It was 13 years ago when the veterinarian, who specialises in fish, was called to a small hatchery to investigate sudden, unexplained anomalies interfering with the embryos.

"They were having problems getting their fish to survive and they'd noticed some strange development in the eggs and the larvae of those fish in their hatchery," he says.

"They had had some problems over the preceding couple of years which they suspected may have been related to the practices of their neighbour operating a commercial macadamia farm and utilising registered agricultural sprays on their crop."

The hatchery operator had taken her concerns to the Queensland government, suspecting pesticide spray drift had introduced chemicals into the water in which the fish were bred. An initial investigation found the neighbour had complied with the necessary regulations.

"They essentially advised her that the operator was in compliance with regulations around application of spraying and therefore there may be other reasons why her fish were having problems. She rang me up and asked me as a veterinarian to come and investigate what was going on with her fish, to try and understand if there were other problems."

Landos was particularly troubled by a group of bass, which had spawned in the springtime.

"Those larvae began developing their bodies and started bifurcating, so that they had two heads on the one body in a large number of the larvae that were developing."

They died after 48 hours.

"It was a clear sign that the signalling that cells have early on was becoming deranged due to something," Landos says.

The vet raised his concerns with then Queensland minister for primary industries and fisheries, the late Tim Mulherin. A task force was set up to try to establish what had caused the problems at the hatchery and whether it had anything to do with reported declining native fish stocks in the local catchment.

"That ran for about 12 months before putting together a final report. However there was really at no stage a consensus reached within the group about causation," says Landos. "In the final report - the government-authored report - concluded that there was no definitive involvement of chemicals."

All these years later, he still takes issue with the report's findings, saying it was trying to provide a definitive answer, which he says science is unable to do. And given most of the report's recommendations related to the use of chemicals, it was clear from his perspective that chemicals were the culprit but the government just didn't want to say so.

"The tension within the task force committee was such that they in fact stopped operating a proper committee process with minutes and actually broke it into meetings with individuals, which was very unusual for a committee." Landos says there was disagreement over whether there was in fact any spray drift onto the hatchery. But his investigation found there was.

"We metered a swimming pool some 800 metres away from the macadamia farm, which was right next door to the fish farm and found the chemicals that were being sprayed. We hung filter paper in the air inside the closed hatchery building and we measured levels of the chemical being sprayed in the neighbour's property on the filter paper. It was clearly moving its way into the shed and ended up on the filter paper and we detected it so we demonstrated that exposure was happening."

Critically, he says, that exposure occurred at the same time the fish were developing. "It was happening at the specific time that these cells were trying to divide in these embryos. This is a critical timing of exposure."

Landos concluded that the embryos were being deformed through their exposure to endocrine disrupting chemicals (EDCs) in the pesticide. And it wasn't just the fish.

"Over time, we also identified frogs on the property that were developing deformed legs. There were horses that had abortions, there were horses showing clinical signs as in muscle tremors and a loss of ability to walk properly that responded to an antidote specific for treating organophosphate pesticide poisoning.

"We had a dog on the property that had pups and many of the pups were stillborn. That same dog had pups a couple of years later that had no eyes during their development. They were born without eyes. These things may all be aberrations however when you dig into the peer reviewed literature you see that some of the ways the chemicals involved affect in laboratory studies is the development of eyes."

Landos says his investigation triggered a lightbulb moment.

"Could these low doses in fact be enough to disturb these body systems and alter the way that animals both develop as embryos but also their ultimate health as they get older?"

He began immersing himself in the growing body of scientific research which suggests there is a link between exposure to even tiny doses of endocrine disrupting chemicals and developmental problems and health issues later in life.

"There had been a decade or more of hormone disrupting research but it wasn't taught in my undergraduate degree at university. So I hadn't run across it. It was sitting in a separate science silo that I hadn't found my way to. Since finding that silo and cracking the lid on the thing it's a treasure trove of knowledge."

That knowledge is disturbing. Endocrine disrupting chemicals (EDCs) are everywhere. They're applied to food and the packaging it comes in. They make their way into the water supply. They're on the clothes we wear, in the cars we drive and the furniture on which we sit. The research into their effects, Landos says, should raise alarm bells about human exposure to toxic chemicals and the regulations governing their use, which he maintains, fall way too short.

The endocrine system, common to all vertebrates, regulates hormones, which are critical to development and health.

"Hormones are incredibly powerful at tiny doses," he says. "Tiny exposure levels of hormones can mediate huge effects on development. So small amounts of thyroid hormone are involved in helping the brain develop normally. As animals develop, we see small amounts of testosterone having tremendous effects on the development of different tissues in the animal and of course ultimately in the reproductive capacity of those animals."

The pesticide being sprayed next to the fish hatchery, he says, might have been applied legally as far as the regulation was concerned. "But what the investigation highlighted was that there were problems with our regulation in that it was not safe and that exposures at levels below those which were permitted were causing harm."

Landos says the system of regulating chemicals hasn't been able to keep up with the growing body of research which identifies harms associated with exposure to even tiny amounts of EDCs. Its benchmarks, such as the exposure required for a chemical to become lethal, miss other effects which may be more subtle but still have lasting consequences.

"The issue is one of which part of the testing - which of the end points, as we call them - are considered in the regulatory process. The coarsest end point might be considered to be death of the animal. So at a certain level of exposure the animal's systems might not be able to sustain themselves, the animal may perish. And this would establish a lethal end point for a study.

"A more subtle end point might be loss of body weight or an impact on liver function or an inability to breed or a change in organ size.

"So there are many different end points that can be selected to study the effects of exposure to chemicals. In the last couple of decades there has been a growing understanding that there are a group of end points that are extremely sensitive and these are called the endocrine end points. Or end points which are affecting the function of hormones in the body."

Landos has campaigned vigorously for the past decade for a more robust regulatory system, both through his membership of the Australian Veterinary Association and as a member of the International Pollutants Elimination Network, an international advocacy group. Landos speaks at conferences, including SoilCare's Australian Biological Farming Conference in Lismore in December, and contributes papers focused on chemical exposure and ocean pollution.

"The signal to regulate further is very clear and that is the decline in human health. The signal is one in six Australian couples need fertility treatment to have a child. The signal is that we are heading towards a quarter of Australians being pre-diabetic before 2025. The signal is that obesity is expanding in our population. The signal is that rates of depression are climbing in our population. The signal is that children with learning difficulties are at their highest rates that they've ever been in schools. There are some very strong public health signals out there."

While exposure to EDCs might not be the sole cause of these problems, it could well be contributing.

A very clear signal over one of the most pervasive classes of EDC, perfluoroalkyl and polyfluoroalkyl substances - commonly known as PFAS - emerged this year in the US. A University of California study found high exposure to PFAS can increase a person's risk of non-viral hepatocellular carcinoma - a common liver cancer - by up to 4.5 times. PFAS are most commonly used in non-stick cookware but are also present in tap water, waterproof clothing and cleaning products.

The toxic legacy of PFAS has been an invisible torment for a number of Australian communities near defence bases - including Newcastle and Jervis Bay in NSW and Katherine in the Northern Territory - where firefighting foam containing the substance leached into surrounding waterways and the soil.

In June, the US Environmental Protection Agency cut the allowable use of PFAS in household products by 99 per cent.

More than 500 scientists from 28 countries gathered recently in Adelaide to hear about the scale of chemical use worldwide and how it's affecting human and environmental health. Of particular concern was the ubiquity of PFAS. The Australian government recently released the third draft of its plan to manage PFAS but whether it will satisfy the scientific community which warns of a tsunami of chemicals remains to be seen.

"PFAS have now been nominated to be listed, the entire class of those chemicals, on the Stockholm Convention on persistent organic pollutants," says Landos. "But Australia has not sought to remove those at this stage. Australia still has relatively high levels of tolerance in terms of it permitting - as a water safety guideline - relatively high levels in water compared to the EU, for example, which in order of magnitude are lower than Australia in their tolerance."

He says Australia, while a signatory to the Stockholm Convention, drags its feet when it comes to ratifying the ban on troublesome chemicals.

"It doesn't automatically ratify new listed chemicals to say that Australia will immediately remove them. Australia takes an approach where it says we will decide in our own time when we'll remove them. So initially when we signed there were a dozen or so dangerous chemicals. We ratified those but since then Australia has been a complete laggard globally in ratifying the subsequent ones."

Jo Immig, coordinator of the National Toxics Network, a non-profit which raises awareness about chemical pollutants, describes the regulatory system for chemicals in Australia as "a bit of a spaghetti junction".

Pesticides are regulated by the Australian Pesticides and Veterinary Medicines Authority, industrial chemicals are overseen by the Australian Industrial Chemicals Introduction Scheme and food ingredients and packaging come under the purview of the Australia New Zealand Food Standards.

In August, Immig wrote on behalf of the National Toxics Network to the new federal Agriculture Minister Murray Watt, urging tighter regulation of agricultural and veterinary (AGVET) chemicals.

"The previous government did untold damage to the regulation of AGVET chemicals," she said. "They repealed critical legislation introduced under the Gillard government which established a systematic re-registration scheme for AGVET chemicals to ensure they met contemporary regulatory and scientific standards, as well as provided an effective mechanism to remove dangerous pesticides from the market. Given the extensive consultation that was undertaken to develop and implement that legislation perhaps this is something that could be easily achieved ... Re-registration schemes have been part of regulatory regimes in Canada, the US and the EU for years."

Ms Immig was particularly critical of the restructure of the APVMA, which she said had been gutted by the Morrison government which controversially and at great cost moved its operations to Armidale, in the electorate held by former Nationals leader Barnaby Joyce. The restructure, argued then agriculture minister David Littleproud, would "mean the APVMA runs more efficiently, will reduce some costs, and mean that farmers can access safe and effective chemicals quickly". This was diametrically opposed to the tougher regulatory approach being urged by scientists concerned about chemical exposure.

"The lengthy and costly reform process they recently undertook was marred by conflict of interest and culminated in legislation which further deregulated AGVET chemicals, while blatantly ignoring the science and evidence given by numerous stakeholders," Immig wrote.

It was "shameful and dangerous Australia still uses many pesticides long banned in other countries and still has no effective mechanism to get them off the market or to incentivise farmers to move away from their use. We are a dumping ground for pesticides long banned by other more cautious countries, which is ultimately not to our competitive advantage and nor is it protective of public health or the environment."

Australia, she says, should move to the precautionary approach to regulation adopted by the European Union, where chemicals need to be demonstrated to be safe before they are allowed on the market. The National Toxics Network has had notable success.

"We've been successful at having some dangerous pesticides removed from the market such as endosulfan," says Immig. "We were largely responsible for the Gillard government introducing the re-registration scheme for pesticides which would have been great but the Abbott government dumped it."

This year it brought to public attention concerns about the waste-to-energy incinerators being rolled out across NSW.

While Landos pushes for stronger regulation, he is taking his own small steps to keep himself and his family safe. You won't find plastic in his home, nor non-stick cookware. "I have a cast iron frypan and no one ever complains about my eggs," he says. Out too are fragranced cleaning products and personal care products. He buys his fruit and vegetables from organic farms.

But not everyone is in the position to make such choices.

Dr Shanna Swan, author of Count Down: How Our Modern World Is Threatening Sperm Counts, Altering Male and Female Reproductive Development, and Imperiling the Future of the Human Race, says poorer people face greater challenges avoiding chemical exposure.

"It's much harder to learn about it if you don't have the resources to access the information and you can't buy your way out of it," she says. "Maybe you're in a food desert and there's no organic food nearby, there's no farmers market. You can't take the steps necessary to decrease your exposure."

Swan, a professor from New York's Mount Sinai School of Medicine, says exposure to EDCs is a likely culprit not only in declining fertility and fecundity rates but also genital disorders.

Brominated flame retardants used in electronics, clothing and furniture, such as sofas and mattresses, to reduce flammability have been linked to abnormal hormone function in the thyroid. Adding to the risk of exposure, they often migrate out of their products over time and contaminate household dust and food. Polychlorinated biphenyls (PCBs) were used in hundreds of industrial and commercial applications due to their non-flammability, as well as chemical stability and insulating properties. Although now banned, PCBs are still present in insulation, electrical equipment, caulking, oil-based paint and more, and do not break down readily. They have the strongest and longest-known associations with neurological disorders.

Phthalates interfere with the production of androgen (testosterone), a hormone critical in male development and relevant to females as well. They are used in many food and beverage containers and plastic wraps and leach into foods when containers are microwaved. Many companies have voluntarily removed phthalates from their products and advertise them as "phthalate-free". Other plastic containers, which contain phthalates, have the number "3" and "V" or "PVC" in the recycling symbol.

Chlorpyrifos, an insecticide used in commercial agriculture, is a potent neurotoxicant that causes developmental delays, attention problems, and ADHD in children. It accumulates in soil, water, food and air, as well as in buildings. DDT, one of the best-known pesticide EDCs, was used extensively worldwide until it was banned in the 1970s by several countries, including Australia. It remains in use in India and Africa to fight insect-borne disease. Evidence suggests exposure to this neurotoxin might be associated with breast cancer, preterm birth, early pregnancy loss, reduced semen quality, disrupted menstruation and problems with lactation. Atrazine, a widely-used herbicide, has been shown to affect the hypothalamus and pituitary glands. Some studies have also proposed causal relationships between glyphosate, used to kill weeds on lawns and farms, and obesity, behavioral and cognitive disorders.

Per- and polyfluoroalkyl substances (PFAS) are man-made chemicals used as oil and water repellents and coatings for common products including cookware, carpets and textiles. They were also used extensively in firefighting foam until the manufacturer withdrew the product from sale because of fears it was unsafe. These EDCs do not break down when they are released into the environment, and they continue to accumulate over time.

Source: US Endocrine Society