Risk Assessment of Cyanobacterial Toxins

Detection, Analysis and Risk Assessment of Cyanobacterial Toxins... 

The final article, by S. G. Bell and G. A. Codd of the University of Dundee Department of Biological Services, is concerned with detection, analysis, and risk assessment of cyanobacterial toxins. These can be responsible for animal, fish, and bird deaths and for ill-health in humans. The occurrence of toxic cyanobacterial blooms and scums on nutrient-rich waters is a world-wide phenomenon and cases are cited from Australia, the USA, and China, as well as throughout Europe. The causes, indentification and assessment of risk, and establishment of criteria for controlling risk are discussed. 

The detection and analysis, including quantification, of cyanobacterial toxins are essential for monitoring their occurrence in natural and controlled waters used for agricultural purposes, potable supplies, recreation and aquaculture. Risk assessment of the cyanobacterial toxins for the protection of human and animal health, and fundamental research, are also dependent on efficient methods of detection and analysis. In this article we discuss the methods developed and used to detect and analyse cyanobacterial toxins in bloom and scum material, water and animal/clinical specimens, and the progress being made in the risk assessment of the toxins. 

For assessing the risk of exposure to cyanobacterial toxins it is crucial to understand the occurrence of the toxins in surface waters. For predicting the occurrence of cyanobacterial toxins, the following factors have to be considered ... 

It is obvious from the provisional risk assessment values for microcystins, and, being of the same order of magnitude of mammalian toxicity, similar values may be calculated for the cyanobacterial neurotoxins, that sensitive detection methods are required to detect these low concentrations of toxins. Of the biological methods of detection discussed earlier, the mouse and invertebrate bioassays are not sensitive enough without concentration of water samples, in that they are only able to detect mg of microcystins per litre. Only the immunoassays (ng-/rg 1 and the protein phosphatase inhibition assays (ng O... 

For a risk assessment it is therefore crucial to define accurately the part of a water body concerned by the specific water use. Raw water abstraction for drinking water production, for example, requires the monitoring of toxin concentration close to the off take site. Data on average concentration in the entire water body are valuable to judge whether cyanobacterial toxins are present at all but likely provide only insufficient or even misleading information for drinking water safety. 

Burch, M. and House, J. Australasia and Oceania cyanobacteria, cyanotoxins and their management. In Cyanonet a Global Network for Cyanobacterial Bloom and Toxin Risk Management Initial Situation Assessment and Recommendations, Codd, G.A., Azevedo, S.M.E.O., Bagchi, S.N., Burch, M.D., Carmichael, W.W., Harding, W.R., Kaya, K., Utkilen, H.C., Eds., International Hydrological Programme (IHP) of UNESCO, Paris, France, p. 47, 2005. 

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