Copyright Mark Thorson 1995, 1996

SBGA is the cyanobacteria (blue-green algae) known as

_Aphanizomenon_flos-aquae_.  Whether or not it is a good

idea to eat this stuff may be judged by reviewing the

scientific and medical literature.

Quoting from _The_Lancet_, "Hazardous Freshwater Cyano-

Bacteria (Blue-Green Algae)", June 12, 1993, volume 341,

pages 1519 and 1520:

"Cyanobacteria, especially members of the genera

_Microcystis_, _Anabaena_, _Aphanizomenon_, and

_Oscillatoria_, are common and potentially harmful

inhabitants of freshwater.  Many species contain

lipopolysaccharide endotoxins, but also, more

importantly, can produce several potent hepatotoxins

(microcystins) and neurotoxins (eg, anatoxins,


"Whenever a diagnosis of cyanobacterial intoxication

is a possibility, it is essential (in the UK) to notify

the local Consultant in Communicable Disease Control.

Control measures may need to be instituted as a

priority to minimize the risk to others.  Furthermore,

early notification of potential outbreaks will

facilitate proper prospective epidemiological studies,

which are essential if the risks from cyanobacteria

are to be properly measured."

Quoting from _Journal_of_Medical_Microbiology_,

"Cyanobacteria and Human Health", 1992, volume 36,

page 301:

"_Aphanizomenon_flosaquae_ produces neosaxitoxin, which

causes paralysis by reversibly blocking sodium

conductance in neurones.  In addition, lipopolysaccharide

endotoxins have been demonstrated in some blooms.  Some

algal toxins are also potent tumor promoters in animal


"It is clear that cyanobacteria are a potential hazard

to human health."

Quoting from _Nature_, "Fatal Attraction To

Cyanobacteria", September 10, 1992, volume 359, page


"The buoyant growth habit of the widely encountered

toxigenic, planktonic genera such as _Microcystis_,

_Anabaena_, _Aphanizomenon_, _Nodularia_ and some

_Oscillatoria_ species can result in scum formation in

lakes and ponds during calm weather, so that an acutely

toxic dose of cyanobacterial toxins can be presented ..."

Quoting from _Journal_of_Applied_Phycology_,

"Anatoxin-A Concentration in _Anabaena_ and

_Aphanizomenon_ Under Different Environmental

Conditions And Comparison Of Growth By Toxic And

Non-Toxic _Anabaena_ Strains:  A Laboratory Study",

1993, volume 5, number 6, page 581:

"Anatoxin-a-concentration in cells of _Anabaena_-

and _Aphanizomenon_-strains and in their growth

media were studied in the laboratory in batch

cultures at different temperatures, light fluxes,

orthophosphate and nitrate concentrations and with

different nitrogen sources for growth."

"The highest light flux studied did not limit the

growth or decrease the level of the toxin in the

cells of _Aphanizomenon_."

Quoting from _Journal_of_Applied_Bacteriology_,

"Cyanobacteria Secondary Metabolites--the Cyanotoxins",

1992, volume 72, pages 448 and 449:

"The production of neurotoxin by _Aphanizomenon_

_flos-aquae_ was first demonstrated by Sawyer _et_al._

(1968).  These neurotoxins were later shown to be

saxitoxin (STX) and neosaxitoxin (NEOSTX) (LD50 i.p.

mouse equals about 10 micrograms/kilogram), the two

primary toxins of red tide paralytic shellfish

poisoning (PSP)."

"Acute hepatotoxicosis involving the hepatotoxins

(liver toxins) is the most commonly encountered

toxicosis involving cyanobacteria.  These toxins are

produced by strains of species within the genera

_Microcystis_, _Anabaena_, _Nodularia_, _Oscillatoria_

and _Nostoc_.  In addition, chemically undefined

hepatotoxins are being studied in _Cylindrospermopsis_,

_Aphanizomenon_, _Gloeotrichia_ and _Coelosphaerium_.

Clinical signs of hepatotoxicosis have been observed

in field poisonings involving cattle, sheep, horses,

pigs, ducks and other wild and domestic animals.

Most laboratory studies have involved the use of

mice, rats, guinea pigs, rabbits and pigs.

Collectively, the signs of poisoning in these animals

include weakness, anorexia, pallor of mucous membranes,

vomiting, cold extremities, and diarrheoa."