Co-Occurrence of Taste and Odor Compounds and Cyanotoxins in Cyanobacterial Blooms: Emerging Risks to Human Health?

Abstract

Cyanobacteria commonly form large blooms in waterbodies; they can produce cyanotoxins, with toxic effects on humans and animals, and volatile compounds, causing bad tastes and odors (T&O) at naturally occurring low concentrations. Notwithstanding the large amount of literature on either cyanotoxins or T&O, no review has focused on them at the same time. The present review critically evaluates the recent literature on cyanotoxins and T&O compounds (geosmin, 2-methylisoborneol, β-ionone and β-cyclocitral) to identify research gaps on harmful exposure of humans and animals to both metabolite classes. T&O and cyanotoxins production can be due to the same or common to different cyanobacterial species/strains, with the additional possibility of T&O production by non-cyanobacterial species. The few environmental studies on the co-occurrence of these two groups of metabolites are not sufficient to understand if and how they can co-vary, or influence each other, perhaps stimulating cyanotoxin production. Therefore, T&Os cannot reliably serve as early warning surrogates for cyanotoxins. The scarce data on T&O toxicity seem to indicate a low health risk (but the inhalation of β-cyclocitral deserves more study). However, no data are available on the effects of combined exposure to mixtures of cyanotoxins and T&O compounds and to combinations of T&O compounds; therefore, whether the co-occurrence of cyanotoxins and T&O compounds is a health issue remains an open question.

Temporal Dynamics and Influential Factors of Taste and Odor Compounds in the Eastern Drinking Water Source of Chaohu Lake, China: A Comparative Analysis of Global Freshwaters

“…Over the past few decades, the frequency and intensity of harmful cyanobacterial blooms in freshwater environments worldwide have increased, primarily due to eutrophication and global warming [ 1 , 2 , 3 , 4 , 5 ]. In addition to their association with oxygen depletion and the production of cyanotoxins, cyanobacteria are linked to taste and odor (T/O) compounds [ 6 , 7 , 8 , 9 , 10 , 11 , 12 ]. Undesirable tastes and odors have been observed to manifest genotoxic and estrogenic effects on fish hepatocytes, thereby posing potential risks to human health through the consumption of aquatic products [ 13 ].…”

qPCR-Based Monitoring of 2-Methylisoborneol/Geosmin-Producing Cyanobacteria in Drinking Water Reservoirs in South Korea

“…In water reservoirs, several species of cyanobacteria produce earthy- or musty-smelling compounds as secondary metabolites [ 2 , 3 , 4 ]. The main cyanobacterial odorants affecting the quality of drinking water in reservoirs are 2-methylisoborneol (2-MIB) and geosmin [ 5 , 6 ]. The odor threshold value for both is <10 ng L −1 , but their presence is often observed at 5 ng L −1 [ 7 ].…”

Managing the Taste and Odor Compound 2-MIB in a River-Reservoir System, South Korea

“…Geosmin and 2-MIB are non-toxic and are not harmful to the human body [18]. However, they psychologically influence substances that induce undesirable taste and odor even when present in minimal quantities in water [19].…”