Water that looks and smells bad may be toxic

WASHINGTON - If water present in a lake or reservoir has earthy or musty odours and has blue-green algae, then it is not fit for use, a new study has suggested.

In a USGS study of cyanobacterial blooms in Midwest lakes, taste-and-odour compounds were found almost every time cyanotoxins were found, indicating odour may serve as a warning that harmful toxins are present.

“It is commonly believed that there are no health risks associated with taste-and-odour compounds,” said Jennifer Graham, lead scientist on the study.

“While taste-and-odour compounds are not toxic, these pungent compounds were always found with cyanotoxins in the blooms sampled.

“This finding highlights the need for increased cyanotoxin surveillance during taste-and-odour events so that the public can be advised and waters can be effectively treated,” she said.

Keith Loftin of USGS said: “Exposure to these toxins has caused a range of symptoms including skin rashes, severe stomach upset, seizures, or even death.

“Pets and livestock are most susceptible to direct exposure, but people can also be affected during recreation, by eating contaminated foods, or by drinking contaminated water that has not been treated properly.”

For this study, a cyanobacterial bloom from each of 23 lakes in Iowa, Kansas, Minnesota and Missouri was sampled and analysed for thirteen toxins and two taste-and-odour compounds. Lakes were targeted based on a known history of cyanobacterial bloom occurrence.

Microcystins, a specific type of toxin, are often the only cyanotoxin considered when evaluating risks associated with cyanobacteria in waters used for recreation or drinking water supply.

Microcystins were found in all samples; however, this study also indicates that toxins other than microcystins may be more common than previously thought.

Taste-and-odour compounds were detected in 91 percent of samples.

Since toxins occurred more frequently than taste-and-odor compounds, odor alone does not provide sufficient warning to ensure human-health protection against cyanotoxin exposure. (ANI)