Science and Monitoring the Human Health Effects of Cyanobacterial Toxins

By Jennifer Boehme, IJC

Huge algal bloom fossils appear in rocks that are 3 billion years old. These organisms survived when other life couldn’t, and helped to form our atmosphere.  Today, similar blooms are visible from outer space. Cyanobacterial blooms continue to form around the world where waters have abundant or excess nutrients, like nitrogen or phosphorus.

In the Great Lakes, these blooms often float on surface water as a mat of blue-green scum.  Some blooms of cyanobacteria may produce toxic compounds (cyanotoxins), which can harm animal and human health. As a result, cyanobacteria blooms and cyanotoxins threaten Great Lakes recreational waters and drinking water supplies. These bacteria deserve our respect, and the stakes are huge: the Great Lakes provide drinking water for 35 million people and millions rely on it for recreation.

algal blooms erie pelee
Algal blooms impacting Pelee Island in western Lake Erie during the summer of 2015. Credit: NASA

To better understand the human health and management challenges for cyanobacteria and toxins common to the region, IJC’s Health Professionals Advisory Board undertook a science and monitoring assessment of the Great Lakes basin. Reviews of current literature indicate that blooms appear to be getting more frequent and long lasting than in the past, with new cyanobacteria appearing in the Great Lakes that have not been discovered here before. The report cites evidence which suggests we could reduce the risk of cyanobacterial blooms by controlling fertilizing pollutants and slowing the temperature rise in the lakes.

The review also highlights health surveillance gaps, and potential actions toward protecting public health. For instance, the ability of health care providers to associate environmental cyanotoxin exposure with individual cases and illness diagnoses remains a public health challenge. There also are questions as to how well existing public health guidelines for cyanotoxin exposure protect children, and the report makes a case for additional numeric criteria for more toxins.

The report notes that public health risk of cyanotoxin exposure can be reduced with improvements in drinking water monitoring and laboratory testing, though it is difficult to monitor beaches and drinking water to determine cyanotoxin presence. Challenges include the blooms, which can contain many cyanobacterial strains and multiple forms of toxins, complicating the search for simple testing strategies. Other challenges relate to current water treatment strategies, which may remove some toxins while making others worse. As a result, effectively managing cyanotoxin drinking water treatment remains a critical issue for Canada and the United States.

The threat to drinking water isn’t just theoretical: a 2014 bloom shut down the water system of Toledo, Ohio, a major US city. Canada has undertaken large investments in water infrastructure and monitoring, and the US is considering action toward a huge investment in infrastructure.

If the region is to improve water infrastructure the right way, binational efforts are needed. The HPAB report recommends identifying sound cyanotoxin treatment strategies, with technologies to remove mixtures rather than just individual toxins, and shifting treatments if a new toxin appears. These would be improvements over current water treatment practices.

Jennifer Boehme is a physical scientist at the IJC’s Great Lakes Regional Office in Windsor, Ontario, and secretary of the Health Professionals Advisory Board.

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