It might contain a cocktail of 70 potentially harmful chemicals and bloom around Moreton Bay, but fireweed doesn't seem to be causing too many serious health problems.
A study by the National Research Centre for Environmental Toxicology (EnTox), part of the University of Queensland, has revealed fireweed grows in explosive bursts in warm water and sunlight and is most toxic at the peak of its spread and density.
Fireweed is a blue-green algae called Lyngbya majuscula which contains toxins that turn some marine animals off their food and can also cause rashes, itches, burns, tingles blistering and breathing problems.
Despite summer blooms which have been recorded up to 40 square kilometres wide in Moreton Bay, the study found fireweed had not had a dramatic effect on recreational water users.
UQ PhD graduate Dr Nicholas Osborne, who spent several years researching fireweed for the study, surveyed 1370 Bribie Island residents about their exposure to Moreton Bay waters.
About 35 percent of people reported at least one side effect, with skin itching the most reported with 23 percent and fever, the least reported with less than one percent.
About three percent of people surveyed (29 people) reported severe skin symptoms, for which 12 people saw doctors.
"Even though it does have the potential to be a health hazard, at the moment, it doesn't appear to be one," Dr Osborne said.
"People don't go swimming in clumps of weed.
"People tend to walk 50 metres up the beach and go where the weed isn't especially if they are informed about the potentially toxic nature of this organism."
Using fireweed samples he collected from Eastern Moreton Bay, North Deception Bay and Bribie Island, Dr Osborne found ten fold differences in toxin concentrations in samples only metres apart.
"Having different toxins in different areas meant that there is some sort of regulation of toxin production going on," he said.
"If we can work out what factors affect this regulation, we have a good handle on predicting when Lyngbya will be toxic and when the public should be warned."
Younger people were more likely to report skin, eye, fever and headache symptoms and females reported greater skin rashes possibly because of their togs which could trap algae.
He said large Lyngbya blooms often disappeared after big storms and that while strong sunlight helped its growth, it might also reduce its toxicity if washed onto beaches.
The new fireweed discoveries are revealed in Dr Osborne`s 246-page thesis titled, Investigation of the Toxicology and Public Health Aspects of the Marine Cyanobacterium, Lyngbya majuscula.
It was funded under a joint grant from The Australian Research Council and Queensland Government of $217,061 in response to several reports of burns from fireweed in South East Queensland.
Dr Osborne, who also worked for UQ's School of Population Health, said more work had to be done to explain the toxicology of fireweed.
Monthly monitoring of fireweed blooms can be viewed on the Environmental Protection Agency's website www.epa.qld.gov.au
Dr Osborne graduated from UQ last December and is now working as a project officer for the Victorian Cancer Council.
Media: contact Dr Osborne (phone: 0404 769 485, email: s213269@student.uq.edu.au) or Miguel Holland at UQ Communications on (phone: 07 3365 2619, email: m.holland@uq.edu.au)
