The regulator will make a decision after submissions close in September.
Australians' surging appetite for berries has forced the national farm chemical watchdog to review the risk of exposure to harmful levels of a popular pesticide.
Blueberry, blackberry and raspberry consumption has more than doubled in less than a decade, prompting the Australian Pesticides and Veterinary Medicines Authority (APVMA) to propose new regulations for the use of dimethoate.
Executive director of risk assessment capability, Sheila Logan, said current residue levels were unlikely to pose a serious risk to human health but safety margins needed to be reconsidered.
Growers must wait one day after spraying blueberries and seven days after spraying rubus berries (blackberries and raspberries) before they can pick and send the fruit to market.
Dr Logan's authority has proposed that the time between spraying and picking be increased to 14 days.
That has put the watchdog at odds with the $1.3 billion industry.
Growers said the proposal would increase costs.
They said the risks could be managed with a shorter timeframe without disrupting production and pushing up prices.
Meanwhile, food safety experts recommended consumers be aware of the risks, adopt safe handling practices at home and eat a diverse range of fruits.
Margin of safety
Dimethoate has been used in Australia since the 1950s to control more than 80 insect pests in fruit, vegetables and grains.
But it was banned by the European Union in 2019 and has been classified by the United States Environmental Protection Agency as a "possible human carcinogen".
The chemical has also faced increased scrutiny in Australia, most recently when the APVMA banned its use as a post-harvest dip for avocados, mangoes and other tropical fruits.
To use it, growers need a permit from the APVMA, which dictates safe usage based on acceptable residue limits.
The permit details how much of the chemical can be present in food and still be safely consumed.
Dr Logan said berry consumption, excluding strawberries, had risen to 1.3 kilograms per person a year, from 611 grams when the limits were last considered in 2017.
"The key priority for the APVMA is the protection of human health and the environment."
Berries Australia chair Anthony Poiner said extending the restriction period to two weeks would effectively ban the chemical.
"Our tests are telling us that levels of residual dimethoate after 24 hours of being sprayed are low and below the medically acute level."
Dr Poiner, whose PhD is in chemistry, said dimethoate was the most effective option for controlling Queensland fruit fly, a native insect that had cost growers at least $300 million a year in control and trade restrictions.
"This [suspension] would be highly damaging to the berry industry because it is the most efficacious of all the chemical applications," he said.
He said alternatives such as fumigation, irradiation or other chemicals were more costly and less effective, and organic production could not supply the market at scale.
Safe to eat
CSIRO food scientist Rozita Spirovska Vaskoska said all fresh food carried some risk.
She said food produced in an organic system typically involved fewer chemical treatments, but it could carry a higher risk of other contaminants such as bacteria.
Washing produce could reduce, but not eliminate, the risk from both, but she said eating a wide variety of foods and practicing safe food handling at home was best.
"Having variety in our diet and ... following good kitchen storage and cooking practices will maintain our food safety," she said.
Dr Poiner said the industry accepted a need for caution and growers were committed to working with the regulators to find a solution.
"We should have confidence in the food we eat," he said.
He said restrictions would mean higher costs and more on-farm waste for growers in Queensland, New South Wales and Victoria, but Western Australia and Tasmania were largely fruit-fly free and would be less affected.
The APVMA said all other approved uses of dimethoate remained safe and no other chemicals used on berries required action at this stage.
Submissions on the proposed suspension are open until September 2.