Pesticides (original) (raw)

A pesticide is any substance used to kill, repel, or control certain forms of plant or animal life that are considered to be pests. Pesticides include herbicides for destroying weeds and other unwanted vegetation, insecticides for controlling a wide variety of insects, fungicides used to prevent the growth of molds and mildew, disinfectants for preventing the spread of bacteria, and compounds used to control mice and rats.

Table of Contents

Introduction

Pesticides

Pesticides kill, repel, or control forms of animal and plant life considered to damage or be a nuisance in agriculture and domestic life. Used broadly, the term includes these types of chemicals:

Over 800 pesticides are registered for use in the United States, some of which are used in large quantities and may pose risks for a variety of health problems.

Because of widespread use, people are exposed to low levels of pesticide residue through a variety of ways in their homes, schools, workplaces, and other facilities. Pesticides can get inside a body from eating, drinking, breathing them in, and through skin contact.

What is NIEHS Doing?

Agricultural Health Study

Since 1993, NIEHS has led the Agricultural Health Study (AHS), which gathers data on more than 89,000 farmers and their spouses on farms in North Carolina and Iowa. It is funded by NIEHS and the National Cancer Institute in collaboration with the U.S. Environmental Protection Agency and the National Institute for Occupational Safety and Health.

AHS research has led to more than more than 200 papers published in the peer reviewed scientific literature. These studies have linked pesticides to risk for Parkinson’s disease, thyroid disease, diabetes, kidney diseases, rheumatoid arthritis, and shingles (herpes zoster), among other health issues. Evidence suggests that children are particularly susceptible to adverse effects from exposure to pesticides, including neurodevelopmental effects.

Pesticides and Sense of Smell (PASS) Study

This study is related to the Agricultural Health Study. Loss of the sense of smell is common with aging, especially in patients with Parkinson’s and Alzheimer’s diseases. Study participants who reported a high pesticide exposure event, such as getting a large amount of pesticides on their skin, were more likely to report a loss of sense of smell 20 years later. Such high pesticide exposure events, especially when clean-up was delayed and skin contact or inhalation was involved, may cause long-lasting damage to our sense of smell.

Researchers funded by NIEHS also reported that inhalation of the widely used pesticide paraquat reduced the sense of smell in male mice for several months.

Pesticides and Parkinson’s Disease

Parkinson's Disease (PD) is the second most common condition involving loss of brain cells, or neurons, such as those that produce the brain signaling chemical dopamine. Dopamine is important for many functions, including movement. More than 10 million people worldwide are living with PD, according to the Parkinson’s Foundation. Yet it is among the least inheritable diseases — meaning that the causes, to a large extent, are likely environmental.

Pesticides may directly or indirectly disrupt the biological pathways that normally protect brain cells selectively attacked by PD.

NIEHS-funded researchers found that the accumulation in the brain of DOPAL, a toxic residue of dopamine, can increase the risk of PD. Pesticides such as dieldrin and benomyl can cause degeneration of dopamine and inhibit the biological mechanism that reduces DOPAL to a less toxic acid — thus increasing the risk of developing PD.

The Parkinson’s Disease, Environment, and Genes study showed that some pesticides, including paraquat, maneb, ziram, benomyl, and several organophosphate pesticides, including diazinon and chlorpyrifos, contribute to PD onset and progression. Other studies have confirmed PD-related motor, cognitive, or depressive symptom progression with such pesticides.

The National Toxicology Program (NTP) has also identified paraquat exposure as a contributor to PD.

Protective glove use and hygiene practices appeared to reduce risk of PD.

NIEHS Success Stories in Research Translation

Protecting Arctic Communities (1MB) - This NIEHS translational research story shows how the community-based organization Alaska Community Action on Toxics (ACAT) works with scientists to address health risks from contaminant chemicals. The ACAT team has used their research findings to inform local, state, federal, and international policies about toxic chemicals and protect populations who are most likely to be affected.

Protecting Children From Pesticides (1MB) - This translational research story shows how NIEHS-funded researchers worked with pregnant mothers, children, and childcare providers to understand the effects of pesticide exposure on asthma. The team developed toolkits that give clear instructions on how to use integrated pest management and describe its value.

Protecting Farmworkers and Families From Pesticide Exposure (1MB) - This NIEHS translational research story shows how researchers worked with agricultural communities to prevent exposure to organophosphate pesticides. Researchers incorporated community feedback to create pesticide risk messages that are easily understood.

Understanding Pesticide Toxicity (1MB) - This NIEHS translational research story shows how a research team, funded partly by NIEHS, recommended policy reforms to minimize people’s exposure to the pesticide chlorpyrifos. The U.S. Environmental Protection Agency has banned the use of chlorpyrifos on all food sold in the country.

Other Studies

CHAMACOS
unded by NIEHS and other federal agencies, the Center for the Health Assessment of Mothers and Children of Salinas (CHAMACOS) study, at the University of California, Berkeley, is the longest running longitudinal birth cohort study of pesticides and other environmental exposures among children in a farmworker community. CHAMACOS means “little children” in Mexican Spanish.

CHAMACOS research covers:

Research shows young children who are exposed to glyphosate, an herbicide that controls weeds and grasses, may suffer from liver inflammation and metabolic disorder later in life. Study participants lived in Salinas Valley, California. The research suggests that a child’s lifetime exposure to the popular weed killer may increase the risks in young adulthood of conditions that could lead to liver cancer, diabetes, and cardiovascular disease.

Infants’ Environmental Health Study (Infantes y Salud Ambiental — ISA)
ISA is a community-based cohort of nearly 300 mothers and their children (5-7 years old) living in rural underserved areas of Costa Rica. It is funded in part by NIEHS and coordinated by the Central American Institute for Studies on Toxic Substances at Universidad Nacional in Costa Rica. It is one of the first comprehensive examinations conducted in Central America on the health effects of pesticide exposure. Researchers have found that pesticide exposure during pregnancy can lead to thyroid hormonal imbalance, which can result in a number of health problems.

A different study, the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) is an ongoing investigation of environmental factors that contribute to preterm birth. This study found that glyphosate was associated with preterm birth in the first study of a glyphosate byproduct and birth outcomes.

NTP Developmental Neurotoxicity Health Effects Innovation Program
Recognizing the need for a new framework to evaluate chemicals with potential to affect brain development, NTP created the Developmental Neurotoxicity Health Effects Innovation program. It expedites research on industrial and commercial chemicals, such as pesticides, that might play a role in conditions such as attention-deficit hyperactivity disorder (ADHD) and autism spectrum disorder. One pesticide being examined is chlorpyrifos, a common pesticide, early exposure to which may cause long-term damage to the function of a key brain signaling pathway.

Further Reading

Stories from the Environmental Factor (NIEHS Newsletter)

Fact Sheets

Additional Resources