The cause of the outbreak was determined to be the addition of excessive doses of copper sulfate to the water supply of Solomon Dam, which had been added to target a cyanobacteria bloom of Cylindrospermopsis raciborskii. The excessive dosing was following the use of least-cost contractors to control the algae, who were unqualified in the field.[3]
Toxins from the cyanobacteria itself had also been described as a possible cause.[4][5]
^Schembri MA, Neilan BA, Saint CP (October 2001). "Identification of genes implicated in toxin production in the cyanobacterium Cylindrospermopsis raciborskii". Environ. Toxicol. 16 (5): 413–21. Bibcode:2001EnTox..16..413S. doi:10.1002/tox.1051. PMID11594028.
^Griffiths DJ, Saker ML (April 2003). "The Palm Island mystery disease 20 years on: a review of research on the cyanotoxin cylindrospermopsin". Environ. Toxicol. 18 (2): 78–93. Bibcode:2003EnTox..18...78G. doi:10.1002/tox.10103. PMID12635096.
^Wilson, Paul (March 1985). "Black Death White Hands Revisited: The Case of Palm Island". Aust. & NZ Journal of Criminology. 18: 50. doi:10.1177/000486588501800106.
Bourke ATC, Hawes RB, Nielson A, Stallman ND. An outbreak of hepatoenteritis (the Palm Island mystery disease) possibly caused by algal intoxication [abstract]. Toxicon Suppl 1983;45-48.