Diane Rehm Examines the Dangers of Monsanto's Roundup and Dow's Enlist Duo Herbicides
Yesterday on NPR's The Diane Rehm Show, Diane Rehm and her guests discussed the race against pests and weeds, and the recent approval by the U.S. Environmental Protection Agency (EPA) on Dow AgroSciences' herbicide Enlist Duo, a new combination of 2,4-D and glyphosate meant to fight chemical-resistant "superweeds."
Photo credit: Shutterstock
This new herbicide has many in the environmental and health communities concerned because of the dangerous impacts to human health and the environment. The Natural Resources Defense Council (NRDC) and other groups sued to block the EPA's approval because they don't think the EPA considered all of the environmental and health impacts of the new herbicide. Many have joined the NRDC in calling for a new approach to pest and weed control that doesn't wreak havoc on human health and the environment.
Rehm starts the discussion by talking about the most common herbicide, Monsanto's Roundup, which she says, "is steadily becoming less effective." Erik Olson, director of the health program for the NRDC explains why that is:
What we have is a chemical arms race between the pesticide companies, who are developing ever more powerful pesticides to kill bugs and to kill weeds, and the bugs and weeds that keep evolving and become more resistant to those pesticides. So another new generation of pesticides have to be invented. So we're on this treadmill.
During the process of deploying more and more pesticides to deal with pests and weeds that are resistant, we are killing non-target organisms, according to Olson. These non-target organisms are often beneficial insects—bees in particular—that help keep pest populations in check and pollinate crops.
How do these pests and weeds become resistant? "It's basic evolution," says Olson. A pesticide can wipe out 99.9 percent of pests or weeds but that 0.1 percent that survives is resistant and they produce offspring that are even more resistant, according to Olson.
That's why experts like Andy Dyer, professor of biology at the University of South Carolina, author of Chasing the Red Queen: The Evolutionary Race Between Agricultural Pests and Poisons and a guest on yesterday's show, say gigantic monocultures—one single crop in a field—are a huge problem. We've taken highly diversified ecosystems and reduced them to a single species, providing pests with an all-you-can-eat buffet, according to Dyer.
Dyer says he wrote his book because "the connection between pesticide resistance and the underlying principles of evolutionary biology—while they're understood—have not really been closely linked." Dyer says, we have to realize "each chemical pesticide has a lifespan and it will lose its effectiveness over time."
Les Glasgow of Syngenta said on yesterday's show that because herbicides like Roundup are so effective in the short term, they get overused to the point where they lose their effectiveness. "The future really is about diversity" for weed management, says Glasgow. "If we can introduce more diversity in the tactics that we use for weed control, then we can certainly avoid the resistance." Glasgow says products like Roundup and now Enlist Duo are not intended to be used on their own.
That's not common practice, though. Farmers of commodity crops like soy and corn, which tend to be genetically modified, use herbicides like Roundup "more or less indiscriminately" because "it's their one tool" in pest and weed control, says Dyer.
Aaron Hobbs, president of Responsible Industry for a Sound Environment, says pesticides are merely a part of the solution. He calls for integrated pest management, which is an approach to controlling pests that relies on a combination of best practices. Hobbs agrees with the other guests that we've completely overused Roundup, "dousing fields with it" and as a result we've killed off a lot of the milkweed, a plant that Monarch butterflies feed on. With milkweed wiped out, the Monarch butterfly population has collapsed as well. The increased reliance on chemical pesticides is effecting the entire food web.
Not only are these chemical pesticides destroying human health and the environment, but, according to Olson, it can cost millions of dollars to develop a new pesticide, and yet they can become obsolete within a few years. So we need to work with nature using "these more innovative tools of sustainable agriculture," Olson says.
Allen, a listener who called into the show is a former EPA employee, says 2,4-D should have been phased out years ago. "It was half of agent orange and it's just being brought back and it's a really bad idea." Olson and Dyer agree we're on a backwards trend: we're using dangerous chemicals on fewer and fewer crops with less and less genetic diversity. We need a wide variety of crops with high genetic diversity in order to move away from this chemical dependency. Olson says, "I think we can all agree in this room that taking an integrated approach to solve a pest problem is the way to go."
Listen to the full discussion on The Diane Rhem Show.
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By Peter Giger
The speed and scale of the response to COVID-19 by governments, businesses and individuals seems to provide hope that we can react to the climate change crisis in a similarly decisive manner - but history tells us that humans do not react to slow-moving and distant threats.
A Game of Jenga<p>Think of it as a game of Jenga and the planet's climate system as the tower. For generations, we have been slowly removing blocks. But at some point, we will remove a pivotal block, such as the collapse of one of the major global ocean circulation systems, for example the Atlantic Meridional Overturning Circulation (AMOC), that will cause all or part of the global climate system to fall into a planetary emergency.</p><p>But worse still, it could cause runaway damage: Where the tipping points form a domino-like cascade, where breaching one triggers breaches of others, creating an unstoppable shift to a radically and swiftly changing climate.</p><p>One of the most concerning tipping points is mass methane release. Methane can be found in deep freeze storage within permafrost and at the bottom of the deepest oceans in the form of methane hydrates. But rising sea and air temperatures are beginning to thaw these stores of methane.</p><p>This would release a powerful greenhouse gas into the atmosphere, 30-times more potent than carbon dioxide as a global warming agent. This would drastically increase temperatures and rush us towards the breach of other tipping points.</p><p>This could include the acceleration of ice thaw on all three of the globe's large, land-based ice sheets – Greenland, West Antarctica and the Wilkes Basin in East Antarctica. The potential collapse of the West Antarctic ice sheet is seen as a key tipping point, as its loss could eventually <a href="https://science.sciencemag.org/content/324/5929/901" target="_blank">raise global sea levels by 3.3 meters</a> with important regional variations.</p><p>More than that, we would be on the irreversible path to full land-ice melt, causing sea levels to rise by up to 30 meters, roughly at the rate of two meters per century, or maybe faster. Just look at the raised beaches around the world, at the last high stand of global sea level, at the end of the Pleistocene period around 120,0000 years ago, to see the evidence of such a warm world, which was just 2°C warmer than the present day.</p>
Cutting Off Circulation<p>As well as devastating low-lying and coastal areas around the world, melting polar ice could set off another tipping point: a disablement to the AMOC.</p><p>This circulation system drives a northward flow of warm, salty water on the upper layers of the ocean from the tropics to the northeast Atlantic region, and a southward flow of cold water deep in the ocean.</p><p>The ocean conveyor belt has a major effect on the climate, seasonal cycles and temperature in western and northern Europe. It means the region is warmer than other areas of similar latitude.</p><p>But melting ice from the Greenland ice sheet could threaten the AMOC system. It would dilute the salty sea water in the north Atlantic, making the water lighter and less able or unable to sink. This would slow the engine that drives this ocean circulation.</p><p><a href="https://www.carbonbrief.org/atlantic-conveyor-belt-has-slowed-15-per-cent-since-mid-twentieth-century" target="_blank">Recent research</a> suggests the AMOC has already weakened by around 15% since the middle of the 20th century. If this continues, it could have a major impact on the climate of the northern hemisphere, but particularly Europe. It may even lead to the <a href="https://ore.exeter.ac.uk/repository/handle/10871/39731?show=full" target="_blank" rel="noopener noreferrer">cessation of arable farming</a> in the UK, for instance.</p><p>It may also reduce rainfall over the Amazon basin, impact the monsoon systems in Asia and, by bringing warm waters into the Southern Ocean, further destabilize ice in Antarctica and accelerate global sea level rise.</p>
The Atlantic Meridional Overturning Circulation has a major effect on the climate. Praetorius (2018)
Is it Time to Declare a Climate Emergency?<p>At what stage, and at what rise in global temperatures, will these tipping points be reached? No one is entirely sure. It may take centuries, millennia or it could be imminent.</p><p>But as COVID-19 taught us, we need to prepare for the expected. We were aware of the risk of a pandemic. We also knew that we were not sufficiently prepared. But we didn't act in a meaningful manner. Thankfully, we have been able to fast-track the production of vaccines to combat COVID-19. But there is no vaccine for climate change once we have passed these tipping points.</p><p><a href="https://www.weforum.org/reports/the-global-risks-report-2021" target="_blank">We need to act now on our climate</a>. Act like these tipping points are imminent. And stop thinking of climate change as a slow-moving, long-term threat that enables us to kick the problem down the road and let future generations deal with it. We must take immediate action to reduce global warming and fulfill our commitments to the <a href="https://www.ipcc.ch/sr15/" target="_blank" rel="noopener noreferrer">Paris Agreement</a>, and build resilience with these tipping points in mind.</p><p>We need to plan now to mitigate greenhouse gas emissions, but we also need to plan for the impacts, such as the ability to feed everyone on the planet, develop plans to manage flood risk, as well as manage the social and geopolitical impacts of human migrations that will be a consequence of fight or flight decisions.</p><p>Breaching these tipping points would be cataclysmic and potentially far more devastating than COVID-19. Some may not enjoy hearing these messages, or consider them to be in the realm of science fiction. But if it injects a sense of urgency to make us respond to climate change like we have done to the pandemic, then we must talk more about what has happened before and will happen again.</p><p>Otherwise we will continue playing Jenga with our planet. And ultimately, there will only be one loser – us.</p>
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