Arsenic
in drinking water
Introduction
On March 25, 2022 the Vancouver Sun reported that arsenic levels in the drinking water at a Powell River school was above the maximum acceptable concentration.
On November 10, 2022 a front page story appeared in the Coast Reporter concerning elevated arsenic levels in domestic water pumped from a local community well.
It was reported that Vancouver Coastal Health, issued an "advisory" and a “do not use” notice, respectively, in response to these arsenic levels.
This is not the first nor is it likely to be the last time that reports of high arsenic levels in some sources of drinking water come to our attention in such a public fashion. Every time this issue surfaces, we are all faced with the same question: what’s going on? As always, our response is to gather information and share it with you here; it seems to have started in 1993.
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1993
In 1993 a Powell River family failed to recover from a long illness. The family’s well water was tested and found to be 13 times higher that the maximum allowed. This caused great concern throughout the Sunshine Coast area and triggered an immediate response and study funded by Ministry of Health. The study data collected confirmed the presence of arsenic in some wells and precipitated the publishing of additional analysis and studies, primarily focused on the fractured bedrock aquifers from where the arsenic came.
Powell River and the Sunshine Coast are set on bedrock, covered by a thin veneer of unconsolidated sediments. This bedrock is primarily intrusive igneous rock, which is highly variable in type and nature. The bedrock has been subjected to intense deformation forces as evidenced by the extensive system of joints, fractures crevices and faults that provide pathways for groundwater movement and the dissolution of arsenic, from both accessory minerals, and the fabric of the rock itself.
The original 1994 study funded by Ministry of Health can be read by Clicking here to read PDF
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Arsenic
Arsenic, designated “As” on the periodic table, is the 20th most abundant element on Earth and is widely dispersed in our environment. Arsenic can be found in rocks, soil, water, air, and in plants and animals and as such is present in our food and drink. Arsenic is highly toxic and there is continuing concern about its presence in our diet. For most Canadians, the primary source of exposure to arsenic is food, followed by drinking water, soil, and air.
Because of its toxicity, arsenic was often used to change history; one of its early uses as a poison caused it to be dubbed "poison of kings”. More productive uses followed in early metallurgy, munitions, glassmaking and many other areas including cosmetics and even paint pigment. Today arsenic is important in solar cells, light emitting diodes, lasers and integrated circuits. For a time it was used in wood preservatives, pesticides and fertilizer, but these uses are generally no longer permitted. Today, arsenic is increasingly subject to regulation world-wide. For instance, in 2003, both the United States and Canada voluntarily stopped using chromate copper arsenate (CCA) in residential wood preservatives.
While many of the early uses are no longer permitted, arsenic can still enter the environment through:
-the burning of coal and other fossil fuels;
-metallurgical industry including gold and base metal mining;
-the emergency use of arsenic in agricultural pesticides and fertilizer; and
-the burning of waste.
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Arsenic may also enter lakes, rivers or underground water naturally in:
-mineral deposits or rocks containing arsenic;
-the discharge of industrial wastes; and
-arsenic particles in dust, or dissolved in rain or snow.
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In Canada, testing has shown that levels of arsenic in drinking water are usually less than 0.005 milligrams per litre (mg/L). However, because there were and are locations where arsenic levels are much higher and also because new health information became available, Health Canada, in 2006, lowered the Maximum Acceptable Concentration (MAC) for arsenic in drinking water from .025 to 0.010 mg/L. This limit is used in most countries today and is “based on a lifetime of daily and consistent consumption”.
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Water sourced from most Canadian lakes, streams and rivers generally has low levels of arsenic. However, in some parts of Canada and the world, arsenic, dissolved in drinking water pumped from wells drilled into underground aquifers, has become a serious health concern.
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According to HealthLinkBC: “In B.C., natural minerals are the most common sources of arsenic in drinking water.”
Responsibilities?
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Here, in the Garden Bay area, the SCRD’s North Pender Harbour Water System provides treated, tested and monitored domestic drinking water sourced from Garden Bay Lake. Residents who are served by this system enjoy domestic water that is regulated by government standards. For everyone else, it’s a different story.
Those residents living on property not served by the North Pender Harbour Water System, but who have a water source available on or near their property, might access water for their domestic needs from the following general sources:
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Lake water
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Stream water
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Ground water (an underground aquifer, accessed by a well)
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Rain water collection is another option, but it can be difficult to bridge the dry summer months. To clarify: the B.C. Government does not have ownership of surface water such as artificially collected precipitation or surface runoff that has not yet reached a stream.
Lake and stream water access for single family domestic use is fairly straight forward. The property owner is responsible for obtaining and maintaining a water licence or registration and for any necessary filtering and also for detecting and removing of arsenic and other pollutants in the water they consume. Our lakes and streams are primarily fed by rainwater and, according to government officials, arsenic has, to date, not been found to be a concern in our local waterbodies.
On the other hand, obtaining ground water (by drilling wells) for domestic use requires more caution because in some areas of B.C. , wells may encounter arsenic or other contaminants in the water drawn up to the surface.
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There are a few places where independent water systems have been approved. under the Water Users' Communities Act (WUC). This act governs groups of six or more water licensees who join together to construct and maintain a water diversion and storage or delivery system. “Any WUC supplying drinking water is required by the Ministry of Health to meet the requirements of the Drinking Water Protection Act and the Drinking Water Protection Regulation. Click here:Learn more about WUC Act
Yet another scenario is the Private Water Utility Act which governs small private waterworks that are also required to meet Ministry requirements. Click here: Learn more about Private Water Utility Act.
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Returning to the single family private well, registered or not, there is no government oversight or collection of data concerning the water quality being drawn from that well.
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In BC, our Provincial Health Officer holds oversight and accountability under the Drinking Water Protection Act (DWPA) for drinking water protection. In her report to the Minister of Health (signed in June 2019), PHO Dr. Bonnie Henry MD, MPH, FRCPC, explains, as clearly as it is possible to do, just one of the limits of government:
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“A single-family residence on its own water supply system is considered a private water system and exempt from most of the requirements of the Drinking Water Protection Act (e.g., construction and operating permits). Property owners on a private water supply are responsible for the safety of their own water supply and are not monitored or inspected by drinking water officers under the Act. Private water supplies do, however, benefit from the parts of the act related to threats to drinking water and source water protection.” To read Dr. Henry’s full report, click here
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Testing for Arsenic
Arsenic is not visible in water and is tasteless and odourless which means that a laboratory test is the only way to measure the level of arsenic in your domestic water. A private well owner has sole responsibility for the testing, filtration, and any necessary treatment of the domestic-use groundwater pumped up from their well. In Area A, the testing of water can be difficult because the required tests must be done in a lab and no such lab exists on the Sunshine Coast. Because of this inconvenience, it might be the case that not all private wells are routinely tested for water quality, arsenic and other contaminants.
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The Provincial government recommends: "Test your private wells regularly for water quality. For more information about private well water testing, see http://www.vch.ca/Documents/Testing-Your-Well-Water.pdf. Contact your local public health unit or environmental health officer for more information on the testing process in B.C."
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We took a close look at this advice and had a chat with our local Fraser Health, Drinking Water Officer, Darren Molder. His phone number is 604 885 8711 and, if you have a question, he is the right person to speak with. As a result of that conversation we have included the link above to an excellent pdf with all the info you need to test your well water. In the pdf there are 6 laboratories listed that do the water testing but a strict requirement is that the water sample must arrive at the laboratory within a specified number of hours (whatever the lab specifies). The cost of the test kit and testing alone is reasonable but the costs of transportation can be high, unless you do that yourself.
To explain this from a local point of view, here is the story as told by a neighbour who recently did this. "We chose a lab (in Burnaby) and made contact. Then we drove to the lab and picked up the test kit and brought it up to Garden Bay. The next time we headed into Vancouver, we took a sample just before we left, kept it on ice and delivered it to the laboratory within the time limit. The lab then invoiced us and emailed the results within a few days." As our neighbour put it: "Easy Peasy”.
Arsenic in Your Domestic Water
Let’s say, after testing and confirming, you discover that you have arsenic in your domestic water and that it is over the MAC limit; what do you need to know and what can you do about it?
Your primary concern and responsibility is to prevent all humans and pets from drinking or ingesting the water and to stop using the water when preparing food or watering edible plants. Boiling the water is not a solution as that may increase the concentration of arsenic in the water.
Showering, washing hands, laundry, dish washing, toilet flushing, etc., are considered safe.
After reading these restrictions, you might, as many of our neighbours have done, be proactive and purchase drinking water in large 5 gallon/ 18.9 litre plastic bottles along with a dispenser. Even if you have an elaborate filtration system, you might choose this strategy year-round, regardless of water source and quality issues, just to be on the safe side.
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Fraser Health occasionally issues a “do not use notice” letter when it is made aware of high arsenic levels in a particular ground water source and we include some of the essential wording from that notice here:
“What you need to do now during this DO NOT USE NOTICE.
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Use an alternate source of drinking water for:
- consumption by all persons and pets
- washing and/or cooking foods
- personal hygiene such as brushing teeth or where water is used internally -
Safe to continue to use your water for:
- bathing and showing
- cleaning of cookware, plateware, glassware, utensils and food prep surfaces
- laundry
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Note that:
- Boiling water will NOT remove Arsenic from the water"
As you can see this notice requires the same response as we suggested earlier.
Fifteen percent of Sunshine Coast residents get their water from groundwater or the lakes in the Egmont and Pender Harbour areas and wells on the South Coast.
About Arsenic and Humans
Arsenic can be absorbed orally or by breathing. Once in the GI tract or lungs, arsenic is distributed throughout the body in the blood stream. The human body deals with arsenic reasonably quickly. A process called biomethylation occurs in the liver and within two days about 70% of arsenic is excreted in urine. According to studies, two to four weeks after exposure to arsenic ceases, most of the arsenic remaining in the body is found in keratin-rich tissues such as hair, nails, skin, and to a lesser extent, in bones and teeth.
Consuming water with very high (well above the MAC) levels of arsenic for days or weeks can result in arsenic poisoning with a wide range of symptoms such as stomach pain, vomiting, diarrhea and impaired nerve function (sensations of pins and needles, numbness and/or burning in hands and feet). Skin changes include skin flushing and rashes, skin darkening and wart-like or corn-like growths which usually occur on the palms of the hands or bottoms of the feet.
Because children tend to drink more water per unit of body weight than adults, their exposure to arsenic in drinking water may be proportionally greater and they may be at greater risk of illness.
Long-term exposure to even relatively low amounts of arsenic in drinking water, over years or decades, can increase your risk of developing certain cancers, including:
Skin, Lung, Kidney, Bladder, Prostate and Liver cancer
Other developmental impairments include:
Cardiovascular Disease, Adverse Birth Outcomes and
Impacts on the Immune and Endocrine Systems.
The risk of cancer is the reason for developing the Canadian guideline for arsenic in drinking water. For more information on The Guidelines for Canadian Drinking Water Quality,
This water treatment image is for illustration purposes only
and is not a recommendation of any particular system or device
What Can You do About High Arsenic Levels in Your Well?
Governments suggest you might try and find another source; but where? More realistically you might consider treating your current source.
Arsenic in a private well may be treated by a growing number of technologies, such as ion exchange, distillation or adsorption/filtration, etc. We read that the most prevalent system in use is reverse osmosis, which, in a given volume of ground water, produces 25% potable water but also creates 75% residual water containing arsenic and other contaminants, but in a more concentrated form.
Because removal technologies frequently remove other contaminants in addition to arsenic, the residual waste may also have concentrated levels of co-occurring contaminants, such as lead, barium, radionuclides, etc. Residual waste with co-occurring contaminants may present disposal problems even when the arsenic levels in the processed residuals are not high enough to lead to a hazardous waste classification or interfere with local limits. The advice given is that operators of water purification systems should thoroughly test their wastes prior to making disposal decisions.
Disposing of contaminated waste into wetlands, streams or lakes would presumably require testing of the waste and a permit to do so.
Why do Arsenic Levels Vary Between Wells?
Why do Levels Sometimes Rise and Fall?
Over the past 20 years, several well locations in the North Pender and Kleindale areas tested over MAC for arsenic. In one well that was being treated by ion exchange and routinely tested, the arsenic levels remained below MAC except for a few occasions when levels exceeded MAC; why is this happening? Is this a treatment issue or are there arsenic level fluctuations in the raw water from the aquifer?
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Because of arsenic concerns in the 1990s, a local study was done in 1994. The final report was published in 2000 titled An Investigation of High Arsenic Levels in Wells in the Sunshine Coast and Powell River Regions of B.C. Although this data is almost 30 years old, it is the cornerstone of our still-limited knowlege in these matters. You can access this report here; it is also the second item in our "References"section at the end of this web page.
On page 13 of a 2000 follow up study, the following statement appeared: "areas of extreme arsenic levels, such as the Middlepoint, Secret Cove, and Kelly Creek areas”. The Garden Bay area was not identified as"extreme" on that list. On the map above, which is data associated with the 1994 study, we have circled Pender Harbour and you will see numerous blue and red dots denoting wells with elevated arsenic. Keep in mind that in 1994, the MAC for arsenic in water was much higher at 0.025ppm.
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A few of the conclusions reached are listed below:
"The spatial distribution of arsenic is most likely regulated by the fracture patterns in the bedrock which are almost impossible to map"
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"Approximately 20% of the samples had fluoride and boron above guidelines"
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"No significant correlation was found between arsenic and well depth."
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"On-going monitoring of arsenic concentrations should be performed, perhaps in conjunction with the B.C. Ministry of Environment-Groundwater Section.
Certainly, more well testing would be useful and might also provide more information to explain why arsenic readings rise and fall but unfortunately no comprehensive governmental monitoring of arsenic concentrations was initiated as a result of this study.
Delving into the daunting number of world-wide scientific papers and studies requires the intellect and training of a geologist, biochemist, mathematician, environmental scientist, seismologist and microbiologist, to name a few. Finding answers to our questions can be frustrating. We did find a partial answer in a 2021 study: Assessing the Impact of Drought on Arsenic Exposure from Private Domestic Wells….in which the following finding appears:
”The current findings suggest that drought has an adverse impact increasing the potential exposure to arsenic.”
In another study, we learned that cities and towns which access well water for domestic distribution will generally drill wells much deeper than private wells. This may be to guarantee water access in times of lower water table levels during droughts but it is also known, from studies, that wells 500 feet or deeper are acknowledged to have lower levels of arsenic than shallower wells in the same area. That 2011 study funded by the US National Institute of Environmental Health Sciences' Superfund Research Program demonstrates that “deep sediments can remove arsenic and take it out of circulation. In this process, called adsorption, arsenic sticks to the surfaces of deep sediment particles and is naturally removed from the ground water.”
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In a 2018 study in Finland, "Dissolved concentrations (of arsenic) appear to be directly dependent on the distance from faults and deformation zones (FDZs) detected via geological and geophysical surveys. ....Dissolved As exceeding 100 μg/L was found at distances below 4 km from the detected FDZs, while concentrations drop below the drinking limits at about 8 km from the FDZs."
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In trying to apply this finding to our south coastal area of B.C., we came across a 2019 UBC research article that identified a new fault line 65 km under Georgia Strait. Estimated to be 20 km long, the fault is believed to be part of an “earthquake nest” of faults that may one day trigger a magnitude 6.0 earthquake. Located just south of Texada Island, the fault was identified by studying data from 30 years of quakes in the area. We made contact with one of the researchers, to explain our question: could nearby tectonic activity be the cause of higher arsenic levels in adjacent freshwater aquifers along the Sunshine Coast. But the extreme depths of these new faults made that connection unlikely. Instead we were sent a 2000 report that studied the June 24, 1997 earthquake which occurred in local shallow crustal faults.
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This report is titled Characterization of Active Faulting Beneath the Strait of Georgia, British Columbia, and it can be accessed in our reference section below. It begins:
“Southwestern British Columbia and northwestern Washington State are subject to megathrust earthquakes, deep intraslab events, and earthquakes in the continental crust. Of the three types of earthquakes, the most poorly understood are the crustal events. “
The map below, from the study, shows the epicentre and also the relatively shallow crustal faults in our coastal area, the closest running up Agamemnon Channel between Texada Island and the Sunshine Coast.
Reading the study you will appreciate (Table 2) that tabulates the forshocks, that occurred during the two weeks prior, and the larger number of aftershocks, that followed June 24, 1997. Despite all this geological activity, only two of the shocks were "felt" by humans.
Figure 4. from 2000, study,
Characterization of Active Faulting Beneath the Strait of Georgia, British Columbia
by John F. Cassidy, Garry C. Rogers, and Felix Waldhauser
Today, without a great deal more data about our aquifer, there is a limit to what is discoverable. Research sources, studies and papers offer differing findings from around the world but these can still help us to understand some of the complex processes that may be in play here in Pender Harbour.
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One day, we may read local scientific studies corroborating that the seismic shocks and the shaking of our crustal zone disturbs fractured granite aquifers such that arsenic deposits are increasingly exposed to ground water causing dissolved arsenic concentrations to rise and that drought conditions or well depth are also contributing factors.
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While we wait for that to happen, the suggestion to drill a deeper well, might be worth considering, despite the added expense. Government recommendations that each well owner test and treat to remove impurities in their ground water, will if followed, lead to better health outcomes and peace of mind.
Footnote
Is There Arsenic in Food?
Humans may ingest arsenic in drinking water but the primary intake of arsenic is food. The leading food sources of arsenic are generally presented to be: Rice, rice cereal, seafood, mushrooms, cruciferous vegetables.... the list continues. We came upon this interesting article, "How much arsenic is in your rice?". (Click Here). This article/report was published in 2012 and 2013. Ten years later, on August 17, 2022, Health Canada announced the addition of the following two maximum levels (MLs) for inorganic arsenic to the List of Contaminants and Other Adulterating Substances in Food, which is incorporated by reference into the Food and Drug Regulations:
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A ML of 0.1 ppm (100 ppb) for inorganic arsenic in rice-based foods intended for consumption by infants and young children.
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A ML of 0.01 ppm (10 ppb) for inorganic arsenic in fruit juices and fruit nectars, except grape juice and grape nectar for which the ML is 0.03 pm (30 ppb).
References:
On our website menu, in the section “About Hotel Lake”, you will find a page titled “Domestic Water” which describes the various ways in which Garden Bay area residents obtain domestic drinking water. That page is intended to underscore that our drinking water comes from several different sources and that the responsibility for the quality of that water varies depending on which source. If you would like to refresh your memory by reviewing that page, please do so at your leisure as it complements the subject above. Click here to read
1994, Well Water Survey for Arsenic in the Powell River and Sunshine Coast Communities of British Columbia - March to June 1994 This is the original study funded by Ministry of Health, Click here to read PDF
2000, An Investigation of High Arsenic Levels in Wells in the Sunshine Coast and Powell River Regions of B.C. Prepared for the Coast Garibaldi Community Health Services Society
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2000, Characterization of Active Faulting Beneath the Strait of Georgia, British Columbia, by John F. Cassidy, Garry C. Rogers, and Felix Waldhauser. Click here to read PDF.
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Environmental Health Services - Coast Garibaldi Area, a repository of data, studies and information
https://healthspace.ca/Clients/VCHA/CoastGaribaldi/CoastGaribaldi_Website.nsf/e8db9633a9d595f98
Testing Your Well Water- Vancouver Coastal Health
http://www.vch.ca/Documents/Testing-Your-Well-Water.pdf
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2021, Assessing the Impact of Drought on Arsenic Exposure from Private Domestic Wells in the Conterminous United States. Melissa A. Lombard,* Johnni Daniel, Zuha Jeddy, Lauren E. Hay, and Joseph D. Ayotte . An abstract of this study can be read at the link below :
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Carex Canada, Arsenic and Arsenic Compounds Profile
https://www.carexcanada.ca/profile/arsenic/
Arsenic Toxicity, What is the Biologic Fate of Arsenic in the Body?
https://www.atsdr.cdc.gov/csem/arsenic/biologic_fate.html
How Does Arsenic get into Drinking Water?
https://umaine.edu/arsenic/how-does-arsenic-get-into-the-groundwater/
2017, Small Water System Guidebook, by BC Ministry of Health (excellent & comprehensive)
https://smallwatersystemsbc.ca/resource/small-water-system-guidebook
Environmental Health Services - Coast Garibaldi AreaVancouver Coastal Health, data on water testing
https://www.healthspace.ca/Clients/VCHA/CoastGaribaldi/CoastGaribaldi_Website.nsf
Canadian Cancer Society – Arsenic in Drinking Water
https://cancer.ca/en/cancer-information/reduce-your-risk/know-your-environment/arsenic
How much arsenic is in your rice?
https://www.consumerreports.org/cro/magazine/2015/01/how-much-arsenic-is-in-your-rice/index.htm
Health Canada – Arsenic in drinking water
World Health Organization – Arsenic in drinking water
https://www.who.int/news-room/fact-sheets/detail/arsenic
CBC New Earthquake Fault