Nature's Poisons

You can find them in drinking water.

Research is being conducted on toxins in lakes and farm dugouts that supply drinking water in Saskatchewan and Alberta. The researchers involved are Steve Hrudey and Ellie Prepas of the University of Alberta, and Hans Peterson of the Saskatchewan Research Council.

The team is looking in particular at cyanobacteria (commonly known as blue-green algae), which produce a number of odour-causing as well as toxic substances. The toxins and odorous substances apparently are produced independently of each other, which means that odour is not always a reliable warning of toxic potential.

Samples taken last year from Alberta lakes showed that some algae cells contained relative high portions of a toxin called microcystin LR, which can cause liver damage in humans if consumed in high enough concentrations. The presence of the toxin may not be a health risk to humans as long as the algae cells remain intact and are trained out of drinking water through normal water treatment processes. However, they can pose a threat when the cell membrane is ruptured, releasing the toxin for distribution through the drinking water supply.

That rupture and distribution could happen as a result of a chemical treatment (copper sulphate) commonly used to control the growth of algae. The treatment is not used on Alberta lakes, but is often used to treat farm water dugouts that are sources of drinking water around the world.

Human poisoning by these particular toxins has not yet been clearly documented although there have been a few incidents which suggest adverse health effects have been caused by toxins. The available evidence does not warrant a panic response. However, there is a responsibility for regulatory and health agencies to learn more about these toxins.

Having more information about natural contaminants should provide a basis for more informed decisions about environmental health risks. This insight into natural toxin risks will also help provide a comparative context for the assessment of environmental health risks arising from human activities. This work is being funded by the Natural Sciences and Engineering Research Council.