Man spraying pesticides on farm

Photo by Gilmer Diaz Estela via pexels

I remember being taught about the importance and use of pesticides in my agricultural science class back in high school. I had no knowledge of the health effects of pesticides. I thought pesticides were good. I mean, they help get rid of pests and insects that could damage crops and make us sick, so why not?

Just like me in high school, many people do not have the knowledge or a proper understanding of the impact pesticides have on our health. There’s so much talk about the positives of pesticides, but what’s the actual cost? The negatives of these substances far outweigh the positives. Let’s get into the details.

But can we afford to ignore the fact that we are now filling the environment with chemicals that have the power to strike directly at the chromosomes, affecting them in the precise ways that could cause such conditions? Is this not too high a price to pay for a sproutless potato or a mosquitoless patio?
– Rachel Carson: Silent Spring

What are Pesticides?

According to the Food and Agricultural Organization (FAO) of the United Nations, a pesticide is: “any substance, or a mixture of substances, of chemical or biological ingredients intended for repelling, destroying, or controlling any pest, or regulating plant growth.” 

Several types and classes of pesticides exist based on their use and chemical composition. As highlighted by the FAO, pesticides include all insecticides, herbicides, fungicides, rodenticides, molluscicides, wood preservatives, plant growth regulators, defoliants, and desiccants, among other substances. Each of these pesticides has a specific purpose: insecticides for insects, herbicides for plants, rodenticides for rodents, and so on.

Organochlorines, organophosphates, pyrethrins, pyrethroids, and carbamates are pesticides classified based on their chemical composition. For instance, the very popular pesticide, dichloro-diphenyl-trichloroethane (DDT), belongs to the pesticide class organochlorines. Due to the chemicals contained in them, they have different modes of action in humans.

Pesticides and Human Health

There has been a rise in pesticide use, especially for agricultural purposes, which has led to their increasing concentration in the environment. Pesticides aren’t just made of random stuff. They contain harmful substances, which multiple studies have shown to have negative health effects. A number of these substances in pesticides are carcinogenic (causing cancer), mutagenic (causing mutation), and endocrine disrupting. Take the commonly used herbicide, Roundup, for example. Roundup is known to have glyphosate as its main ingredient. The World Health Organization’s International Agency for Research on Cancer (IARC) identified glyphosate as a probable human carcinogen (Group 2A) in 2015. This is just one of the numerous chemicals found in pesticides.

Exposure and Health Effects of Pesticides

Exposure to pesticides occurs through several means. Exposure routes are generally classified into oral, inhalation, and dermal contact. Oral exposure to pesticides involves ingestion of pesticides and pesticide-contaminated substances such as food or water. To quote Rachel Carson, “The common salad bowl may easily present a combination of organic phosphate insecticides.”

The fact that every meal we eat carries its load of chlorinated hydrocarbons is the inevitable consequences of the almost universal spraying or dusting of agricultural crops with these poisons.
– Rachel Carson: Silent Spring

Inhalation of pesticides involves breathing in pesticide vapors, powders, or droplets, while dermal exposure can occur through pesticide spills, splashes, or direct skin contact with pesticide bottles, equipment, or clothing. Based on these exposure routes, two types of effects occur: acute and chronic. 

Acute health effects are usually short-term and immediate. They arise through exposure to pesticides over a short period of time and could be in the form of headaches, dizziness, irritation of the throat and nose, nausea, rashes, and other skin irritations. These effects are some of the symptoms of pesticide poisoning.

Over the years, there have been several cases of pesticide poisoning and pesticide-related deaths in several countries. In 2020, Boedeker, W., Watts, M., Clausing, P. et al. published a research article to “systematically review the prevalence of unintentional, acute pesticide poisoning (UAPP), and to estimate the annual global number of UAPP.” The study, which covered 141 countries, estimated that about 385 million cases of UAPP occur globally every year, including around 11,000 fatalities. Southern Asia had the highest estimated number of UAPP cases. 

In 2013, Ikpesu, Thomas & Ariyo, A.B. published a review article, Health Implication of Excessive Use and Abuse of Pesticides by the Rural Dwellers in Developing Countries: The Need for Awareness, which they highlighted some cases of pesticide poisoning in Nigeria.

Chronic health effects arise from exposure to pesticides in small or large doses over a long period of time. These effects are not immediate and occur several months or years after exposure. Chronic health effects associated with pesticide exposure include stillbirths, birth defects, and other developmental effects; chronic diseases like cancer; neuro, endocrine, and reproductive damage, among others. Overall, the effects pesticides produce in humans depend on the pesticide type, exposure route, and state of the individual (is the individual’s health already compromised?).

A systematic review by M. Sanborn et. al. in 2007 on the non-cancer health effects of pesticides showed strong evidence linking pesticide exposure with neurologic outcomes, genotoxicity, and reproductive effects such as birth defects, fetal death, and altered growth.

Vulnerable Population

Among the various human populations, infants, children, and older adults (the elderly) are the most vulnerable when it comes to pesticide exposure. In infants and children, organs and systems are still developing, and as such, they cannot detoxify and excrete these toxic substances. Children also tend to spend more time outdoors and on the ground, in addition to their frequent hand-to-mouth tendency, all of which exposes them to pesticides through various routes.

In mother-child cohort studies, pesticide residues have been detected in breast milk, spurring concerns about prenatal exposure. The result of a 2022 study on pesticides and thyroid function in pregnant women showed that “pesticide exposure during pregnancy can lead to thyroid hormonal imbalance, which can result in under-activation and over-activation of the gland, known as hypo- and hyperthyroidism, respectively.”

Another vulnerable group is agricultural workers due to their direct contact with pesticides on a day-to-day basis. Several studies have shown a correlation between chronic diseases like cancer and pesticide exposure in agricultural workers. It’s important to note that there are several environmental justice issues that have contributed (and are still contributing) to increasing the vulnerability of agricultural workers to pesticides.

How Can You Protect Yourself?

While pesticides are still in use, there are precautions and safety measures you can take to limit exposure and protect yourself. For starters, ensure you’re wearing the proper gear (masks, gloves) when applying pesticides. Exposure through ingestion of pesticide-contaminated food can be limited by purchasing organically grown food or growing your own food (unfortunately, these options aren’t readily available to everyone). While washing your fruits and food crops before consumption may not completely eliminate pesticides, research has shown that washing or peeling can reduce the concentration (eliminate residues).

The ultimate solution is to avoid using pesticides if you can. Adopt greener and more sustainable agricultural methods such as biological control and integrated pest management. Use traps and baits. If you live in an area where mosquitoes are prevalent, using a mosquito-treated net is a better alternative to insecticide.

What’s Being Done?

Due to the harmful effects of pesticides, efforts have been made by individuals, scientists, organizations, and governments to implement pesticide bans worldwide. On September 10, 1998, the Rotterdam Convention, an international treaty on hazardous chemicals and pesticides, was adopted, of which 72 and 165 countries are signatories and parties, respectively. The Rotterdam Convention covers a number of pesticides that have been banned in signatory countries.

In Nigeria, pesticides banned by the National Agency for Food and Drug Administration and Control (NAFDAC) include aldrin, DDT, dieldrin, and lindane, among others. 

Organizations like Earthjustice are actively working towards pesticide bans through legal action. In August 2021, the United States Environmental Protection Agency (EPA) finally banned the organophosphate pesticide, Chlorpyrifos, which is known to cause harm to the developing brains of children, as a result of a lawsuit by Earthjustice

The Natural Resources Defense Council (NRDC) is also actively involved in legal actions against agrochemical giants like Dow and Bayer, as well as against government agencies. Pesticide Action Network (PAN) International is another organization working towards phasing out pesticides. 

Unfortunately, while some pesticides have been banned in some countries, other countries are still actively using them. In some cases, laws aren’t strict on these banned pesticides, and as such, farmers and individuals still have access to these banned pesticides.

What Can You Do?

A lot of work needs to be done to completely phase out pesticides. To name a few…

You can create awareness concerning the health effects and risks associated with pesticides and pesticide use to enable more people to take action and make decisions that will impact their health positively. You can do this by sharing posts – blogs, articles, and more – covering pesticide issues and working – individually or in partnership with organizations – to educate agricultural workers and other people in rural communities on pesticide use.

At the community level, you can also work towards providing gear and protective equipment to farmers and farm workers. If you’re working at any level in government, you can work towards fueling policy change, which can result in bans, and enforcing current bans. You can also follow the science to stay updated, take an active part in campaigns, uplift voices in the space, and support organizations working on pesticide-related issues.


Here are some resources to help you learn more about pesticides, pesticide use, and actions to take:

Silent Spring by Rachel Carson


A 3-part bilingual series by Environmental Health News and palabra that examines the impacts of pesticide exposure on rural communities of color, and how they’re organizing for change.

Photo: EHN via Twittter

Podcast episode: Nayamin Martinez on organizing for farmworker justiceAgents of Change in Environmental Justice Podcast 

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