Health Canada has released a final notice of the objective for a maximum level of per- and polyfluoroalkyl substances in drinking water.
Better known as PFAS, the new threshold of 30 ng/L replaces the perfluorooctane sulfonate (PFOS) and perfluorooctane acid (PFOA) final Guidelines for Canadian Drinking Water Quality created over 2018 and 2019.
The 30 ng/L threshold for drinking water now covers 25 types of PFAS, according to Health Canada’s recent report.
Exposure to certain PFAS “has the potential to affect multiple systems and organs,” the report states.
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Health Canada notes that PFAS monitoring conducted at 29 freshwater sites across Canada from 2013 to 2020 sampled for 13 different PFAS to determine concentrations and trends. The monitoring found that PFAS were detected in the surface water of every province tested. Detection limits ranged from 0.4 to 1.6 ng/L. Of the 13 PFAS detected in 566 freshwater samples, PFBA, PFPeA, PFHxA, PFHpA, PFOA and PFOS had higher detection frequencies than the other PFAS.
The report also notes the results of some tap water testing for PFAS. In a study that included five tap water samples from Ontario’s Niagara-on-the-Lake, for instance, PFOA and PFOS were found at concentrations of 2.1 ng/L and 3.3 ng/L.
At seven sites in Quebec, source and treated water samples were collected monthly between April 2007 and March 2008. PFOA was detected in 75% of treated water samples (method detection limit of 0.3 to 0.6 ng/L), with a median value of 2.5 ng/L and a maximum value of 73 ng/L.
When it comes to standardized methods available to quantitate PFAS compounds in drinking water, Health Canada recommends the use of U.S EPA Method 533, as it follows current best practices related to isotope dilution. Method 533 is a solid phase extraction liquid chromatography-tandem mass spectrometry method.
While there are treatment technologies that can effectively remove certain PFAS, Health Canada states that no single treatment can remove a wide range of PFAS under all conditions. To ensure continued and effective removal, the department’s report suggests that each facility should establish operational conditions and parameters based on the selected treatment technology and the characteristics of the raw water, including PFAS type, concentration and treatment goals.
“The key issues to consider when selecting treatment technologies for PFAS removal are the presence of competing anions and PFAS species, organic matter and the frequency of regeneration or replacement required for the sorptive media used,” states Health Canada’s report.
The PFAS objective was prepared in collaboration with the Federal-Provincial-Territorial Committee on Drinking Water and is based on potential health concerns for the group of PFAS, as well as treatment and analytical considerations.
Public consultations for the guideline took place in 2023.
