‘One sip can kill’: why a highly toxic herbicide should be banned in Australia

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Nedeljka Rosic, Southern Cross University; Joanne Bradbury, Southern Cross University, and Sandra Grace, Southern Cross UniversityThere’s a weedkiller used in Australia that’s so toxic, one sip could kill you. It’s called paraquat and debate is brewing over whether it should be banned.

Paraquat is already outlawed in many places around the world. The Australian Pesticides and Veterinary Medicines Authority has been reviewing paraquat’s use here for more than two decades, and its final decision is due later this year.

We are medical and environmental scientists, and have researched the harmful effects of paraquat, even when it’s used within the recommended safety range. We strongly believe the highly toxic chemical should be banned in Australia.

The potentially lethal effects on humans are well known. In Australia in 2012, for example, a farmer died after a herbicide containing paraquat accidentally sprayed into his mouth. And our research has found paraquat also causes serious environmental damage.

Paraquat is used to spray crops, but can harm humans and wildlife.
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Paraquat: the story so far

Paraquat is the active ingredient in Gramoxone, among other products. It has been used since the 1950s, mostly to control grass and weeds around crops such as rice, cotton and soybeans.

Paraquat is registered as a schedule 7 poison on the national registration scheme, meaning its use is strictly regulated.

Suppliers of paraquat say it should not be banned, insisting herbicides containing it are safe for people and the environment when used for their intended purpose and according to label instructions.

Farmers have also argued against a ban, saying it would force them to use more expensive, less effective alternatives and reduce crop yield.

Paraquat has been banned in more than 50 countries, including the United Kingdom, China, Thailand and European Union nations. However, it’s still widely used by farmers in the developing world, and in Australia and the United States.

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Ban on toxic mercury looms in sugar cane farming, but Australia still has a way to go

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Paraquat is now banned in Thailand, among other nations.
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A chemical peril

Paraquat is a non-selective herbicide, which means it kills plants indiscriminately. It does so by inhibiting photosynthesis, the process by which plants convert sunlight into chemical energy.

Paraquat stays in the environment for a long time. It’s well known for causing collateral damage to plants and animals. For example, even at very low concentrations, paraquat has been found to harm the growth of honey bee eggs.

Exposure to living organisms can occur by spray drift or when paraquat is sprayed on crops then reaches surface and underground sources of drinking water.

Paraquat can have unintended consequences for biological organisms and the environment, particular in waterways. Our recent paper summarised the evidence of the harmful effects of paraquat at realistic field concentrations.

We found evidence that paraquat can severely inhibit healthy bacterial growth in aquatic environments, which in turn affects nutrient cycling and the decomposition of organic matter.

The research also shows paraquat can distort tropical freshwater plankton communities by negatively impacting metabolic diversity and reducing phytoplankton growth.

In fish, paraquat has been found to lead to a death rate of common carp three times higher than the weed it is used to control.

Research shows paraquat kills common carp at a higher rate than the weed it’s meant to control.
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‘One sip can kill’

In addition to the environmental effects, of course, paraquat is highly toxic to humans. A small accidental sip can be fatal and there is no antidote.

The US Centers for Disease Control and Prevention says paraquat is a leading cause of fatal poisoning in parts of Asia, the Pacific Islands, and South and Central Americas.

Paraquat enters the body through the skin, digestive system or lungs. If ingested in sufficient amounts, it causes lung damage, leading to pulmonary fibrosis and death through respiratory failure. The liver and kidney can also fail.

Several recent incidents in Australia demonstrate the risks of paraquat poisoning due to human error, even within the current strict regulations.

According to news reports, the Queensland farmer poisoned by paraquat in 2012 was filling a pressure pump to control weeds on his property. The unit cracked and paraquat sprayed over his body and face, entering his mouth.

In 2017, an adult with autism took a sip from a Coke bottle used to store paraquat. The bottle had been left in a disabled toilet at a sports ground in New South Wales. The man was initially given 12 hours to live, but fortunately recovered after two weeks in hospital.

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A Queensland farmer died in 2012 after paraquat accidentally sprayed in his face when he filled a pressure pump.
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Paraquat: not worth the risk

There’s a growing awareness of the threats posed by global chemical use. In fact, a paper released this week suggests the potential risk to humanity is on a scale equivalent to climate change.

Paraquat is no doubt an effective herbicide. However, in our view, the risks it poses to humans and the environment outweigh the agricultural benefits.

Current regulation in Australia has not prevented harm from paraquat. It’s time for Australia to join the movement towards a global ban on this toxic chemical.

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Editor’s note: the article has been updated to reflect the fact products other than Gramoxone also contain paraquat.

Nedeljka Rosic, Senior Lecturer, Southern Cross University; Joanne Bradbury, Senior Lecturer, Evidence Based Healthcare, Faculty of Health, Southern Cross University, and Sandra Grace, Professor, Southern Cross University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Ban on toxic mercury looms in sugar cane farming, but Australia still has a way to go

Phil / CC BY (https://creativecommons.org/licenses/by/2.0)

Larissa Schneider, Australian National University; Cameron Holley, UNSW; Darren Sinclair, University of Canberra, and Simon Haberle, Australian National University

This month, federal authorities finally announced an upcoming ban on mercury-containing pesticide in Australia. We are one of the last countries in the world to do so, despite overwhelming evidence over more than 60 years that mercury use as fungicide in agriculture is dangerous.

Mercury is a toxic element that damages human health and the environment, even in low concentrations. In humans, mercury exposure is associated with problems such as kidney damage, neurological impairment and delayed cognitive development in children.

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Australia emits mercury at double the global average

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The ban will prevent about 5,280 kilograms of mercury entering the Australian environment each year.

But Australia is yet to ratify an international treaty to reduce mercury emissions from other sources, such as the dental industry and coal-fired power stations. This is our next challenge.

Prime Minister Scott Morrison visiting a sugar cane farm in 2019. Mercury-containing pesticides will be banned.
Cameron Laird/AAP

A mercury disaster

Mercury became a popular pesticide ingredient for agriculture in the early 1900s, and a number of poisoning events ensued throughout the world.

They include the Iraq grain disaster in 1971-72, when grain seed treated with mercury was imported from Mexico and the United States. The seed was not meant for human consumption, but rural communities used it to make bread, and 459 people died.

In the decades since, most countries have banned the production and/or use of mercury-based pesticides on crops. In 1995 Australia discontinued their use in most applications, such as turf farming.

Emissions of the element mercury are a threat to human health and the environment.
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Despite this, authorities exempted a fungicide containing mercury known as Shirtan. They restricted its use to sugar cane farming in Queensland, New South Wales, Western Australia and the Northern Territory.

According to the sugar cane industry, about 80% of growers use Shirtan to treat pineapple sett rot disease.

But this month, the Australian Pesticides and Veterinary Medicines Authority cancelled the approval of the mercury-containing active ingredient in Shirtan, methoxyethylmercuric chloride. The decision was made at the request of the ingredient’s manufacturer, Alpha Chemicals.

Shirtan’s registration was cancelled last week. It will no longer be produced in Australia, but existing supplies can be sold to, and used by, sugar cane farmers for the next year until it is fully banned.

Workers and nature at risk

Over the past 25 years, Australia’s continued use of Shirtan allowed about 50,000 kilograms of mercury into the environment. The effect on river and reef ecosystems is largely unknown.

What is known is that mercury can be toxic even at very low concentrations, and research is needed to understand its ecological impacts.

The use of mercury-based pesticide has also created a high risk of exposure for sugar cane workers. At most risk are those not familiar with safety procedures for handling toxic materials, and who may have been poorly supervised. This risk has been exacerbated by the use itinerant workers, particularly those from a non-English speaking background.

South Sea Islanders hoeing a cane field in Queensland, 1902. Cane workers have long been exposed to mercury.
State Library of Queensland

Further, in the hot and humid conditions of Northern Australia, it has been reported that workers may have removed protective gloves to avoid sweating. Again, research is needed to determine the implication of these practices for human health.

To this end, Mercury Australia, a multi-disciplinary network of researchers, has formed to address the environmental, health and other issues surrounding mercury use, both contemporary and historical.

Australia is yet to ratify

The Minamata Convention on Mercury is a global treaty to control mercury use and release into the environment. Australia signed onto the convention in 2013 but is yet to ratify it.

Until the treaty is ratified, Australia is not legally bound to its obligations. It also places us at odds with more than 100 countries that have ratified it, including many of Australia’s developed-nation counterparts.

Australia’s outlier status in this area is shown in the below table:

Accession, acceptance or ratification have the same legal effect, where parties follow legal obligations under international law.

Mercury-based pesticide use was one of Australia’s largest sources of mercury emissions. But if Australia ratifies the convention, it would be required to control other sources of mercury emissions, such as dental amalgam and the burning of coal in power stations.

The three active power stations in the Latrobe Valley, for example, together emit about 1,200 kilograms of mercury each year.

The coal-burning Mount Piper Power station near Lithgow in NSW. Government efforts to reduce mercury emissions should focus on coal plants.
David Gray/Reuters

Time to look at coal

If Australia ratified the Minamata Convention, it would provide impetus for a timely review and, if necessary, update of mercury regulations across Australia.

Emissions from coal-fired power stations in Australia are regulated by the states through pollution control licences. Some states would likely have to amend these licences if Australia ratified the convention. For example, Victorian licences for coal-fired power stations currently do not include limits on mercury emissions.

Pollution control technologies were introduced at Australian coal plants in the early 1990s. But they do not match state-of-the-art technologies applied to coal plants in North America and Europe.

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Read more:
Why won’t Australia ratify an international deal to cut mercury pollution?

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Australian environment authorities have been examining the implications of ratifying the convention. But progress is slow.

The issue of mercury emissions does not attract significant public or political attention. But there is a global scientific consensus that coordinated international action is needed.

The pesticide phase-out and ban is an important step. But Australia still has a way to go.

Larissa Schneider, DECRA fellow, Australian National University; Cameron Holley, Professor, UNSW; Darren Sinclair, Professor, University of Canberra, and Simon Haberle, Professor, Australian National University

This article is republished from The Conversation under a Creative Commons license. Read the original article.

Are toxic algal blooms the new normal for Australia’s major rivers?

Darren Baldwin, La Trobe University

For much of this year, up to 1,700 kilometres of the Murray River has been hit by a serious outbreak of potentially toxic blue-green algae, which has flourished in the hotter-than-average conditions. After three months, the river is now recovering with the arrival of wet weather. But we are unlikely to have seen the last of these poisonous microbes.

Large blue-green algal blooms are a relatively new phenomenon in inland waterways. In 1991 an algal bloom affected more than 1,000 km of the Darling River, the first time such an event had been reported in an Australian river, and one of the few times internationally. It was an environmental disaster, killing livestock and striking a telling blow against Australia’s reputation as a clean, green farming nation.

The response was decisive: a state of emergency was declared, and the bloom ultimately gave rise to significant investment by state and federal governments into freshwater research, particularly in the Murray-Darling Basin.

Why no emergency now?

Fast forward two and a half decades to the latest bloom afflicting the Murray River, one of Australia’s most socially, economically and culturally significant waterways. The past decade has seen four similar blooms on the Murray River: in 2007, 2009, 2010 and now. Yes, they have garnered press attention, but there has not been the same call to arms that we saw when the Darling River was struck in 1991.

It is almost as if such significant environmental events are now simply seen as the new normal. Why the apparent complacency?

The 2007, 2009 and 2010 algal blooms on the Murray River all happened during the Millennium Drought, and hence were probably ascribed to an aberration in the weather. In reality, the situation may have more to do with how we manage water in Australia – particularly during periods of scarcity, such as the one we may well be entering now.

Those three earlier events all started in Lake Hume, a large reservoir in the Murray River’s upper reaches, originally created in the 1930s to help “drought-proof” Australia. All of the blooms began after the water level was drawn down to below 10% of the lake’s capacity. At these low levels, disturbances (such as when transferring water between the Snowy River and Murray River systems) can easily lead to the mixing of warm surface waters (ideal for bloom formation) with nutrient-rich water at the bottom of the reservoir (ideal for feeding the bloom).

The resulting blooms were then released downstream into the Murray River by managed water releases from Lake Hume. The blooms most likely reformed in other constructed water bodies downstream – most notably Lake Mulwala, a shallow reservoir about 250 km along the river from Lake Hume.

Lake Mulwala’s principal purpose is to create hydraulic pressure to allow irrigation water to be diverted into farmland in southern New South Wales and northern Victoria. As a result, its shallow depth and mostly still waters make it an ideal incubator for blue-green algae.

The climate factor

This year’s algal bloom on the Murray River is different. The main blue-green alga in the current outbreak, Chrysosporium ovalisporum, has previously been reported in the river, but generally in very low numbers. It has never before formed a bloom in the Murray River since monitoring began in 1978. But crucially, this species flourishes in very warm temperatures; overseas blooms of this species have occurred when water temperatures reach 26℃.

The other difference between the current and earlier blooms is that, when this year’s event started, Lake Hume was much fuller, at about 30% capacity. So reservoir operation probably had less to do with the bloom’s formation than other factors, such as the climate. Both the maximum and minimum temperatures were consistently above the long-term average during the past few months, as was the amount of sunlight reaching the surface of Lake Hume.

The algae-stricken river at Barmah in northern Victoria.
Darren Baldwin, Author provided

We still do not know exactly what triggered this year’s bloom, but if it was indeed a result of unusually warm temperatures, it is very likely that we will see more blooms of this type in the future.

Are we really ready for recurrent blue-green algal blooms on the Murray River? These blooms come at a significant economic cost: drinking water has had to be specially treated to remove potential toxins, and the bloom has impacted on regional tourism, coinciding with the Labour Day and Easter long weekends. It also hit farmers, who had to get drinking water for their livestock from elsewhere.

More importantly, what do these frequent blooms say about how we manage water in this country – especially as we start to see the impacts of climate change on our environment? Dwindling water could mean more than just drought – it could also fill much of the water that remains with poisonous microbes.

Darren Baldwin, Environmental Scientist, La Trobe University

This article was originally published on The Conversation. Read the original article.

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