The toxicity of cyanobacterial toxins in the mouse: II Anatoxin-a

Blooms of cyanobacteria are known to have caused poisoning in fish, waterfo wl, animals and man, One of the low molecular weight toxins responsible for this is the neurotoxin anatoxin-a which has been detected in reservoirs us ed for domestic water supplies. While the acute behaviour of this alkaloid is clear, there is uncertainty regarding the effects on man of ingestion of anatoxin-a at low levels over longer periods. In order to assess this risk , a series of in vitro and in vivo experiments were undertaken to investiga te the pharmacology, subacute toxicity, and the teratogenicity of anatoxin- a in the mouse. The results of this work were as follows: (1) Pharmacologic al screening studies confirmed that anatoxin-a is a potent nicotinic agonis t which can produce neuromuscular blockade and death by respiratory arrest. Recovery from a single sub-lethal dose is rapid and complete; (2) Repeated sub-lethal oral administration over 28 days in the mouse did not produce a ny reliable evidence of treatment-related toxicity; (3) From a preliminary screening study anatoxin-a does not appear to be a developmental toxicant i n the mouse. These results indicate that a guideline value for anatoxin-a i n drinking water of 1 mu g l(-1) would provide an adequate margin of safety .