Cyanotoxin Mixtures and Taste-and-Odor Compounds in Cyanobacterial Blooms from the Midwestern United States

Abstract

The mixtures of toxins and taste-and-odor compounds present during cyanobacterial blooms are not well characterized and of particular concern when evaluating potential human health risks. Cyanobacterial blooms were sampled in twenty-three Midwestern United States lakes and analyzed for community composition, thirteen cyanotoxins by liquid chromatography/mass spectrometry and immunoassay, and two taste-and-odor compounds by gas chromatography/mass spectrometry. Aphanizomenon, Cylindrospermopsis and/or Microcystis were dominant in most (96%) blooms, but community composition was not strongly correlated with toxin and taste-and-odor occurrence. Microcystins occurred in all blooms. Total microcystin concentrations measured by liquid chromatography/mass spectrometry and immunoassay were linearly related (r(s) = 0.76, p < 0.01) and LC/MS/MS concentrations were lower than or similar to ELISA in most (85%) samples. Geosmin (87%), 2-methylisoborneol (39%), anatoxin-a (30%), saxitoxins (17%), cylindrospermopsins (9%), and nodularin-R (9%) also were present in these blooms. Multiple classes of cyanotoxins occurred in 48% of blooms and 95% had multiple microcystin variants. Toxins and taste-and-odor compounds frequently co-occurred (91% of blooms), indicating odor may serve as a warning that cyanotoxins likely are present. However, toxins occurred more frequently than taste-and-odor compounds, so odor alone does not provide sufficient warning to ensure human-health protection.

Cyanotoxins in inland lakes of the United States: Occurrence and potential recreational health risks in the EPA National Lakes Assessment 2007

“…No samples exceeded even the lowest state saxitoxin threshold of 0.80 mg/L. These samples were all integrated photic zone samples and as such tend to be lower in both toxin and biomass compared to near-shore, targeted harmful algal bloom samples as has been shown by other studies (Lindon and Heiskary, 2009;Graham et al, 2010).…”

“…Previous investigations (Yilmaz et al, 2008;Williams et al, 2009;Graham et al, 2010) have documented cylindrospermopsin occurrences in Florida, the midwestern U.S. and New York (Boyer, 2007). Boyer et al (2007) reported cylindrospermopsins were detected rarely in New York (1.6%) contrasted with 22% in Florida (Williams et al, 2009).…”

“…Samples were processed by three sequential freeze/thaw cycles to lyse intact cyanobacteria and release toxins into the dissolved phase (Loftin et al, 2008;Graham et al, 2010). Lysed sample aliquots were filtered with a 10 mL Norm-Ject polypropylene syringe (ThermoFisher Scientific, Waltham, MA, USA) coupled to a 0.45 mm PVDF Syringe filter (Millex 1 -HV, 33 mm diameter, Millipore Corp., Bellerica, MA) and then stored frozen (À20 8C) until analysis.…”

“…A subset of 2.2% of samples were also analyzed by a direct inject, multiclass cyanotoxin liquid chromatography tandem mass spectrometry mass spectrometry (LC/MS/MS) method (Loftin et al, 2008;Graham et al, 2010) that included anatoxin-a (ANAA), cylindrospermopsin (CYLS), deoxycylindrospermopsin (DCYL), DMAC (domoic acid), lyngbyatoxin-a (LYGA), microcystin-LA (MCLA), microcystin-LF (MCLF), microcystin-LR (MCLR), microcystin-LW (MCLW), microcystin-LY (MCLY), microcystin-RR (MCRR), microcystin-YR (MCYR), nodularin-R (NODR), and okadaic acid (OKAC) with an estimated minimum reporting level of 0.010 mg/L for each toxin. Laboratory replicates were analyzed for 5 of the 27 samples analyzed by LC/MS/MS with a % RSD of 28.3% considered as acceptable.…”

“…Results from mid-lake, integrated photic zone (ambient samples) such as acquired in the 2007 NLA provide a contrast to studies focused on near-shore cyanobacteria accumulations. It is known that toxin occurrence and concentration can be much higher in near-shore cyanobacteria accumulations (Lindon and Heiskary, 2009;Graham et al, 2010) and therefore ambient sampling efforts can produce the minimum risk associated with cyanoHABs in comparison. Mid-lake, integrated photic zone sampling is important for assessing cyanotoxin exposure during recreational activities that could aerosolize cyanotoxins (e.g.…”