The heartbreak of watching thousands of fish grow with twisted spines and deformed skulls has taken Greg Semple to a "pretty dark place, mentally".

The owner of Murray Cod Hatcheries in the south-western New South Wales town of Wagga Wagga took over the business in 1996.

"It's all been downhill since then," Mr Semple said.

"In the spring-summer breeding season in 1996, we produced 1.2 million healthy native fingerlings in just one hectare of ponds.

"Other ponds were being used to grow tons of food-sized fish.

"By 2005, though, we were struggling to produce any healthy fish at all and we've run at a loss ever since."

The 63-year-old blames PFAS contamination from the nearby Royal Australian Air Force (RAAF) Base.

Investigations by the Department of Defence have confirmed PFAS is leaving the base through the stormwater network, which drains into wetland near the Murray Cod Hatcheries.

Mr Semple believes the chemicals leached into the surface and bore water used at the hatchery, where he still lives, and ruined his fish stocks.

And experts agree.

Ian Rae, an expert on chemicals in the environment at the University of Melbourne and an environmental advisor to the United Nations, said Mr Semple's was the worst case of real damage caused by PFAS contamination he had seen.

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"The examples that have turned up around the country have largely been from monitoring," Dr Rae said.

"So, people have known of these chemicals washing down local streams and into the groundwater but there have been very few cases where you could actually demonstrate there was a problem coming from that.

"This is the worst one I've seen."

Although still a fully licensed fish hatchery, Mr Semple made the tough decision last year to shut down the business after half a century of operation for safety and financial reasons.

"I've worked it out and I believe I will have lost $120 million because of PFAS contamination — and that figure is based on scientific and industry evidence," he said.

"To come to that figure, I've taken into account the devaluation of the business and the devaluation of the resale value of the property."

Mr Semple is currently building his case against the Department of Defence and will look at taking action to recover his losses in the coming months.

The link to human health

A significant number of Greg Semple's fish stocks developed with abnormally short bodies. ( Supplied: Greg Semple )

Per- and poly-fluoroalkyl substances, known as PFAS, are a group of synthetic chemicals that have been used in firefighting foams since the 1970s.

These chemicals have contaminated groundwater, surface water, sediments and soil at 28 Department of Defence sites around the country, including the RAAF Base in Wagga Wagga.

Defence started phasing the chemicals out in 2004 and has undertaken a national review of their impact on the environment around the bases.

Their investigation into the impact around Wagga's RAAF Base found the risks to residents living nearby were relatively low, and an Expert Health Panel Report also investigating the potential impacts of PFAS had similar findings.

It found limited or no evidence to link exposure to human disease or an increased risk of cancer, but also said health effects could not be ruled out and that exposure should be minimised as a precaution.

That plays heavily on Mr Semple's mind.

"My own health, and that of others who have spent time here, is always a concern," he said.

"PFAS screening tests costs between $550 and $600, and should be considered basic health research, in my opinion.

"Other communities affected by PFAS contamination, like Williamtown, Katherine and Oakey, have been granted voluntary blood testing but my requests to the Department of Defence for government-funded blood testing have been denied and I know requests by other affected residents in Wagga have also been denied.

"But I guess, once I get those results, what do I do with them? "There's nothing I can do now — I've already had high exposure for long periods of time."

A Defence spokesperson said Community Support Packages, which included voluntary blood testing as well as mental health and counselling services, were being offered in investigation areas where the extent of PFAS contamination and the human exposure pathways were well understood.

"Given the different circumstances of each site, the Australian Government will consider where an extension of the Community Support Package arrangements, including voluntary blood testing, is required on a site-by-site basis, as further evidence becomes available."

The spokesperson added that blood testing was not recommended for individuals.

"On an individual level, blood testing for PFAS isn't recommended as there is insufficient evidence for a medical practitioner to be able to tell a person whether their blood level will make them sick now or later in life," they said.

"It is also unable to tell you if any current health problems are related to the PFAS levels found in your blood or guide clinical management."

Deformed fish, blind horses, and infertile livestock

Having seen the physical changes in his fish stocks, and the animals living on his and neighbouring properties since he moved in, has not eased Mr Semple's concerns.

"A lot of things have gone weird around here," he said.

"We've had fish with an extra fin and some silver perch had what's called axe head, which means they develop with depressed skulls. Basically, their skull hasn't formed properly.

"Far more had stunted, shortened bodies and what looked like scoliosis and spina bifida, and tens of millions died as embryonic young.

"Those fish that managed to survive had poor reproductive success and died when still quite young.

"I've been doing this my whole life and to see that happen to my fish, it's taken me to a pretty dark place mentally."

It was not just Mr Semple's fish that developed abnormalities over the years.

"We had a race horse brood mare that appeared to become infertile and a pedigree stock horse that went blind after delivering a severely undersize foal," he said.

"Nanny goats, mares and miniature cattle have had reproductive problems and looked bloated with distended udders, so much so that vets thought they were pregnant and ready to give birth but they weren't."

A foal born unusually undersize (left) is just one example of the health issues that plagued animals on Greg Semple's property. ( Supplied: Greg Semple )

Defence's investigations have only considered whether a risk of exposure to PFAS existed for animals in contaminated areas, not what that exposure could do to them.

"The ecological risk assessment is screening only and does not seek to assess potential effects of PFAS on specific species," a Defence spokesperson said.

It did find the risk of exposure to land animals coming into contact with soil in PFAS-contaminated areas was acceptable, and that there was only a potential risk of exposure for aquatic animals in direct contact with impacted surface water as well as for birds and mammals that consumed aquatic animals from impacted waterways.

Highest contamination levels detected

Since 2017, Mr Semple has worked with engineers and scientific researchers contracted by the Department of Defence to test the extent of PFAS contamination in the water used at Murray Cod Hatcheries.

He had PFAS levels in his aquatic animals tested by the contractors and found levels in their flesh to be up to 103 times that considered the assumed safe standard for eating finfish in Australia.

The groundwater was found to have 65 times the amount of PFAS toxicity currently considered acceptable for Australian drinking water and the PFAS readings in some of the surface water were 101 times the provisional assumed safe levels for agricultural use.

Other detailed water testing completed in 2017 also found there was no significant level of any other environmentally toxic chemical at the fish hatchery.

Contamination has been blamed for fish stocks suffering from bent and unusually shaped backbones. ( Supplied: Greg Semple )

The Department of Defence has said the PFAS concentration detected in water at the Murray Cod Hatcheries were the highest detected in off-base locations as part of their investigations in Wagga Wagga.

"However, it's important to note that Defence has been advised that the surface water in the ponds and the groundwater bores at Murray Cod Hatcheries are not currently used as a source of drinking water," a Defence spokesperson said.

"The Human Health and Ecological Risk Assessment did not identify unacceptable exposure risks from incidental contact with water at the hatcheries.

"Incidental contact may occur when washing hands or wading in the pools for maintenance activities."

But Mr Semple said the advice given to him by Defence, the NSW Environmental Protection Authority, and the Department of Health escalated following the water testing.

"At first I was told not to drink or use the bore water or to eat foods produced or washed in it," Mr Semple said.

"Then I was told to avoid contact with the water altogether.

"It's a bit hard to run a hatchery when you can't touch the water."

Eliminating the toxins is possible

A spokesperson for the Department of Defence said placing fish in clean water could eliminate PFAS concentrations from their systems.

"The Human Health and Ecological Risk Assessment refers to published studies of PFAS depuration in various fish and crustacean species and notes that when placed in clean water, the time taken to remove PFAS from their systems ranges from hours to weeks depending on the species," they said.

"The assessment indicates that there should not be any exposure risks in relation to consumption of fish and crustaceans, assuming these were placed in a PFAS-free environment for at least two weeks.

"Depuration studies on the species produced at the Murray Cod Hatcheries would be needed to confirm actual depuration rates."

Mr Semple had not attempted depuration of his fish but said the process would take much longer than two weeks.

"The only freshwater fish studied in detail have been American bluegill sunfish and studies with that species found depuration of PFAS concentrations from the flesh takes 152 days," he said.

"The PFAS levels found in some of the native fish at Murray Cod Hatcheries were around 103 times the safe level so, if you apply the American findings, it would take in excess of eight years of depuration for them to reach an assumed safe level."

Mr Semple conducted his own controlled fish breeding trials in 2008 and 2017 using perch larvae supplied by the NSW Department of Primary Industries.

"The larvae held in Murray Cod Hatcheries' surface and bore water died within days," he said.

"Controls held in town and river water had high survival rates.

"The birth defects and diminished fish stocks and reproductive capacity mirrored the scientific findings published overseas on fish and ecosystems exposed to PFAS concentrations, even those with far lower levels than found here."

PFAS likely to blame: experts

The University of Melbourne's Dr Ian Rae said the impacts described at Murray Cod Hatcheries were "classic symptoms of poisoning with PFAS".

"These are developmental toxins so they don't actually kill organisms in the way some toxins do but they ruin their development, which means they may not have eggs or the eggs may be at a very low concentration or they may be deformed in some way," Dr Rae said.

"And when new fish are born, they may have serious developmental problems, their organs may not be properly developed or there may be a very low yield of new fish.

"Given the evidence from the hatchery, I think it's a classic example of PFAS poisoning."

Julie Mondon, an associate professor of aquatic ecotoxicology at Deakin University, agreed that PFAS contamination was likely to be to blame for the abnormalities reported at the hatchery but added that it was difficult to prove a clear cause-and-effect.

"Without the benefit of knowing what other pollutants have been present prior to the 2017 findings, it can't be definitively claimed that PFAS has been responsible," Dr Mondon said.

"However, there is a strong weight of evidence suggesting that the presence of the suite of chemicals detected in 2017 and the concentrations at which they were detected, both in the environment and in the fish, would correlate with the significant health issues evident.

"Secondary fins and severe spinal curvature in the fish, in particular, are indicative of chemical toxicity response.

"The evidence of decreased reproduction rate and decreased reproduction in offspring indicates an intergeneration toxicity.

"This is not an unusual characteristic of these types of chemicals but often not well-documented due to the time involved in assessing one generation's response through to the next."

A number of fish at Murray Cod Hatcheries grew with twisted spines and suffered early deaths. ( Supplied: Greg Semple )

Dr Mondon also said the abnormalities were occurring at a much higher rate than would normally be expected in a fish breeding environment.

"In an aquaculture breeding program, it is expected that some abnormalities across the population might occur, not necessarily spinal curvature, but at a very low percentage and certainly not to the extent described by the owner of Murray Cod Hatcheries," she said.

"If a significant number are showing gross deformity then chemical poisoning is the most likely culprit causing these mutations."

Both experts agreed that it was also possible that chemical contamination might be responsible in the case of the cattle, horses and goats around Mr Semple's property.

"The bodies of those animals are quite different and will manage the toxins better than fish, but there's still likely to be effects," Dr Rae said.

"Still, I don't think Mr Semple needs to go on doing any more experiments. There's enough evidence there to be satisfied that these chemicals are the cause of the problem."

Goats at Murray Cod Hatcheries had abdomens so swollen they looked pregnant, according to Greg Semple. ( Supplied: Greg Semple )

The next step

Mr Semple was still a long way from taking any official steps towards remediation for his estimated $120 million loss.

"This was one of the best hatcheries in the country and now we're out of commercial operation," he said.

He said he was waiting for the Department of Defence to publish its PFAS Management Area Plan for Wagga RAAF Base, due in the coming months, which will outline the department's plan to manage, monitor and reduce the risks of PFAS exposure at and around the base.

"I'm waiting to see if the government will accept the nine recommendations proposed in the parliamentary inquiry into the management of PFAS contamination before taking further action," he said.

"But how do you compensate for half a person's working life?"

A Defence spokesperson said the Department would welcome a claim from Mr Semple, if he believed "the Commonwealth is liable" for his losses.

"The Commonwealth is always open to receiving claims directly from individuals and businesses who have suffered a loss or injury and consider the Commonwealth is liable," the spokesperson said.