Abstract
Cyanotoxins produced by cyanobacteria pose significant challenges to water resource management due to the potential impacts they have on human health. Cylindrospermopsin (CYN) and microcystins (MC) are the more commonly detected cyanotoxins in Singapore’s reservoirs. Among the MC congeners monitored locally, the most frequently detected variants are MC-RR (37.6%), followed by MC-LR (25.6%). MC-LA and MC-YR are the least frequently detected variants (7.1%). No cyanotoxins have been detected in Singapore’s treated drinking water. Singapore’s National Water Agency (PUB) and the National Environment Agency (NEA) developed recreational water quality guidelines using Chl a concentrations of 50 μg/L. In local surface waters, long-term data showed that at 50 μg/L of Chl a, MC-LR concentrations ranged from a concentrations, Microcystis cell counts in reservoir water have also been used to manage cyanotoxin risk in drinking water. Specifically, routinely monitored data from all 17 Singapore reservoirs indicated that to keep MC-LR concentrations below the WHO provisional guideline of 1 μg/L in drinking water, Microcystis cell counts needed to be Microcystis isolates showed M. aeruginosa produced the most MC compared to M. ichthyoblabe, M. flos-aquae, and M. viridis. Based on the maximum toxin cell quota equivalent to the WHO provisional guideline for MC-LR of 1 μg/L in drinking water, a 5000 cells/ml cell count guideline was derived for M. aeruginosa. This cell count has also been incorporated into Singapore’s cyanotoxin risk management framework for reservoirs.
Highlights
The excessive production of cyanotoxins, produced by cyanobacteria, is increasingly recognised as a major challenge facing water resource management worldwide [1] [2]
Cyanotoxins produced by cyanobacteria pose significant challenges to water resource management due to the potential impacts they have on human health
Used parameters indicative of cyanobacterial biomass include phytoplankton cell numbers, biovolume or pigment concentrations (e.g. chlorophyll-a (Chl a) or other cyanobacterial pigments detected by fluorometry) [11]
Summary
The excessive production of cyanotoxins, produced by cyanobacteria, is increasingly recognised as a major challenge facing water resource management worldwide [1] [2]. The USEPA 10-day Health Advisory (HA) value of MC in drinking water for bottle-fed infants and young children of pre-school age is 0.3 μg/L, while that for school-age children through adults is 1.6 μg/L. Because adequate data on health effects are available for CYN, the USEPA developed 10-day HA values for this cyanotoxin in drinking water; 0.7 μg/L for bottle-fed infants and young children of pre-school age and 3 μg/L for school-age children through adults [10]. These USEPA and WHO guidelines form an important basis upon which individual countries develop their own locally-relevant standards. Part of these results has been published [21]
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call