More than 1.1 billion pounds of pesticides are applied annually to crops in the US, and many weed-killers are used in combination with seeds that are genetically engineered to withstand them. This combination breeds resistant “superweeds.” Superweeds are so called because they require increasingly toxic formulas to overcome them. This pattern of resistance over time to pesticides is not unusual: scientifically speaking, it is predictable and to be expected.
Intensive or prolonged exposure to many commonly used pesticide chemicals can be hazardous to public health, the environment and to the farmers and farmworkers who use them. Consumers can help reduce the demand for products grown with pesticides by purchasing organic or low-spray produce and by joining organizations building power against the powerful multi-billion-dollar pesticide industry.
Industrial agriculture relies on two types of chemicals: fertilizers and pesticides. The former boosts soil fertility, making crops more productive, while the latter protects crops by controlling weeds (herbicides), insect and animal infestation (insecticides and rodenticides) and fungal/mold diseases (fungicides). 1
Pesticides come in a variety of applications that treat everything in their path, making specific targeting of a specific pest or disease impossible. For example, fumigants are applied as gases to control soil pests, and “systemic” pesticides function by migrating through a plant’s cells to get absorbed by the roots later. But these chemicals can harm many healthy elements of the ecosystems to which they are applied, including the soil, which is exposed to all of them. Additionally, many insecticides have been designed to attack insects’ nervous systems, while others act as growth regulators or endotoxins.
The most recent report on pesticide sales and use from the US Environmental Protection Agency (EPA) puts US pesticide use at 1.1 billion pounds in both 2011 and 2012, which amounts to 23 percent of the nearly six billion pounds used worldwide. Agriculture accounts for nearly 90 percent of pesticides in the US, with industry/commercial/government and home and garden making up the rest.
Herbicides are the most common type of pesticide used comprising 90 percent of the US agricultural market. 2 Monsanto’s genetic engineering of seeds to resist glyphosate, the active ingredient in its Roundup herbicide, has made this suite of agricultural technology ubiquitous: in 2012, glyphosate use was more than four times that of atrazine, the second most common agricultural chemical. 3
More than 90% of corn, soybeans and cotton in the US are genetically modified to be resistant to herbicides.
The total volume of glyphosate that was applied to the three largest, genetically engineered (GE) crops — corn, cotton and soybeans — increased ten-fold, from 15 million pounds in 1996 to 159 million pounds in 2012. 4 A 2014 study performing tests across 38 states found glyphosate in the majority of rivers, streams, ditches and wastewater treatment plants as well as in 70 percent of rainfall samples. 5 The use of the GE herbicide-resistance technology keeps increasing, however, and more than 90 percent of corn, cotton and soybeans planted today are herbicide-resistant. 6
The pesticide industry likes to point out that some pesticides are approved by the USDA Organic program, to blur the difference between organic and conventional practices. But significant differences exist between biological pest controls and industrial chemical controls.
Organic pesticides are typically derived from naturally occurring compounds, though not all naturally occurring substances, such as nicotine and arsenic, are allowed. There may be times when one judicious application of a synthetic pesticide causes less environmental impact than multiple doses of the equivalent organic pesticide. On balance, however, the greatest environmental and health exposure damage is due to synthetic pesticides.
Pesticides are not a modern invention. Ancient Sumerians used elemental sulfur to protect crops from insects, and medieval farmers and scientists experimented with chemicals like arsenic. Nineteenth-century research focused on compounds made from plants, including chrysanthemum. In 1939, better known as DDT, was discovered to be extremely effective against both agricultural and disease-carrying insects. It rapidly became the most widely used insecticide in the world. Twenty years later, after Rachel Carson’s Silent Springshed light on the devastating effects of DDT on the environment, serious concerns about its impact on human and animal health led the US and 80 more countries to ban its use. The book also galvanized the environmental movement and the creation of the EPA, which is still responsible for monitoring pesticide use.
However, despite widespread scientific recognition that many pesticides are toxic not only to pests, the tendency toward increasingly industrialized growing practices — such as monocropping, which is more vulnerable to pests — ensures that ever increasing toxic pesticides will be required.
The outcry following the publication of Silent Spring succeeded in banning DDT in the US and created an awareness of the hazards of other pesticides. But dangerous herbicides, insecticides and fungicides continue to be used on fields at extraordinary rates. In addition to cumulative exposure to pesticides and residues over time, these chemicals mean negative consequences for the environment, public health and (perhaps most concerning) on everyone who administers or comes in contact with them (directly or secondarily) throughout the production and supply chain.
Pesticides are assessed by the EPA for risks posed to ecosystems, human health and cumulative toxic effects; the EPA also establishes tolerances (amounts allowed on or in a food) for each pesticide. The US Food and Drug Administration (FDA) and USDA annually survey and publish information regarding pesticide residues in the food supply. 7 8 However, many tolerances are outdated and do not take into account all of the modern toxicological endpoints, such as hormone disruption. Moreover, the risks assessed only pertain to non-cancer endpoints — while many pesticides have positive cancer classifications. Our government does not assess the effects of acute or chronic exposures to multiple pesticides, either.
While USDA testing consistently finds that nearly all food samples have pesticide levels well below the residue levels established by the EPA, it also shows that multiple, different residues are found on any given produce item frequently. Follow-up analysis by the Environmental Working Group (EWG) has instead shown that 70 percent of samples were contaminated with pesticide residues but cautions that there are stark differences in amounts of residue based on the kind of produce sampled. EWG’s annual Dirty Dozen and Clean Fifteen lists provide details about the most and least contaminated.
Even if low use of some pesticides is regarded as safe for humans or the environment, safety studies may not accurately account for real-life exposure to many different chemicals over a lifetime. In fact, some studies have shown that long-term, intensive exposure has adverse effects.
One 2011 meta-study of common endocrine disrupter pesticides, for example, showed that wildlife and certain human populations were negatively impacted in significant ways. Atrazine, a widely used endocrine disruptor, leads to complete chemical castration and feminization of male frogs and other abnormal side effects. In infants and children, as well as people who live or work in agricultural areas, endocrine disruptors have been linked to low birthweight, abnormal brain development, increased incidence of cancers, reduced male fertility and other issues.
While farmers have lower overall cancer rates than the general population, rates of certain diseases and some particular types of cancer are much higher among agricultural workers. Farming communities have higher rates of leukemia, non-Hodgkin lymphoma, multiple myeloma and soft tissue sarcoma, as well as cancers of the skin, lip, stomach, brain and prostate. There has not yet been research to pinpoint the causes of these illnesses, but the National Cancer Institute points out that “the range of environmental exposures in the farming community is of concern,” and related studies have shown elevated cancer risks from regular contact with atrazine and several other pesticides.
There is some debate about possible cancer risks of glyphosate, the world’s most widely used herbicide. Research in 2015 by the cancer agency of the World Health Organization showed limited evidence of glyphosate linked to non-Hodgkin lymphoma in humans, as well as cancer in animals. The US EPA and the UN Food and Agriculture Organization, however, have said that glyphosate is unlikely to pose a carcinogenic risk to humans exposed to it through food. A recent court case found Monsanto liable for damages to a man who alleged the company’s glyphosate-based weed-killers made him lethally ill.
In addition to cancers, pesticides have been linked to other health problems, including problems with cognition, and risk factors for diabetes and obesity. Research has also shown that exposing bacteria to the herbicides glyphosate, dicamba and 2,4-D can result in resistance to antibiotics, even when the chemicals are used at legal levels.
While eating a lot of produce is best for public health, limiting exposure and ingestion of pesticides should be the next priority. Generally, the less exposure to pesticides over a lifetime the better.
Pesticide that is sprayed on crops leaves a residue on the dead plant material that settles into the soil and can run off into waterways or leach into groundwater. Even at levels deemed “safe,” pesticides have been shown to cause a loss of biodiversity, including reduced numbers of beneficial insects, such as dragonflies, as well as birds and amphibians. The EPA maintains a list of the potential effects of pesticides on aquatic life and other animals as a reference for researchers investigating water quality.
New research has demonstrated that the controversial neonicotinoid pesticide has a dramatic impact on migratory songbirds, showing that even very small amounts can cause birds to lose their sense of direction and even to suffer weight loss. The evidence of effects from neonicotinoids on honeybees and other pollinators is detailed below.
While farmers use pesticides to increase crop yields, many of the starkest problems caused by pesticides are most evident on the farm, apart from the health concerns outlined above.
Evidence is rapidly growing that several classes of pesticides are implicated in pollinator decline, including honeybee colony collapse disorder. Vegetable, fruit and nut farmers rely on insect and small mammal pollinators; even self- or wind-pollinated row crops like corn and soybeans have better yields when a healthy population of pollinators is present. Neonicotinoid pesticides are conclusively linked to widespread honeybee decline, with recent evidence showing traces of those and other pesticides in a large sample of local honey from around the world.
A more obvious problem for farmers is pesticide resistance and the development of “superweeds.” Over time, some weeds that have been exposed to glyphosate adapt to survive the herbicide. These weeds then reproduce, passing their ability to resist the herbicide to the next generation of weeds. Herbicide resistance is increasingly common, and some areas may have multiple herbicide-resistant weed species in their fields, making weed control even more difficult. A 2016 survey of states across the Midwest found that one third to well over three quarters of fields showed resistant weeds.
Chemical companies like Monsanto and Dow are heavily invested in their seed technology — seeds genetically modified to resist herbicides — which means that they are tied to herbicides, as well. If weeds develop resistance to one chemical, the “solution” is now to combine it with an older, more toxic poison; to promote any other strategy would mean the end of their business model. Thus 2,4-D, a toxic chemical that was a major component in Agent Orange, has been approved by the EPA in combination with glyphosate. The new use of 2,4-D is expected to lead to a 300 to 700 percent increase in the chemical’s use by 2020.
Another older herbicide, dicamba, which was previously approved only for ground spreading, was EPA-approved in 2017 for aerial spraying in conjunction with soybean seeds genetically engineered to be resistant to the chemical. Dicamba is extremely volatile: after it is sprayed on a field it can turn back into gas and drift several miles, killing or damaging any plant material wherever it lands — which in this case could be on practically any plants aside from protected GE soybeans.
Crop-damaging pesticide drift can ruin a neighboring farm’s organic certification. Dicamba is prone to pesticide drift, even when applied according to label instructions. In 2017, damage from dicamba drift was reported in 25 states, mostly to non-GE soybeans, but also to vegetables, fruits, vineyards and trees. Rather than rejecting this damaging chemical altogether and sanctioning the seed and chemical manufacturer for bad practices, the soybean growers decided instead to plant dicamba-resistant seeds; this has further expanded the use of the herbicide, benefiting the bottom line of the seed and chemical manufacturer, and also increasing the possibilities of dicamba drift.
For farmers, pesticides are labor saving and generally provide a higher yield: it can mean the difference between saving a crop and losing it to disease. Some farmers, especially those who grow produce at a smaller scale, use pesticides sparingly as needed. For example, fruit trees are susceptible to disease in northeastern regions, especially at the blossom stage. An apple or peach grower may spray her fruit trees with a fungicide once in the spring to ensure that the fruit sets, but use no further chemicals for the rest of the season.
For many large row crop farmers, on the other hand, regular pesticide use is as much a part of farming as planting seeds. Spraying Roundup on a field of corn genetically engineered to withstand the chemical kills the weeds without affecting the corn. In comparison to mechanically weeding hundreds or thousands of acres, using pesticides is a game-changer. Some farmers spray their wheat with a weed-killer at the end of the season to kill the wheat itself and to speed its drying process. Farmers growing fruit or vegetables on a large scale, especially delicate varieties like strawberries, will blanket the field with pesticides to ward off any possible disease.
The carpet-bombing approach to pesticide use is a hard habit to break. Even while farms are increasingly industrialized, with growing plants fed by chemical fertilizer in sterile soil, a farm is still ultimately an ecosystem with complicated interrelationships among organisms. A dependence on pesticides has meant that many farmers do not know other methods of addressing weed or disease problems, which may leave them out of options if and when the chemicals fail. The many farmers using the GE seed/pesticide combination have invested a lot of money and time in that system, and there is no easy way to break the cycle. Even if your fields are now full of Roundup-resistant weeds, it makes more sense to try a stronger pesticide than to get off the treadmill and head in another direction.
The agricultural chemical companies and their trade associations (e.g., CropLife) are highly invested in keeping farmers on the pesticide treadmill, because that is where their profits come from. Pesticides are a $14 billion industry in the US; two thirds are for agricultural use. Most of those sales are herbicides paired with genetically modified seeds, but these numbers do not include sales of the seed itself. In 2017, Monsanto’s net sales of genetically engineered (GE) corn, soybean and cotton seeds and traits totaled $9.5 billion.
As the industry has exploded, the companies involved have grown and merged. What had been six major agricultural chemical companies by 2018 had merged into just three: DowDuPont, ChemChina and Syngenta and Bayer/Monsanto. This much control concentrated in a few mega-corporations means fewer options and also higher prices for farmers, as well as an evermore politically powerful industry.
The agrochemical industry has been politically powerful for many years. As a bloc, the agricultural inputs sector spent nearly $33 million in lobbying Congress in 2016, and the “revolving door,” by which former industry leaders serve in the government agencies overseeing their industries, is well-used by agribusiness.
Critics have repeatedly pointed to the influence of industry resulting in the enactment of less stringent pesticide regulations: in one recent example, a 2016 report examined how political pressure was weakening and delaying bee-protection plans. Research, as well, has been a victim of the powerful pesticide industry: as public spending on agricultural research and development has fallen precipitously, industry now funds a much larger share. This means that they may decide not to investigate certain issues or may withhold results that are unfavorable to their products.
Reducing or eliminating pesticide use means turning instead to ecosystem management, using crop rotations and investment in soil health to build a population of beneficial microorganisms, insects and plants that will do the work of warding off diseases and weeds. There are many ways to do this and even a reduction in pesticide use can have huge benefits. A 2012 Iowa study, for example, found that simply adding an additional crop such as oats into the common rotation of corn and soybeans allowed farmers to use far less herbicide for weed control and to dramatically cut water contamination, while maintaining similar yields.
Integrated Pest Management (IPM) embraces a continuum of practices among farms of all sizes, beginning with identifying pests before spraying. For instance, an IPM farm may grow pest-resistant crop varieties, use predatory insects to kill plant-eating pests, employ mechanical pest traps and eliminate pest nesting areas by plowing under harvested crops. If further control is needed, IPM farmers would employ a targeted approach, using broadcast spraying only as a last resort.
Other techniques used by sustainable farms to reduce the need for pesticides include crop rotation, cover cropping, spring weed management, deciding whether to till the soil and when, deciding when to plant the harvest crop and other methods to disrupt the pest life cycle.