Cyanobacteria were present on the earth 3.5 billion years ago; since then they have colonized almost all terrestrial and aquatic ecosystems. They produce a high number of bioactive molecules, among which some are cyanotoxins. Cyanobacterial growth at high densities, forming blooms, is increasing in extension and frequency, following anthropogenic activities and climate changes, giving rise to some concern for human health and animal life exposed to cyanotoxins. Numerous cases of lethal poisonings have been associated with cyanotoxins ingestion in wild animal and livestock. In humans few episodes of lethal or severe human poisonings have been recorded after acute or short-term exposure, but the repeated/chronic exposure to low cyanotoxin levels remains a critical issue. The properties of the most frequently detected cyanotoxins (namely, microcystins, nodularins, cylindrospermopsin and neurotoxins) are here critically reviewed, describing for each toxin the available information on producing organisms, biosynthesis/genetic and occurrence, with a focus on the toxicological profile (including kinetics, acute systemic toxicity, mechanism and mode of action, local effects, repeated toxicity, genotoxicity, carcinogenicity, reproductive toxicity; human health effects and epidemiological studies; animal poisoning) with the derivation of health-based values and considerations on the risks for human health.

This review focuses on the risk assessment associated with human exposure to cyanotoxins, secondary metabolites of an ubiquitous group of photosynthetic procariota. Cyanobacteria occur especially in eutrophic inland and coastal surface waters, where under favorable conditions they attain high densities and may form blooms and scums. Cyanotoxins can be grouped according to their biological effects into hepatotoxins, neurotoxins, cytotoxins, and toxins with irritating potential, also acting on the gastrointestinal system. The chemical and toxicological properties of the main cyanotoxins, relevant for the evaluation of possible risks for human health, are presented. Humans may be exposed to cyanotoxins via several routes, with the oral one being by far the most important, occurring by ingesting contaminated drinking water, food, some dietary supplements, or water during recreational activities. Acute and short-term toxic effects have been associated in humans with exposure to high levels of cyanotoxins in drinking and bathing waters. However, the chronic exposure to low cyanotoxin levels remains a critical issue. This article identifies the actual risky exposure scenarios, provides toxicologically derived reference values, and discusses open issues and research needs.

This report presents the extensive literature search conducted on 1) the occurrence of different cyanotoxins in food matrices; 2) the analytical methods for their detection; 3) their toxicological profile; 3) the environmental factors affecting toxicity of cyanobacterial population and 4) the combined effects of mixtures of cyanotoxins and other chemicals. It also includes a review of guidelines values or health-alert levels for cyanotoxins in food (or drinking water) adopted world-wide. The methodological aspects and the queries used in the extensive literature search, the collection and screening of retrieved papers and the inventory are briefly described in the report; all details are available in 3 supplementary appendices to this report. The analysis of collected papers indicated that most of them are focused on a single microcystin (MC) variant (MC-LR) out of the almost 100 MC known. Many studies on occurrence are affected by limited quality, due to analytical drawbacks in the detection methods and were not considered in the exposure assessment. Toxicity studies useful for the derivation of health based reference values are few, being many of them carried out using i.p. injection, which is poorly representative of actual human exposure. In addition, those toxicological studies carried out with poorly characterised cyanobacterial extracts or focused on single parameters, using a single dose, devoted to elucidation of mechanism of action, reporting qualitative description of effects were not used for data extraction. The relevant exposure scenarios are also described, although being the available data on exposure very limited, no definite conclusion on the health risks for the exposed population could be drawn. However, the possibility of risky exposure is evidenced for fish and shell-fish consumers and for blue-green algae supplements (BGAS) as well in relation to MC contamination. Finally, many data gaps were identified. © European Food Safety Authority, 2016Key words: Cyanobacteria, cyanotoxins, occurrence, toxicity, exposure, risk assessment, data gaps. Question number: EFSA-Q-2015-00141Correspondence:sc.secretariat@efsa.europa.eu Cyanotoxins in foodThe present document has been produced and adopted by the bodies identified above as author(s). This task has been carried out exclusively by the author(s) in the context of a contract between the European Food Safety Authority and the author(s), awarded following a tender procedure. The present document is published complying with the transparency principle to which the Authority is subject. It may not be considered as an output adopted by the Authority. The European Food Safety Authority reserves its rights, view and position as regards the issues addressed and the conclusions reached in the present document, without prejudice to the rights of the authors.www.efsa.europa.eu/publications 2 EFSA Supporting publication 2016:EN-998NDisclaimer: The present document has been produced and adopted by the bodies identified above as author(s). This task has b...

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Abstract. Change in climate and water cycle will challenge water availability but it will also increase the exposure to unsafe water. Floods, droughts, heavy storms, changes in rain pattern, increase of temperature and sea level, they all show an increasing trend worldwide and will affect biological, physical and chemical components of water through different paths thus enhancing the risk of waterborne diseases. This paper is intended, through reviewing the available literature, to highlight environmental changes and critical situations caused by floods, drought and warmer temperature that will lead to an increase of exposure to water related pathogens, chemical hazards and cyanotoxins. The final aim is provide knowledge-based elements for more focused adaptation measures.Key words: climate change, waterborne diseases, microbial pathogens, chemical contaminants, toxic cyanobacteria.Riassunto (Effetto dei cambiamenti climatici sulle malattie trasmesse dall'acqua). I cambiamenti climatici e del ciclo idrologico metteranno a rischio la disponibilità d'acqua e aumenteranno l'esposizione ad acqua contaminata. Le alluvioni, le siccità, le grandi tempeste, le variazioni nella frequenza ed intensità delle piogge, il riscaldamento e l'aumento del livello del mare crescono in ogni parte del mondo e influenzeranno le caratteristiche biologiche e chimico-fisiche dell'acqua attraverso diversi meccanismi, con il conseguente aumento del rischio di malattie trasmesse dall'acqua. L'analisi della letteratura disponibile, presentata in questo articolo, evidenzia i cambiamenti ambientali e le situazioni critiche causate da alluvioni, siccità e crescente riscaldamento che causeranno un aumento di esposizione a patogeni, inquinanti chimici e cianotossine, legati all'acqua. Lo scopo è di fornire gli elementi scientifici di base per misure di adattamento mirate.Parole chiave: cambiamenti climatici, malattie trasmesse dall'acqua, microrganismi patogeni, contaminanti chimici, cianobatteri tossici.

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In the summer of 2005, about 200 people who spent time on or near beaches in a stretch of the northwest Italian coast around the city of Genova, sought medical treatment for