Regulating and removing PFOA and PFOS to protect public health

By Saleha Kuzniewski

Among per- and polyfluoroalkyl substances (PFAS), only perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS) have been sufficiently studied to develop regulations in Canada. Chemicals are regulated in Canada under the Canadian Environment Protection Act, 1999 (CEPA, 1999). CEPA, 1999 provides the legislative foundation for environmental and health protection in Canada. It gives authority to the Minister of Health to regulate toxic substances, including PFOA and PFOS.

Toxic substances are defined in CEPA, 1999 in terms of the risks they pose to human or environmental health. Part 5, Section 64 of CEPA, 1999 says that a substance is toxic if it enters the environment in a high concentration, or under the conditions that it may have a harmful effect on the environment, or may constitute a danger to the environment or human health.

To assess whether a substance is toxic, information is collected in regard to the health effects from exposure to the substance as specified in Part 5, Section 68 of CEPA, 1999. Weight of evidence and precautionary principles are applied when conducting and interpreting results from the assessment of the substance and from reviews of the decisions from another jurisdiction, as specified in Part 5, Section 76.1, and substances that are toxic are added by the Minister of Health to the list of toxic substances called Schedule 1.

In 2006, Environment Canada and Health Canada concluded from their studies that while PFOS were not a health concern at the exposure levels at that time, they declared PFOS and its salts to be environmentally toxic and added these to Schedule 1 of CEPA, 1999. Two years later, in 2008, the Canadian industry shifted from using PFOA and PFOS to other PFAS as alternatives. This move was on par with the PFOA Stewardship Program launched by the U.S. EPA and eight major companies in 2006 to reduce the emission and products’ content of PFOA by 95% by 2010 and to completely eliminate PFOA content by 2015.

In 2018, Health Canada set the maximum acceptable concentration (MAC) in drinking water at 0.2 µg per litre for both PFOS and PFOA. Health Canada also recommends the use of activated carbon filters and reverse osmosis (RO) systems to treat well and tap water and to test the water for concentrations of PFAS prior to, and after installing the treatment.

As both PFOS and PFOA could be found together in water, testing is not straightforward. Therefore, Health Canada has published an equation for this situation: the sum of the concentration of PFOS in water divided by the MAC for PFOS and the concentration of PFOA in water divided by the MAC for PFOA. The MAC here is a fixed value: 0.2 µg per litre, as mentioned above. For testing the concentrations of PFAS other than PFOS and PFOA, Health Canada has published a table on Drinking Water Screening Values (DWSV). This table consists of the DWSVs for a number of PFAS and is available in the publication by Health Canada Water Talk – Perfluoroalkylated substances in drinking water, 2019.

According to this, while the DWSV values are based on limited review of the existing science and not peer-reviewed, the table is based on assessment done by other jurisdictions in Canada. There is no risk from the drinking water if it has a concentration of a PFAS below the DWSV. If the concentration is higher, then the above-mentioned treatment options are recommended.

Activated carbon filtration, one of the technologies recommended by Health Canada for removing PFOA and PFOS from drinking water, is effective as it is highly porous and its large surface area allows chemicals to adsorb to it. Adsorp-

A lot can be learned from samples of PFAS in the soil, sediment and water taken on site.

Credit: Adwo, stock.adobe.com

tion is a chemical process in which a substance accumulates at the interface of the liquid and solid phases.

The activated carbon in the commercially sold filters is in the form of granulated activated carbon (GAC). The depth of the carbon bed and type of carbon used to make the GAC, the types of PFAS to be removed from the water, and the organic contents in the water are factors that affect the performance of the GAC filters. GAC filters are more effective in removing long-chain PFAS such as PFOA and PFOS relative to short-chain PFAS.

The other technology recommended by Health Canada is reverse osmosis (RO). It uses a semi-permeable membrane to separate contaminants from the water. Specifically, the contaminants stay on top of the filter and the clean water moves through.

The pressure applied and the pore size of the membrane are factors that affect the performance of RO filters to remove the contaminants from the water. According to the U.S. EPA, RO filters are more than 90% effective in removing a range of PFAS, including PFOA and PFOS.

There are a number of GAC and RO filters sold commercially that are capable of removing PFOA and PFOS and can be installed on household taps. However, these GAC and RO certified filters for removing PFOA and PFOS can be expensive. Also, like all water filters, they need to be changed periodically.

Depending on the types of filters suited for the specific drinking water issues, installation might not be simple. On the other hand, not all cheaper filters have the capability to remove PFOA and PFOS from drinking water.

Although GAC and RO filters could remove PFOA and PFOS from drinking water, this is not a complete solution. These chemicals are still in the water source, so there is an urgent need to remove them due to their toxicity and environmental health risks. There are companies that offer solutions to municipal drinking water providers and also to airports and military bases for PFAS removal from water sources.

In addition to filtration, there are also other physical, chemical and biological methods.

Soil excavation and disposal transfer the PFAS to another location such as a landfill to avoid long-term exposure and liabilities. The PFAS at a landfill could eventually leach into the groundwater, and contaminate water supplies, becoming another long-term liability.

In soil capping, contaminated soil is contained in a geomembrane and a sand and gravel layer is added on top, followed by a vegetative layer on the surface. The capped area may face limitations to property redevelopment, require engineering controls, and longterm monitoring of the groundwater.

Bioremediation is a biological method and several micro-organisms have been identified for their capability to reduce the concentrations of PFAS in the envi-

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ronment. This includes the micro-organism Acidomicrobium sp. strain A6, which is capable of removing up to 60% of 100 mg per litre PFOA and PFOS in about three months.

Chemical methods have proven to be effective in the removal of PFAS including for PFOA and PFOS and these methods work on the principle of chemical sorption using activated carbon as a binding agent. Specifically, the binding agent is injected into the contaminated soil and the PFAS sorb onto the binding agent.

An example of this chemical technology is the use of colloidal activated carbon as a sorbing agent for PFAS as discussed in an article in the June 2021 issue of Environmental Science & Engineering Magazine by Ryan Moore from REGENESIS. They are now using PlumeStop®, which, according to the article is basically activated carbon created by milling coconut fibre activated charcoal to 1 – 2 µm in size and then suspending it in a substance to prevent it from clumping.

When PlumeStop is pumped into an aquifer, the contaminants, including the PFOA, sorb to it and the clean groundwater passes through. This technology has been tested in Eastern Canada at a site contaminated with PFOA. This site was a former industrial furniture manufactur-

According to the U.S. EPA, activated carbon, ion exchange and reverse osmosis (pictured), have been found to remove PFAS from drinking water. Credit: navintar, stock.adobe.com

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ing site located near a fire training facility. After a year of using PlumeStop, PFOA and PFOS were below detection limit.

The use of nanomaterials in catalytic processes is another technology for treating PFAS-contaminated water. This was also discussed on Environmental Science & Engineering Magazine's website on August 9, 2021. As PFAS are negatively charged in water, they can be removed by the positively charged anion in an electrochemical environment. Surface-active foam fractionation is another technology proven to remove PFOA from groundwater and its effectiveness depends on the adsorption coefficient at the gas-liquid interface.

PFAS are prevalent in water across Canada. In February 2021, the drinking water intake area connected to Lake Memphremagog in Quebec reported 14 ng per litre PFAS. A map of PFAS hotspots in Canada, based on several sources including the Environment and Climate Change Canada report, showed that PFAS are widespread.

The median sum of PFAS was 8.9 ng per litre for Waterford River (NL), 41 ng per litre for Hamilton Harbour (ON) and 62 ng per litre for Mill Creek (B.C.). While these values are lower than the MAC for PFOA and PFOS (0.2 µg per litre), it is still concerning considering that these chemicals are widespread in blood samples taken from people and they are also found in other animals. Additionally, the concentrations detected indicate that these chemicals possibly bioaccumulate in high trophic organisms.

Legislative regulations and mitigation technologies for any toxic chemical go together and must be progressive to protect health and the environment.

Replacement chemicals for PFAS include GenX, perfluorobutane sulfonic acid, and other shorter chain-length PFAS telomeric substances. However, we do not know yet if these PFAS-replacement chemicals bioaccumulate in high trophic organisms. Furthermore, their toxicity and effects on the environment due to their breakdown products are a concern and, while this is being studied, it is also imperative to be ready with effective and practical technologies to prevent their contamination of water supplies.

Recommendation for the assessment of PFAS-replacement chemicals was also made by a number of Canadian organizations, including the Canadian Environment Law Association in their reply to the Notice of Intent under CEPA, 1999 to address the broad class of PFAS published in the Canada Gazette in April 2021.

These organizations also requested a shorter timeline for the release of the Government of Canada’s State of the PFAS report. The longer we wait for stakeholders to take action, the more PFAS will spread everywhere, leading to decreased productivity due to health issues, and negative effects on the economy.

Saleha Kuzniewski, PhD, is an environmental scientist specializing in remediation and biotechnology research. Email: skuzniewski1@gmail.com

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