Imported mushrooms may contain deadly bacteria, but they are hardly being screened

Shipments of mushrooms potentially contaminated with deadly bacteria are coming into Australia largely unchecked by federal authorities despite concerns they could pose a serious health threat.

Imported mushrooms, particularly varieties from East Asia, have been linked to serious and fatal outbreaks of listeria and salmonella in countries across the world, including Australia.

Documents obtained by The Age through freedom of information show the government has been aware of the health risks posed by imported mushrooms since at least 2021 but is reluctant to screen shipments for deadly bacteria.

It comes as new data shows nearly 300 Victorians have been hospitalised with mushroom-related poisoning in the past decade, with the number of incidents soaring 250 per cent since 2012.

More than half of all mushroom poisoning incidents have an unknown origin, with about one-third attributed to wild, field or home-grown mushrooms causing illnesses, according to data from the Victorian Injury Surveillance Unit. This data does not include illnesses caused by so-called “magic mushrooms”.

The Age filed freedom of information requests with the Commonwealth Department of Agriculture and the Victorian Department of Health after the fatal poisoning in the Victorian regional town of Leongatha in July 2023, where three people died and another fell seriously ill.

Erin Patterson flanked by her lawyers in Melbourne’s legal district last August.Credit: Chris Hopkins

Leongatha woman Erin Patterson has been charged with three counts of murder and five counts of attempted murder. Police allege she fed her lunch guests a beef Wellington cooked with death cap mushrooms, a highly poisonous fungi responsible for 90 per cent of mushroom poisoning deaths.

In an unsworn written statement from Patterson before her arrest, the 49-year-old claimed that she had bought the dried mushrooms at a suburban grocery store in Mount Waverley, but police allege she acted with intent and had attempted to poison her husband before the fatal lunch.

Last October, The Age found dried mushrooms being sold to the public from plastic bins without labels at independent grocery stores. In some cases, the bins had handwritten labels in another language that offered no clear product information.

Translations of the available labels referred to the mushrooms as simply “high-grade (black) fungus” or “red-brown fungus that grows in a high-altitude area”.

Mushrooms found by The Age in grocery stores in Melbourne’s suburbs.Credit: Chris Vedelago

Unpackaged foods such as dried mushrooms are not required to be labelled, but the seller must be able to provide a “specification sheet” that includes information such as the grower, region, possible allergens and test results, according to the Australia New Zealand Food Standards Code.

Australians consume about 70,000 tonnes of mushroom products each year, with more than 1880 tonnes brought into the country mainly from South Korea and China by a small number of importers.

But internal documents from the Department of Agriculture obtained under freedom of information show the department has failed to implement any kind of safety monitoring regime despite being warned about the risks to health and human safety.

The department’s lack of action on the growing risk to health and public safety became a live issue when food safety authority Food Standards Australia New Zealand (FSANZ) flagged concerns in 2022 following a deadly listeria outbreak in the US and Canada linked to imported enoki mushrooms.

“We think this is something that we should also be front-footing for Australian public health given the growth in popularity of these types of mushrooms,” an FSANZ senior microbiologist wrote in an email to the department in November 2022.

In internal correspondence, the Department of Agriculture, Fisheries, and Forestry conceded it had the power to implement a surveillance program but hadn’t done so.

“While we do have powers under the Imported Food Control Regulations to implement a surveillance program, we currently do not have a framework in place to manage this process,” an email dated January 2023 read.

“Actioning the request from FSANZ means using powers under the IFC legislation that we have not previously used, and we need to consider carefully before implementing.”

Following the outbreaks, Food Standards Australia New Zealand suggested the government start surveillance testing enoki mushrooms at the border for the listeria bacteria, but the department expressed reluctance to introduce the scheme.

“Before we can sample goods at the border using these powers, we must seek importer permission and the department would be responsible for covering the cost of the testing and analysis,” it said in an internal email in January 2023.

“We also need to consider how to manage this within our systems, as it would be a change to the usual 5 per cent referral of surveillance food.”

In a statement, a Department of Agriculture, Fisheries and Forestry spokesperson said the department had asked FSANZ to provide risk advice on imported enoki mushrooms after the outbreaks, which the agency published in 2024.

Enoki mushrooms are prone to carrying the listeria bacteria.Credit: iStock

“Consistent with the risk advice provided by FSANZ, the department has commenced a process for implementing additional risk management measures in line with the objectives of the Imported Food Control Act 1992,” the spokesperson said.

The decision to introduce more stringent monitoring of imported enoki mushrooms coming into the country is supported by the Australian Mushroom Growers Association.

“It’s worth reminding consumers that all Australian-grown mushrooms, sold at major retailers, are safe, healthy and of the highest quality. AMGA members adhere to world-leading food safety standards and work closely with major retailers to ensure traceability through the supply chain,” an association spokesperson said in a statement.

Enoki mushrooms are commonly used in Japanese and Chinese cooking, but are prone to carrying the listeria bacteria, which can cause vomiting, nausea, muscle aches, headaches, and neck stiffness. In some cases, listeriosis has been known to cause death, and spontaneous abortions and stillbirths in pregnant women. A national survey conducted by FSANZ in 2023 found 11 per cent of imported enoki mushroom samples were positive for listeria.

The mushrooms can become contaminated with the bacteria, which can survive at low temperatures, during the production and processing stage. Cooking the mushrooms reduces the risk of developing the illness, but the concentration of the bacteria in enoki mushrooms can be so high that the risk remains.

In Australia, between 2017 and 2020, six people fell ill and a man died after consuming contaminated enoki mushrooms that were linked to an outbreak in North America. The deceased, a 77-year-old man from Queensland, had bought the imported mushrooms from Korea from his local supermarket.

FSANZ said enoki mushrooms had a long history of safe use in other cultures familiar with how to prepare them, but some consumers in Australia might be unaware they need to cook them before eating them.

“There has been considerable effort to understand the nature of the risk associated with some imported mushrooms and implement evidence and risk-based regulatory action,” the food safety agency said.

In March 2023, the department put out a public alert to raise awareness of the potential health threat posed by enoki mushrooms.

“Recently, there has been an increase in the number of overseas food incident alerts and notifications concerning enoki mushrooms contaminated with L. monocytogenes,” it said.

“The consumption of contaminated enoki mushrooms has been associated with illness and deaths.”

Since then, Australian authorities have issued several recalls for enoki products over issues with the packaging and dangerous concentrations of bacteria, and held shipments from some suppliers previously linked to contaminated batches at the border for testing. In Victoria, the Department of Health also uncovered a shipment of enoki mushrooms contaminated with listeria in a warehouse in Knoxfield in August last year. The mushrooms had been imported into the state by an unregistered supplier.

A department spokesperson said state health regulators regularly conducted surveillance and testing of food products in addition to national food surveys led by the federal government. However, it was up to local councils to ensure shops selling mushrooms in Victoria comply with the Australia New Zealand Food Standards Code.

A study conducted by the Chinese Centre for Disease Control and Prevention found that “mushroom poisoning has become a serious food safety issue in China”. In 2022, there were 482 mushroom poisoning incidents in which 1332 people fell ill and 28 died. There were 23 incidents in which the mushrooms were purchased from markets or supplied by friends. The study also found several incidents where poisonous mushrooms were accidentally mixed with edible mushrooms.

Canada introduced a hold-and-test policy for enoki mushroom imports from South Korea and China in March 2023. The US also requires importers to prove shipments from the same countries do not carry listeria before they are released.

There have also been a notable number of serious illnesses such as listeria and salmonella from imported mushrooms that have been served in restaurants or sold to consumers by retailers in the United States.

In late 2020, dried wood ear mushrooms were traced to an outbreak of salmonella to more than 40 diners at restaurants in 11 US states.

Data from the Victorian Injury Surveillance Unit reports 14 Victorians were admitted to hospital in 2012 with mushroom poisoning, compared to 44 people in 2022. There have been nearly 300 people over the decade.

About one-third of those who fell ill reported the mushrooms were sourced from the wild, fields or their own gardens.

It’s also an affliction that is far more likely to strike city rather than country people, with 69 per cent of those falling ill residing in metropolitan areas.

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