Exposure to Pesticides, Herbicides, & Insecticides: Human Health Effects

Pesticides and a wide variety of other chemicals persist in the environment and make their way into our everyday lives. Researchers have learned a great deal in recent years about how these toxicants affect the human population, where they originate, and how to improve our ability to detoxify in a toxic world. How can clinicians help patients manage the health risks of exposure to these ubiquitous substances?

Pesticides

Pesticide use is steadily increasing worldwide. Estimates suggest that global pesticide use grew 20% over the last decade and by 153% in low-income countries, specifically.¹ Organophosphate pesticides are one of the most extensively applied insecticides in the field of agriculture.² Approximately 40% of all pesticides produced and used commercially belong to this category.² Pesticides have been associated with short- and long-term effects on human health, including elevated cancer risks³ and potential disruption of the body’s metabolic functioning⁴ as well as the reproductive, immune, and nervous systems.^5-7 A 2022 systematic review and meta-analysis suggests that pesticide exposure is a major risk factor for metabolic syndrome.⁴ The analysis included 12 studies for a total of 6,789 participants, in which 1,981 (29.1%) had metabolic syndrome; overall exposure to pesticides and their contaminants increased the risk of metabolic syndrome by 30%.⁴

Exposure to pesticides predominantly comes from dermal absorption or through ingestion,² particularly through food—either on or within fruits and vegetables or in the tissues of fish and other animals we eat—through contaminated drinking water, or in the air we breathe.⁸ Respiratory pathologies may be related to occupational exposure to pesticides, including asthma, chronic obstructive pulmonary disease (COPD), and lung cancer.⁹ 

Insecticides & Herbicides

Neonicotinoid pesticides are a class of chemicals used as insecticides in agricultural settings and to target ticks and fleas on domestic pets. They have been detected in water, soil, dust, various crops, birds, and humans.¹⁰ Exposure routes for humans may include dietary and water intake as well as dust and pollen inhalation, and recent research indicates neonicotinoids and their metabolites may have adverse health effects such as oxidative stress, neurological symptoms, osteoporosis, and cancer.¹⁰

Organophosphates (carbon- and phosphate-containing molecules) are commonly used components of insecticides and herbicides in the US in all market sectors (i.e., agriculture, home and garden, industrial, commercial, and government).¹¹ Increased cancer risk has been associated with several organophosphate insecticides in epidemiological studies in the US, Canada, and Italy.^11,12 In addition to cancer, studies suggest that organophosphates may be tied to a wide variety of other negative health effects, including ADHD,¹¹ muscle weakness, and numbness.¹³

GLYPHOSATE

Use of the herbicide glyphosate began in the 1970s, and the chemical swiftly attained widespread use in modern agriculture, becoming the most commercially successful and widely used herbicide of all time as of 2016.¹³ Levels of glyphosate and its primary metabolite have been detected in the air, soil, water, and food.¹⁴

A formal review of glyphosate by the Department of Health and Human Services and the Agency for Toxic Substances and Disease Registry was published in 2020, finding some statistically significant links to some cancers like non-Hodgkin’s lymphoma.¹⁵ In addition, studies suggest that glyphosate may be associated with increased breast cancer risk.^16,17 In 2020, Bayer, the company behind Roundup weed killer, which contains glyphosate, settled most of the current and possible future lawsuits brought against it by plaintiffs alleging that glyphosate causes cancer.¹⁸ However, glyphosate continues to be used around the world, and the US Environmental Protection Agency continues to indicate that glyphosate products pose no risks of concern to human health when used according to label directions.¹⁹

Clinical Considerations

A large part of reducing a patient’s total toxic burden is through education—bringing the patient into a level of awareness regarding different sources of toxicants so they can avoid potential exposures. From here, many functional medicine strategies for detoxification have a nutritional focus to support the body’s natural processes for mobilization, biotransformation, and elimination of toxic compounds. 

Optimizing a patient’s nutritional status, ensuring adequate fiber and water intake, eating more phytonutrient-dense and diverse foods, and supporting liver function through targeted, nutrient-dense diets are all treatment approaches within the functional medicine model that may be part of a patient’s personalized therapeutic strategy.

At IFM’s Environmental Health Advanced Practice Module (APM), learn more about how your patients’
physical environment and toxicant exposure levels may impact their health outcomes and what lifestyle-based
tools may benefit their wellness path.