Toxic cyanobacteria: an example of interrelation between environment and health

The dependence of water by all living species point out that this resource can be considered as the main factor for understand the relationship of environment and health. The growing of population and economic activities is linked with water availability to agricultural and industrial use, energy and domestic purposes increasing demand pressures on local and regional water supplies. These forces are undergoing rapidly accelerating and often with unpredictable changes and it represents new uncertainties for water managers and increasing risks for public health. At the same time, climate change is creating new uncertainties with regard to freshwater supplies and to the multiple water use sectors.

Human health is both directly and indirectly impacted by water quality. Outbreaks of waterborne diseases can occur as a result of contaminated or inadequate water supplies. Besides this classical scenario of hazards related with water quality other impacts on human and ecosystem health through water can arise from natural toxic agents. The importance of toxic aquatic microorganisms and their toxins as cyanobacteria/cyanotoxins has only emerged in the half of the twentieth century by recognition of artificial eutrophication as a growing problem since the 1950s. Increasing eutrophication of fresh and coastal water bodies has been produced by human activities causing anthropogenic nutrient and other pollutant enrichment. It has become more widespread mainly in some regions where the growth of agriculture, industry and urbanization rate have undergone rapid increase but these process were not followed by an improvement in wastewater treatment. Cyanobacteria cannot be considered as pathogenic microorganisms in the classical sense, because although several strains of different species can produce bioactive and toxic secondary metabolites for mammalians and other eukaryotic organisms, a large part of these compounds are only release into the water after cyanobacterial cell lysis. Therefore, to understand relationship between toxic cyanobacteria dominance in water bodies and consequences to human and ecosystem health is very complex and mediated by several factors involving a multidisciplinary challenge and some of those aspects will be point out during this presentation.