AWWA WQTC64114

Cyanobacterial blooms occur worldwide in marine, brackish, and freshwaters. At least one-third of these genera are capable of producing toxins. In 1998 and 2005, freshwater algal toxins were added to the Contaminant Candidate List (CCL) by the United States Environmental Protection Agency (USEPA). Shortly after the 1998 announcement, a priority list was released that included five hepatotoxins, microcystin- LR, -RR, -LA, -YR, and cyclindrospermopsin, and the neurotoxin anatoxin-a. Current World Health Organization (WHO) monitoring guidelines incorporate a sequence of alert levels based on algal cell counts and/or taste and odor production that were established in 1993. These alert levels start at cell counts of 2000 units/mL and increase the frequency of monitoring. This paper describes a preliminary study funded by the USEPA to evaluate the prevalence of the algal toxin microcystin in drinking water supplies. An Enzyme-Linked Immunosorbant Assay (ELISA) was used to screen the source and distribution water samples for microcystin. The ELISA kit has a range limit of 0.05 ppb to 0.83 ppb microcystin. Total and toxin-producing algal counts were conducted on weekly source and distribution water samples from utilities located in five US states. Four of the five utilities experienced algal blooms in their source water. All of these conventional plants effectively removed the algae and all distribution water samples showed microcystin levels below the detection limit of 0.05 ppb. Four of the utilities source water did show detectable levels of microcystin within the range limits of the kit. Selected source water samples were analyzed by high pressure liquid chromatography (HPLC). The paper describes this HPLC method capable of quantifying intracellular microcystin toxin variants, as well as cylindrospermopsin and anatoxin-a, and compares it to the ELISA. The WHO algal toxin monitoring framework and monitoring cost was evaluated against for different analytical methods and scenarios. Includes 3 references, figures.