Leigh Dayton and Matthew Denholm | April 11, 2009

Article from:  The Australian

WHEN fisheries veterinarian Matthew Landos got his first look at the double-headed fish embryos in a Queensland hatchery, he had no idea he would soon team up with a Tasmanian doctor worried that the widespread use of agricultural and forestry chemicals was making her patients sick.

"In hindsight it makes perfect sense. If exposure to agricultural chemicals could cause deformed and dying fish, as the evidence suggests, of course the chemicals had the potential to trigger serious health problems with other animals, including people," says Landos, who runs a consulting practice called Future Fisheries Veterinary Services and is a research associate and honorary lecturer with the University of Sydney.

Late last year hatchery owner Gwen Gilson hired Landos to find out why - after years of healthy hatchings - embryos and fish fry were dying in huge numbers, while others showed bizarre physical or behavioural abnormalities. His investigation suggested the problem was the result of a cocktail of chemicals sprayed on a nearby macadamia plantation.

Pathology reports on Gilson's fish, written by Roger Chong of Queensland's Biosecurity Sciences Laboratory, backed Landos's conclusion. It revealed the deaths, deformities and behavioural abnormalities of fish and fish fry were consistent with exposure to the types of agrichemicals used to treat macadamia trees.

Landos's work led to a report last January in The Australian of a possible cancer cluster among residents living close to the plantation. The residents have since asked Queensland Health to investigate. That coverage struck a chord for Alison Bleaney, a GP at St Helens on Tasmania's east coast.

About a decade ago Bleaney began wondering why so many of her patients were getting so sick. "I just started feeling something wasn't right. It just didn't make sense." She was seeing a rise in cancers, auto-immune diseases, diabetes, thyroid problems, reproductive difficulties, children with behavioural problems and lots of flu-like illnesses.

The situation puzzled her for years until, in 2003, a helicopter used for aerial spraying of agrichemicals crashed in a forest plantation in the upper George River catchment. A short time later, there were mass deaths of oysters in Georges Bay.

"Suddenly I thought, 'What is happening to our drinking water?'," Bleaney says. "There had been a rapid increase in plantation areas in the catchment and a corresponding increase in pesticide use. It struck me, and still strikes me, as being consistent with the timing."

Turning to scientific reports, Bleaney concluded that the rise in local cancer cases she had documented between 1995 and 2005 made sense. Agrichemicals and cancer go hand in hand, she thought, despite Tasmanian Director of Public Health, Roscoe Taylor, finding no evidence to back her fears.

Although Taylor found no proof of a cancer cluster in Bleaney's data, he remains concerned about some commonly-used agricultural chemicals which are applied by aerial spraying in drinking water catchments. He has called for an end to all aerial spraying.

Today, Landos and Bleaney are waving the warning flag for all Australians, not just Queenslanders and Tasmanians. They point to a growing body of international scientific and circumstantial evidence suggesting that the fungicides, pesticides and weed killers used on the nation's farms and forests can cause a range of human health problems. These run from transient stomach pain and headache to far more serious conditions such as reproductive and neurological disorders, and even cancer.

While many of the studies are conducted on experimental animals such as fish, experts suggest that because backboned animals share biological systems with people, the findings are worrying.

One scientist exposing human cells to agrichemicals such as endosulfan in the laboratory is Dayanthi Nugegoda, , an ecotoxicologist with RMIT in Melbourne.

"Endosulfan is terrible," says Nugegoda. "We found it's very toxic in our in-house experiments."

The active agents in the so-called agrichemicals on Landos's and Bleaney's personal hit-list include wetting agents that break down into compounds such as nonylphenol, known to disrupt hormonal production, organophosphate, a known neurotoxin, and carbendazim, a hormone disruptor which also causes developmental abnormalities in foetuses.

Farmers often use more than one of these toxic agents on their crops, says Landos.

"A NSW Department of Primary Industries study of vegetable residues found up to six residues on individual vegetable crops."

Worse, when two or more such chemicals are combined they may pack a mightier punch than each would individually. Earlier this year US researchers reported they had observed exactly that in a study of the effects on young fish of various mixtures of organophosphate and carbamate pesticides.

"Several combinations of organophosphates were lethal at concentrations that were sublethal in single-chemical trials," they wrote in the journal Environmental Health Perspectives (doi:10.12889/ehp.0800096).

Then there's atrazine and a related compound called simazine. Used to prevent weed growth in tree plantations and in most agricultural food productions in Australia, these "triazines" disrupt human hormones.

Developmental endocrinologist Tyrone Hayes, with the University of California at Berkeley, has conducted laboratory experiments that show atrazine promotes the growth of breast cancer cells by altering the production of the hormone oestrogen.

On a visit to Hobart last month, organised by Bleaney, Hayes told Weekend Health the triazine-cancer phenomenon had been neatly exploited by industry.

"The same company that makes atrazine (as a herbicide) spun out a new company that makes an anti-breast cancer medication that blocks its action," he says, noting that the company involved has complained formally to UC administrators about his public pronouncements on the subject.

Similarly, Landos's and Bleaney's concerns are not welcome in Australian industry circles. The Australian Macadamia Society and forestry giant Gunns Limited, for instance, dispute the suggestion that their agrichemicals make anyone sick.

They argue that they follow safety guidelines set by state authorities and the national regulator, the Australian Pesticides & Veterinary Medicines Authority.

Setting aside the possibility of misuse of the agrichemicals, both outfits are right. The chemicals are approved for use by the APVMA. And that's exactly the problem, the critics argue.

Speaking of the triazines, Hayes says: "My professional opinion is that I don't think they can be used safely. They harm the environment and human health and reproduction. We need to protect the people using it and manufacturing it".

Hayes may get his wish, at least in the US. Atrazine is at present under review by the US Environmental Protection Agency. As well, a bill to ban it outright is before Congress, where Congressman Keith Ellison is leading the push to get a full hearing on the matter in key committees.

In Australia, the APVMA has no plans to review atrazine. But the Tasmanian Government has requested a formal review of triazines due their persistence in waterways potentially sourced for drinking.

As to organophosphates, they too are approved for specific uses by the APVMA. And carbendazim? It's been under review by the AVPMA since 2007.

According to Hayes, they too should be banned, along with another group of insecticides, the pyrethroids.

"They're so toxic I don't study them because the harm they cause to animals is so early in development it's too early to study their endocrine systems," he says.