New generation: Growing up reading Rachel Carson, scientists unravel risks of new pesticides
Part 13 of Winged Warnings
By Alanna Mitchell
Environmental Health News
September 25, 2014
SASKATOON, Saskatchewan – Christy Morrissey is driving her white pickup truck along the endless prairie highway, windows open, listening for birds. She points to the scatter of ponds glinting in the landscape, nestled among fields of canola that stretch as far as the eye can see.
Formed by retreating glaciers 12,000 years ago and fed each spring by melted snow, these tiny potholes are the lifeblood of the prairies, the kidneys that drain impurities and the cradle that replenishes life.
But when Morrissey looks at these ponds, she sees something few others do. An ecotoxicologist at the University of Saskatchewan, she knows that nearly every pond is laced with neonicotinoids, the world’s most widely used insecticides, deadly to insects at a minute dose of a few parts per trillion.
Like biologist Rachel Carson, whose 1962 book Silent Spring warned about the devastating effects of DDT, Morrissey is mounting a scientific quest to figure out if these new pesticides are harming living things they’re not intended to kill, including birds. She is part of a new generation of scientists in North America and Europe investigating a new generation of chemicals. Growing up reading Carson’s work, these researchers are using more sophisticated diagnostic tools to continue the work Carson started more than a half-century ago.
“Both Christy and Rachel started in the same place, with a profound appreciation for wildlife and natural systems,” said Cynthia Palmer, director of pesticide science and regulation for the American Bird Conservancy, an advocacy group in Washington, D.C. “Both came to realize that the chemical cocktails of their day threatened to derail conservation efforts for the wild organisms they studied and cared about.”
Unlike DDT, neonicotinoids don’t appear to accumulate in the tissues of warm-blooded creatures but they may have other subtle, widespread effects that Morrissey and other researchers are only now beginning to pinpoint. Several studies have found that the chemicals are killing so many ecologically important insects that they are having widespread effects on whole ecosystems, particularly bees. In addition, evidence is mounting about effects on birds: In the Netherlands, birds are declining in proportion with neonicotinoid levels in waters. In the Canadian prairies, Morrissey’s early results suggest that birds and chicks are unhealthier near the treated fields. An experiment in Spain found that when captive partridges consumed neonic-coated seeds, they had fewer chicks and suppressed immunity. And one analysis concluded that birds might be poisoned if they eat just one or two seeds.
Born two years after the 1972 DDT ban, Morrissey said its legacy and lessons – which she still teaches to her students – underpin how her generation of chemical sleuths investigates these new compounds. Ecotoxicologists today, she said, are at the forefront of informing a public that has become complacent about the dangers of chemicals.
“In this field we all have to have some bulldog in us, some tenacity,” said Karen Kidd, an ecotoxicologist and Canada research chair in chemical contaminants of food webs at the University of New Brunswick. Morrissey, she said, is tackling some of the toughest emerging questions. “We’re driven to find out what’s going on.”
But Morrissey, like most scientists, is not a campaigner; she’s a cautious investigator. The key ingredients of her work are striving for impeccable methodology, refusing to draw conclusions ahead of the facts and continuing to press for answers to new questions. Pierre Mineau, an expert on pesticides and their effects on birds who served with Morrissey on a global task force on systemic pesticides, said she frequently pushed the members of that group to be more moderate in their conclusions. But on the other hand, he said, once the science is clear, she refuses to pull her punches.
A basic question haunts Morrissey. Bug-eating birds are in decline and if that’s from unintended consequences of pesticides used worldwide – as it was for DDT in the 1960s – she wants to know so she can advise regulators. Because of this, Palmer calls her “the most important researcher out there” when it comes to neonicotinoids and birds.
It helps that new tools allow today’s scientists to find concentrations in the parts per trillion, unimaginably low to researchers even a few decades ago, but, as it turns out, significant to some creatures. Even though concentrations are often low, the sheer number of manmade chemicals in the environment today is much greater and the span far wider than during Carson’s days.
“Sometimes I feel like it’s a Hydra: You cut off one head and several more spring up,” says Cynthia de Wit, a professor of environmental science at Sweden’s Stockholm University who studies wildlife and human exposures to chemicals. “It becomes almost a frantic feeling. You’re just looking at one and they’ve developed 10 more. You just can’t keep up with the pace.”
Intense and increasing scrutiny
Four years ago, when Morrissey was 36 years old, fresh out of a post-doc in Wales and newly arrived on the prairies, she didn’t even know what neonicotinoids were, much less that they were contaminating prairie waters. In fact, she’d never heard of them until she called Mineau, who then was working with Environment Canada. She asked his advice about what to study.
He said: “Neonicotinoids!” She paused for a beat. And then she said: “You’re going to have to spell that for me.”
Today, these pesticides, cherished by farmers for the past 20 years for their effectiveness in killing crop pests, are under intense and increasing scrutiny around the world. They are used to coat most canola and corn seeds and many soy seeds in North America, as well as treat some fruit and vegetable crops and garden plants. The best-selling neonicotinoid compound, imidacloprid, is registered for use on more than 140 crops in 120 countries and is used in more than 400 products sold in the United States, according to the National Pesticide Information Center. Now accounting for one-third of all insecticides used globally, the neonicotinoid market was worth $2.63 billion in 2009 and is on the rise.
Last year, the European Commission banned neonics on some crops for two years due to concerns that they are poisoning bees. The U.S. Environmental Protection Agency, which says its scientific conclusions about acute effects on bees are “similar” to those that led to Europe’s ban, plans to complete its review of neonicotinoids in 2016 or 2017. Canada’s most populous province, Ontario, is considering reducing or eliminating them; honey producers there filed a $360-million class action lawsuit against the two main manufacturers.
Morrissey says the effect on bees is only one piece of a more complex picture. Even more important to her is the pesticides’ presence in water, and what might be happening to the creatures that depend on the water – especially birds.
It’s clear that the biggest threat to prairie birds is the loss of the places they live due to conversion to farmland, cities and other human development, according to the Cornell Lab of Ornithology. But some birds, including swallows and others that scoop up insects as they fly, are in sharp, recent decline across Europe and North America for unknown reasons. Barn swallow numbers, for example, have plummeted 70 to 80 percent in the past few decades, a phenomenon that has scientists mystified. One of the few links among these imperiled flying bug-eaters is that many of them nest in areas where pesticides are common.
But Morrissey knows that if neonics are playing a role, it’s a subtle one. They aren’t the virulent, obvious bird-killers that some older chemicals were, poisoning hawks, eagles and robins and depleting their populations by thinning their eggs. Nevertheless, she wondered, could neonics be posing an indirect, potentially more widespread threat to birds?
Going to the heart of an ecosystem
Growing up in Vancouver, British Columbia, Morrissey didn’t start off interested in pesticides or toxicology. She wanted to be a veterinarian and got her first degree in zoology. But an internship in the late 1990s changed everything when several scientists in the Canadian Wildlife Service hired Morrissey to help figure out what was killing bald eagles in British Columbia. “My eyes just opened to possibilities I didn’t know about,” she said.
It turned out that the bald eagles were eating the corpses of ducks that had died after consuming crops treated with a class of pesticide that came before neonics and after DDT: the cholinesterase inhibitors such as carbamates. There was still so much pesticide in the ducks’ bodies that the eagles that fed on them were poisoned, too. Morrissey and her colleagues were rushing to find antidotes and even to get the sick eagles into veterinary labs so surgeons could cut into their gullets and remove the poison. It was the most exciting work she could imagine, going right to the heart of how a whole ecosystem works.
“It ticked all the boxes for me,” she says, driving along a Saskatchewan highway, on her way to check some of her field stations.
A couple more degrees and a four-year stint in Wales after her PhD, and Morrissey found herself in Saskatoon in 2010 with a teaching position, grad students, a new pesticide in her vocabulary and a $5,000 grant to map where neonics were being used and how much was left on the land. She was shocked to learn that more than 27 million acres of Canadian prairie were seeded with canola and that virtually every seed was covered with neonics – either in pink or in blue, depending on the manufacturer – before it was planted. And that didn’t count all the other crops, such as corn, soy, oats and barley, planted with treated seeds.
Morrissey started wondering whether the chemical stuck around like DDT did. So in the spring of 2012, with her grad student Anson Main, she sampled 136 potholes before crops were seeded, just to get baseline measurements of their chemistry. They didn’t expect to find neonics in the water, so they were surprised that more than one-third of the ponds contained at least one neonic compound that spring. That number rose shortly after seeding, as expected, and fell in the fall.
But the real shocker came the following spring – 2013 was a wet one – when they tested the same ponds again before seeding. Ninety-one percent of the ponds contained neonics at levels toxic to insects. Their conclusion: The chemicals must persist in the soil and then be washed into ponds. In other words, they not only stick around, they migrate far beyond the fields they are intended to treat.
phenomenon was reported across the U.S. Midwest. Neonics were present in rivers throughout Iowa – where corn and soybeans treated with the chemicals are grown intensively, in watersheds stretching more than 320,000 square miles. The chemicals were found “more frequently and in higher concentrations” than earlier generations of pesticides, the authors said.A similar
For an ecotoxicologist like Morrissey, all this was a game-changer. Pesticides’ toxicological profiles fall into two categories, either acute or chronic, according to how long they last. A pesticide that kills and then vanishes quickly is assessed as an acute toxicant. The ecosystem can tolerate high levels but only for a short period. If it persists for 10 percent or more of a creature’s lifespan that means it needs to be assessed as chronic or long-term. And that means the amount that can cause harm is far lower because it’s spread out over time. Morrissey’s pond results meant that neonics now had to be examined through the lens of the long-term toxicant.
To make matters more pressing, Morrissey’s lab results showed that neonics were far more toxic to some insects than the manufacturers' studies had shown. To obtain approval for use, the companies performed short-term toxicity tests on the water flea, Daphnia magna, a standard for pesticides. But Morrissey’s work showed that the water flea, a crustacean rather than an insect, is unusually insensitive to the chemicals – about 1,000 times less sensitive than the average of all other species tested. When neonics are tested on key wetland insects such as midges, caddisflies and mayflies, they are between 10,000 and 100,000 times more toxic than they are to the water fleas. That means that ecologically important invertebrates are likely affected at levels already present in the wild.
“It’s now crystal clear. Neonicotinoids have the chemical properties of long persistence, solubility in water and acute toxicity to some insects,” Morrissey says. “And that triggers concern.”
It was only the beginning.
(Continued on Page 2)