This review aims to summarise the outcomes of some recent European research concerning toxic cyanobacteria and cyanotoxins, with an emphasis on developments within the framework of the CYANOCOST Action (COST Action ES1105, Cyanobacterial Blooms and Toxins in Water Resources: Occurrence, Impacts and Management). State of the art research and management capabilities in Europe on cyanobacteria have benefitted from input from the pure and applied life sciences, the human and animal health sectors, water engineers, economists and planners. Many of these professional groups have been brought together and they interacted favourably within the framework of CYANOCOST.Highlights of the Action include phycological and ecological studies, development of advanced techniques for cyanotoxin analysis, elucidation of cyanotoxin modes of action, management techniques to reduce cyanobacterial mass development, and research on methods and practices for cyanotoxin removal during drinking water treatment. The CYANOCOST Action has had an active outreach policy throughout its lifetime, resulting in e.g. three handbooks, two special issues in scientific journals and activities in the social media. The many contact channels to end-users, including environmental and drinking water supply authorities, health professionals and the general public are described in this review.Furthermore, the authors have identified a number of gaps in knowledge. Proposed directions for future research in the field of toxic cyanobacteria and cyanotoxins are also discussed.

Surface water, often used for irrigation purposes, may sometimes be contaminated with blooming cyanobacteria and thereby may contain their potent and harmful toxins. Cyanotoxins adversely affect many terrestrial plants, and accumulate in plant tissues that are subsequently ingested by humans. Studies were undertaken to (1) examine the bioaccumulation of microcystins (MCs) in leaves and fruits of pepper Capsicum annuum and (2) examine the potential effects of MCs on antioxidant capacity of these organs. Plants were irrigated with water containing MCs for a period of 3 mo. Data showed that MCs did not accumulate in leaves; however, in fruits the presence of the MC-LR (0.118 ng/mg dry weight) and dmMC-LR (0.077 ng/mg dry weight) was detected. The concentrations of MC-LR in fruit approached the acceptable guideline values and tolerable daily intake for this toxin. Lipid peroxidation levels and flavonoids content were significantly enhanced in both organs of treated plants, while total phenolic concentrations were not markedly variable between control and treated plants. Significant decrease in 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging capacity was noted for both organs. The levels of superoxide anion in fruits and hydroxyl radical in leaves were markedly reduced. Data suggest that exposure to MCs significantly reduced antioxidant capacity of experimental plants, indicating that MCs affected antioxidant systems in C. annuum.

Today, the occurrence of harmful cyanobacterial blooms is a common phenomenon and a potential global health problem. Cyanobacteria can produce metabolites highly toxic to humans. More than 80% of reservoirs used for water supply in Central Serbia have bloomed over the past 80 years. A 10-year epidemiological study showed a significant increase in the incidence of primary liver cancer (PLC) in the regions where water from the blooming reservoirs was used for human consumption. At the same time, no correlation was found between the incidence of PLC and other risk factors, such as cirrhosis and hepatitis viruses. Given the strong association with PLC induction and various known possible mechanisms of carcinogenic action, it is highly possible that, cyanotoxins—acting as initiator and promoter—may be the major risk factor that acts synergistically with other risk factors to cause increased incidence of PLC. However, at present, it is still not certain whether cyanotoxins alone were sufficient to induce PLC. Therefore, additional assessment of the health risks that may arise from human exposure to cyanotoxins is advisable.