 certain marine algae produce potent toxins that impact human health through the consumption of contaminated shellfish and finfish and through water or aerosol exposure . over the past three decades , 
 the frequency and global distribution of toxic algal incidents appear to have increased , and human intoxications from novel algal sources have occurred . 
 this increase is of particular concern , since it parallels recent evidence of large - scale ecologic disturbances that coincide with trends in global warming . 
 the extent to which human activities have contributed to their increase therefore comes into question . 
 this review summarizes the origins and health effects of marine algal toxins , as well as changes in their current global distribution , and examines possible causes for the recent increase in their occurrence.imagesfigure 2figure 3 
Images