Results (
Thai) 1:
[Copy]Copied!
Faced with this ambiguity, some groups have selected subsets ofharms and metrics, as well as specific thresholds, to define HABs froman operational standpoint. The International Joint Commission (IJC;Watson and Boyer, 2013) and the Ohio Environmental ProtectionAgency (Ohio EPA; Kasich et al., 2014), for example, have defined HABsbased on thresholds for microcystin, chl a, and cell concentrations. Formicrocystin, theWorld Health Organization (WHO) has defined 1 μg/Lmicrocystin as the threshold for drinking water intended to be safe forlife-long exposure (World Health Organization, 2004), and 10 μg/L(mild probability of health effects) and 20 μg/L (moderate probability ofhealth effects) as the thresholds for recreational water use (WorldHealth Organization, 2003). The two higher WHO thresholds have beenadopted for monitoring pelagic and benthic sites by the IJC (Watsonand Boyer, 2013), while the Ohio EPA has adopted the 1 μg/L and20 μg/L thresholds for “Do not drink” and “Do not use,” respectively(Kasich et al., 2014). Similarly, WHO has thresholds for chl a of 10 μg/Lfor increased odds of irritative or allergenic effects, and 50 μg/L for increasedprobability of irritative symptoms and toxic impacts, bothunder conditions of cyanobacterial dominance (Falconer et al., 1999).These thresholds are equivalent to cyanobacterial abundance thresholdsof 20,000 and 100,000 cells/mL based on toxicological assumptions(Falconer et al., 1999). The IJC and Ohio EPA have selected chl a thresholdssimilar to the WHO range, namely a 30 μg/L threshold for IJC (Watson andBoyer, 2013), and 2, 5, and 50 μg/L (or 4,000, 10,000, and 100,000cyanobacterial cells/mL) thresholds adopted by the Ohio EPA for minor,moderate, and severe blooms, respectively (Kasich et al., 2014). Beyondmicrocystin and chl a, the IJC has also adopted 80% biomass of harmfulspecies as another threshold indicative of HABs
Being translated, please wait..
