A commonly available medical dye which has been used in Australia for decades was revealed just three months ago by scientists as an antidote to potentially fatal poisoning by Death Cap mushrooms.

Indocyanine Green, also known as Diagnostic Green and ICG, is available in a 100 gram bottle for $429 from ChemSupply Australia, although the company would not confirm if it can be sold to ordinary Australians or just doctors.

An injectable fluorescent dye used in humans as a diagnostic aid since 1959, ICG is employed in imaging techniques such as angiography and other processes to determine function in the heart, brain, liver and eye.

A Townsville eye specialist who uses ICG to diagnose inflammatory eye disease, and age-related macular degeneration told Daily Mail Australia said the 'can only be administered by a specialist'.

But according to a study globally published in May this year, even if the ICG had been used on guests who ate beef Wellington pie on July 29, they would have to have been injected intravenously within four hours of the lunch.

Chinese scientists published a study after testing the Indocyanine Green on mice injected with the major toxic component of death cap mushrooms, amatoxin or AMA.

One of the reasons for the study appears to be that thousands of poisonings and deaths in China have resulted from 'Amanita phalloides ... the world’s most poisonous mushroom'.

China recorded a 'total of 10,036 exposure events, resulting in 38,676 illnesses and 788 deaths ... between 2010 and 2020'.

'Among all poisonous mushrooms, Death Caps ... are responsible for more than 90pc of deaths,' says the scientific paper by researchers at Sun Yat-sen University in Guangzhou.

Erin Patterson's lunch guests would have had to have been injected within four hours with the medical dye to survive, going by the calculations of Chinese researchers

Researchers at Sun Yat-sen university (above, their diagram) infected mice with Death Cap mushroom poison then with a common medical dye used globally since the late 1950s, giving the injected mice twice the survival rate

The scientists said there was 'an urgent need' for antidotes to the Death Cap mushroom as there had been 38,676 illnesses and 788 deaths ... between 2010 and 2020' in China

The study concluded 'ICG treatment is an effective antidote for treating AMA toxicity in mice'.

'Amatoxin poisoning is commonly associated with poor outcomes, mainly owing to the irreparable acute failure of the liver or kidney.

'Since consumption of Death Cap leads to a high rate of mortality, there is an urgent need to better understand the molecular toxicology (and facilitate) the discovery of effective antidotes to treat mushroom poisoning.'

The Chinese researchers tested ICG as an AMA antidote on mice, which were all male and aged between four and five weeks old, and given free access to food and water during the experiment.

Half the mice exposed to amatoxin and then given ICG died.

However the scientists concluded the mice were more than twice as likely to survive than rodents only given the Death Cap toxin, and that the earlier they were given the antidote, the better.

The Chinese university study on using ICG tp treat mice injected with Death Cap mushroom toxins showed how the dye was rapidly distributed all over the body but selectively taken and concentrated in the liver

Heather and Ian Wilkinson were taken to hospital too many hours after the beef Wellington lunch to have survive, even if the Indocyanine Green had been available as an antidote for humans

Results suggested 'it should be injected within the first few hours after mushroom poisoning', specifically a four-hour interval between poisoning and treatment.

'This 4 hour interval was the same as that used in previous studies to mimic actual human poisoning and treatment scenarios,' the study said.

'ICG loses its treatment effect on AMA toxicity when it was delivered 8 and 12 hours post AMA injection.

'This may be because AMA has caused irreversible damage during early hours of cytotoxicity, which is unable to be salvaged by ICG treatment. This suggests that ICG should be given as early as possible during treatment.'

Indocyanine Green does not appear to be used anywhere in the world on humans with mushroom poisoning, and the alleged Australian Death Cap victims were not admitted to hospital until long after four hours following the beef Wellington lunch.

Indocyanine Green is commonly used in Australia for diagnosing eye, heart and liver conditions via infrared monitoring of the fluorescent dye, but Chinese researchers who have tested it on mice says it inhibits Death Cap mushroom toxins attacking the liver

Don and Gail Patterson are believed to have gone to hospital early on Sunday morning, by which time Amatoxin from Death Cap mushrooms would have been attacking their livers and kidneys

Host Erin Patterson had her former husband's parents Don and Gail Patterson, and his aunt and uncle Heather and Ian Wilkinson over for lunch on Saturday, July 29.

Erin Patterson, who said she made the dish with button mushrooms from the supermarket and dried mushrooms from an unspecified Asian grocery store in Melbourne, said she allowed the guests to choose their plate for the meal.

That evening, the four guests came down with serious gastro-like symptoms and, in the early hours of Sunday, went to Leongatha and Korumburra hospitals.

They were soon transferred to hospitals in Melbourne in a critical condition.

Gail, 70, and Heather, 66, both died on Friday, August 4 and Don Patterson, 70, died the next day.

Ian Wilkinson remains in Melbourne's Austin Hospital, in a critical condition and needing a liver transplant.

All four suffered symptoms consistent with the ingestion of Death Cap mushrooms; from gastro-like illness to nausea, stomach pain, and, in the case of at least Ian, liver damage.

Erin Patterson went to a Leongatha Hospital and was then transferred to Melbourne, but did not suffer so severely from the beef Wellington dish as her guests

The commonly available diagnostic dye is available for a few hundred dollars for 100g, although a Queensland ophthalmologist said only a specialist can administer it

Erin Patterson, who was also taken to Leongatha Hospital and then transferred to Melbourne with gastrointestinal symptoms, said her children ate leftovers of the been Wellington the following night, but she removed the mushrooms because they didn’t like them.

Daily Mail Australia does not suggest Erin Patterson intentionally poisoned her four relatives.

In the Chinese laboratory experiments, Indocyanine Green was injected intravenously into the mice after the administration of the amatoxin.

An infrared monitor showed the ICG was rapidly distributed all over the body but selectively taken and concentrated in the liver.

The scientists said the doses of ICG, equivalent to approximately 0.5 mg/kg in humans, were deemed 'safe for treating AMA poisoning in mice (because) we did not observe obvious side effects in the ICG-only mice'.

'The ICG can be metabolised and excreted via the liver and the hepatobiliary system (bile ducts) with a half-life of around 3–4 minutes.'

In humans, the use of ICG in medical diagnostic work can cause side effects, such as a sore throat, hot flushes, and occasional anaphylaxis.

ICG was developed in the Second World War as a dye in photography and tested in 1957 at the Mayo Clinic, and granted FDA approval in 1959.

The Chinese researchers said that because 'ICG is metabolised ... in the liver and only excreted via the liver and bile ducts, since it is not absorbed by the intestinal mucous membrane, the toxicity can be classified as low'.

The Sun Yat-sen University team said that more research will be required to identify exactly how ICG works to block the mushroom’s toxicity, but suggested that the blockage of the toxin into circulation in the liver is a likely contributing factor.