Excessive growth or blooms of blue-green algae known as cyanobacteria in the water produce compounds in the water that are toxic to people. Called cyanotoxins, research conducted by scientists associated with the United States Geological Survey (USGS) has shown that harmful cynobacterial blooms produce odor and taste related compounds that can warn those on the water of potential danger.
Dangers of Contact With Toxins Produced by Cyanobacteria Highlighted
Contact with water contaminated by cyanotoxins can cause allergic reactions, impair respiration, harm kidney and liver function, and attack the central nervous system. Researchers previously thought that only one type of toxin was produced by cyanobacteria. The study Cyanotoxin mixtures and taste-and-odor compounds in cyanobacterial blooms from the Midwestern United States, published by the journal Environmental Science and Technology, shows the presence of a number of different toxins in an algae bloom.
Compounds that affect the taste and odor of water provide important cues to its safety and quality. Boaters should avoid contact with water that is discolored by an algae bloom and has a musty or earthy odor.
In an USGS press release concerning the study, Research Chemist Dr. Keith Loftin says, “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.”
Results Stemming From the Research Study
Scientists collected multiple water samples from 23 lakes found in Midwestern United States used for recreational purposes. Among six types of cyanotoxins analyzed for in the tests, five were present in at least one of the samples. The toxin known as microcystin was found in all of the samples taken. Compounds related to taste and odor were found in 91 percent of the samples taken from waters experiencing algal blooms, highlighting their role in the detection of potential toxins.
Concentrations of total micocystins in some samples reached 19,000 micrograms per liter (µg/L), which is about three times higher than the guidelines recommended by the World Health Organization for recreational activities on the water.
In the same press release, Limnologist Dr. Jennifer Graham, lead scientist for the study says, “It is commonly believed that there are no health risks associated with taste-and-odor compounds. While taste-and-odor 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-odor events so that the public can be advised and waters can be effectively treated.”
Directly contacting water associated with cyanobacterial blooms is risky. Boaters who encounter discolored water with an earthy or musty odor should take steps to avoid the area and contact local lake managers or health officials. Boaters and others on the waterfront should understand that activities like washing boats or dishes can promote the explosive growth of harmful algae.
Alan Sorum - Alan Sorum is the Maritime Operations Project Manager for the Prince William Sound Regional Citizens' Advisory Council (PWSRCAC). Alan is ...
