The Pesticide Dilemma

1. The Pesticide Dilemma Salad-vac. (or “bug-vac) Picture a giant vacuum cleaner slowly moving over rows of vegetable crops, sucking insects off the plants. Each vacuuming eliminates the need for one application of pesticide. It sucks insects through whirling fan blades, killing them instantly. The dead insects are sprayed out the back to fertilize the soil. Salad-vac. (or “bug-vac) Picture a giant vacuum cleaner slowly moving over rows of vegetable crops, sucking insects off the plants. Each vacuuming eliminates the need for one application of pesticide. It sucks insects through whirling fan blades, killing them instantly. The dead insects are sprayed out the back to fertilize the soil.

2. What is a Pesticide? Any organism that interferes in some way with human welfare or activities is a pest. Pesticides are chemicals that control pest populations. Insecticides kill insects Herbicides kill plants Fungicides kill fungi Rodenticides kill rodents

3. What is a Pesticide? The ideal pesticide: Narrow-spectrum (kills only the organism for which it was intended and not harm other species) Readily break down Stay exactly where put and not move through the environment Break down by natural chemical decomposition or by biological organisms into harmless materials (water, carbon dioxide, oxygen)Break down by natural chemical decomposition or by biological organisms into harmless materials (water, carbon dioxide, oxygen)

4. What is a Pesticide? There is no such thing as an ideal pesticide Actual pesticides: Broad-spectrum (kills a variety of organisms, including beneficial ones) Do not degrade readily or break down into compounds as dangerous as, or more dangerous than, the original pesticide Move around a great deal through the environment

5. What is a Pesticide? First-Generation Pesticides Inorganic compounds (e.g., lead, mercury) Botanicals (e.g., nicotine, pyrethrin) Earliest pesticides to be used. Inorganic compounds harm other organisms and accumulate in water and soil. Botanicals are plant-derived pesticides evolved by plants to protect them from insects. Botanicals are easily degraded by microorganisms and do not persist for long in the environment. However, they are highly toxic to aquatic organisms and bees. Earliest pesticides to be used. Inorganic compounds harm other organisms and accumulate in water and soil. Botanicals are plant-derived pesticides evolved by plants to protect them from insects. Botanicals are easily degraded by microorganisms and do not persist for long in the environment. However, they are highly toxic to aquatic organisms and bees.

6. What is a Pesticide? Second-Generation Pesticides Synthetic botanicals (e.g., pyrethroids) DDT Second-generation pesticides are all organic synthetic chemicals. (Synthetic botanicals are human-made insecticides produced by chemically modifying the structure of natural botanicals.) Still in use today. An important group of synthetic botanicals are the pyrethroids, which are chemically similar to pyrethrin. Pyrethroids do not persist in the environment; they are slightly toxic to mammals and bees and toxic to fish. DDT(dichlorodiphenyl-trichloroethane) was the first second-generation pesticide. DDT being sprayed to control mosquitoes at New York’s Jones Beach State Park in 1945. Sign reads “DDT. Powerful Insecticide. Harmless to Humans.” Potential as insecticide discovered in 1939. Dangers to humans not realized until many years later. Second-generation pesticides are all organic synthetic chemicals. (Synthetic botanicals are human-made insecticides produced by chemically modifying the structure of natural botanicals.) Still in use today. An important group of synthetic botanicals are the pyrethroids, which are chemically similar to pyrethrin. Pyrethroids do not persist in the environment; they are slightly toxic to mammals and bees and toxic to fish. DDT(dichlorodiphenyl-trichloroethane) was the first second-generation pesticide. DDT being sprayed to control mosquitoes at New York’s Jones Beach State Park in 1945. Sign reads “DDT. Powerful Insecticide. Harmless to Humans.” Potential as insecticide discovered in 1939. Dangers to humans not realized until many years later.

7. What is a Pesticide? The Major Groups of Insecticides Chlorinated hydrocarbon (e.g., DDT) Organophosphates (e.g., malathion) Carbamates (e.g., carbaryl) Insecticides are the largest category of pesticides. Classified based on chemical structure. Organic compound containing chlorine. Broad-spectrum; slow to degrade; persist in the environment and organisms; widely used from 1940s to 1960s but have since been completely banned or restricted (3 in use in US) Contain phosphorus. Developed during WWII as an outgrowth of German research on nerve gas. Broad-spectrum; highly toxic to many organisms, including humans; do not persist in environment for as long as hydrocarbons; highly used in large-scale agriculture but not available to consumers due to toxicity. Derived from carbamic acid. Broad-spectrum; not as toxic to mammals as organophosphates. Insecticides are the largest category of pesticides. Classified based on chemical structure. Organic compound containing chlorine. Broad-spectrum; slow to degrade; persist in the environment and organisms; widely used from 1940s to 1960s but have since been completely banned or restricted (3 in use in US) Contain phosphorus. Developed during WWII as an outgrowth of German research on nerve gas. Broad-spectrum; highly toxic to many organisms, including humans; do not persist in environment for as long as hydrocarbons; highly used in large-scale agriculture but not available to consumers due to toxicity. Derived from carbamic acid. Broad-spectrum; not as toxic to mammals as organophosphates.

8. What is a Pesticide? The Major Kinds of Herbicides Selective herbicides (e.g., 2,4-D – kills broad-leaved plants) Nonselective herbicides (e.g., glyphosate, aka: Round-UpTM) Herbicides are grouped according to how they act or what they kill. Selective herbicides kill only certain types of plants. (broad-leaf, grass) Broad-leaf herbicides are important because many crop plants are grasses (wheat, corn, rice) Nonselective herbicides kill all vegetation. 2,4,5-T banned in the US by EPA after harmful side effects on humans became apparent during the Vietnam War. (Agent Orange was 2,4,5-T and 2,4-D combined).Herbicides are grouped according to how they act or what they kill. Selective herbicides kill only certain types of plants. (broad-leaf, grass) Broad-leaf herbicides are important because many crop plants are grasses (wheat, corn, rice) Nonselective herbicides kill all vegetation. 2,4,5-T banned in the US by EPA after harmful side effects on humans became apparent during the Vietnam War. (Agent Orange was 2,4,5-T and 2,4-D combined).

9. Benefits and Problems with Pesticides Benefit: Disease Control DDT has been successfully used to control malaria outbreaks (spread by female mosquitoes). DDT is still used in at least 20 tropical countries to control mosquitoes. These countries have decided that it is more beneficial to control the spread of malaria and will risks the health effects of DDT. DDT has been successfully used to control malaria outbreaks (spread by female mosquitoes). DDT is still used in at least 20 tropical countries to control mosquitoes. These countries have decided that it is more beneficial to control the spread of malaria and will risks the health effects of DDT.

10. Benefits and Problems with Pesticides Benefit: Crop production Farmers save ~$3 - $5 in crops for every $1 invested into pesticides Pesticides reduce crop loss by competition with weeds, consumption by insects, and diseases caused by fungi or bacteria. Pests are a problem in our fields because they are a monoculture.Pesticides reduce crop loss by competition with weeds, consumption by insects, and diseases caused by fungi or bacteria. Pests are a problem in our fields because they are a monoculture.

11. Benefits and Problems with Pesticides Problem: Evolution of Genetic Resistance Pests can become resistant to many or all legal pesticides.Pests can become resistant to many or all legal pesticides.

12. Benefits and Problems with Pesticides Problem: Evolution of Genetic Resistance Creates a pesticide treadmill A predicament faced by pesticide users, in which the cost of applying pesticides increases (because they have to be applied more frequently or in larger dose) while their effectiveness decreases (as a result of increasing genetic resistance in the target pest) A predicament faced by pesticide users, in which the cost of applying pesticides increases (because they have to be applied more frequently or in larger dose) while their effectiveness decreases (as a result of increasing genetic resistance in the target pest)

13. Benefits and Problems with Pesticides Problem: Evolution of Genetic Resistance Resistance Management Strategies for managing genetic resistance in order to maximize the period in which a pesticide is useful Insects in the refuge remain susceptible to the insecticide, when they migrate into the area, they mate with genetically resistant individuals After a herbicide is applied, resistant, living plants should be manually removed before they spread their seeds. Plant seeds that are certified free of weed seeds.Strategies for managing genetic resistance in order to maximize the period in which a pesticide is useful Insects in the refuge remain susceptible to the insecticide, when they migrate into the area, they mate with genetically resistant individuals After a herbicide is applied, resistant, living plants should be manually removed before they spread their seeds. Plant seeds that are certified free of weed seeds.

14. Benefits and Problems with Pesticides Problem: Imbalances in the Ecosystem Natural predators of pests are killed either directly by eating many organisms with pesticide residue or indirectly due to starvation (or migrate to another area). No natural predators mean pest populations become larger. Increase in pests also due to genetic resistance and monocultures.Natural predators of pests are killed either directly by eating many organisms with pesticide residue or indirectly due to starvation (or migrate to another area). No natural predators mean pest populations become larger. Increase in pests also due to genetic resistance and monocultures.

15. Benefits and Problems with Pesticides Problem: Imbalances in the Ecosystem Creation of New Pests Aka a minor pest becomes a major pest An infestation of red scale insects on lemons occurred after DDT was sprayed to control a different pest. A comparison of red scale populations on DDT-treated trees (blue line) and untreated trees under biological control (red line). Aka a minor pest becomes a major pest An infestation of red scale insects on lemons occurred after DDT was sprayed to control a different pest. A comparison of red scale populations on DDT-treated trees (blue line) and untreated trees under biological control (red line).

16. Benefits and Problems with Pesticides Problem: Persistence, Bioaccumulation, and Biological Magnification Bioaccumulation—organisms accumulate high concentrations of persistent pesticides over time due to the pesticides being stored in their fatty tissues Biological magnification—increase in pesticide concentrations as the pesticide passes through successive levels of the food web Bioaccumulation—organisms accumulate high concentrations of persistent pesticides over time due to the pesticides being stored in their fatty tissues Biological magnification—increase in pesticide concentrations as the pesticide passes through successive levels of the food web

17. Biological magnification of DDT in the tissues of falcons and other birds of prey caused a decline in their reproductive success in the US during the 1960s and early 1970s. DDT caused the birds to lay eggs with extremely thin, fragile shells, causing the chicks’ deaths. DDT was banned in the US in 1972. Biological magnification of DDT in the tissues of falcons and other birds of prey caused a decline in their reproductive success in the US during the 1960s and early 1970s. DDT caused the birds to lay eggs with extremely thin, fragile shells, causing the chicks’ deaths. DDT was banned in the US in 1972.

18. Benefits and Problems with Pesticides Problem: Mobility in the Environment Pesticides in water and air are a risk to human health (cancer).Pesticides in water and air are a risk to human health (cancer).

19. Risks of Pesticides to Human Health Short-term Effects of Pesticides Handling of food with pesticide residue Pesticides poison approx. 67,000 people in the US each year. Mostly farm workers or others exposed to large quantities of pesticides on a daily basis. Mild cases include nausea, vomiting, and headaches. Serious damage includes permanent nervous system or internal organ damage or death. WHO estimates that pesticides poison more than 3 million people globally; about 220,000 result in death. Highest in developing countries (use more highly poisonous pesticides, less training, less safety regulations).Pesticides poison approx. 67,000 people in the US each year. Mostly farm workers or others exposed to large quantities of pesticides on a daily basis. Mild cases include nausea, vomiting, and headaches. Serious damage includes permanent nervous system or internal organ damage or death. WHO estimates that pesticides poison more than 3 million people globally; about 220,000 result in death. Highest in developing countries (use more highly poisonous pesticides, less training, less safety regulations).

20. Risks of Pesticides to Human Health Short-term Effects of Pesticides Case-in-Point: The Bhopal Disaster 1984 Occurred at a Union Carbide pesticide plant in Bhopal, India. Erupted from an underground storage tank after water leaked in and caused an explosive chemical reaction. Some of the gas converted into a more dangerous chemical in the atmosphere. In 1989, Union Carbide agreed to pay $470 million in compensation and spend more than $100 million to build a hospital for victims. Most individuals received $500. Clean up has still not been addressed, meaning individuals living in the area are still at risk.1984 Occurred at a Union Carbide pesticide plant in Bhopal, India. Erupted from an underground storage tank after water leaked in and caused an explosive chemical reaction. Some of the gas converted into a more dangerous chemical in the atmosphere. In 1989, Union Carbide agreed to pay $470 million in compensation and spend more than $100 million to build a hospital for victims. Most individuals received $500. Clean up has still not been addressed, meaning individuals living in the area are still at risk.

21. Risks of Pesticides to Human Health Long-term Effects of Pesticides Potentially higher risk of cancer Sterility Miscarriage / birth defects Potentially higher risk for Parkinson’s disease Endocrine Disruptors Hormones are chemical messengers produced by organisms in small quantities to regulate growth, reproduction, and other important biological functions. Release is controlled by the endocrine system. Pesticides have been shown to mimic hormones when in organisms, especially estrogen, interfering with normal functioning. Can cause health problems at relatively low doses. Reproductive disorders, sterility, cancer. SEE PAGE 153 Hormones are chemical messengers produced by organisms in small quantities to regulate growth, reproduction, and other important biological functions. Release is controlled by the endocrine system. Pesticides have been shown to mimic hormones when in organisms, especially estrogen, interfering with normal functioning. Can cause health problems at relatively low doses. Reproductive disorders, sterility, cancer. SEE PAGE 153

22. Alternatives to Pesticides Using Cultivation Methods to Control Pests Interplant mixtures of plants Strip cutting Planting, fertilizing, and irrigating at proper time Crop rotation Strip cutting—only one segment of the crop is harvesting at a time. The unharvested portion of the crop provides an undisturbed habitat for natural predators and parasites of the pest species. Plants are healthier and can better resist pests.Strip cutting—only one segment of the crop is harvesting at a time. The unharvested portion of the crop provides an undisturbed habitat for natural predators and parasites of the pest species. Plants are healthier and can better resist pests.

23. Alternatives to Pesticides Biological Controls Using naturally occurring diseases, parasites, or predators to control a pest Pheromones and Hormones Use pheromones to attract insects to traps Natural & synthetic hormones induce abnormal development Reproductive Controls Sterile-male technique – inundate pest population with large numbers of sterile males Biological controls can also include bacteria or viruses to attack pests. Pheromones—sexual attractants (often used to attract mates). Each insect produces its own. Sterile male technique must be used continuously and is expensive Biological controls can also include bacteria or viruses to attack pests. Pheromones—sexual attractants (often used to attract mates). Each insect produces its own. Sterile male technique must be used continuously and is expensive

24. Alternatives to Pesticides Genetic Controls Using Genetically Modified (GM) plants Case-in-Point: Bt, Its Potential and Problems Genetically modified corn to produce Bt toxin Potential problem: may affect non-target species, such as monarch butterfly Quarantine Pests evolve quickly to attack GM plant Bacillus thuringiensis (Bt)—soil bacterium produces a natural pesticide toxic to some insects. Has been improved to affect a wider range of insects. GM crops have been made that release Bt. However, pests are becoming resistant to it. Quarantine—restriction of the importation of exotic plants and animal material that may harbor pests. If farms do acquire a foreign pest, the farm is quarantined and all crops may be destroyed. Pests evolve quickly to attack GM plant Bacillus thuringiensis (Bt)—soil bacterium produces a natural pesticide toxic to some insects. Has been improved to affect a wider range of insects. GM crops have been made that release Bt. However, pests are becoming resistant to it. Quarantine—restriction of the importation of exotic plants and animal material that may harbor pests. If farms do acquire a foreign pest, the farm is quarantined and all crops may be destroyed.

25. Alternatives to Pesticides Integrated Pest Management A combination of pest control methods that, if used in the proper order and at the proper times, keep the size of a pest population low enough that it does not cause substantial economic loss. Requires knowledge about your pests and crops (life cycle, feeding habits, travel, nesting habits, interactions with other organisms). Important part of sustainable agriculture (Chapter 19). Management rather than eradication of pests. A combination of pest control methods that, if used in the proper order and at the proper times, keep the size of a pest population low enough that it does not cause substantial economic loss. Requires knowledge about your pests and crops (life cycle, feeding habits, travel, nesting habits, interactions with other organisms). Important part of sustainable agriculture (Chapter 19). Management rather than eradication of pests.

26. Alternatives to Pesticides Integrated Pest Management

27. Alternatives to Pesticides Irradiating Foods Predominantly used on meats Kills many microorganisms Food does not become radioactive, so they do not expose you to radiation. Does produce chemicals called free radicals, some of which are carcinogens in lab animals.Food does not become radioactive, so they do not expose you to radiation. Does produce chemicals called free radicals, some of which are carcinogens in lab animals.

28. Laws Controlling Pesticide Use Food, Drug, and Cosmetics Act (1938) Pesticide Chemicals Amendment (1954) Delaney Clause (1958) Federal Insecticide, Fungicide, and Rodenticide Act (1947) FDCA—recognized the need to regulate pesticides found in food but did not provide a means of regulation. Pesticide Chemicals Amendment—required the establishment of acceptable and unacceptable levels of pesticides in food. Delaney Clause—stated that no substance capable of causing cancer in test animals or in humans would be permitted in processed food. (Pesticides tend to concentrate in condensed processed foods). Problems: did not cover raw foods, only applied to chemicals tested after 1978. FIFRA—Originally designed to prevent the sale of pesticides that did not work. Has been amended to require the testing and registration of active ingredients in pesticides. All must meet tolerant standards. EPA now regulates pesticide use based on the FDCA and FIFRA. Four assumptions were made in arriving at values in chart 1) the entire US crop is treated, 2) with all pesticides that are registered for use on that crop, 3) the pesticides are applied the maximum number of times, 4) at the maximum rate, or amount, each time. FDCA—recognized the need to regulate pesticides found in food but did not provide a means of regulation. Pesticide Chemicals Amendment—required the establishment of acceptable and unacceptable levels of pesticides in food. Delaney Clause—stated that no substance capable of causing cancer in test animals or in humans would be permitted in processed food. (Pesticides tend to concentrate in condensed processed foods). Problems: did not cover raw foods, only applied to chemicals tested after 1978. FIFRA—Originally designed to prevent the sale of pesticides that did not work. Has been amended to require the testing and registration of active ingredients in pesticides. All must meet tolerant standards. EPA now regulates pesticide use based on the FDCA and FIFRA. Four assumptions were made in arriving at values in chart 1) the entire US crop is treated, 2) with all pesticides that are registered for use on that crop, 3) the pesticides are applied the maximum number of times, 4) at the maximum rate, or amount, each time.

29. Laws Controlling Pesticide Use Food, Drug, and Cosmetics Act (1938) Pesticide Chemicals Amendment (1954) Delaney Cause (1958) Federal Insecticide, Fungicide, and Rodenticide Act (1947) Food Quality Protection Act (1996) Amended both the FDCA and FIFRA. Revised the Delaney Clause by establishing identical pesticide residue limits for both raw produce and processed foods. Takes into account infants and children when setting limits. Established for all health risks, not just cancer.Amended both the FDCA and FIFRA. Revised the Delaney Clause by establishing identical pesticide residue limits for both raw produce and processed foods. Takes into account infants and children when setting limits. Established for all health risks, not just cancer.

30. The Manufacture and Use of Banned Pesticides Some US companies still make banned or seriously restricted pesticides and export the product. This can potentially lead to the importation of food tainted with banned pesticides When countries are caught importing food with residues of pesticides outlawed in the US, they are fined, but not enough to discourage them.When countries are caught importing food with residues of pesticides outlawed in the US, they are fined, but not enough to discourage them.

31. The Manufacture and Use of Banned Pesticides The Global Ban of Persistent Organic Pollutants Stockholm Convention on Persistent Organic Pollutants went into effect in 2004. Important international treaty. Requires countries to develop plans to eliminate the production and use of these persistent organic pollutants (POPs). 12 most toxic chemicals; 9 are pesticides. Exception of DDT for countries where malaria is a problem and no affordable alternatives exist. To be more effective, more countries, including the US, will have to ratify and adhere to it. Stockholm Convention on Persistent Organic Pollutants went into effect in 2004. Important international treaty. Requires countries to develop plans to eliminate the production and use of these persistent organic pollutants (POPs). 12 most toxic chemicals; 9 are pesticides. Exception of DDT for countries where malaria is a problem and no affordable alternatives exist. To be more effective, more countries, including the US, will have to ratify and adhere to it.