TOXINS PRODUCED BY BLUE GREEN ALGAE
Report No FR0150
M G C BAKER AND J K FAWELL
To review and assess the available information concerning the problems associated with blue-green algae.
Blue-green algal blooms in lakes and reservoirs have been common for many years. The deaths of domestic animals and livestock associated with heavy blooms in 1989 and 1990 have resulted in a much greater public awareness of the potential problems which can arise as a consequence of the events.
Blue-green algae appear to have been forming blooms in ponds and lakes for hundreds and possibly thousands of years. Evidence suggests that toxin production has been a feature for as long as blooms have been occurring.
In more recent times intensive use of waters for recreational purposes and abstraction of drinking water have focused attention on the problems caused by blue-green algae. Over the past two years the problems have achieved public prominence.
The aggregations of large numbers of algae, often around the shore-line constitute the greatest hazard to livestock, domestic animals and water users. The risks to water users are related to the potential for ingestion of, or exposure to, these high densities of algae.
There is some evidence from other countries that under extreme circumstances drinking water contaminated with toxins may pose a hazard to consumers health. The extent of such contamination and the risk from it in the UK cannot be properly assessed without appropriate validated analytical methods and a significant improvement in the database on toxicity. However, the presence of blooms in water supply reservoirs is not a new phenomenon and there have been no signs of any major outbreaks of illness associated with such blooms. Therefore it is reasonable to postulate that any effects, if they do occur, are very limited in severity.
There is a need for much more data on the blue-green algae and their toxins in order to judge the risks and make appropriate decisions regarding remedial actions.
In particular data are needed on the following:
This report is presented as an extended summary with a discussion of the problems and outstanding questions related to blooms of blue-green algae. More detailed reviews of the available data, with references, are given in the appendices. It primarily concentrates on the issues relating to drinking water supply and reservoirs also used for recreation.
Copies of the Report are available from FWR, price £15 less 20% to FWR Members.