Flight attendants fear they could have been put at risk of long-term brain disorders including Parkinson's disease by regular exposure to insecticides sprayed on long-haul flights.
Five flight attendants who have developed Parkinson's have contacted law firm Turner Freeman to ask about taking legal action against the Australian government, which requires the spraying in line with World Health Organisation guidelines to prevent the spread of potentially deadly mosquito-borne viruses.
The Daily Telegraph reported the case of former Qantas steward Brett Vollus, who has been diagnosed with Parkinson's, a degenerative brain condition that can severely impact on a person's ability to control their own movements.
Turner Freeman lawyer Tanya Segelov said she was investigating a claim on Vollus' behalf.
"When Brett was diagnosed, his neurologist asked him what he did, and he said he worked for Qantas, and his response was: 'Oh, another one,' " she said.
"We have now had four more long-haul flight attendants come forward this morning, and I think we are going to see more and more people coming out of the woodwork."
Segelov said that, until about the turn of the century, the Australian government had mandated that all spraying had to be done while aircraft were full, whereas, now, at least for flights coming in, it was done before passengers boarded.
"We need to know why the government mandated that spraying on board, and why they switched," she said.
But there is little evidence proving that regular, low-level spraying with insecticide could cause Parkinson's disease.
The World Health Organisation is reviewing the chemicals used in insecticides sprayed on aircraft. But its last review of the available research, published in 2005, concluded that, while unnecessary exposure to the chemicals should be avoided, there was no evidence of long-term risk.
"They do not pose any significant health risk when they are used in compliance with their directions for use, which are intended to limit human exposure within the levels recommended for their specific applications," the report found.
Parkinson's expert Kay Double, from the University of Sydney Medical School and Neuroscience Research Australia, said epidemiological evidence was beginning to emerge linking pesticides and herbicides to increased risks for Parkinson's disease.
"Most of the research is on farmers, who are using it in higher concentration, but are also using it in much more open spaces," she said.
"This is a relatively new suggestion; it's not something that has been around a long time."
Associate Professor Double said, in her opinion, the evidence that exposure could cause Parkinson's was "tenuous".
"Exposure to environmental toxins could contribute to it, but it's unlikely that it's going to make you get Parkinson's," she said. "Being able to prove it scientifically or legally would be very difficult."
A spokeswoman for the federal Department of Health said aircraft were treated with insecticides because Australia is free from several very serious diseases, including yellow fever and malaria.
"If any of these diseases became established, they could have a devastating effect on our community, as these diseases cause significant numbers of deaths and illness in many other countries," she said.
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