LEVELS OF ANATOXIN-A AND MICROCYSTIN-LR IN RAW AND TREATED WATERS
Report No FR0460
H A JAMES, C SMITH AND A SUTTON
The levels of two of the commonly occurring blue-green algal toxins, microcystin-LR and anatoxin-a, in reservoir waters and the derived drinking waters when significant levels of blue-green algae were present in the reservoir waters have been determined. The results provide information required to allow risk assessments of the potential presence of these toxins in such waters to be undertaken.
To determine the levels of microcystin-LR and anatoxin-a in reservoir water and drinking water samples.
The health implications of the presence of blue-green algae in reservoirs is currently unclear. The main concerns relate to the recreational use of affected waters, and the potential presence of algal toxins in the derived drinking waters when significant algal numbers are present in reservoir waters. In addition to good toxicological data on the toxins, information on the levels of the toxins in reservoir waters and drinking waters is required to properly address these concerns.
IV RESUME OF CONTENTS
Samples from ten locations in England, Northern Ireland and Scotland were analysed for microcystin-LR and anatoxin-a. The former toxin, either dissolved or intra-cellular, was not detected in any of the samples analysed but anatoxin-a was detected in some samples. The highest level found was 1.3 µgl-1. Although only preliminary toxicity information is available, it is not considered that this level is of concern. The effect of boiling on toxin levels was briefly investigated; the results indicated that levels were not significantly reduced.
On the basis of results from samples examined during 1992-93 and 1993-94, levels of microcystin-LR in reservoir water are likely to be significant only when blooms occur. No detectable levels have been found in drinking waters. However low levels of anatoxin-a (up to 1.3 µgl-1) have been detected in two drinking water samples when detectable levels were present in the associated raw water. The significance of this latter finding can only be fully assessed when data from a toxicity testing programme, currently in its final stages, are available.
Further data on the levels of algal toxins are required to establish whether the results obtained are representative, as samples from relatively few sites have been analysed.
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