Perfluoroalkyl and polyfluoroalkyl (PFAS) substances cover a list of thousands of synthetic chemicals that are known to be persistent in the environment and in our bodies. Two of the most common PFAS chemicals that are now causing concerns in drinking water include perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA). The industry has responded by developing test procedures to verify a water filter’s performance for reducing these chemicals in drinking water to safe levels.
PFAS chemicals have been utilized in various industries around the globe because of their ability to repel oil and water. They’ve been manufactured since the 1940s and can be found in Teflon nonstick products, stain and water repellants, paints, cleaning products, food packaging, and firefighting foams. PFOA and PFOS have been extensively produced and can even be found in the blood of animals as remote as polar bears because of their persistence in the environment.
PFOS and PFOA are the two most-studied PFAS chemicals and have been identified as contaminants of emerging concern by the U.S. Environmental Protection Agency (EPA). In November 2016, the EPA released a non-enforceable health advisory1 that limited combined PFOA and PFOS exposure to 0.07 parts per billion (ppb) in drinking water. According to the document, “EPA’s health advisories are based on the best available peer-reviewed studies of the effects of PFOA and PFOS on laboratory animals (rats and mice) and were also informed by epidemiological studies of human populations that have been exposed to PFASs. These studies indicate that exposure to PFOA and PFOS over certain levels may result in adverse health effects, including developmental effects to fetuses during pregnancy or to breastfed infants (e.g., low birth weight, accelerated puberty, skeletal variations), cancer (e.g., testicular, kidney), liver effects (e.g., tissue damage), and other effects (e.g., cholesterol changes).”
Drinking water treatment products, such as activated carbon filters and reverse osmosis (RO) equipment, can be tested and certified for the reduction of PFOA and PFOS in accordance with NSF/ANSI 53: Drinking Water Treatment Unit Standard for Health Effects (filters) or NSF/ANSI 58: Reverse Osmosis Drinking Water Treatment Systems (ROs).
Test Protocol
In 2016, NSF International published a test protocol, NSF P473: Drinking Water Treatment Units – PFOA and PFOS. In 2007, prior to the NSF test protocol, the Water Quality Association (WQA) worked with the Minnesota Department of Public Health to create a protocol to evaluate the ability of activated carbon filters and ROs to reduce PFOA and PFOS from drinking water. The WQA study demonstrated that properly designed home water treatment products did have the ability to reduce PFOA and PFOS to safe levels.
The recently published NSF/ANSI 53-2018 includes a test protocol to evaluate an activated carbon filter’s ability to reduce PFOA and PFOS chemicals. Also, NSF/ANSI 58-2018 includes a test protocol to evaluate an RO system’s ability to reduce PFOA and PFOS chemicals from drinking water. These two recently published standards allow laboratories and product certification bodies the ability to test and certify products for PFOA and PFOS reduction.
NSF/ANSI 53 and NSF/ANSI 58 PFOA and PFOS Reduction Claims
NSF/ANSI 53 and NSF/ANSI 58 contain test provisions to evaluate activated carbon water filters and reverse osmosis systems for the reduction of PFOA and PFOS chemical contamination from drinking water. The two standards contain three primary categories of testing requirements:
- Materials
The material safety sections of NSF/ANSI 53 and NSF/ANSI 58 contain test protocols to ensure the product(s) materials that contact drinking water do not add contaminants to the water above safe levels. - Structural Performance
The structural integrity sections of NSF/ANSI 53 and NSF/ANSI 58 contain test protocols to ensure that plumbed in systems subject to water pressure are designed and fabricated to be structurally sound so that they will be able to withstand typical water pressures and water hammer. - Elective Performance Claims
The elective performance claims sections of NSF/ANSI 53 and NSF/ANSI 58 contain test protocols for reducing a variety of drinking water contaminants, including PFOA and PFOS. The table below outlines the required influent concentration of PFOA and PFOS and the allowable effluent concentration after the treatment device. Annex L of NSF/ANSI 53 and Annex F of NSF/ANSI 58 provide a test method for analyzing PFOA and PFOS in water by LC/MS/MS in electrospray negative ionization mode. The typical detection limit using this method is 10 ng/L.
Plumbed in activated carbon water filters must reduce PFOA and PFOS from the challenge water for the life of the filter. Testing is conducted to 120 percent of the filter’s rated capacity if the filter is designed with a performance indicating device (PID) that warns the user when the capacity is reached, or to 200 percent of the rated capacity if the filter does not contain a PID. Testing is conducted at the rated service flow of the filter, cycled (on/off) with a 15 to 40 min cycle, and operated up to 16 hours per day. Because RO systems use a semipermeable membrane that typically has a three-year life, they undergo a seven-day test to evaluate their performance reducing PFOA and PFOS.
Consumers concerned about these chemicals being in their drinking water can now purchase certified water treatment products. Several certification bodies, including ASSE, IAPMO, NSF, and WQA have products listed for PFOA and PFOS reduction.
- U.S. Environmental Protection Agency. FACT SHEET: PFOA & PFOS Drinking Water Health Advisories. November 2016. https://www.epa.gov/sites/production/files/2016-06/documents/drinkingwaterhealthadvisories_pfoa_pfos_updated_5.31.16.pdf
