A Conference Sponsored by the Rachel Carson Council at George Mason University, 1998 Excerpts and Updates: by Dr. Diana Post, Executive Director, Rachel Carson Council, Inc.
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A unique opportunity for interaction, this conference brought government scientists together with academics, students, environmentalists, and interested citizens. Internationally recognized experts discussed the impact of pesticides on wildlife and ecosystems.
The following speakers were featured:
- Dr. David Pimentel presented the keynote address
- David Brower was the banquet speaker
Wild animals and plants are essential elements of the healthy ecosystems on which we all depend. Therefore, even without considering their intrinsic worth, damage to them should be of concern to all humanity. In addition, pesticide effects on wild species predict pesticide harm for people. In this regard they serve as sentinels.
In 1995 20,000 Swainson's Hawks were killed from applications of the pesticide monocrotophos to fields in Argentina. Wild birds continue to be poisoned with diazinon, a common lawn and garden insecticide. Declines in English songbird species have been linked to widespread herbicide use. A massive Florida fish kill in 1994 was due to the application of the insecticide fenamiphos on a golf course. Researchers believe that pesticides may be contributing to the increased hind limb deformities of frogs.
Birds or fish have greater visibility than the invertebrates whose heavier losses from pesticides go largely unrecognized. Plants serving as food and habitat for animals can be eliminated by herbicides. Non-fatal pesticide exposures can alter the behavior and the reproductive capacity of a population.
Currently, pesticides are being applied at nearly twice the rate they were 35 years ago when Rachel Carson wrote Silent Spring. This "chemically-based paradigm for pest control" (M.L. Winston in Nature Wars), is especially threatening to wildlife. Lacking airtight shelters, protective clothing and unable to read warning signs, birds, fish and insects neither have man-made safeguards nor for the most part their own defenses against the chemical barrage.
U.S. Fish and Wildlife Service (FWS) scientists consider pesticides to be among their more critical problems. EPA has the principal mandate, of course, and until recently the Agency has tended to give wildlife/pesticide problems less focus.
Keynote Address: Wildlife, Pesticides, and People: The Relationship Dr. Pimentel, Cornell University
Session One: Pesticides' Characteristics and Uses Lisa Lefferts, Moderator
Pesticide Modes of Action Dr. Joel Coats, ISU
Public Health and Non-Agricultural/Agricultural Uses J. Marenda
Veterinary Medical Uses Dr. Dennis Blodgett
Session Two: Pesticides' Fate in Various Ecosystems & Habitats Dr. Val Beasley, Moderator
Pesticides Sales & Usage Dr. Arnold Aspelin
Aquatic Environments Dr. Robert Gilliom
The Fate of Pesticides in the Environment Dr. Clive Edwards
Session Three: Toxicities of Pesticides for Taxa and Species Birds Dr. Pierre Mineau
Beneficial Insects Dr. William Quarles
Fish and Amphibians Dr. Greg Smith, Dr. Carol Meteyer, Dr. Jim Burkhart
Aquatic Invertebrates Dr. Keith Cooper
Soil Organisms Dr. Sara Wright
Marine Mammals Dr. John Reif
Plants Dr. Richard C. Petrie, EPA
Pesticides and Pollinators Dr. Gary Paul Nabhan
Farm-scale Pesticide Use: Impacts on Wildlife Based on 30 Years of Monitoring Dr. Julie Ewald
Monocrotophos and Swainson's Hawks in Argentina Dr. Mike Hooper
Toxicity of Pesticides to Early Life Stages of Fish Eric A. Paul
Pesticides as Endocrine Disrupters Dr. Theo Colborn
Incident Data on Pesticide-related Bird Mortality Dr. Nimish Vyas
Effects on Non-target Insects of Pesticides Used for Gypsy Moth Control Dr. Linda Butler
Reduced Pesticide Use to Protect and Restore the Environment Dr. Clive Edwards Pesticides and the Migratory Bird Treaty Act Dr. Jewell Bennett
Pesticides and Endangered Species Dr. Larry Turner, EPA
Final Session: Relating Effects of Pesticide Use on Wildlife to Human Health Dr. Theo Colborn
Summarizing highlights and key points Dr. Lee Talbot
The Wildlife, Pesticides and People Conference was dedicated to our beloved colleague Edward Lee Rogers, Esquire, killed in an auto accident March 10, 1998, who with his wife Ailene was a Board Member of the Rachel Carson Council. Lee Rogers, a pioneering environmental lawyer, first general counsel of the Environmental Defense Fund, put his environmentalist ideas into practice by becoming a leader of the nationwide movement to ban the pesticide DDT. He was devoted to environmental causes and justice and gave generously of his time, expertise and caring in helping to battle for the earth on many fronts.
On September 25 and 26, 1998, Rachel Carson Council, Inc., in conjunction with George Mason University's Department of Biology, held a conference on Wildlife, Pesticides and People. Twenty-eight outstanding scientists from academia, government and environmental organizations made presentations to over 160 attendees from 23 states and 2 foreign countries. The conference was dedicated to Lee Rogers Esq., RCC Board Member and devoted environmental lawyer, tragically killed March 10, 1998.
The body of information compiled in just two days is sufficiently troubling so as to shake to their very core any notions that wildlife can be safe from pesticide toxicity if use of these chemicals continues at the present rate.
Most speakers advocated Integrated Pest Management (IPM) as a way of dealing with unwanted species while reducing chemical use.
Topics ranged from mode of action and environmental fate of chemical pesticides to the hazards they pose for wildlife such as: invertebrates, fish, birds, mammals, fungi and plants. Most naturally occurring non-target vegetation including trees and wild flowers have been given virtually no protection from herbicides by pesticide regulators. Beneficial insects (except for honeybees) and beneficial fungi are not considered when pesticide toxicity is evaluated by regulators. Although avians are included in pre-registration toxicity tests they are still threatened. An estimated 67 million birds are killed yearly by pesticides in the U.S. Chemicals too toxic for use in our own country, but freely available abroad threaten migratory birds journeying thousands of miles from the Arctic to the Southern Hemisphere. Tiny, obscure but essential aquatic invertebrates are highly vulnerable to commonly-occurring low levels of pesticides in our streams, lakes and rivers. Even marine mammals with few natural enemies are at risk from the persistent pesticides that gradually accumulate in their tissues. Indirect effects of pesticides predicted by Rachel Carson are beginning to receive documentation. Herbicides intended for plants can indirectly affect insects. Insecticides, by killing off pollinating insects, can lead to reductions in plants. Both herbicides and insecticides have indirectly reduced bird populations.
Summaries of Conference Presentations
- Nearly All Surface Water is Contaminated with Chemical Pesticides
- Chemical Pesticides Promote Pests by Killing Beneficial Insects
- Direct and Indirect Effects of Chemical Pesticides
- Wildlife Losses Directly Related to Pesticides Are Estimated to Cost Billions of Dollars
- Effects of Pesticides on: Aquatic Invertebrates, Plants, Fish, Fungi and Birds
- The Value of Current Methods for Predicting Pesticide Toxicity to Aquatic Invertebrates
- Super-Potent Herbicides Harm Distant Trees. No Methods Exist to Detect Their Presence
- Early Life Stages of Game Fish at Risk from Herbicides and Insecticides
- Effects on Beneficial Mycorrhizal Fungi Are Not Factored Into EPA's Environmental Evaluation of Pesticides
- Pesticides and Birds Parts I and II
- Endocrine Disruptors
- Notes on Wildlife at Work
- Pesticide Regulations and Wildlife:
- Swainson's Hawk and Pesticides Dr. Mike Hooper
- Pesticides and Marine Mammals Dr. John Reif
- Pesticides, Wildlife and Human Health Dr. Theo Colborn
- Veterinary Pesticides' Effects on Wildlife Dr. Dennis Blodgett
- Insecticides' New Modes of Action Dr. Joel Coats
- Effects on Non-Target Insects of Pesticides Used for Gypsy Moth Control Dr. Linda Butler
- Reducing Chemical Pesticides in Agriculture Dr. Clive Edwards
Robert Gilliom of the U.S. Geological Survey reported that in nearly every sample of stream water from a developed watershed, researchers found one or more pesticide contaminants. Based on toxicity data for individual chemicals, pesticide levels during certain times of the year have been found sufficiently high to threaten water-dwelling organisms. Moreover, as reported by Dr. Keith Cooper, another conference speaker, a pesticide mixture can pose a greater hazard than the aggregate toxicity of its constituents would indicate, due to interaction among its components (synergism). Urban streams were found to have higher organophosphate insecticide levels (the organophosphates diazinon and chlorpyrifos were found most often) and agricultural streams to have higher herbicide levels (with atrazine as the leading chemical detected). In each case levels of breakdown products could exceed levels of the parent compounds by 50 to 100 times. (Some of these breakdown products are more toxic than the parent chemicals!) For 11 streams, the concentration of dissolved pesticides in the water was the most reliable predictor of endocrine disruption in the resident carp.
Dr. William Quarles of the Bio-lntegral Resource Center discussed the effects that chemical insecticides can have on natural enemies of insect pests, the so-called beneficial insects. Regrettably, beneficial insects appear to be more easily poisoned by insecticides than are the targeted pests. As explained by Dr. Quarles this enhanced sensitivity to the toxic effects of chemicals on the part of beneficials has contributed to the higher levels of pesticide-resistant insect pests. Over 500 instances of pesticide-resistant pest insects have been found while only 30 cases of beneficial insect resistance to pesticides have been documented. An early study found that heavy applications of DDT in citrus trees resulted in enhanced growth of scale, an insect pest. Removal of the beneficial insects by hand from citrus tree limbs in a parallel experiment resulted in growth of the scale pest to a level approximating the DDT-treated tree limbs. When, in both cases the beneficial insects which had effectively controlled the scale pest infestations were eliminated, the pest was able to thrive. Pest problems from spider mites and other invertebrates have been linked to the use of DDT and the broad spectrum insecticides which followed after 1972. EPA does not require the testing of insecticides for their effects on beneficial insects, which act as natural pest controls and are vital members of the ecosystem. More attention needs to be paid to these important organisms.
Here is a catalogue of effects that pesticides can exert, followed by examples taken from Silent Spring as well as from the Conference presentations of Drs. Ewald and Nabhan describing pesticides' indirect effects on wildlife.
Overview of pesticides' effects on wildlife
Like a handful of stones hitting the water from a single toss, release of a pesticide formulation into the environment produces ripples of change. The effects can be described as pesticidal and as "chemicidal" (the latter are toxic effects related to the chemical action of the pesticide). These effects can be due to actions by the active ingredients, breakdown products, contaminants and/or inert ingredients. The effects can be both direct and indirect.
Direct effects may be immediate and fatal or non-fatal. They can be delayed, as with a tree's reduced fruit yield or an animal's developmental disorders, immune system dysfunction, liver or kidney failure or cancer. Indirect effects exerted over time are by their very nature, delayed actions.
Direct Pesticidal Effects
Chemical pesticides can act directly in their intended way on organisms related to the target pest. Examples of this are: herbicides poisoning trees and underwater grasses; fungicides poisoning beneficial intracellular mycorrhizal fungi which produce glomalin.
Direct "Chemicidal" Effects Related to the Primary Mode of Action
Chemical pesticides can act directly in a "chemicidal" way associated with their pesticidal mode of action on organisms not structurally related to the targeted pests. Examples of this are: organophosphate insecticides poisoning the nervous systems of birds, aquatic invertebrates, fish and human beings or anticoagulant (warfarin-type) rodenticides preventing blood clotting in birds or mammals.
Direct "Chemicidal" Effects Unrelated to the Primary Mode of Action
Pesticides behaving as toxic chemicals can have "chemicidal" effects bearing little relationship to the pesticidal mode of action. Examples include the herbicide 2,4-D acting as a nervous system poison, the herbicide, paraquat, acting as a respiratory system poison and carcinogenic pesticides such as the fungicides benomyl and chlorothalonil.
Indirect Pesticide Effects: Examples from Silent Spring, Dr. Julie Ewald and Dr. Gary Nabhan
Indirect actions of pesticides were reported by Rachel Carson in Silent Spring. The most dramatic case from Clear Lake, California involved the Western grebe and was researched by Dr. Robert Rudd. DDD (a relative of DDT) was repeatedly sprayed over the lake to kill gnats. After years of bioaccumulation beginning with the plankton, which had absorbed the poison from the water, through the progressively larger fish species, DDD reached life threatening levels in the tissues of the fish-eating grebes, described by Rachel Carson as birds of "spectacular appearance and beguiling habits." The concentration of DDD in the grebes' bodies reached over 80,000 times that of the water. The birds' population was reduced from 1,000 nesting pairs prior to the insecticide applications to just 30 (most of which did not successfully reproduce) 10 years later. Chlorinated hydrocarbons such as DDT are still contaminating our environment due to previous as well as present-day usage. They can be carried on the wind, in the ocean currents or in the tissues of migrating animals to every part of the planet.
In India thousands of tons of DDT were used to control malarial mosquitoes between 1995 and 1996. A recent report shows that large numbers of vultures there are dying and have high levels of DDT in their carcasses. Vultures are at the same level of the food chain as humans and serve as sentinels warning of greater pesticide hazards through indirect effects unless there is a change in the Indian government's pesticide policy.
Partridge Populations Plummet When Pesticides Eliminate Insects
Dr. Julie Ewald from England reported on indirect effects of herbicides and insecticides on birds. She explained a different type of indirect effect by pesticides that, unlike DDT, do not bioaccumulate. However, these chemicals were applied regularly over a long time span. Her presentation showed that it is not necessary for pesticides to bioaccumulate in the food chain (as with DDD and DDT) in order to produce indirect effects if such chemicals are applied with sufficient frequency. A thirty year study in Sussex found that continuous agricultural applications of even short-lived chemicals created conditions capable of reducing partridge populations. Coveys of grey partridge had lived at the field edges in Sussex for hundreds of years before wide-spread use of herbicides eliminated plants essential for insect cover and food. Broad spectrum insecticides further reduced insect populations. The lack of available insects during the birds' first two weeks of life turns out to be the chief reason for diminished numbers of the grey partridge. Young partridge must consume insects in order to thrive. The study's conclusions were further supported by the finding that planting field perimeters in native wild flowers to foster insect populations seems to have the potential for reversing the decline of the grey partridge in Sussex.
Loss of Pollinators by Insecticides Results in Declines of Rare Desert Plants
Dr. Gary Nabhan from the Sonoran Desert Museum in Arizona described the indirect effects of insecticides on plants through reduction of essential pollinators. In his own words, "Rachel Carson not only worried that pesticides would create 'silent springs' where no bees droned among the blossoms [but she also recognized that where] there was no pollination...there would be no fruit." He further stated, "Lethal and other effects such as behavior changes, have been associated with bee exposure to currently-used pesticides. In 1995 the USDA declared that we are facing the worst pollination crisis in American history. Insecticide and herbicide spraying causing chemical habitat fragmentation, could impact the over 5,000 species of native wild pollinators nesting in wild lands adjacent to the croplands." Certain Arizona farms have used conservation areas to help rehabilitate wildlife populations damaged by pesticides.
Dr. David Pimentel of Cornell University, the Conference Keynote Speaker, in his manuscript "Economic and Environmental Costs of Pesticide Use," provided estimates of the cost in economic terms of pesticide use in the United States:
* The estimated pollination losses to food production from pesticides' effects on honey bees and wild bees is $200 million per year. (p.131)
* Destruction by pesticides of the natural enemies of pests can cost an estimated $520 million per year in the U.S. (p.128)
* A conservative estimate of fish (6-14 million) killed per year by pesticides ranges from $24 to $56 million. "...the actual loss is probably several times the $24 to $56 million estimate when all the indirect impacts are taken into account." (p.137)
* The total number of wild birds killed by pesticides is estimated at 67 million. The value of this bird loss to pesticides is $2.1 billion annually. (p.139)
* "Although...invertebrates and microorganisms are essential to the vital structure and function of all ecosystems, it is impossible to place a dollar value on the damage caused by pesticides to this large group of organisms." (p.140)
Dr. Keith Cooper of Rutgers University described pesticides' effects on aquatic invertebrate organisms, like the tiny water flea, existing near the bottom of food chains. Although these insects are among the most vulnerable species to pesticides' effects, their loss within a stream or lake is usually not readily apparent until the more visible fish species decline or a recreational feature is disturbed. By then it may be too late to remedy the situation. Frequently, aquatic invertebrates exist in contact with low levels of combinations of chemicals. Knowing the toxicities of chemicals considered singly and added together might not be sufficient to predict the risk that their concurrent presence poses to aquatic invertebrates. Researchers have found that toxic effects of low-level combinations of certain chemical pesticides can be greater than the sum of the effects of the individual components. When the herbicide atrazine is combined with certain organophosphates, the resulting lethality to aquatic invertebrates is higher than could be predicted from the toxicities of the individual chemicals because of synergistic effects among the components. This is not only worrisome for the extremely vulnerable aquatic invertebrates but for all organisms in an aquatic environment and those who depend on them.
Richard Petrie offered some of the most startling revelations of the conference in his presentation and in a manuscript by Petrie, Schneider and Czerkowicz, "Plants and Pesticides" reprinted in the proceedings book. His work stresses the importance of plants and their need for protection so that they can continue to provide essential services.
Rain and fog frequently carry herbicides such as atrazine to the forests, the Chesapeake Bay and our own farms and gardens. Yet the EPA requires no testing of herbicides' toxic effects on woody plants or underwater grasses. Only non-target crop-type plants and aquatic algae have been routinely included in the Agency's required test groups.
New and very powerful sulfonylurea herbicides have been registered without requirements for testing on trees or without the development of a chemical test for detecting them in the environment. Many of these sulfonylurea herbicides have half-lives in years, are widely used, and are reported to have damaged woody plants at a fraction (1/100 to 1/10,000) of the label dose. As described in the "Plants and Pesticides" manuscript: "Following grower complaints of yield losses in cherry and apricot orchards downwind from wheat fields treated with chlorsulfuron, a sulfonylurea herbicide, the EPA conducted limited tests on cherry trees and chlorsulfuron. Reduced cherry yields were observed the year following the application of chlorsulfuron at 1/500 the label rate...a 1/10,000th dilution of chlorsulfuron sulfonylurea label dosage resulted in the inhibition of seed production in crop plants..." (p.12)
According to Richard Petrie, two important ecosystems, the Great Lakes and the Chesapeake Bay, threatened by contamination, will not have restoration of their commercial and recreational resources until the plant life is renewed to previous historic levels (Petrie, et al). A recent report confirmed that the underwater grasses are seriously deficient in the Chesapeake Bay. From various sources we know that pesticides are continually present in the Chesapeake Bay. There is clear evidence that critical data is lacking for an accurate picture of pesticides' effects on plants.
Eric Paul explained that numbers of the game fish muskellunge in a New York lake decreased following widespread introduction of an herbicide to control underwater grasses. Research performed at New York State's Rome Field Station showed that concentrations of the herbicide diquat, produced when the label recommendations were followed could be toxic to early life-stages of fish. After labeling changes lowered the use levels in New York State the muskellunge populations showed signs of recovery.
Eric Paul has researched the effect of insecticides used to control mosquitoes on the early life stages of trout. He found that at non-lethal levels pyrethrins reduced the swimming ability of young fish. The ability was further diminished when the synergist, piperonyl butoxide, which enhances the action of the pyrethrin, was present as would be true for a great many final pesticide formulations. Final formulation tests are not required to include fish. Active ingredient toxicity tests on fish do not reflect hazards of any synergists found in final formulations. The enhanced toxicity for young fish of formulations with synergists over and above that of the active ingredient alone needs to be considered when pesticides' impact on wild fish are being estimated. Recommended application rates may need to be revised in light of this research.
Dr. Sara Wright with the USDA has shown the important role played by arbuscular mycorrhizal fungi. She discovered that these fungi produce glomalin, a protein that contributes to soil fertility by facilitating the aggregation of fine soil particles. Glomalin, as it was named by Dr. Wright, has also been called soil superglue. Pesticides can interfere with glomalin production. Mycorrhizal fungi living within in the root cells of plants can be harmed by fungicides or indirectly by the herbicides which poison the host plant. Canadian authorities intend to require the preregistration testing of pesticides for effects on glomalin production. Although our own EPA has not yet established such a policy, we need to be aware of the potential for pesticides to harm these organisms.
Dr. Pierre Mineau of the Canadian Wildlife Service, Dr. Mike Hooper of Texas Tech University, Dr. Nimish Vyas of Patuxent Wildlife Research Center, and Dr. Jewell Bennet of the Fish and Wildlife Service, internationally-known avian toxicologists presented findings on the effects of pesticides on birds. Recognizing our society's reverence for wild birds and the body of research data on how pesticides affect them, the Conference devoted a significant amount of time to this subject.
Birds by their very nature are vulnerable to the direct toxicity of organophosphate (OP) and carbamate insecticides. Dr. Mineau explained that the greatest direct threat to birds comes from these pesticides. His research shows that with complex mixtures of pesticides used in orchards, the breeding success of birds is inversely correlated with the levels of organophosphates and carbamates.
An example of the lethal effects of these chemicals is the deaths of an estimated 20,000 Swainson's Hawks in Argentina resulting from the use of monocrotophos and other organophosphates. Although monocrotophos may no longer be used in our own country, it can still be manufactured here and sold abroad.
Songbirds, especially, can suffer what Dr. Mineau calls invisible mortality. These small creatures do not die in a pile but can die where no one will find them, so that confirmation of pesticide involvement in the death is not possible. Another effect following continuous use of chemical pesticides is degradation of the land to such a degree that no bird populations can be supported in the surrounding areas, so that no birds die there.
Dr. Mineau noted that for certain pesticide products the harm they cause doesn't depend on how they are used, but only whether certain birds are in the vicinity when applications take place. With the granular pesticides even one particle can be fatal to certain birds. In December 1998 we heard that all uses of granular carbofuran in Canada had been canceled. This is wonderful news, but because birds migrate, even if all the granular organophosphate products were banned in the U.S. and Canada, they would still represent a significant threat to birds since they are sold all over the world.
Under the current practice of pesticide registration each country is free to establish conditions of use. Lax standards in one country could prove fatal to migratory birds which are cherished and protected by high standards in another. Drs. Hooper, Mineau and Vyas emphasized the need for uniform protection from pesticide poisoning all along migratory routes in the Americas and beyond. Accumulated knowledge about a pesticide product should be available through a world-wide data bank and utilized for pesticide registration instead of each country being treated as a new situation.
Dr. Mineau explained that the concept of tolerating or allotting a certain number of birds to be killed by pesticides is not acceptable because science does not allow us to set such limits. Dr. Bennet noted that in the U.S. under the Migratory Bird Treaty Act it is illegal to kill even one migratory bird with a pesticide.
5e) Pesticides and Birds: Part 2
Dr. Nimish Vyas of the Patuxent Wildlife Research Institute compared our knowledge of pesticides' adverse effects on birds to a pyramid-shaped iceberg (in which the widest portion remains unseen). The tip of the pyramid represents mortality events that have been observed, reported and confirmed. The pyramid base represents the majority of pesticide-related avian mortality which goes undetected. The lack of documentation for most such fatalities is due to a number of factors. Up to 92% of the bird carcasses may be scavenged and removed from the site of the pesticide kill within the first 24 hours. Once a bird kill is observed, it must be reported to appropriate state and federal wildlife authorities so that a systematic carcass search and sample collection can be conducted. Often a mortality event may go unreported when an observer finds only one or two carcasses. If the event is reported there is often a time lag between poisoning and collection of carcasses by wildlife professionals. This invariably reduces the chance of collecting samples suitable for laboratory analysis.
There is great need for public awareness that pesticides may be involved when a dead bird is found. But unless there is a reliable method carried out by knowledgeable professionals of investigating and compiling such reports the public could become frustrated and cynical about the value of vigilance.
Dr. Theo Colborn of the World Wildlife Fund spoke on disruption of the endocrine system by pesticides. In 1992, 40% of the pesticides tested were designated as endocrine disruptors. Five years later that number had increased to 60%. Two of the most widely used herbicides (atrazine and 2,4-D) have been classified as endocrine disruptors by Dr. Colborn's group. There is special concern about the sulfonylurea herbicides since they are from the same chemical class as drugs which affect thyroid and pancreatic functions in people. In addition, these new sulfonylurea herbicides are used at much lower concentrations than are other herbicides, and chemical tests are not available to detect some of the most widely used sulfonylureas such as chlorsulfuron once they have been released into the environment. Dr. Colborn cited a study showing that herbicides have been associated with birth abnormalities in both farmers and non-farm residents living in high pesticide use agricultural areas of Minnesota (Dr. V. Carry, et al, "Pesticide appliers, biocides and birth defects in rural Minnesota," EHP, v 104, #4, April 1996).
Thoreau called wilderness, "the raw material for civilization." Although a number of natural areas have become chemically fragmented through loss of biodiversity from pesticide use since Thoreau's time, certainly many areas still support vital life-sustaining processes. People today are beginning to realize our dependence on the wild organisms which are capable of producing these services and the responsibility on our shoulders to protect them from further degradation as well as to help chemically-damaged areas regenerate into healthy ecosystems.
The term "beneficial" as used by environmentalists traditionally refers to those insects acting as natural enemies of pests. The Conference showed that "beneficial" can also refer to plants, insects, fungi, reptiles, amphibians and bacteria which by their very existence maintain ecosystems and make the earth livable for people.
Wild plants generate oxygen and food. They regulate the air and water temperatures and help make the earth suitable for people and other living organisms. Recent reports indicate that trees may absorb twice as much pollution each year as was earlier believed.
Approximately one third of all human food is dependent on pollinators. Pollination is required for increased crop yields and increased quality of fruits and vegetables. (pp.130-131 Pimentel)
Dr. Rosen of the Hebrew University in Jerusalem estimates that 90% of the control of pest species achieved in agricultural and natural ecosystems is due to natural processes. Dr. Pimentel of Cornell University puts the number at about 50%. Natural enemies of insect pests include pest-control insects, pest-control nematodes, pest-control fungi and pest-control birds as well as others.
Birds provide a valuable service to growers and to the public through controlling insects. A case in point occurred in China during the 1950s. Chinese officials grew concerned that flocks of birds were allegedly devouring large amounts of grain. They declared any sparrow-like perching bird to be a major scourge. "With regimented enthusiasm" the citizens killed over 800,000 birds. As a consequence there were major outbreaks of insect pests. Realizing their mistake the leaders changed course and removed small birds from the list of scourges. (Baskin, Y. The Work of Nature. Island Press. Washington, DC. pp.42-43) It is difficult to know precisely how the killing of birds by pesticides relates to pest insect populations. However, the estimated bird losses due to pesticides given by Dr. Pimentel, 67 million per year, far exceeds the 800,000 bird deaths in China that resulted in greater insect numbers.
It has been estimated that before 1880 resident oysters in the Chesapeake Bay were able to filter all the Bay's water in 2-3 days. In 1988 the time required for oysters to provide the same service was 325 days or 100-fold longer. We do not know what effect pesticides may have had on the loss of water filtering service provided by these bivalves. We have determined that pesticides have been identified as toxic to mollusks.
We know that many vital services from nature are threatened by chemical pesticides, and that biological alternatives to the use of chemicals for control of unwanted species are underutilized. More attention needs to be given to the urgent problems resulting from the use of chemical pesticides. ~ May 1999
Wildlife are the organisms most vulnerable to pesticide toxicity and most exposed to chemical pesticides on a daily basis, yet they are the least sheltered from these hazards. The 1996 Food Quality Protection Act (FQPA) regulations, intended to safeguard children from pesticides, do provide some indirect benefits to wildlife but this is not their primary purpose (as explained in section 1-A).
EPA-mandated studies for the scientific assessment of pesticides' hazards to wildlife fail to give a complete picture. Final decisions on the assessment of pesticides' risks to wildlife are made not by EPA scientists but by EPA managers under a vague and subjective risk/benefit standard.
Migratory birds are supposed to be preserved under the Migratory Bird Treaty Act (as discussed in section 1-C) and individuals of the endangered or listed species (explained in section 1-B) are entitled to special preservation under the Endangered Species Act. EPA spokespersons have declared that birds are the wildlife group designated to receive the highest Agency protection from pesticide harm.
Nevertheless, Dr. Pimentel's estimated direct losses of birds from pesticides continues to rise and is now at 72 million birds per year. Our nation's overall legislative record of bird protection from pesticides is dubious and protection of other wildlife is even more doubtful.
In 1996, a new federal law, the Food Quality Protection Act (FQPA), reflecting the nation's greater concern for child safety, imposed stricter standards on EPA's pesticide risk assessment procedures for human beings. Now risk assessment standards give humans more protection from pesticides than they give to wildlife.
As described by Mr. Merenda of the EPA the contrast is clear: the human health risks, "[from pesticides] must meet an absolute standard of 'reasonable certainty of no harm,' while ecological [wildlife] risks must be balanced against the benefits of using the pesticide."
Another way to characterize the risk evaluation standard for wildlife is; "[pesticide use] will not pose an unreasonable risk to the environment" (Joseph Merenda). The FQPA at times provides some protection for wildlife, but indirectly.
Recently, EPA has taken steps to improve evaluation of pesticides' effects on the environment through collecting information from the Ecological Incident Information System and the Pesticide Ecological Database as well as implementing a new program with the acronym ECOFRAM. Information collection and new paradigms notwithstanding, the final decision about how well wildlife can be protected from an individual pesticide remains, not from EPA's scientific reviewers, but with EPA's managers working under the vague and subjective 'risk balanced against benefit' standard previously described.
Examples of FQPA providing greater protection for wildlife while safeguarding children are pesticide cancellations. Household uses of the neurotoxic organophosphates chlorpyrifos and diazinon are being phased out as the result of actions initiated by EPA Administrator Carol Browner under FQPA. Birds, beneficial insects and aquatic organisms among those most adversely affected by contact with these potent nerve toxins will benefit through their removal from the homeowner market. Some agricultural uses for both organophosphates are still permitted and represent continuing dangers for wildlife.
In the 1980s EPA made a controversial decision to no longer require field-testing of pesticides prior to marketing. Such tests might well have detected ecological impacts such as the contamination of plant nectar with the insecticide imidacloprid (discussed under topic #3, Insecticides' New Modes of Action). Some effects have been discovered through the Ecological Incident Information System after pesticide products are already on the market -- too late to prevent wildlife losses.
Birds, Pesticides and Regulations
Although migratory birds are not the most vulnerable to pesticide toxicity, they are closer to the public eye (aided by binoculars) and dearer to the public heart than most other wildlife. EPA claims to have designated birds for greater protection from pesticides.
Support for this assertion is EPA's recent refusal to register the insecticide chlorphenopyr due to its adverse effects on birds. In this case public input also played a role in the Agency's decision. EPA's record of wildlife protection falters when it continues to permit use of the highly toxic organophosphates and carbamates such as fenthion, carbofuran and others. In addition, the Agency has failed to seriously evaluate indirect effects and low level exposures of birds to pesticides.
According to one wildlife toxicologist "'safe' pesticides are driving birds to extinction," (Dr. R. O'Connor). The Agency's record has disappointed Canadian Wildlife Toxicologist Dr. Pierre Mineau and other scientists who have investigated avian health issues. As if to confirm their concerns, the estimated direct losses of birds from pesticides by Dr. Pimentel has risen from 67 million in 1998 to 72 million in 2001.
EPA is required by the Endangered Species Act (ESA) to avoid jeopardizing the continued existence of federally defined endangered or threatened wild species. Those designated as endangered, also known as listed species, are to be given the highest level of protection from pesticides of any wildlife. Listed wildlife are to be protected as individuals, not populations, and their habitat is to be protected as well.
In addition to the direct effects on listed species, EPA is required to evaluate the indirect effects of pesticides, such as hazards to host organisms for developing phases of listed individuals, hazards to pollinators of listed plants, and hazards to food sources for listed species. For these indirect effects it is sufficient to protect populations rather than individuals.
The most notable EPA action protecting endangered species occurred in 1972 with the banning of DDT. However, listed species still need the Agency's protection from chemical hazards. For example, the insecticide carbofuran has killed a number of Bald Eagles when applied according to the label and it is still registered for use. A recent lawsuit by environmentalists seeks better EPA protection of salmon, a listed species, from levels of the insecticide diazinon too low to be lethal but able to damage the salmons' ability to avoid predation and to find the streams of their birth through their legendary homing ability.
EPA's endangered species program continues to be hampered by lack of funding and other hindrances.
The Migratory Bird Treaty Act (MBTA), a law protecting migratory birds, is "...one of the most important Federal statutes for birds native to North America and other parts of the world" (Dr. Jewell Bennett). Under this law the killing of migratory birds with pesticides can be considered a violation even if the intent was not to do so and the pesticide was being used according to the label.
The deliberate misuse of a pesticide to kill birds would also be a violation of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) as well as the MBTA.
Individuals and companies have been prosecuted under the MBTA for killing birds with pesticides. The MBTA is administered by the Fish and Wildlife Service. As described in RCC's brochure "A Nature Lover's Alert" an Oak Brook, Illinois lawn care company was fined for being responsible in the deaths of 47 mallard ducks after they legally applied diazinon to the turf of a condominium in Indianapolis. They were fined $4,700 and found guilty of a misdemeanor under the Migratory Bird Treaty Act.
In another example of an MBTA violation, a paper company had used an EPA registered avicide product containing the organophosphate insecticide, fenthion to kill problem starlings in 1997. Within days of the application, a red-tailed hawk and a great horned owl were fatally poisoned after consuming poisoned starlings. Although the use of fenthion had been legal where the starlings were concerned, the killing of the protected birds feeding on the starlings violated the MBTA and the company was charged.
Swainson's hawks spend spring and summer in western North America where they feed on rodents, birds and reptiles. During the northern winter (or austral summer) they migrate to Argentina's rich grassland habitat where thousands of hawks become insect-eaters. In the past they shared the pampas pastures with grazing cattle. When the agricultural crops of soybean, sunflower, corn, and alfalfa replaced cattle, the hawks fed on grasshoppers and other insects infesting the fields.
An Argentinean farmer first reported the killing of a number of Swainson's hawks in 1995, after the insecticide monocrotophos was sprayed on sunflowers by a neighbor to control grasshoppers. This highly toxic organophosphate had been withdrawn from use in the U.S. in the late 1980s. Because it was not officially banned it did not raise alerts as to its inherent wildlife toxicity and it continued to be used around the world.
Thousands more hawk deaths occurred in the next two years setting the stage for scientists from Argentina, the U.S. and Canada, as well as environmentalists and multinational corporations, to join forces in an effort to prevent such disasters from happening in the future.
As a consequence, one company withdrew its monocrotophos-containing products worldwide (accounting for less than 20% of the world's supply), an effort was made to establish a way of tracking incident reports internationally, and a dialogue was started on pesticide use and migratory bird welfare among scientists.
RCC Update: As a result of this focus, the highly toxic monocrotophos is, as of 2001, withdrawn from the markets of Argentina and Australia. This action to protect migratory birds is an inspiring tribute to concerned farmers, dedicated wildlife professionals and caring individuals from the industry. This cooperation should be taking place in other parts of the world where unfortunately monocrotophos and other pesticides like it are still available to poison birds and other wildlife.
Organochlorine pesticides in combination with other contaminants are routinely found in the tissues of marine mammals such as bottlenose dolphins, Baikal seals, harbor seals, striped dolphins and Beluga whales. Certain contaminants can be mobilized and eliminated from the mother by way of the milk, passing these contaminants along to their offspring. The fact that male dolphins do not lactate contributes to higher contaminant levels in adult males than in adult females.
Even higher levels of three contaminants (a DDT metabolite, chlordane metabolites and PCBs) were found to be associated with poor health in dolphins. In dolphin calves that died, levels of the same three contaminants were up to 10 times as high as those among the calves that survived.
In other marine mammals high levels of organochlorine contaminants have been linked to reduced immune function, and increased cancer rates. Tumors in beluga whales have been found at 20% in certain populations contaminated with chemicals as a result of living in the Gulf of St. Lawrence. This level of cancer is considered as significantly higher than in non-contaminated populations of marine mammals.
Certain pesticides can act as endocrine disruptors in wildlife and laboratory animals. They may act in a similar way in people. Research needs to address what effects pesticides can have during the 266 day gestation period for the human being. During this time bounds are being placed on the progeny's potential and quality of life. The association between effects in children and chemical pesticides may be indirect so that the agents are not detected in the child's body but only in the body of the mother.
For example: wild caught fish eaten by those living in the Great Lakes area have been associated with problems in children. In the 1970s there was widespread concern over thyroid problems in Great Lakes fish. Infants born of women who ate two to three meals a month of Lake Michigan fish prior to their pregnancies were found to have delays in neuromuscular and neurological development. They showed short-term memory problems and reduced academic skills as they matured.
DDE, the breakdown product of DDT has been associated with reduced reproductive capacities in alligator populations in Lake Apopka, Florida. In the laboratory, female mice fed DDE during gestation produced male offspring that looked much more like females and DDE was found to have anti-androgen (male hormone) activity. The fungicide vinclosalin, also found to have anti-androgen properties, resulted in abnormal males when fed to females during gestation.
A condition in humans called hypospadias, an abnormal opening of the penis, is a "visible external marker of prenatal exposure" to anti-androgen type chemicals. Hypospadias in the US has doubled between 1970 and 1990. See "Toxic Legacies" and Lawn and Garden Pesticide Clusters for further pesticide human health effects.
Veterinarians are accustomed to focusing on the health of domestic animals primarily and human beings secondarily. The effects of veterinary products on wildlife and ecosystem services are not generally weighed when a therapeutic agent is chosen.
However, such products can reach the environment in an active form by various means including through the feces of large animal patients. Sprays, dips and shampoos used on small as well as large animal patients can contaminate terrestrial and aquatic environments.
Activity of ivermectin-containing pesticides and anthelmintics (used to "deworm" animals) passed in animal feces can reduce the numbers of insects associated with waste matter in fields. These insects perform important ecological functions when they break down organic waste matter, provide food for other wildlife, and pollinate plants.
For example, when ivermectin is present, dung degradation may be impaired for 100 days. In other cases, domestic fowl have died after picking out dichlorvos-containing pellets in horse feces.
Pyrethrin (natural) and pyrethroid (synthetic) insecticides have been replacing the organophosphates/carbamates as animal/premise insect control agents. "Horse stables often have mist sprayers that emit permethrin at set intervals. Dairy barns and swine confinement operations often control fly populations with these agents" (Dr. Blodgett).
In general, the more biodegradable pyrethrins and the more persistent pyrethroids have low mammalian and avian acute toxicity (an exception is permethrin - highly toxic for cats). However, both natural and synthetic forms are considered toxic for aquatic organisms. Snakes, amphibians and bees are also extremely vulnerable to pyrethrins and pyrethroids. Hazards to aquatic life forms occur when there is contamination of surface water with runoff of pyrethrin-type chemicals from spraying or disposal.
Summary: Newly-developed insecticides can be referred to as "selective" if they are not as highly toxic for most mammals and most birds as they are for insects and other wildlife. Four classes of insecticides act on sites in the nervous system that may be common to many animals.
Avermectins and fiproles act at sites known as chloride channels located along the body of the nerve cell. Neonicotinoids and spinosads act on the acetyl choline sites found at the gap (synapse) between nerve cells. A single example is provided along with an RCC toxicity update for each insecticide.
More research is needed to better predict effects of these chemicals in the field including multiple exposures and long term actions on non-target invertebrate and sensitive vertebrate populations (including humans).
Avermectins are derived from natural products made by soil microorganisms. Ivermectin is an example.
RCC Toxicity Update: In general, members of this class are toxic for terrestrial insects, aquatic invertebrates and fish. Environmental persistence and adverse effects on beneficial insects are a problem for ivermectin discussed under topic #5, Veterinary Pesticides' Effects on Wildlife.
Fiproles are a new class of synthetic compounds. Fipronil is an example.
RCC Toxicity Update: Fipronil shows low acute avian toxicity except for certain seed-eating birds such as the Bobwhite quail and the pheasant, which are extremely sensitive to this chemical. Rabbits are also very sensitive to it. Fipronil is highly toxic to aquatic invertebrates, crustaceans, and honeybees. It is also highly toxic to fish and oysters.
Neonicotinoids are synthetic analogs of nicotine. Imidacloprid, a chloronicotinyl, is an example.
RCC Toxicity Update: An imidacloprid-containing product has been associated with "mad bee" disease in France. Beekeepers there report it has killed millions of bees and destroyed the insects' sense of direction. Imidacloprid can also travel throughout the plant and accumulate in the nectar and the pollen.
Imidacloprid could be a problem for honeybees when sprayed into a flowering crop or used as seed treatment. Imidacloprid is highly toxic to house sparrows. In an adverse incident report to the EPA a number of songbirds were found dead after consuming grubs that had come to the surface of a lawn previously treated with imidacloprid.
Spinosads are natural products produced by microorganisms. Spinosad is an example.
RCC Toxicity Update: Spinosad is highly toxic to honeybees and very highly toxic to the Eastern Oyster.
The gypsy moth is an alien insect species that has threatened forests from Massachusetts to the southern states and other parts of the country. Broad-spectrum chemicals used against the pest have contributed to the disappearances of rare species of native moths and butterflies in states along the infestation's path.
Three chemical pesticides, diflubenzuron, terbuphenozide and Bacillus thuringiensis currently used for gypsy moth control have individual ecological effects.
The chemical diflubenzuron, a broad-spectrum inhibitor of chitin formation is extremely persistent on land and in water where it is especially toxic to invertebrate life forms. The total abundance of arthropods, butterflies and moths on foliage in a West Virginia study site remained significantly reduced for over two years after treatment with a diflubenzuron-containing product.
Field testing of the chemical terbuphenozide raised the issue of whether at the level of use needed to control the gypsy moth there would be unacceptable losses of non-target insects. More work is needed to answer this question.
The least persistent and the least toxic to non-target insect life forms is the biological agent, Bacillus thuringiensis (B.t.).
Although persistent chemicals present the most obvious hazard to non-gypsy moth insects, even easily degraded agents such as B.t. if used repeatedly, could be expected to result in loss of sensitive non-targets. Continued widespread use of these chemicals could contribute to further elimination of butterflies, moths and other insects while failing to accomplish the elimination of the gypsy moth.
Ohio State University Professor Dr. Clive Edwards is a researcher of ecological farming methods. Frustrated by the lack of ways to communicate practices through the usual channels, he started Innovative Farmers of Ohio, a group meeting over coffee on regular Saturday mornings to facilitate the exchange of information between organic and conventional farmers.
The group learned about a local farmer who had used organic methods for 20 years and was outproducing neighboring conventional farmers, as well as the enhanced health of plants grown in soil from the organic field compared to those grown in soil from the conventional field.
RCC Update: From Pennsylvania, Maryland's Eastern Shore, Florida, Arizona, Washington, and Indonesia, reports indicate that by reducing chemical pesticides or using organic methods farmers can meet or surpass conventional crop output and/or provide more favorable habitats for birds, aquatic organisms and other wildlife including bacteria.
"The Rodale Farming Systems Trial, started in 1981, found that after a transition period of four years crops grown under organic systems yield as well as and sometimes better than crops grown under the conventional systems."
"Soils managed organically show higher levels of microbial activity and greater diversity of microorganisms. Moreover, organic systems can out-produce the conventional system in years of less-than-optimal growing conditions such as drought."
~ The Rodale Institute Farming Systems Trial: The First 15 Years, 1999
On Maryland's Eastern Shore, farmers were encouraged to reduce the chemical pesticides and fertilizers on their fields through using Integrated Pest Management (IPM). Fish counts and aquatic macroinvertebrates increased significantly in the German Branch, a tributary of the Chesapeake Bay when IPM was adopted by farmers in the watershed. Farmers using IPM also saved money.
~ Frances Breeding, Local Government Pollution Prevention Toolkit, CBP/TRS 202/98, EPA 903-K-98-001
Preliminary data from Florida found that bird densities and the number of bird species associated with organic fields were higher than those associated with conventional fields.
~ Jones, G.A., et al, "An assessment of bird faunas utilizing conventional and organic farmlands of north-central Florida," 2001
Tubac Farms of Arizona economically benefited from implementing wildland habitats near agricultural areas, protected from chemical sprays, in which pollinators could roost, nest and feed in the off-season.
~ Dr. Gary Nabhan, 1998
Organic apple growing in Washington state resulted in healthier soil, better environmental quality, and greater energy efficiency than did growing apples with conventional methods.
~ Nature, April 19, 2001
In Indonesia where most of the pesticide was applied to rice, Dr. I.N. Oka was able to reduce pesticide use by 65% and increase rice yields by 12%.
~ Pimentel, D., "Environmental effects of pesticides on public health, birds and other organisms," 2001