Potent human toxins prevalent in Canada’s freshwaters

River Algae

River AlgaeOTTAWA – Nutrient pollution, one of the greatest threats to our freshwater resources, is responsible for the algal blooms that blanket our lakes and waterways in summer months. Potent human toxins prevalent in Canada’s freshwaters. Large blooms of cyanobacteria (‘blue green algae’) can cause fish kills, increase the cost of drinking water treatment, devalue shoreline properties, and pose health risks to people, pets, and wildlife. A new paper just published in the Canadian Journal of Fisheries and Aquatic Sciences shows that microcystin, a toxin produced by cyanobacteria, is present in Canadian lakes in every province.

“Canadians enjoying their summer at the cottage need to know that those green scums of algae washing up on their beach are not only unsightly, but can also be a threat to their health and their children’s health,” stated lead author, Diane Orihel, a researcher with the Department of Biological Sciences at the University of Alberta. “It’s time to get serious about cleaning up the nutrients polluting our lakes.”

Microcystins are well-established as potent liver toxins to humans and other mammals, and are classified as possible human carcinogens.

“Blue-green algae present a growing health concern for domestic, agricultural and recreational water use in Canada and world-wide”, warns Dr. David Kinniburgh, the Director of the Alberta Centre for Toxicology at the University of Calgary. “The microcystin toxins they produce can cause acute liver failure in humans and may even cause cancer with long-term exposure.”

This study is the first to report on microcystin prevalence at a national scale–data from 246 bodies of water across Canada were collected. The authors determined that water quality was most at risk in lakes with the highest concentrations of nutrients. Nutrient-rich lakes and reservoirs, particularly in central Alberta and southwestern Manitoba, proved to have highest toxin concentrations, though all regions in Canada contained lakes that reached microcystin levels of concern.

A very important finding–that calls for further research–was the strong association between low nitrogen-to-phosphorus ratios and high microcystin concentrations. The authors recommend whole-ecosystem experiments be performed to understand how changing nutrient inputs to lakes affects microcystins and other cyanobacterial toxins. This information is essential for governments to develop effective management strategies for improving water quality in nutrient-polluted lakes.

“Harmful algae blooms are a growing problem worldwide. The more we look, the more we find,” remarked international water expert Dr. Stephen Carpenter, Director of the Center for Limnology at the University of Wisconsin-Madison, “Orihel and colleagues help define the conditions when we would expect highly toxic freshwater. These insights make it possible to focus management and research on the highest-risk situations.”

“This study addresses an issue that has important health consequences, but also highlights the importance of both the underlying basic science and monitoring programs essential to determine environmental changes,” says Don Jackson, Co-Editor of the Canadian Journal of Fisheries and Aquatic Sciences.

The paper “High microcystin concentrations occur only at low nitrogen-to-phosphorus ratios in nutrient-rich Canadian lakes”, published in the Canadian Journal of Fisheries and Aquatic Sciences, is available Open Access.

“High microcystin concentrations occur only at low nitrogen-to-phosphorus ratios in nutrient-rich Canadian lakes”

A new paper on the prevalence of a potent human toxin in Canada’s freshwaters

 

Background information on eutrophication:

  • ·         Nutrient pollution is one of the greatest threats to our freshwater resources, not only here in Canada, but around the world
  • ·         Excess nutrients from sewage, agricultural fertilizers, and animal feedlots are responsible for the ‘eutrophication’ of lakes and reservoirs
  • ·         The term ‘eutrophication’ refers to the increase in the frequency and severity of algal blooms in lakes, ponds, or reservoirs that occurs in response to nutrient pollution
  • ·         Algal blooms in eutrophic bodies of water are predominately composed of ‘blue green’ algae known to scientists as ‘cyanobacteria’
  • ·         Eutrophication of freshwater ecosystems results in serious water quality problems:
    • Produces unsightly blooms of nuisance algae that accumulate on beaches
    • Sucks oxygen out of bottom waters, resulting in massive fish kills
    • Depreciates the value of lakeshore real estate
    • Threatens the sustainability of sport and commercial fisheries
    • Negatively impacts tourism and recreation opportunities in and around lakes
    • Increases the cost of treating drinking water
    • Poses health risks to people, pets, livestock, and wildlife

 

Background information on microcystins:

  • ·         Globally, microcystins are one of the most commonly-occurring toxins produced by freshwater cyanobacteria
  • ·         Microcystins harm humans and other mammals by blocking certain enzymes in the body, which – in high enough doses –  can lead to hemorrhaging of the liver
  • ·         Microcystins are not only potent liver toxins, but are also possible carcinogens; exposure to microcystins may be linked to the incidence of liver cancer in human populations
  • ·         People are potentially exposed to microcystins through drinking water and recreational contact with lake water infested with cyanobacterial blooms
  • ·         Human fatalities have occurred in other countries, but not yet in Canada
  • ·         In some Canadian provinces, beach advisories are being posted when levels of microcystin exceed the safe level for recreational contact

 

Main findings of this paper:

  1. 1.    A potent human liver toxin produced by cyanobacteria – microcystin – is now an issue of national concern, as it is detected in lakes, ponds, and reservoirs across Canada.
  2. 2.    The presence of microcystins in Canadian lakes has potential implications for human health because concentrations of toxins in our lakes can be above human safety guidelines for drinking water, as well as for recreational contact.
  3. 3.    The highest levels of microcystin in Canada are found in nutrient-rich lakes and reservoirs on the Prairies, particularly in central Alberta and southwestern Manitoba.
  4. 4.    The toxin microcystin was only found in nutrient-polluted lakes, and high levels of microcystins were associated with low nitrogen-to-phosphorus ratios.
  5. 5.    The authors call for whole-lake experiments to determine how altering nutrient ratios entering lakes and other waterbodies affect levels of cyanobacterial toxins.

 

Quotes from authors of this study:

  • ·         “Canadians enjoying their summer at the cottage need to know that those green scums of algae washing up on their beach are not only unsightly, but can also be a threat to their health and their children’s health. It’s time to get serious about cleaning up the nutrients polluting our lakes”.We found unsafe levels of microcystins in lakes with high levels of nutrients, especially where there was relatively less nitrogen compared to phosphorus. This may have important ramifications for the government’s nutrient management strategies, but we need to conduct large-scale experiments to establish cause-and-effect relationships”. Diane M. Orihel (lead author), PhD Candidate, Department of Biological Sciences, University of Alberta; Email: orihel@ualberta.ca, Tel: 204-979-2395

 

  • ·         “Blue-green algae are not just an unwelcome visual problem in our lakes. They present a growing health concern for domestic, agricultural and recreational water use in Canada and world-wide. The microcystin toxins they produce can cause acute liver failure in humans and may even cause cancer with long term exposure.” Dr. David Kinniburgh, Director, Alberta Centre for Toxicology, University of Calgary; Email: dkinnibu@ucalgary.ca; Tel: 403-220-5762

 

  • ·         “This paper reveals that the group of algal toxins known as microcystins are truely a pan-Canadian issue.  Based on this model, government regulators will be able to use simple, commonly collected water chemistry measurements to identify areas or periods of time where the risk of toxic microcystin levels is high.”

Dr. Rebecca C. Rooney, Research Associate, Department of Biological Sciences, University of Alberta; Email: rrooney@ualberta.ca, Tel: 780-722-7633.

 

  • ·         “Potentially dangerous levels of toxins were detected throughout southern Canada, any place there was high population density or intensive resource management. This study underlines the challenge facing Canadians – how to we sustain modern society without damaging lakes and rivers to the point that we poison ourselves? The problem is especially severe in the Prairies, where naturally high nutrient levels, increasingly warm summers, and widespread fertilization due to farming and urban growth has led to a triple whammy of stresses. When combined with naturally dry conditions in the middle of the continent, you have the recipe for some spectacularly bad water quality.”  Dr. Peter R. Leavitt, Canada Research Chair in Environmental Change and Society, University of Regina; Email: Peter.Leavitt@uregina.ca, Tel: 306-585-4253

 

  • ·         “Our findings point to continued careless release of phosphorus-laden products, such as lawn fertilizers, into naturally productive lakes further degrading their ecosystem services to humans – including recreational quality, delivery of potable water, and wildlife habitat – by stimulating production of toxins by bluegreen algae.” Dr. Rolf D. Vinebrooke, Associate Professor, Department of Biological Sciences, University of Alberta; Email: rolf@ualberta.ca, Tel: 780-492-1870 

Quotes from internationally-acclaimed scientists about this study:

  • ·         “Harmful algae blooms are a growing problem worldwide. The more we look, the more we find. Orihel and colleagues help define the conditions when we would expect highly toxic freshwater. These insights make it possible to focus management and research on the highest-risk situations.” Dr. Stephen R. Carpenter, Director of the Center for Limnology at the University of Wisconsin-Madison; Email: srcarpen@wisc.edu, Tel: 608-262-3014, Website: http://limnology.wisc.edu/personnel/carpenter/

 

·         “Despite Canada’s huge size, much of which is characterized by lakes and ponds, it is disconcerting to see that 41% of the water bodies included in this database exceeded water quality guidelines for this important toxin. It is another “wake-up call” that all is not well with our aquatic ecosystems, and reminds us of some of the new challenges we will be facing with our rapidly changing environment.”

Dr. John P. Smol, Professor and Canada Research Chair in Environmental Change, Department of Biology, Queen’s University; Email: smolj@queensu.ca, Tel: 613-533-6147 or 613-328-2522; Website: http://www.queensu.ca/biology/people/faculty/smol.html 

·         “Water quality is an important issue for Canadian citizens, and Environment Canada has noted that not since the 1970s has concern about nutrient pollution to aquatic environments been so high.  This timely paper provides clear and compelling evidence that the supplies of nitrogen and phosphorus jointly regulate toxic algal blooms in Canadian lakes, and it contributes exceptionally valuable new information that can assist water quality managers in minimizing this highly undesirable public health threat.” Dr. Val H. Smith, Professor of Ecosystem Ecology, Department of Ecology and Evolutionary Biology, University of Kansas; Email: vsmith@ku.edu, Tel: 785-864-4565; Website: http://www2.ku.edu/~eeb/faculty/smithv.shtml

·         “This study shows that harmful algae blooms may occur almost anywhere in Canada, but they can often be remedied by effective waste water treatment and environmental controls on agricultural, municipal and residential effluents. It’s another example of how we have the ability to improve our lakes and waterways for future generations through responsible environmental regulations.” Dr. Jules M. Blais, President of Society of Canadian Limnologists, Professor of Biology and Environmental Toxicology, University of Ottawa; Email: jules.blais@uottawa.ca, Tel: 613-562-5800×6650; Website: http://mysite.science.uottawa.ca/jblais/

·         “Microcystins are regarded as potent tumor promoters. Scientific studies have shown an association between chronic low-dose consumption of microcystins in drinking water and increasing incidence of primary liver cancer. Microcystin toxicity is mediated through its ability to induce oxidative stress and genetic mutations, while altering cellular growth.  Recent evidence suggests that in addition to being carcinogenic, microcystins may act as endocrine disrupting compounds. Therefore persistent exposure to microcystins poses a potential threat to human health.” Meaghan Labine, PhD Candidate, Dept of Pharmacology and Therapeutics Section Hepatology, Faculty of Medicine, The University of Manitoba, Email: meaghanlabine@hotmail.com