Per- and Poly-Fluoroalkyl Substances (PFAS) in Ontario’s Groundwater

Background

In Canada, about 30% of people depend on groundwater as a source of drinking water, whereas 80% of rural Canadians depend on it for the same purpose. Due to rapid industrialization and the invention of new chemicals, our environment is constantly contaminated with these new chemicals — one of the most critical emerging contaminants is Per- and poly-fluoroalkyl substances (PFAS).

Per- and poly-fluoroalkyl substances (PFAS) are chemicals invented in the 1940s and have been used in various industrial and consumer products since then. It includes more than 4700 different types of chemicals.  Due to their lipophobicity and hydrophobicity properties, they are used in various consumer products such as non-stick cookware, firefighting foams, firefighting clothing, water-repellent clothing, etc. (USEPA, 2021). Because of their heat, water, and oil-resistant properties, they are highly persistent in the environment and difficult to break down. The extensive and rampant use of these chemicals has resulted in their presence in the groundwater of many different regions across the world, including in Ontario (Environment and Climate Change Canada, 2018).

Major Challenges

PFAS's persistent nature poses serious problems for human health and environmental management. One of the main problems is that these chemicals have a long half-life, which means they can remain (persist) in the environment for a long time, bioaccumulate, and be biomagnified in the food chain (Cousins et al., 2020).

Because PFAS are used widely in many different industries, it is challenging to identify and manage the numerous sources of PFAS contamination, such as consumer products, firefighting foams, and industrial discharges. (USEPA, 2021). In Ontario, the point sources of PFAS contamination are municipal waste disposal sites, wastewater treatment plants, composting of PFAS-containing food packaging municipal incineration, and fire-fighter training sites, whereas the non-point sources are agricultural use of municipal biosolids, surface runoff from human settlement areas, and widespread use of precursor chemicals by the general public, and which can be volatile and can migrate into water bodies. 

The high cost and energy-intensive nature of current solutions make remediating PFAS-contaminated areas difficult. This restricts the feasibility of broad implementation, particularly in underdeveloped and resource-restricted regions (Scheringer et al., 2014).

Health Effects

PFAS exposure has been associated with numerous adverse health effects, leading to increased concern about their presence in drinking water and the environment. Studies have linked PFAS to various health issues, including Cancer, Immune System Impairments, Hormonal Disruptions, and Developmental Issues.

Exposure to PFAS is linked to a higher risk of developing several cancers, especially kidney and testicular cancer (Barry et al., 2013). Further, the immune system may be weakened by PFAS, which could decrease the effectiveness of vaccinations and make people more vulnerable to illnesses (Grandjean et al., 2012). Furthermore, Low birth weight, developmental delays, and other negative consequences in infants have been associated with prenatal exposure to PFAS (Fei et al., 2007).

Technologies in Use:

The technologies include analytical methods and filtration systems, which are currently employed to detect and remediate PFAS in groundwater in Ontario. The analytical methods are liquid chromatography and high-resolution mass spectrometry, which are used to identify and measure PFAS in environmental samples, support regulatory compliance, and monitor these chemicals (Houtz & Sedlak, 2012). The water purification systems include Reverse osmosis, Activated carbon, Biochar, Metal-Organic Frameworks, Nanofiltration (NF), and Ion-Exchange Resins, frequently used techniques to extract PFAS from water. Although these techniques work well, they can be expensive and need constant upkeep. (Rahman et al., 2014).

In-Situ Remediation: To address PFAS contamination at its source, extraction of groundwater, treatment of it, and re-dumping into the ground have been proposed and used. Other methods, such as bioremediation and in-situ chemical oxidation, are being investigated. These techniques seek to convert PFAS chemicals into less dangerous forms (Ross et al., 2018).

Recent Policy Changes

In response to the growing concerns about PFAS, on April 24, 2021, the Government of Canada published a “Notice of Intent” to treat PFAS as a “class” and designate a combined acceptable limit of PFAS in drinking water. On May 20, 2023, the Government of Canada released the “Draft State of the Per- and Polyfluoroalkyl Substances (PFAS) Report,” which guided decision-making for provinces and territories.  To reduce PFAS exposure among the Canadian population, the government of Canada set 30 ng/L for the sum of the concentration of 25 per- and polyfluoroalkyl substances (PFAS) detected in Canadian drinking water (Government of Canada, 2024). These 25 PFAS are:

Ontario has introduced several policy changes to improve groundwater quality and public health protection. In 2017, the Ministry of Environment Conservation and Parks (Government of Ontario) set the 70 ng/L of PFAS level (for a total of 11 PFAS) in drinking water. After the changes in the PFAS level from Health Canada in May 2023, the Government of Ontario is considering lowering its limit, which is yet be enforced. Apart from the changes in regulatory measurements, the other activities the government of Ontario conducting are a regular sampling of PFAS in wastewater treatment plants, monitoring water from 20 landfills across Ontario, and where possible monitoring of groundwater and surface water near the vicinity of the municipal landfills (Minister’s Annual Report on Drinking Water, 2023).

Hence, my research project is focussed on monitoring PFAS in Ontario’s groundwater, conducting the cost-benefit analysis of the existing PFAS treatment technologies that can be or are being used at the rural household level, and exploring the existing knowledge on PFAS prevention among the well-users in rural Ontario. This project will help assist the existing Ontario effort to mitigate PFAS-related exposure prevention and bring new knowledge to policymakers to devise better policies to combat this problem. In Ontario, managing groundwater is severely hampered by PFAS and other newly discovered pollutants. These compounds need strong detection, monitoring, and remediation techniques since they are persistent and bioaccumulate. Addressing the hazards posed by PFAS and ensuring the security of Ontario's groundwater will require cooperation from both public and private sectors.