pyrethroid
Thirty years after Montreal pact, solving the ozone problem remains elusive.
Did the Montreal Protocol fix the ozone hole? It seemed so. With chlorofluorocarbons (CFCs) and other ozone-eating chemicals banned, many scientists said it was only a matter of time before the ozone layer recharged, and the annual hole over Antarctica healed for good.
ANALYSIS
Thirty Years After Montreal Pact, Solving the Ozone Problem Remains Elusive
Despite a ban on chemicals like chlorofluorocarbons, the ozone hole over Antarctica remains nearly as large as it did when the Montreal Protocol was signed in 1987. Scientists now warn of new threats to the ozone layer, including widespread use of ozone-eating chemicals not covered by the treaty.
BY FRED PEARCE • AUGUST 14, 2017
Did the Montreal Protocol fix the ozone hole? It seemed so. With chlorofluorocarbons (CFCs) and other ozone-eating chemicals banned, many scientists said it was only a matter of time before the ozone layer recharged, and the annual hole over Antarctica healed for good.
But 30 years on, some atmospheric chemists are not so sure. The healing is proving painfully slow. And new discoveries about chemicals not covered by the protocol are raising fears that full recovery could be postponed into the 22nd century – or possibly even prevented altogether.
In mid-September, the United Nations is celebrating the protocol’s 30th anniversary. It will declare that “we are all ozone heroes.” But are we patting ourselves on the back a bit too soon?
The ozone layer is a long-standing natural feature of the stratosphere, the part of the atmosphere that begins about six miles above the earth. The ozone layer filters out dangerous ultraviolet radiation from the sun that can cause skin cancer and damage many life forms. It may have been essential for the development of life on Earth.
So there was alarm in the 1970s when researchers first warned that extremely stable man-made compounds like CFCs, used in refrigerants and aerosols, were floating up into the stratosphere, where they released chlorine and bromine atoms that break down ozone molecules. In the 1980s, Antarctic researchers discovered that these chemical reactions went into overdrive in the super-cold polar stratospheric clouds that formed over the frozen continent. They had begun creating a dramatic “hole” in the ozone layer at the end of each austral winter.
The ensuing panic resulted in the signing of the Montreal Protocol on September 16, 1987. It and its successors have phased out production of a range of man-made chlorine and bromine compounds thought to persist for the several years needed for them to reach the stratosphere. Besides CFCs, they include carbon tetrachloride, hydrochlorofluorocarbons (HCFCs), and methyl bromide, a fumigant once widely used to kill pests.
So far so good. The amount of ozone-depleters in the atmosphere has dropped by more than 10 percent since peaking in the late 1990s. In response, the total ozone in the atmosphere has been largely unchanged since 2000.
Satellite imagery depicting the annual maximum extent of the ozone hole over Antarctica from 1979 to 2013. Credit: NASA GODDARD SPACE FLIGHT CENTER
But in the past five years, evidence has emerged that potential ozone-eating compounds can reach the ozone layer much faster than previously thought. Under some weather conditions, just a few days may be enough. And that means a wide range of much more short-lived compounds threaten the ozone layer – chemicals not covered by the Montreal Protocol.
These compounds are all around us. They are widely used as industrial solvents for tasks like degreasing and dry cleaning. And their releases into the atmosphere are increasing fast.
These new ozone-busters include dichloromethane (DCM), a common and cheap paint stripper, also used in foam-blowing agents and, ironically, in the manufacture of “ozone-friendly” alternatives to CFCs. With emissions now exceeding one million tons a year, the concentration of DCM in the lower atmosphere has more than doubled since 2004. Even so, it has not been regarded as a threat to the ozone layer, because its typical lifetime in the atmosphere before it is broken down in photochemical reactions is only about five months. It should, atmospheric chemists concluded, remain safely in the lower atmosphere.
But that view collapsed in 2015, when Emma Leedham Elvidge at the University of East Anglia in England examined air samples taken on board commercial aircraft cruising at the lower edge of the stratosphere. She found high levels of DCM, especially over the Indian subcontinent and Southeast Asia, and particularly during the Asian monsoon season, when strong updrafts fast-track air from the ground to the stratosphere. It seems they were taking DCM along for the ride.
Alarm bells are ringing about dozens of other short-lived ozone-destroying chlorine compounds accumulating in the atmosphere.
How much should we worry? Ryan Hossaini, an atmospheric chemist at Lancaster University, recently did the math. He calculated that DCM currently contributes less than 10 percent of the chlorine in the ozone layer. But on current emission trends, it could be That could delay the ozone hole’s recovery by 30 years, until at least 2095, he suggested.
Others share that concern. “Growing quantities of DCM are leaking into the stratosphere, where it is exceptionally effective in destroying the ozone,” says David Rowley, an atmospheric chemist at the University College London, who was not involved in the research. “The potential for DCM to affect the global ozone budget is profound.”
Alarm bells are ringing about dozens of other short-lived, potentially ozone-destroying chlorine compounds accumulating in the atmosphere as a result of fast-rising global manufacturing. They include 1,2-dichloroethane, a chemical widely used in the manufacture of PVC pipes. There are few atmospheric measurements of this compound yet, “but sporadic data suggest it is a significant source of chlorine in the atmosphere,” says Hossaini.
The risks of such chemicals reaching the ozone layer are greatest in the tropics, where manufacturing is booming in fast-industrialising countries such as China and India, and where, as luck would have it, atmospheric circulation patterns are favorable. The Asian monsoon can propel the gases to the stratosphere in as little as ten days, according to unpublished research seen by Yale Environment 360.
The movement of ozone-depleting chemicals through the atmosphere, shifting from the tropics and concentrating in Antarctica. NASA GODDARD SPACE FLIGHT CENTER
Thirty years on, the Montreal Protocol has not begun to come to grips with these chemicals, warns Rowley. “The naïve view until recently,” he says, “was that short-lived [chemicals] didn’t present a threat to stratospheric ozone. Wrong.”
Other loopholes in the protocol are concerning researchers as well. In 2014, colleagues of Leedham Elvidge’s at the University of East Anglia warned that three CFCs supposedly banned under the protocol were turning up in increasing amounts in the clean air blowing round the Southern Ocean and captured at Cape Grim in Tasmania. Johannes Laube, an atmospheric chemist at the University of East Anglia, calculated that global emissions of CFC-113a, once an important feedstock in manufacturing both refrigerants and pyrethroid pesticides, doubled in two years.
How come? It turns out that the Montreal Protocol never completely banned CFCs. “CFC-113a is covered by a loophole that allows industries to apply for exemptions,” Laube says. Confidentiality clauses in the treaty about these exemptions mean that “we simply don’t know if we have found exempted emissions, or if they are from some illegal manufacture somewhere. Either way, they are increasing fast, which makes this worrying.” Trade in banned ozone-depleting chemicals has declined in the past decade, but remains a problem, and has been documented particularly for hydrochlorofluorocarbons.
Scientists knew recovery of the ozone layer would take time because of the long lifetimes of many of the dangerous compounds we unleashed in past decades. But last year, Susan Solomon of MIT – who back in the 1980s became one of the world’s most celebrated scientists for uncovering the chemistry of the polar stratospheric clouds — declared that she had detected the first “fingerprints” of the hole closing. “The onset of healing of Antarctic ozone loss has now emerged,” she wrote.
“The signature of ozone recovery is not quite there yet,” says one expert.
But other researchers remain cautious. There have been some recent bumper springtime holes in Antarctic ozone. The 2015 hole was the fourth largest since 1991, peaking at an area larger than the continent of North America. It was also deeper than other recent holes and lasted longer. 2016 was also worse than average and 2017 is expected to be severe, too.
Solomon blamed 2015 on the Calbuco volcano in Chile, which ejected sulphur particles that enhanced the ozone-destroying properties of polar stratospheric clouds. But Susan Strahan of NASA’s Goddard Space Flight Center warns that the size of the hole in any given year is still dominated by year-to-year variations in the temperature of the stratosphere and the vagaries of meteorology. “The signature of ozone recovery is not quite there yet,” she says, adding that day will come, but we may have to wait until the 2030s.
Meanwhile at the other end of the planet, ozone losses over the Arctic may still be worsening. The Arctic is less susceptible to the formation of ozone holes than Antarctica, because the weather is messier. The stable air that causes the ultra-cold conditions where polar stratospheric clouds form in Antarctica is much less likely. But it does happen whenever temperatures get cold enough for polar stratospheric clouds to form.
A deep hole briefly formed over the Arctic in 2011. In places, more than 80 percent of the ozone was destroyed, twice the loss in the worst previous years, 1996 and 2005. In both the past two winters, researchers saw polar stratospheric clouds over parts of Britain, says Jonathan Shanklin of the British Antarctic Survey. But they were brief and did not lead to major ozone loss.
Shanklin says an important reason for the sluggish recovery of the ozone layer is global warming. As increased levels of greenhouse gases such as carbon dioxide trap more solar heat radiating from the Earth’s surface, less warmth reaches the stratosphere, which cools as a result. This trend has been evident for almost 40 years. A colder stratosphere improves conditions for ozone loss. Climate change “could delay the recovery of the ozone hole well into the second half of this century,” he says.
Protecting the ozone layer “presents a much greater industrial and political challenge than previously thought,” says one researcher.
Should we be frightened? Some of the crazier hype in the early days of the ozone hole – like blind sheep in Patagonia and collapsing marine ecosystems – proved nonsense. But the raised risk of skin cancers from the extra ultraviolet radiation streaming through the thinned ozone layer is real enough – particularly for reckless white-skinned sunbathers. The ozone layer is still as thin as it was 30 years ago.
The good news is that without the Montreal Protocol things would have been a great deal worse, says Martyn Chipperfield, an atmospheric chemist at the University of Leeds. The Antarctic hole would be 40 percent bigger than it is; the ozone layer over Europe and North America would be 10 percent thinner; the 2011 Arctic hole would have been Antarctic-sized; and we would be looking at about two million more cases of skin cancers by 2030, according to research conducted by Chipperfield and colleagues.
Even so, the idea that the Montreal Protocol is doing its job and the recovery is under way begins to look complacent. If emissions of uncontrolled ozone-depleting chemicals such as DCM continue rising, then the gains could be lost. The answer is obvious. “We should be looking into controlling DCM and other solvents, much in the same way as we did CFCs,” says Leedham Elvidge.
The World Meteorological Organization and other UN agencies overseeing the protocol acknowledge that DCM and other short-lived ozone depleting substances “are an emerging issue for stratospheric ozone,” but the government signatories have yet to take action to limit their emissions.
That would involve getting rid of a far wider range of chemicals than so far done under the protocol. Protecting the ozone layer “presents a much greater industrial and political challenge than previously thought,” says Rowley. Thirty years on, there is evidently still a lot to do.
Fred Pearce is a freelance author and journalist based in the U.K. He is a contributing writer for Yale Environment 360 and is the author of numerous books, including "The Land Grabbers, Earth Then and Now: Potent Visual Evidence of Our Changing World," and "The Climate Files: The Battle for the Truth About Global Warming." MORE ABOUT FRED PEARCE →
TOPICS
Climate
PUBLIC HEALTH
POLLUTION
ENVIRONMENTAL LAW
REGIONS
Antarctica and the Arctic
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Thirty years after the Montreal Protocol, solving the ozone problem remains elusive.
Scientists warn of new threats to the ozone layer, including widespread use of ozone-eating chemicals not covered by the treaty.
Despite a ban on chemicals like chlorofluorocarbons, the ozone hole over Antarctica remains nearly as large as it did when the Montreal Protocol was signed in 1987. Scientists now warn of new threats to the ozone layer, including widespread use of ozone-eating chemicals not covered by the treaty.
BY FRED PEARCE • AUGUST 14, 2017
Did the Montreal Protocol fix the ozone hole? It seemed so. With chlorofluorocarbons (CFCs) and other ozone-eating chemicals banned, many scientists said it was only a matter of time before the ozone layer recharged, and the annual hole over Antarctica healed for good.
But 30 years on, some atmospheric chemists are not so sure. The healing is proving painfully slow. And new discoveries about chemicals not covered by the protocol are raising fears that full recovery could be postponed into the 22nd century – or possibly even prevented altogether.
In mid-September, the United Nations is celebrating the protocol’s 30th anniversary. It will declare that “we are all ozone heroes.” But are we patting ourselves on the back a bit too soon?
The ozone layer is a long-standing natural feature of the stratosphere, the part of the atmosphere that begins about six miles above the earth. The ozone layer filters out dangerous ultraviolet radiation from the sun that can cause skin cancer and damage many life forms. It may have been essential for the development of life on Earth.
So there was alarm in the 1970s when researchers first warned that extremely stable man-made compounds like CFCs, used in refrigerants and aerosols, were floating up into the stratosphere, where they released chlorine and bromine atoms that break down ozone molecules. In the 1980s, Antarctic researchers discovered that these chemical reactions went into overdrive in the super-cold polar stratospheric clouds that formed over the frozen continent. They had begun creating a dramatic “hole” in the ozone layer at the end of each austral winter.
The ensuing panic resulted in the signing of the Montreal Protocol on September 16, 1987. It and its successors have phased out production of a range of man-made chlorine and bromine compounds thought to persist for the several years needed for them to reach the stratosphere. Besides CFCs, they include carbon tetrachloride, hydrochlorofluorocarbons (HCFCs), and methyl bromide, a fumigant once widely used to kill pests.
So far so good. The amount of ozone-depleters in the atmosphere has dropped by more than 10 percent since peaking in the late 1990s. In response, the total ozone in the atmosphere has been largely unchanged since 2000.
But in the past five years, evidence has emerged that potential ozone-eating compounds can reach the ozone layer much faster than previously thought. Under some weather conditions, just a few days may be enough. And that means a wide range of much more short-lived compounds threaten the ozone layer – chemicals not covered by the Montreal Protocol.
These compounds are all around us. They are widely used as industrial solvents for tasks like degreasing and dry cleaning. And their releases into the atmosphere are increasing fast.
These new ozone-busters include dichloromethane (DCM), a common and cheap paint stripper, also used in foam-blowing agents and, ironically, in the manufacture of “ozone-friendly” alternatives to CFCs. With emissions now exceeding one million tons a year, the concentration of DCM in the lower atmosphere has more than doubled since 2004. Even so, it has not been regarded as a threat to the ozone layer, because its typical lifetime in the atmosphere before it is broken down in photochemical reactions is only about five months. It should, atmospheric chemists concluded, remain safely in the lower atmosphere.
But that view collapsed in 2015, when Emma Leedham Elvidge at the University of East Anglia in England examined air samples taken on board commercial aircraft cruising at the lower edge of the stratosphere. She found high levels of DCM, especially over the Indian subcontinent and Southeast Asia, and particularly during the Asian monsoon season, when strong updrafts fast-track air from the ground to the stratosphere. It seems they were taking DCM along for the ride.
Alarm bells are ringing about dozens of other short-lived ozone-destroying chlorine compounds accumulating in the atmosphere.
How much should we worry? Ryan Hossaini, an atmospheric chemist at Lancaster University, recently did the math. He calculated that DCM currently contributes less than 10 percent of the chlorine in the ozone layer. But on current emission trends, it could be That could delay the ozone hole’s recovery by 30 years, until at least 2095, he suggested.
Others share that concern. “Growing quantities of DCM are leaking into the stratosphere, where it is exceptionally effective in destroying the ozone,” says David Rowley, an atmospheric chemist at the University College London, who was not involved in the research. “The potential for DCM to affect the global ozone budget is profound.”
Alarm bells are ringing about dozens of other short-lived, potentially ozone-destroying chlorine compounds accumulating in the atmosphere as a result of fast-rising global manufacturing. They include 1,2-dichloroethane, a chemical widely used in the manufacture of PVC pipes. There are few atmospheric measurements of this compound yet, “but sporadic data suggest it is a significant source of chlorine in the atmosphere,” says Hossaini.
The risks of such chemicals reaching the ozone layer are greatest in the tropics, where manufacturing is booming in fast-industrialising countries such as China and India, and where, as luck would have it, atmospheric circulation patterns are favorable. The Asian monsoon can propel the gases to the stratosphere in as little as ten days, according to unpublished research seen by Yale Environment 360.
The movement of ozone-depleting chemicals through the atmosphere, shifting from the tropics and concentrating in Antarctica. NASA GODDARD SPACE FLIGHT CENTER
Thirty years on, the Montreal Protocol has not begun to come to grips with these chemicals, warns Rowley. “The naïve view until recently,” he says, “was that short-lived [chemicals] didn’t present a threat to stratospheric ozone. Wrong.”
Other loopholes in the protocol are concerning researchers as well. In 2014, colleagues of Leedham Elvidge’s at the University of East Anglia warned that three CFCs supposedly banned under the protocol were turning up in increasing amounts in the clean air blowing round the Southern Ocean and captured at Cape Grim in Tasmania. Johannes Laube, an atmospheric chemist at the University of East Anglia, calculated that global emissions of CFC-113a, once an important feedstock in manufacturing both refrigerants and pyrethroid pesticides, doubled in two years.
How come? It turns out that the Montreal Protocol never completely banned CFCs. “CFC-113a is covered by a loophole that allows industries to apply for exemptions,” Laube says. Confidentiality clauses in the treaty about these exemptions mean that “we simply don’t know if we have found exempted emissions, or if they are from some illegal manufacture somewhere. Either way, they are increasing fast, which makes this worrying.” Trade in banned ozone-depleting chemicals has declined in the past decade, but remains a problem, and has been documented particularly for hydrochlorofluorocarbons.
Scientists knew recovery of the ozone layer would take time because of the long lifetimes of many of the dangerous compounds we unleashed in past decades. But last year, Susan Solomon of MIT – who back in the 1980s became one of the world’s most celebrated scientists for uncovering the chemistry of the polar stratospheric clouds — declared that she had detected the first “fingerprints” of the hole closing. “The onset of healing of Antarctic ozone loss has now emerged,” she wrote.
“The signature of ozone recovery is not quite there yet,” says one expert.
But other researchers remain cautious. There have been some recent bumper springtime holes in Antarctic ozone. The 2015 hole was the fourth largest since 1991, peaking at an area larger than the continent of North America. It was also deeper than other recent holes and lasted longer. 2016 was also worse than average and 2017 is expected to be severe, too.
Solomon blamed 2015 on the Calbuco volcano in Chile, which ejected sulphur particles that enhanced the ozone-destroying properties of polar stratospheric clouds. But Susan Strahan of NASA’s Goddard Space Flight Center warns that the size of the hole in any given year is still dominated by year-to-year variations in the temperature of the stratosphere and the vagaries of meteorology. “The signature of ozone recovery is not quite there yet,” she says, adding that day will come, but we may have to wait until the 2030s.
Meanwhile at the other end of the planet, ozone losses over the Arctic may still be worsening. The Arctic is less susceptible to the formation of ozone holes than Antarctica, because the weather is messier. The stable air that causes the ultra-cold conditions where polar stratospheric clouds form in Antarctica is much less likely. But it does happen whenever temperatures get cold enough for polar stratospheric clouds to form.
A deep hole briefly formed over the Arctic in 2011. In places, more than 80 percent of the ozone was destroyed, twice the loss in the worst previous years, 1996 and 2005. In both the past two winters, researchers saw polar stratospheric clouds over parts of Britain, says Jonathan Shanklin of the British Antarctic Survey. But they were brief and did not lead to major ozone loss.
Shanklin says an important reason for the sluggish recovery of the ozone layer is global warming. As increased levels of greenhouse gases such as carbon dioxide trap more solar heat radiating from the Earth’s surface, less warmth reaches the stratosphere, which cools as a result. This trend has been evident for almost 40 years. A colder stratosphere improves conditions for ozone loss. Climate change “could delay the recovery of the ozone hole well into the second half of this century,” he says.
Protecting the ozone layer “presents a much greater industrial and political challenge than previously thought,” says one researcher.
Should we be frightened? Some of the crazier hype in the early days of the ozone hole – like blind sheep in Patagonia and collapsing marine ecosystems – proved nonsense. But the raised risk of skin cancers from the extra ultraviolet radiation streaming through the thinned ozone layer is real enough – particularly for reckless white-skinned sunbathers. The ozone layer is still as thin as it was 30 years ago.
The good news is that without the Montreal Protocol things would have been a great deal worse, says Martyn Chipperfield, an atmospheric chemist at the University of Leeds. The Antarctic hole would be 40 percent bigger than it is; the ozone layer over Europe and North America would be 10 percent thinner; the 2011 Arctic hole would have been Antarctic-sized; and we would be looking at about two million more cases of skin cancers by 2030, according to research conducted by Chipperfield and colleagues.
Even so, the idea that the Montreal Protocol is doing its job and the recovery is under way begins to look complacent. If emissions of uncontrolled ozone-depleting chemicals such as DCM continue rising, then the gains could be lost. The answer is obvious. “We should be looking into controlling DCM and other solvents, much in the same way as we did CFCs,” says Leedham Elvidge.
The World Meteorological Organization and other UN agencies overseeing the protocol acknowledge that DCM and other short-lived ozone depleting substances “are an emerging issue for stratospheric ozone,” but the government signatories have yet to take action to limit their emissions.
That would involve getting rid of a far wider range of chemicals than so far done under the protocol. Protecting the ozone layer “presents a much greater industrial and political challenge than previously thought,” says Rowley. Thirty years on, there is evidently still a lot to do.
Keep reading...Show less
Zika didn't drive her from Miami Beach - but questions about the pesticide being used to stop it did.
Some Miami Beach residents are more afraid of naled, an insecticide being used to curb the spread of Zika, than the disease itself.
Zika’s arrival in Miami Beach didn’t drive away Miriam Haskell, who is pregnant with her first child. But her questions about one of the chemicals being used to combat the mosquitoes that are spreading the virus did.
Last week, the 36-year-old public interest lawyer packed up and flew to Atlanta, where she plans to stay with a friend until planes stop spraying the insecticide naled over her neighborhood.
She is not alone in her fears.
Naled has been banned in the European Union since 2012, and the governor of Puerto Rico refused to allow aerial spraying with the insecticide in the fight against Zika this summer.
In Miami-Dade County, the only region on the U.S. mainland with confirmed local transmission of Zika, some believe naled poses greater risks to people and wildlife than the virus itself.
Concerned residents and environmental activists have been holding demonstrations outside the Miami Beach town hall to protest weekly aerial spraying that began this month.
They filled a recent city commission meeting, booing and jeering elected officials who argued that the region is facing a public health emergency and must use every tool available to halt the spread of a virus that can cause severe neurological defects in babies born to women infected during pregnancy.
For Haskell, it’s not a question of which is more dangerous. “I have felt like I can personally take precautions against Zika,” she said.
She stayed indoors in her air-conditioned apartment and used a car to get to her air-conditioned office. When she had to be outside, she put on pants and long-sleeved shirts and applied mosquito repellent.
But she did not know what, if anything, she should do to protect herself from naled.
The Environmental Protection Agency says the insecticide, which has been registered for use in the United States since 1959, does not pose risks to people when it is applied according to label instructions.
“I just don’t have any information on how to gauge that,” Haskell said.
She was also alarmed to read that millions of bees were killed when they were exposed to naled during spraying in South Carolina in August.
“I can only make a decision that is best for me,” Haskell said. “I understand that the county has to make a decision that is best for everyone in it — I hope that they are taking things like the environmental impact into account.”
How dangerous is the insecticide? Here is what we know:
How does naled work?
When naled is sprayed, fine droplets drift through the air and kill adult mosquitoes on contact. It does this by inhibiting an enzyme called acetylcholinesterase, which is critical for controlling nerve signals.
Humans — along with most animals — also have the enzyme targeted by naled.
Is it safe?
“Everything can be toxic,” says Keith Solomon, a professor emeritus at the University of Guelph in Canada who researches the effects of pesticides in the environment. “It’s the dose that makes the poison.”
If exposed to large enough amounts of naled, people can suffer confusion, dizziness or nausea. Severe poisoning can even cause convulsions, respiratory failure and death.
But according to the EPA and the Centers for Disease Control and Prevention, aerial spraying in the United States is done in ultra-low volumes — about an ounce, or two tablespoons, per acre. At those levels, people aren’t likely to breathe in, touch or ingest anything with enough insecticide on it to harm them, Solomon said.
Even before Zika arrived, naled was widely use for mosquito control in Florida. Nearly 6 million acres of land in the state were sprayed with the pesticide in 2014 alone, the CDC says.
Still, the EPA and CDC say it is a good idea to reduce unnecessary exposure to pesticides whenever possible. Those who tend to be sensitive to chemicals might experience short-term effects, such as irritation to the eyes, skin and nose.
The bigger danger, however, is to other insects, including bees that are needed to pollinate crops and flowers. The EPA recommends covering up hives or, if possible, moving them during aerial spraying.
Mosquito-control teams from Miami-Dade County have been spraying at dawn, when most people are at home and bees are less likely to be foraging. Winds also tend to be lower at that time, so there is less chance that the insecticide will spread outside the target area, Solomon said.
Although naled does pose some risk to aquatic invertebrates, such as shrimp and water fleas, and to terrestrial wildlife, studies have found that it dissipates rapidly in sunlight and water and does not persist in the environment.
If the EPA is right, why is naled banned in the EU?
The EU decision cited “a potential and unacceptable risk” to human health and the environment. It also said that officials weren’t persuaded that the chemical is effective enough.
The EPA disagrees with that assessment. It is required by law to consider not only the risks, but also the benefits of allowing an insecticide to be used, something that was not discussed in the EU decision.
Europe does not currently have a problem with mosquitoes spreading the Zika virus.
“I suspect that if Zika were to arrive in Europe and become locally transmitted, that they would probably consider lifting their ban on aerial application,” Solomon said.
Can’t they do something else?
There is no vaccine or treatment for Zika, so the only way to contain an outbreak is to go after the mosquito species that spreads the virus: Aedes aegypti.
It’s a wily adversary. Experts recommend using a combination of strategies, including draining or covering pools of standing water where mosquitoes breed, installing screens on windows and doors, and spraying with insecticides that kill adult mosquitoes and their larva.
In Miami-Dade County, mosquito control agents have used two types of pyrethroid insecticides that are sprayed using equipment carried in backpacks or mounted on trucks. But Dr. Thomas Frieden, the CDC director, told reporters at the beginning of August that those methods weren’t working as well as hoped, and the mosquito species might be resistant to the chemicals.
CDC officials credit the decision to begin aerial spraying of naled, which targets adult mosquitoes, and Bti, a bacterial agent that kills larva, with rapidly reducing the Aedes aegypti population in Miami’s Wynwood district.
No new cases of mosquito-spread Zika have been reported in the area, the first in the county where local transmission was confirmed, since early August.
But in Miami Beach, the area of concern was expanded last week from roughly 1.5 square miles to 4.5 square miles after a cluster of new Zika cases was discovered.
Another round of aerial spraying is planned there Saturday.
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U.S. fights Zika mosquitoes with limited arsenal.
Over Wynwood, the Miami neighborhood where Zika gained a foothold in the continental United States, low flying planes have been spraying naled, a tightly controlled pesticide often used as a last resort.
WORLD NEWS | Fri Sep 2, 2016 8:17am EDT
U.S. fights Zika mosquitoes with limited arsenal
Pesticides a controversial weapon against Zika02:19
By Julie Steenhuysen
Over Wynwood, the Miami neighborhood where Zika gained a foothold in the continental United States, low flying planes have been spraying naled, a tightly controlled pesticide often used as a last resort. It appears to be working, killing at least 90 percent of the target mosquitoes.
Across the Biscayne Bay in Miami Beach, wind and high-rise buildings make aerial spraying challenging. So, the effort in the popular tourist destination has focused on ground-sprayed pyrethroids - pesticides that are safer but don't always work.
The arrival in Florida of Zika, a virus that can cause a crippling birth defect known as microcephaly, has drawn into focus the limitations of the U.S. mosquito control arsenal.
Larvicides reduce future populations relatively safely. But for use against the mature mosquitoes that spread disease, only two classes of pesticides are approved. Each has drawbacks.
Organophosphates, such as naled, are effective. But there are strict controls to limit risk. Pyrethroids are safer but have been used so much that mosquitoes, in many places, are immune.
"That's really the weak link in much of the United States," said Michael Doyle, director of the Florida Keys Mosquito Control District. "We're kind of caught off guard."
DENGUE PREVIEW
Doyle led a 2009 effort against a dengue outbreak in South Florida, the first in the United States in nearly a century. Authorities threw everything they had at the Aedes aegypti, the same mosquito that carries Zika: backpack fogging, door-to-door yard inspections looking for watery breeding sites and larvicide spraying.
Still, 88 people were infected before the virus was brought under control more than two years later, and there continue to be sporadic cases in Florida.
The outbreak highlighted gaps in the mosquito control arsenal that remain, according to pesticide makers, abatement officials and entomologists. Few companies make pesticides for use in public health outbreaks, a niche market that is expensive to get into, has a limited upside and varies season to season.
Safety testing a new pesticide can cost up to $250 million and take 10 years, said Karen Larson, vice president of regulatory affairs at privately held Clarke Mosquito.
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A vector control team vehicle displays a sign warning of West Nile Virus before the early morning spraying of a neighborhood due to increasing numbers of mosquitoes having tested positive for West Nile virus in San Diego, California, U.S. May 18, 2016. REUTERS/Mike Blake/File Photo
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As long as a product remains on the market, companies must continue testing for unforeseen side effects, an expense that some makers have blamed for decisions to abandon products.
"There's not a lot of profit," Larson said.
Sales of the Dibrome brand of naled have been estimated at $12 million a year. By comparison, total crop pesticide sales for some companies can exceed $500 million in a single quarter.
Bayer, Dow Chemical, BASF and other agricultural pesticide makers "are not interested in going after a $20 million or $30 million a year market," said William A. Kuser, investor relations director at Dibrome maker American Vanguard Corp.
The U.S. Environmental Protection Agency has approved several new pesticides in recent years. But it has received few requests for using them against mosquitoes, said Jim Jones, Assistant Administrator for the agency's Office of Chemical Safety and Pollution Prevention.
"Although it's of critical importance, the amount one can sell is small and it's variable, which makes it difficult for business planning," Jones said. "You can go many years without having much of a market at all, then suddenly, whether it's because of a nuisance outbreak of mosquitoes or something like West Nile or Zika, the market grows significantly."
Abatement authorities have pressed for help with the cost of developing mosquito control pesticides. The 1996 U.S. Food Quality Protection Act includes a provision for subsidies to defray the expense of safety testing, but Congress has never funded it.
RISK AND RESISTANCE
At least 49 cases of locally transmitted Zika infections have been reported in Florida, most in Wynwood and Miami Beach. Most people have no symptoms or mild illness.
Because of the microcephaly link, efforts are focused on preventing infection among pregnant women.
In Wynwood, the campaign began with pyrethroids, synthetic versions of a chemical derived from chrysanthemums. Amid signs of resistance, authorities switched to naled.
Developed as nerve agents, organophosphates, at high doses, can cause nausea, convulsions and death. They can be toxic to wildlife, including bees. The EPA considers naled safe at permitted ultra-low concentrations, and it is sprayed annually over 16 million acres in the United States.
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But it is banned in Europe, where the risk is seen as unacceptable. In the U.S. territory of Puerto Rico, where Zika is widespread, the governor prohibited naled amid protests over safety concerns.
Although naled killed more than 90 percent of mosquitoes in traps set in Wynwood, the Aedes aegypti's resilience remains a concern.
"This is truly the cockroach of mosquitoes," said Tom Frieden, director of the U.S. Centers for Disease Control and Prevention.
DROPPING PESTICIDES
CDC entomologist Janet McAllister said pyrethroid resistance typically is limited by the mosquito's small range. When resistance to one pyrethroid develops, another often works.
Still, she said, "we would love to see additional classes of insecticides available because, even in places that may have an effective tool today, that doesn't mean it is going to last down the road."
The EPA can fast-track its evaluation of new pesticides and expand the use of old ones. In response to Zika, it expedited new uses for pesticide-treated bed nets and mosquito traps.
Still, development of pesticides is painstaking. Even if the EPA speeds up its evaluation, required safety data can take years to collect. And the expense of ongoing safety testing has prompted companies to drop products.
Bayer CropScience, for example, told distributors it dropped the pyrethroid resmethrin in 2012, rather than do additional testing. Clarke Mosquito gave up temephos, a larvicide, six years ago, because of costs, Larson said.
That decision led to stockpiling in southwest Florida, said Wayne Gale, director of the Lee County Mosquito Control District.
"We purchased just about every bit," he said.
(Reporting by Julie Steenhuysen; Editing by Michele Gershberg and Lisa Girion)
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Zika surge in Miami neighborhood prompts travel warning.
At least 14 cases of the virus been found in the Wynwood neighborhood in Miami and have been spread by local mosquitoes there.
By PAM BELLUCKAUG. 1, 2016
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The Wynwood arts district of Miami, where cases of Zika have been spread by mosquitoes. Credit Max Reed for The New York Times
Federal health officials on Monday urged pregnant women to stay away from a Miami neighborhood where they have discovered additional cases of Zika infection — apparently the first time the Centers for Disease Control and Prevention has advised people not to travel to a place in the continental United States.
Florida officials said the number of Zika cases caused by local mosquitoes had risen to 14 from the four announced on Friday: 12 men and two women. They declined to say whether either woman was pregnant. All of the cases have been in one neighborhood.
Health officials said they still did not expect the number of local cases to grow into anything comparable to the epidemic that has raged across Latin America in recent months.
The 10 newly identified patients were most likely infected weeks ago, as early as mid-June, the officials said.
But the new information casts doubt over the effectiveness of weeks of intensive mosquito-control efforts in South Florida and raises questions about tourism in the state, which drew more than 100 million visitors last year.
Dr. Thomas R. Frieden, the director of the C.D.C., said that the Aedes aegypti mosquito, which transmits the Zika virus, has proved to be a wily adversary in Wynwood, a crowded, urban neighborhood in north Miami where all the cases were found. The mosquito may be resistant to the insecticides being used or may be able to hide in standing water.
“Aggressive mosquito control measures don’t seem to be working as well as we would like,” he said in a press briefing on Monday.
The authorities had expected additional cases of Zika infection linked to the neighborhood, he said. But officials were particularly concerned by indications over the weekend that “moderately high” numbers of Aedes aegypti mosquitoes and their larvae were still being found in a one-square-mile section in Wynwood, an area of warehouses, art galleries, restaurants, bars, apartments and condominiums.
“We advise pregnant women to avoid travel to this area,” Dr. Frieden said, “and pregnant women who live and work in this area and their partners to make every effort to avoid mosquito bites and practice safe sex.”
Short Answers to Hard Questions About Zika Virus
Why scientists are worried about the growing epidemic and its effects on pregnant women, and how to avoid the infection.
Pregnant women who traveled to the neighborhood on or after June 15 should talk with their doctors about getting tested for possible infection, he said.
In addition, said Dr. Denise J. Jamieson, a leader of the C.D.C.’s pregnancy and birth defects team, “we are recommending women who are considering pregnancy not get pregnant for up to eight weeks after returning from that area.”
No mosquito found in the neighborhood has tested positive for the virus, but this species has a short life span. Health officials said the Florida mosquitoes carrying the virus had probably acquired it by biting an infected traveler from Latin America or the Caribbean.
At the request of the state, the C.D.C. has dispatched an emergency response team of eight experts in fields including birth defects and mosquito control.
Dr. Frieden said mosquitoes in the neighborhood would be tested for resistance to the insecticides being used, which he said were two different types of pyrethroids.
In a sign that the Zika cases might affect tourism in Florida, Britain’s health agency, saying the risk was moderate, advised pregnant women on Saturday to “consider postponing nonessential travel to affected areas until after the pregnancy.”
Jack Ezon, the president of Ovation Vacations in New York, said that his agency received 22 reservation cancellations on Monday for trips to Florida over the next six months, and that about four times as many people called for information about the travel advisory.
“Yesterday, the news was terrorism. Today, the news is Zika,” he said.
The airline JetBlue said in a statement that it would allow refunds for people with “concerns of traveling to Zika-impacted areas confirmed by the C.D.C.”
But Ross Feinstein, a spokesman for American Airlines, which has a hub in Miami, said no refunds would be issued, even for pregnant women. “The C.D.C. advisory doesn’t tell people they shouldn’t travel to Miami,” he said.
Abraham Pizam, the dean of the Rosen College of Hospitality Management, said that if the travel advisory had any effect on tourism, it would be only “for a very short period of time” and would not put a big dent in the diverse range of tourists who visit Florida.
Zika Cases in the United States
Mapping where Zika infections have been reported.
Gov. Rick Scott said in a statement that the Florida health authorities had tested people in three locations in Miami-Dade and Broward Counties and ruled out transmission by local mosquitoes in two of those locations. Six of the 10 newly identified cases were asymptomatic and discovered through the door-to-door testing.
Dr. Frieden said 12 of the 14 cases were linked to a 150-meter area around two workplaces where the initial two cases were identified in July.
Since July 7, when Florida began investigating what turned out to be the first diagnosed local transmission, more than 200 people in Miami-Dade and Broward Counties who live or work near the Wynwood neighborhood have been tested, Mr. Scott said.
Mosquito experts said Aedes aegypti thrives in tiny pockets of water — a bottle cap, a storm drain — making for a notoriously elusive foe.
“Very little historically has worked on Aedes aegypti, owing to its stealthy and domestic behavior,” said Phil Lounibos, a professor of entomology at the University of Florida.
Aerial spraying is largely ineffective in an urban setting like Wynwood. Instead, mosquito control employees have conducted 621 property inspections there, treated 21 properties for mosquito breeding and used portable sprayers against adult mosquitoes on 100 properties, said Gayle Love, the spokeswoman for the Miami-Dade County Department of Solid Waste.
Spray trucks were also sent to the neighborhood, but were legally allowed to spray only at night, while Aedes aegypti mosquitoes tend to bite during the day, said Michael S. Doyle, the executive director of the Florida Keys Mosquito Control District.
“Most of the chemicals that are available for mosquito control are not effective against Aedes aegypti — they are resistant,” he said.
On Monday, in Wynwood, there was little obvious concern.
“I haven’t seen any panic,” said Virgil Cantú, 22, a bartender at the Bar Next Door.
Melanie Hernandez, 20, who was working Monday at the Marine Layer clothing store in Wynwood, said she was worried, even though she did not plan to get pregnant anytime soon. “I looked up the symptoms online after I heard that Wynwood is ground zero for Zika,” she said.
“Obviously you’re scared, because you never know.”
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Is organic agriculture really better for the environment?
The answer isn’t always so clear-cut.
The whole point of organic agriculture is soil. Farm in such a way that your soil stays healthy — rich in organic matter, nutrients and microbial activity — and you can grow crops without the synthetic fertilizers and pesticides used in conventional farming.
Organic farmers employ lots of techniques to improve their soil. They use compost and manure, rotate their crops and grow many kinds of plants. They do use pesticides, but only certain ones (mostly non-synthetic, with a few approved synthetics), and often only when other pest-control methods fail.
But plenty of conventional farmers do a lot of those things, too. When you pony up the extra money to buy organic produce, are you supporting environmental benefits? I wanted to know, and it was probably one of the most difficult questions I’ve tried to answer in this column.
We don’t have data about soil health or environmental pollution (in the form of soil erosion, nutrient runoff or greenhouse gases) that allows us to comprehensively assess all organic and conventional acreage and say whether one type or the other is doing better, but scientists all over the country are working on comparisons, so we do have something to go on.
Go on that, and you find that, yes, organic agriculture — which for purposes of this discussion means farming certified as adhering to rigorous standards defined by the U.S. Department of Agriculture — has some important environmental benefits.
One of the scientists working on the comparison is Michel Cavigelli of the USDA. He runs something I’d call an organic-vs.-conventional smackdown if we weren’t talking about the rarefied world of soil science. It’s a long-running smackdown (okay, let’s go with it), having begun in 1993. The USDA’s farm in Beltsville, Md., tests five kinds of agriculture: two conventional and three organic. (The differences involve crop rotations and types of tillage.)
Laborers pick chard at an organic farm in California. Organics are better for farmworkers because they don’t become exposed to the high levels of pesticides often used in conventional farming operations. (Sam Hodgson/Bloomberg)
Which one wins?
Yeah, right. There’s never a clear-cut answer to a question like that when you’re talking about something as complicated as farming. The first thing Cavigelli told me is that “all conventional is not the same, and all organic is not the same,” and then he went on to mention something about devils and details.
Nevertheless, some important differences among those five systems have bubbled to the surface over the past 23 years.
The organic systems in the USDA test:
●Have more-fertile soil.
●Use less fertilizer and much less herbicide.
●Use less energy.
●Lock away more carbon in the soil.
●Are more profitable for farmers.
The conventional systems:
●Have higher yields.
●Are best at reducing erosion (when a no-till system is used).
After speaking with several scientists who study the differences between the two systems, and after reading countless papers on the subject, I think it’s reasonable to conclude that, although results obviously vary, that list is a reasonable representation of the advantages of each system. (If you find other significant, across-the-board claims for organic farming, check the source. Many organic organizations do make such claims. It’s perfectly reasonable for advocacy groups to focus on the research that presents organic in the best light, just as conventional groups focus on the benefits of efficiency and genetic crop modification, but, for this, I’ve tried to focus on sources that don’t have skin in the game.)
I learned a few interesting things along the way. First, although I’ve heard many claims that no-till farming (growing crops without plowing up the soil) can lock carbon in the soil (keeping it out of the environment, where it contributes to climate change), several sources told me that it appears that the sequestered carbon is found in only the top layer of soil. Dig deeper, and you don’t find any. Cavigelli’s organic systems, by contrast, had sequestered carbon at much deeper levels.
But in considering claims about carbon sequestration in organic systems, we need to look at the whole picture. Phil Robertson, a university distinguished professor at Michigan State, points out that a lot of that carbon is added to the soil in the form of manure. Which means that, although there’s more carbon in that particular soil, there’s less wherever you took the manure from. “It’s robbing Peter to pay Paul,” he says.
Robertson also said some tools that mitigate environmental harm aren’t available to organic farmers; one of them is genetically modified crops. Although reasonable people disagree about how the advantages and disadvantages of those crops balance out, Robertson, along with many scientists and farmers, says that both major types of GMOs — the kind that are resistant to the herbicide glyphosate and the kind that have a built-in organic insecticide — can help cut pesticide use.
Also, it’s difficult for organic farmers to implement no-till. Without herbicides, the best weed-killing tool is tilling, and that can lead to erosion, nutrient runoff and the disruption of the microbial community that organic farmers work so hard to foster.
All in all, though, it’s pretty clear that organic systems generally have healthier soil and some environmental advantages over conventional systems.
In 2005, Safeway launched a line of “lifestyle” stores offering more organic and natural foods. In general, food shoppers pay more for organic goods, so organic farmers reap higher profits on what they sell. (Justin Sullivan/Getty Images)
But there’s a problem. The environmental advantages generally are not why consumers are willing to pay extra for organic products. According to the Organic Trade Association (and other groups ), consumers buy organics primarily because they believe the products are better for their health: either more nutritious or safer. So it’s not surprising that organic food purveyors and advocates often promote a product by implying it’s more nutritious or safer, a claim not supported by most of the evidence.
Organic advocacy groups market safety and nutrition, as with the Organic Center’s “Comprehensive guide for identifying safe and nutritious food,” or the Environmental Working Group’s Healthy Child initiative, touting “more scientific evidence that organic food is more nutritious.” Labels for some organic products use the word “toxic” to describe the pesticides they’re not using, despite the fact that some toxic pesticides (pyrethrin, for example) are allowed in organic agriculture. Although organic farming certainly does use fewer pesticides, and that’s an environmental benefit, the preponderance of the evidence indicates that trace amounts of pesticides in food are not dangerous to human health. (Higher levels of exposure, such as those experienced by farmworkers, are a different story.)
Unfortunately, you can’t believe organic food is more nutritious and safe without believing conventional food is less nutritious and safe, and that infuriates advocates of conventional food. Sometimes that fury takes on a distasteful edge — I’ve noticed some schadenfreude at food-borne illness outbreaks pegged to organic foods — but I understand where it’s coming from. Conventional food is as safe and nutritious as its organic counterparts, and if consumers are told otherwise, they’re being deceived, and conventional producers are being harmed.
And misinformation does nothing to improve the quality of the public debate. On farms, in academic institutions and in regulatory agencies, I’ve found that nearly everyone thinks there is value in having farmers employ and improve all kinds of practices. Feeding our growing population is a big job, and there are many constructive ways — organic and conventional, large-scale and small, urban and rural — in which farmers are tackling it. We need all of them.
According to the Organic Trade Association, grocery shoppers don’t buy organic foods because they’re better for the environment; they buy them because they think the products are safer or more nutritious. (Justin Sullivan/Getty Images)
Sometimes it seems as if every column I write has the same conclusion, but it’s an important one. If we’re going to make progress on food, we need a whole lot less of us vs. them. The USDA’s certified-organic program — from its inception a marketing program, not an environmental initiative — has given organic farmers a way to make a living (and farmers do have to make a living) by connecting with like-minded consumers willing to pay a premium for a product that is grown in a way that is often labor-intensive and lower-yielding, and produces some bona fide environmental benefits.
It has also given consumers a choice. For those with concerns about the way most food is grown in this country, organic is a way to vote no. But if organic’s undeniable positives are overshadowed by the negative of organic-vs.-conventional polarization that prevents progress, we all lose.
food@washpost.com
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