Toxic cyanobacterial bloom problems in Australian waters: risks and impacts on human health

Toxic cyanobacterial blooms have occurred throughout recorded history in Australia, as causes of livestock deaths and water unpalatability. Human injury from cyanobacterial toxins is rarely recorded, but members of two local populations in Australia have suffered from an acute toxicity believed to be a consequence of copper sulphate treatment of water blooms. Minor health effects have been correlated with cyanobacterial contamination of drinking water drawn from rivers. Recreational exposure to toxic cyanobacteria is comparatively common, with demonstrated minor adverse effects on health. The World Health Organization has drawn up guideline values for microcystin in drinking water and recommendations for recreational waters. The major unknown is the potential for cancer stimulation by cyanobacterial toxins, particularly gastrointestinal cancers in Australia and other affluent countries and liver cancer in poorer nations.