water treatment systems such as water softeners do not remove PFAS from drinking water.
Research suggests that PFAS exposure have high health risk among infants and children because they are under biological development and this makes them highly vulnerable to exposure to chemical contaminants such as PFAS
Currently, no medical procedure exists to remove PFAS from the body. However, the best strategy in this regard can be to remove PFAS exposure from the source.
Reverse osmosis filters and two-stage filters have been reported to efficiently remove PFAS up to 94% from drinking water.
Although no MCLs have been set for PFAS in drinking water, however, many states are committed to regulating their occurrence in drinking water and setting local standards in their states. These states mainly include NY, VT, ME, MA, MI, NH, NJ, etc.
PFAS have been detected in NYC tap water. The New York City Department of Environmental Protection (DEP) monitors and tests the water supply regularly. The DEP employs advanced methods to ensure that water quality meets safety standards, and they conduct regular assessments for various contaminants, including PFAS. For more comprehensive analysis, the city collaborates with specialized organizations that offer pfas laboratory testing services to identify and quantify these substances more accurately. The proactive measures taken aim to keep residents informed and to maintain public trust in the city’s drinking water.
Conclusion
PFAS are a group of emerging contaminants widely detected in drinking water globally. These contaminants have also been reported in US drinking water with established health risks associated with exposure. The c-F bond in these compounds makes them persistent in an environment with high toxicity. Because of emerging contaminants, so far no enforceable limits have been set by US EPA.
However, various efforts have been taken continuously by the US government. A strategic roadmap for PFAS was proposed by EPA in 2021 that will lead toward establishing MCLs for PFAS in NYC water. Their exposure has been associated with health risks among the exposed human population. furthermore, their detection and removal from drinking water has also been challenging by the authorities due to limited background data available related to these contaminants and needs systematic and integrated research to address the issue.
References
Ateia M, Alsbaiee A, Karanfil T, Dichtel W. 2019. Efficient pfas removal by amine-functionalized sorbents: Critical review of the current literature. Environmental Science and Technology Letters. 6(12):688-695.
Chow SJ, Ojeda N, Jacangelo JG, Schwab KJ. 2021. Detection of ultrashort-chain and other per-and polyfluoroalkyl substances (pfas) in us bottled water. Water Research. 201:117292.
Daly ER, Chan BP, Talbot EA, Nassif J, Bean C, Cavallo SJ, Metcalf E, Simone K, Woolf AD. 2018a. Per-and polyfluoroalkyl substance (pfas) exposure assessment in a community exposed to contaminated drinking water, new hampshire, 2015. International journal of hygiene & environmental health. 221(3):569-577.
Daly ER, Chan BP, Talbot EA, Nassif J, Bean C, Cavallo SJ, Metcalf E, Simone K, Woolf AD. 2018b. Per-and polyfluoroalkyl substance (pfas) exposure assessment in a community exposed to contaminated drinking water, new hampshire, 2015. International journal of hygiene and environmental health. 221(3):569-577.
Dixit F, Dutta R, Barbeau B, Berube P, Mohseni M. 2021. Pfas removal by ion exchange resins: A review. Chemosphere. 272:129777.
Domingo JL, Nadal M. 2019. Human exposure to per-and polyfluoroalkyl substances (pfas) through drinking water: A review of the recent scientific literature. Environmental research. 177:108648.
Hu XC, Tokranov AK, Liddie J, Zhang X, Grandjean P, Hart JE, Laden F, Sun Q, Yeung LW, Sunderland EM. 2019. Tap water contributions to plasma concentrations of poly-and perfluoroalkyl substances (pfas) in a nationwide prospective cohort of us women. Environmental health perspectives. 127(6):067006.
McCleaf P, Englund S, Östlund A, Lindegren K, Wiberg K, Ahrens L. 2017. Removal efficiency of multiple poly-and perfluoroalkyl substances (pfass) in drinking water using granular activated carbon (gac) and anion exchange (ae) column tests. Water research. 120:77-87.
Ryan DR, Mayer BK, Baldus CK, McBeath ST, Wang Y, McNamara PJ. 2021. Electrochemical technologies for per‐and polyfluoroalkyl substances mitigation in drinking water and water treatment residuals. AWWA Water Science. 3(5):e1249.
- Yasir A. Rehman, Ph.D.
Dr. Rehman was born in Rawalpindi, Pakistan. He completed his MSc from PMAS – Arid Agriculture University Rawalpindi in 2011 where his thesis comprised a health risk assessment of subjects living in the vicinity of wastewater channels in urban settings and its relationship with the incidence of Malaria.
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OTHER RESEARCH ON WATER CONTAMINANTS BY DR. YASIR
