There was no proven link between soil or water pollution and blood cancers, Professor Bernard Stewart said yesterday.
A member of the expert panel set up to investigate any evidence of a cancer cluster in Helensburgh, Professor Stewart said it was "not true that pollution worldwide is associated with these particular cancers".
"Across the worldwide knowledge, we have not identified a level of soil or water pollution that is associated with the causation of leukaemia or lymphoma.
"Widely suspected but never conclusively demonstrated," he said.
"Against that background there is no overt pollution in the Helensburgh area that would compare in any reasonable way with the industrial pollution of certain countries, despite which increased lymphoma and leukaemia have not been found," he said.
"Typically, air pollution is associated with increased risk of lung cancer - which is difficult to detect against smoking-induced lung cancer."
However, in relation to pollution this had not been found to cause leukaemia or lymphoma, he said.
Professor Stewart, who is the head of the Cancer Control Program at the South East Sydney Local Health District, said the panel "appreciates community anxiety, but the panel could not set anxiety as a higher premium above medical knowledge".
"The notion that overt marked pollution causes cancer of some form is intuitive but not valid - it's not true that pollution worldwide is associated with these particular cancers," he said.
"If anything, it causes lung cancer.
"It's not as if we, or anyone else in the world, is aware of a level of soil contamination that we could reasonable say clearly demonstrates an increased risk of leukaemia.
"No such level has ever been specified."
Professor Stewart said the panel's finding was good news.
"It has not been portrayed as good news by anyone - including the panel for that matter.
"In some bizarre way it seems as if people are hoping for a finding of an insidious cause of disease. We found no such cause and we did look."