Wading through the mire: Keeping up with new and changing Canadian Drinking Water Guidelines
Changes to Canadian Drinking Water Guidelines
Over the past year there have been nine new consultations and announcement of eleven new or updated Canadian Drinking Water Guidelines. Keeping up with consultations and announcements can be a challenge for those involved in assessment of drinking water quality and management of drinking water supplies, raising questions of what type of preparations and responses are needed to ensure that drinking water guidelines are met and public health is protected.
How are drinking water guidelines developed?
Health Canada and the Federal-Provincial-Territorial Committee (FPTC) on Drinking Water establish draft guidelines for drinking water quality parameters (chemical, biological and aesthetic) using current published scientific evidence. Draft guidelines go through a process of internal and external peer review, with scrutiny by the FPTC and public consultation. This process can take several years and can result in confirmation or changes to existing guidelines or introduction of new guidelines.
What are some of the updates?
In June 2019 Health Canada updated the drinking water quality summary table that provides a full listing of current Drinking Water Guidelines for Canada. Further action may be needed by regional authorities responsible for safe drinking water where new guidelines have been introduced or existing guidelines have become more stringent.
- New guidelines have been introduced for copper (Cu), perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), and manganese (Mn) where none existed before. For these compounds, a range of actions may be needed. This could include a review of historic monitoring data (where it exists), identifying communities that may be at risk of failing the guideline and collecting baseline data, identifying where and to what extent failures of new guidelines are occurring, and identifying appropriate actions for these communities. Where failures of new guidelines have been detected, there may be concern amongst drinking water users about the health effects of past exposures, and what they can do to minimize any additional impacts on health in the future.
- Changes to existing guidelines over the past year have included lead (Pb) and cyanotoxins (MC-Total) from blue-green algae. The maximum acceptable concentration (MAC) for Pb in drinking water was significantly reduced from 10 µg/L to 5 µg/L. This could have major implications for monitoring programmes in facilities such as schools and daycares, where previous compliance levels were based on 10 µg/L. Additional monitoring to confirm compliance and remedial actions to ensure the new MAC is being met could be needed in some cases where mandatory testing is required (see additional NCCEH resources on Pb in homes and schools).
For the remaining parameters updated this year, no additional action is needed. This is because the review of current evidence confirms that the existing guideline is sufficient for protection of health, as has been the case for uranium, enteric viruses and enteric protozoa.
On the horizon
Currently there are seven parameters that have recently been open for public consultation or are awaiting the results of consultation. Of these, no change is proposed for three (E.coli, cadmium, total coliforms), removing the MAC is proposed for one (chloramines), and increasing the MAC is proposed for one (barium). The proposed changes are unlikely to affect current levels of monitoring, surveillance or compliance.
For the other two parameters a new guideline is proposed (aluminum and 1,4-dioxane). Aluminum- based coagulants are used in drinking water treatment processes and although an operational guideline exists, no health-based guideline had been developed. Evidence of neurological effects of aluminum prompted the proposed introduction of a new MAC at 2.9 mg/L for total aluminum in drinking water. For 1,4-dioxane, a new MAC of 0.05 mg/L is proposed. This compound is used as an industrial and commercial solvent and has been found to be a possible carcinogen (group 2B), with groundwater sources near landfills or industrial sites most likely to be at risk.
Keeping informed and being prepared for changes
Keeping up with changes to drinking water guidelines can help public health to prepare for potential changes well in advance, gathering evidence on the communities that may be affected, and developing guidance to support communities that need advice. The list of parameters recently out for consultation, as well as past consultations over the past 2-3 years, gives an indication of new guidelines on the horizon. Subscribing to receive updates when new content is added to Health Canada’s Water Quality site can help public health practitioners find out as soon as a new consultation is launched or an updated guideline is published.
How can I find out more about drinking water contaminants?
For more information on Canadian Drinking Water guidelines, consultation documents, and drinking water contaminants (Water Talk Fact Sheets), check out Health Canada’s Water Quality – Reports and Publications and your relevant provincial and territorial agencies responsible for drinking water.
For more water-related resources from the NCCEH click here.