Pesticide Use in Agriculture: The Basics

More than a billion pounds of pesticides are applied in the United States every year. Yet, information regarding unintended effects, residue and risk are often not easy to understand. There are common misconceptions about the use of pesticides, including why they are used and their use in organic food production. In this article, we will cover some of the basics of pesticide use in agriculture. Future articles in this series will dive deeper into the role of food companies, some of the most controversial pesticides and ways to reduce pesticide use.

    Without management, pests can destroy entire crops causing huge losses for growers, retailers and consumers. Managing pests without pesticides can require more labor and time than most large-scale growers have.
    A pesticide is a substance designed to kill (or repel, deter or prevent) pests in order to reduce or prevent the resulting damage. There are many kinds of pesticides because there are many kinds of pests; herbicides kill weeds, fungicides kill fungus, insecticides kill insects, and so on.
    A pesticide product is made up of one or more active ingredients that are used to attack the pest, along with various “inactive” ingredients that are used for other purposes like attracting the pest or reducing pesticide drift. For example, Roundup contains the active ingredient glyphosate.
    Pesticide risk depends on two things: toxicity of the ingredients and exposure to the pesticide. Risks are highest when a pesticide is highly toxic and there is great potential for exposure.


Many farms in the U.S. rely on chemical intervention to fight pests and weeds. When farmers use pesticides in a conventional way, without restricting or regulating pesticide use, it can result in killing more pests than necessary, disrupting beneficial insect populations that feed on pests, pesticides drifting to adjacent areas, pesticide runoff into nearby water ways and farmers spending more money than necessary on pesticide products.

Integrated Pest Management (IPM) and Organic farming are two ways to consider non-chemical strategies and significantly reduce pesticide use in agriculture.

Integrated Pest Management (IPM) focuses on only using pesticides when the pest is present at high enough levels to cause economic damage, and after non-chemical strategies have failed. Non-chemical practices include planting pest-resistant crop varieties, attracting or releasing natural predators and managing the land in ways that do not attract pests in the first place. When pesticides are used, the least toxic options are use first, and application strategies that protect the health of the farmers and environment are prioritized.

Organic farming is another approach. Organic farming relies on natural principles like biodiversity and composting to produce healthy, abundant food. Many organic farmers use IPM practices to manage pests before reaching for pesticides, and can use only organic-approved pesticides, which, for the most part, are naturally derived, rather than synthetic. Organic farming does not mean that pesticides are eliminated entirely.


Humans are primarily exposed to pesticides occupationally, from applying pesticides or working in fields where pesticides have been applied. Certain pesticides have been proven to be detrimental to human health. Organophosphates, for example, have been linked to developmental problems in exposed children. Chlorpyrifos is an organophosphate that is still widely used in US agriculture, although it is being phased out in some states including California and was banned for use in homes in 2000. Glyphosate is another active ingredient under scrutiny for possible human health effects. Bayer, the company which acquired Monsanto, the maker of Roundup, will be paying more than $10 billion to settle thousands of lawsuits from plaintiffs claiming that glyphosate caused their cancer. According to estimates by the US EPA, occupational exposure poisons around 20,000 farm workers every year in the US, and rural and agricultural communities have higher rates of many different types of cancer and disease including non-Hodgkin lymphoma and leukemia.

Humans are also exposed to pesticides by consuming food, which can contain residues. Again, risk depends on the toxicity of the pesticide and the amount of exposure. For each active ingredient, the EPA determines the amount of pesticide residue considered safe for consumption (called a tolerance), and the USDA tests thousands of food samples annually for hundreds of different active ingredients. In the most recent testing, over 99% of samples had residues below the established tolerance, meaning the majority of dietary exposure to pesticides is below the level considered safe for consumption. While 1% is low, this still represents millions of servings of food per day with pesticide residues over the established tolerance.

Fruits and vegetables are an essential part of a healthy diet, containing fiber, which is linked to lower incidence of cardiovascular disease and obesity, and supplying vitamins and minerals. Most experts agree that the benefits of consuming fresh produce far outweigh the risks of pesticide exposure.


Pollinators are responsible for one out of every three bites of food and contribute billions of dollars to agriculture. By some estimates, there may be as many as 350,000 different pollinator species. Honeybees provide an estimated $20 billion in pollination services in agriculture, and native pollinators are incredibly important to certain crops such as apples and cherries.

According to the Xerces Society for Invertebrate Conservation, more than 90% of pollen samples from beehives in agricultural landscapes are contaminated with more than one pesticide. Pesticides can have lethal and sub-lethal impacts on pollinator species, and they vary in toxicity. Sub-lethal effects include impaired reproduction, navigation and memory. Neonicotinoids are one of the most widely used classes of insecticide and are highly toxic to pollinators. Some large retailers like KrogerALDI and Walmart are promising to phase out neonicotinoid use in their garden centers and from their store shelves. Other insecticide classes, like pyrethroids and organophosphates, and some fungicides are also highly toxic to pollinators.


Pesticides can have detrimental effects on organisms in the environment other than the pests they target. They can drift into surrounding areas by wind or be carried in water or soil from agricultural fields into waterways and groundwater. When pesticides move beyond their intended target, they can contaminate nearby homes, schools, neighboring farm fields or natural habitats. When pesticides contaminate water sources, there are potential impacts on any organism living in or using the water, including fish, aquatic invertebrates, pollinators or humans. In the United States, groundwater provides drinking water to about 50% of the population.

How a pesticide is applied impacts potential exposure in the environment, and therefore impacts risk. There are various application methods; some, like aerial applications, can increase the risk of drift, while others, like applications directly to the soil, can increase the risk of the pesticide moving off a field during a heavy rain.


There are a variety of strategies that farmers can use to reduce, or mitigate, pesticide-related risks. Buffer zones between an application site and an untreated area like a school, pollinator habitat or body of water are a common risk mitigation strategy. Vegetation planted into strips around bodies of water help to filter pollutants including pesticides, nutrients and sediment out of runoff before it enters the water. Other mitigation efforts include choosing pesticides with the lowest toxicity, wearing personal protective equipment and not applying pesticides before rain or when the wind speeds are too low or too high.


Pesticides can be harmful to humans, particularly the farm workers whose jobs create more opportunities for exposure than the general public, and to organisms in the environment that are not the intended target, including pollinators and other beneficial species. Understanding where the risks are is an important first step in assessing how to best mitigate them. While much of the risk seems to lay in farmers’ hands, we all have the power to impact the way that pesticides are used. Farmers use pesticides to grow the food that we all eat and to meet market demands for high yields of cosmetically perfect produce. Farmers have a history of changing and adapting to new challenges and market and consumer demands. Some advances already underway include a growing market for “imperfect” produce, companies investing in IPM and regenerative agriculture and consumers increasingly seeking transparency into how their food is grown. People have the power to drive change in the food system by making informed purchasing choices and supporting companies that share their values.