Pesticide

Pesticides are substances used to control pests. They include herbicides, insecticides, nematicides, fungicides, and many others. Herbicides are the most common, making up about half of all pesticide use around the world.

Most pesticides are used to protect plants, helping crops grow by keeping away weeds, fungi, and insects. They work by using a chemical or a biological agent like a virus, bacterium, or fungus to stop or drive away pests.

Pesticides help increase how much food we can grow, but they can also be dangerous. Sometimes they may harm humans or other living things, which is why it’s important to use them carefully.

Definition

The word pesticide comes from old words meaning “plague” and “kill.”

The Food and Agriculture Organization says a pesticide is any substance or mix of substances used to stop, hurt, or control pests. Pests can be tiny creatures that spread sickness, plants or animals that we don’t want, or anything that damages food, wood, or animal feed when it is being made, stored, or moved. Pesticides can also help plants grow better, make leaves fall off, or thin out fruit so it doesn’t fall too early. They are also used on crops before or after harvesting to keep them fresh during storage and transport.

Pesticides can be sorted by what they target, like herbicides for plants, insecticides for bugs, fungicides for fungi, and others. Some come from living things and are called biopesticides. They can also be grouped by how they work in the body of a pest, which helps manage when pests become resistant to them. Some pesticides move inside plants to work, while others stay on the surface. They can last a long time in the world or break down quickly. Some lasting pesticides, like DDT, were stopped from use many years ago, except in special cases like fighting malaria vectors.

History

For a long time, people used simple substances from minerals and plants to keep pests away. These included things made from copper, arsenic, and sulfur, as well as plant-based materials like pyrethrum and nicotine. Some of these are still used today in farming without synthetic chemicals.

In the 1940s, scientists created new man-made chemicals such as DDT and 2,4-D. These were very effective but later caused problems because they stayed in the environment and moved through the food chain. This issue was highlighted in the book Silent Spring. Because of this, many countries banned DDT and other similar chemicals in the 1970s.

Over time, farmers have found smarter ways to use these chemicals. They now follow a method called Integrated Pest Management, which means they only use pesticides when necessary. This helps protect crops while using fewer chemicals. With new crop varieties and genetically modified plants, fewer insecticides are needed today. Organic farming, which avoids synthetic chemicals, has also grown in popularity.

Development of new pesticides

Scientists work to create new pesticides that work better and are safer for the environment. They test many different substances to see if they can stop pests like insects, fungi, or plants. Some of these substances come from nature, while others are made in laboratories.

If a substance shows promise, it goes through many tests and changes to make sure it is safe and effective. Before a new pesticide can be used, it must meet strict rules set by regulatory authorities. This process can be very expensive and take a long time. Because of this, finding new pesticides has become more challenging in recent years.

Uses

Pesticides are used in agriculture and many other places to control harmful creatures. They help stop mosquitoes from spreading diseases like West Nile virus, yellow fever, and malaria. They can also remove bees, wasps, or ants that might cause allergic reactions. Insecticides protect animals from sickness caused by parasites like fleas. Pesticides keep food safe by stopping moldy food or diseased produce from making people sick. Herbicides clear weeds from roadsides and can remove invasive weeds that harm the environment. They are also used in ponds and lakes to control algae and plants that make water look bad or smell bad. Pesticides protect buildings from damage by pests like termites and mold. They are used in stores to keep rodents and insects away from food. They are also used on lawns and golf courses to keep them looking nice.

Integrated pest management uses many ways to control pests and is used in places like Indonesia, China, Bangladesh, the U.S., Australia, and Mexico. This method looks at how actions affect nature so balances are kept.

Every use of a pesticide has some risk, but using them properly makes these risks small enough for groups like the United States Environmental Protection Agency and the Pest Management Regulatory Agency of Canada to say it is okay.

DDT was sprayed inside houses to fight malaria mosquitoes since the 1940s, and the World Health Organization suggests this method. But DDT and other similar pesticides have been banned in most countries because they stay in the environment for a long time and can be harmful to people. DDT is not as effective now because mosquitoes have become resistant to it.

Amount used

In 2023, farmers around the world used about 3.73 million tonnes of pesticides to help protect their crops. This amount was a little smaller than the year before but much larger than what was used ten years ago. Brazil used the most pesticides, more than any other country. The United States was the second largest user.

The amount of pesticides used depended on how much land was being farmed. For example, Vietnam used much more per area than Russia. In the United States, the use of a certain type of pesticide has gone down a lot since 1980, mainly because farmers changed the way they grow corn.

Benefits

Pesticides help farmers grow more food. When farmers use pesticides, they can get 12% to 27% more crops. Without pesticides, crop yields drop by about 10%. Using pesticides can also help keep food prices lower and create jobs.

Pesticides have two kinds of benefits. The first kind are direct gains, like better crop yields and healthier plants and animals. The second kind are longer-term benefits, such as saving lives by controlling diseases like malaria and protecting structures from damage. Farmers also benefit because they can grow more crops and sell them year-round, which helps keep food affordable for everyone.

Disadvantages

Using pesticides can affect both the environment and human health. While rules and education aim to protect people from pesticide misuse, not all misuse can be stopped. Using fewer pesticides and choosing safer ones can help lower risks to people and nature.

Health effects

Most health worries about pesticides come from direct use, like by farmers or gardeners. Health risks from tiny amounts of pesticides left on fruits and vegetables are thought to be very small.

Using pesticides at work can sometimes harm health, possibly affecting growth and causing long-term sickness. Some studies link certain pesticides to changes in the brain and nervous system. There is also some evidence that some pesticides might affect birth outcomes, though more research is needed.

Environmental effects

Pesticides can harm the environment in several ways. Often, they do not only affect the pests they are meant for but can spread to air, water, and soil. This spread, called pesticide drift, can pollute areas far from where the pesticide was used.

Pesticides can reduce the number of helpful insects and animals, harm birds, and threaten plants and animals at risk of disappearing. Sometimes, pests can become resistant to pesticides, meaning stronger or more pesticides are needed, which creates more pollution.

Economics

Pesticides help increase food production but also come with costs. In the United States, the benefits of pesticides in farming are much greater than the health and environmental costs. However, registering a new pesticide can take many years and cost a lot of money. Farmers and pesticide companies share these costs.

Resistance

When we use pesticides, there is a chance that pests can become resistant to them over time. This means the pesticides might not work as well in the future. There are ways to apply pesticides that can help slow down this resistance. Also, some natural aspects of the pests and their environment can play a role in how quickly resistance develops.

Alternatives

Alternatives to pesticides are ways to control pests without using chemicals. These include changing how we grow plants, using natural enemies of pests, and even using technology. For example, growing different plants together or changing when and where we plant can help keep pests away.

Other methods involve using natural organisms that fight pests, such as certain fungi, bacteria, or viruses. There are also ways to stop insects from having babies by releasing sterilized males. These methods can be just as effective as chemicals and are often safer. Some studies show that using compost or special plant foods can also help control pests and improve crop growth.

Types

Biopesticides

Main article: Biopesticide

Biopesticides are special kinds of pesticides made from natural things like animals, plants, bacteria, and minerals. Examples include canola oil and baking soda, which can help control pests and are considered biopesticides. Biopesticides are divided into three main groups:

• Microbial pesticides made from bacteria, entomopathogenic fungi, or viruses (and sometimes include things made by bacteria or fungi). Entomopathogenic nematodes are also often included, even though they are made of many cells.
• Biochemical pesticides or herbal pesticides are natural substances that help control pests and diseases.
• Plant-incorporated protectants (PIPs) have genes from other species added to their own genes (i.e. GM crops). Their use is debated, especially in many European countries.

By pest type

Pesticides can also be grouped based on the type of pests they target.

Regulation

International

In many countries, pesticides need to be approved by a government agency before they can be sold or used.

Around the world, most countries have rules about how to store pesticides safely, and many also have rules for getting rid of old pesticides properly. In 1985, the United Nations Food and Agriculture Organization created a set of guidelines to help countries make and follow better rules for pesticides. These guidelines were updated in 1998 and 2002 to help protect people and the environment.

United States

In the United States, the Environmental Protection Agency (EPA) makes sure pesticides are safe to use. They check that pesticides do not harm people or the environment, especially children. All pesticides go through many tests before they can be used. Some pesticides are too dangerous for everyone to use, so only trained professionals can handle them.

Besides the EPA, the United States Department of Agriculture (USDA) and the United States Food and Drug Administration (FDA) also set rules about how much pesticide can be left on food.

Canada

Main article: Pest Management Regulatory Agency

EU

Main article: Regulation of pesticides in the European Union

European Union laws have banned some of the most dangerous pesticides. In 2023, European leaders decided to cut pesticide use in half by 2030, especially the most harmful ones, and to encourage farmers to find safer ways to protect their crops.

Residue

Pesticide residue is the small amount of pesticides that can stay on or in food after it has been treated. Rules are made to keep these amounts safe for people to eat. These rules help make sure that the food is safe by waiting a certain time before harvesting crops that have been treated.

Some older pesticides are no longer used because they stay in the soil for a very long time. But, these older pesticides can still be found in very small amounts in people today. In 2016, most food in the United States either had no pesticides left or had very little, well below the safe levels set by rules.