Occurrence of cyanobacterial toxins - Microcystins and anatoxin-a - in Berlin water bodies with implications to human health and regulations

Main Berlin waterways are lowland rivers Spree, Dahme, and Havel, which are connected to some shallow lakes. High nutrient concentrations support heav y blooms of cyanobacteria which produce toxic substances ("cyanotoxins"). C oncentrations of microcystins (MC), anatoxin-a, chlorophyll-a, and cyanobac terial biomass were analyzed in surface water. Two methods [enzyme linked i mmunosorbert assay (ELISA) and high-pressure liquid chromatography (HPLC)] were used for MC analysis. Different preparation techniques were carried ou t determining dissolved and cell-bound microcystins. Furthermore, the healt h implication for people using lakes for swimming and recreation was assess ed as a basis of a proposal to health and water authorities for further reg ulations. Concentrations of total (cell-bound and dissolved) microcystin (w ith ELISA) varied between 0.14 and 119 mu g/L; 95 of 128 samples showed val ues above 1 mu g/L (nearly 74%), 49 above 10 mu g/L (nearly 38%), and 2 abo ve 100 mu g/L (nearly 2%). With wide variability, concentrations of microcy stins measured with HPLC were 65% (median) of values obtained using the imm unologic method. Compared to total microcystin concentrations (dissolved an d cell-bound toxin) proportion of dissolved toxin varied from 0.3 to 12% (n = 46; mean: 4%). Using animal toxicity data for risk assessment we assume that for children a single intake of 25 mu g MC-LR has no adverse effects. Under conservative uptake assumption for contaminated water a concentration of 100 mu g MC/L in surface water is safe. On this basis, regulations (as provisional orientation) are proposed to health and water authorities. Leve ls of anatoxin-a measured in 14 surface samples of two Berlin lakes (Unterh avel and Muggelsee) were under detection limit of 0.01 mu g/L. (C) 2000 by John Wiley & Sons, Inc.