*The following regulatory news article is intended to be a preview of the legislation and not a replacement for the actual guidance from the government. For the comprehensive data and all relevant information, please visit the linked source material within the article.
Health Canada’s Water and Air Quality Bureau has opened a 60-day consultation period for public comment on its proposed drinking water objective of 30 ng/L for per- and polyfluoroalkyl substances (PFAS).
In 2018 and 2019, Health Canada established drinking water guidelines for perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), as well as screening values for nine other PFAS. The new PFAS exposure limit, if passed, would replace the previous guidelines.
“The proposed objective offers the Canadian drinking water sector an efficient approach for risk management by providing only one target value for the total concentration of this group of chemicals, thereby reducing exposure to PFAS, and potential health risk,” states Health Canada’s draft objective.
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PFAS are a family of thousands of substances that contain linked fluorine and carbon atoms. This chemical link results in a very stable molecule that is essentially unreactive and persists in the environment. It can be used in the production of surfactants, lubricants and repellents, as well as foams, textiles and cosmetics.
Health Canada notes that the use of PFAS in firefighting foams is one of the most common point sources of water contamination.
In a study focused on examining the presence of PFAS in freshwater, 29 sites across Canada were sampled from 2013 to 2020 for 13 different PFAS to determine concentrations and trends. Detection limits ranged from 0.4 to 1.6 ng/L. The highest concentrations were noted to be 138 ng/L for perfluorobutane sulfonic acid, or PFBS.
Another study examined samples of drinking water sourced from 19 sites around Lake Ontario and the St. Lawrence River. Detection limits ranged from 0.1 ng/L to 4.1 ng/L.
The main health consequences from PFAS exposure include risks to the liver, immune system, endocrine system (thyroid), fertility, development and metabolism. Additionally, testicular and kidney cancers have been specifically linked to PFOA exposure.
Health Canada states that the exposure limit of 30 ng/L for PFAS is based on two validated, standardized U.S. EPA analytical techniques that are available for the quantitation of 29 compounds. In Canada, laboratories are generally accredited for EPA Method 537.1, which uses an isotope-dilution, hydrophobic solid-phase extraction, liquid chromatography, and tandem mass spectrometry.
In terms of municipal water treatment, Health Canada states that the most effective treatment technologies for PFAS are granular activated carbon, membrane filtration (reverse osmosis and nanofiltration) and anion exchange.
“Common drinking water treatment technologies (for example, coagulation, flocculation and oxidation) are not effective for PFAS removal,” states Health Canada’s draft objective. “While there are treatment technologies that can effectively remove certain PFAS, no single treatment can remove a wide range of PFAS under all conditions.”
Total organic fluorine (TOF) analysis is also used for PFAS detection in drinking water. It can more comprehensively assess the concentration of PFAS beyond the 29 listed in the EPA technique; however, it is “indiscriminate” and may capture fluorine from non-PFAS compounds, states Health Canada.
Public comments on the new PFAS draft objective must be received before April 12, 2023.
