04
Jan
Work-Related Pesticide Exposure Puts Farmers at Risk of Cognitive (Intellectual) Harm
(Beyond Pesticides, January 4, 2024) A review published in the Journal of Neurosciences in Rural Practice finds an association between farmers’ pesticide exposure and cognitive impairment. Specifically, farmers suffer from attention deficit, lack of information processing, non-comprehension of verbal cues, slow processing speed, memory loss, sluggishness, speech difficulties, and impaired motor function. Additionally, the risk of adverse effects from exposure increases with time spent around pesticides, like in other occupational (work-related) settings. Although pesticide exposure may not be the only factor involved in cognitive impairment, exposure can work synergistically (together) with other factors, triggering neurotoxicity.
Pesticides play various roles in causing or exacerbating adverse health outcomes like neurotoxic effects and chemical damage to the brain. Numerous pesticides impair neurological function, especially for chronically exposed individuals (e.g., farmworkers) or during critical windows of vulnerability and development (e.g., childhood, pregnancy). Mounting evidence over the past years shows that chronic exposure to sublethal (low) levels of pesticides adversely affects the central nervous system (CNS) and neural receptors, such as connections between nerves, the brain, enzymes, and DNA. Specifically, researchers identify agricultural chemical exposure as a cause of many adverse CNS impacts and neurological diseases, including Alzheimer’s, amyotrophic lateral sclerosis (ALS), and Parkinson’s disease.
The researchers reviewed scientific articles published in the Scopus, Web of Science, ScienceDirect, and PubMed databases between 2000 and 2021, all related to “pesticides and cognition” and “pesticides and memory.” The review follows the preferred reporting methodology for systematic reviews and meta-analyses (PRISMA) guidelines. The review results find that ten studies match the specific criteria, with researchers highlighting the lack of comprehensive scientific literature on cognition (or the process of understanding and thought) and pesticide exposure. Half of the studies in the review measure organophosphate (OP) exposure impact on cholinesterase (enzymes necessary for the transmission of nerve impulses), confirming neurotoxicity.
Numerous occupational hazards are associated with chemical exposure, especially among individuals with occupations that involve regular exposure to xenobiotic (foreign substance) compounds. The agricultural sector has a long-standing history of synthetic chemical use, which disproportionally affects farmworkers’ health. Furthermore, farmworkers’ children are at greater risk as their immune system response is immature and especially vulnerable to stressors from pesticide exposure. Synthetic chemicals in pesticides can accumulate in bodies, causing an amalgamation of health effects. These effects can range from heightened risks of various cancers (e.g., prostate, hepatic, liver, etc.) and endocrine disruption to mental health problems (e.g., depression), respiratory illnesses (asthma), and many other pesticide-induced diseases. However, pesticide exposure is ubiquitous and not confined to where the chemicals are applied. Pesticides and other toxic chemicals can enter homes from the workplace via clothes, shoes, and home-based personal protective equipment (PPE) and accumulate residues on laundry, on carpets, and in art/house dust. Some cases demonstrate that levels of chemicals transported into the house can be high enough to cause an adverse health effect in a resident child or spouse.
Many pesticide compounds remain in soils, water (solid and liquid), and the surrounding air at levels exceeding U.S. Environmental Protection Agency (EPA) standards. These compounds have a global distribution, with evaporation and precipitation facilitating long-range atmospheric transport, deposition, and bioaccumulation of hazardous chemicals in the environment. The continuing ubiquity of pesticides concerns public health advocates as current measures safeguarding against pesticide use do not adequately detect and assess total environmental chemical contaminants. Therefore, individuals will continuously encounter varying concentrations of pesticides and other toxic chemicals, adding to the body’s burden of current-use chemicals.
Although studies demonstrate developmental and learning-based deficiencies from prenatal and early life exposure, this review is one of the few to highlight how pesticides can induce neurological issues that manifest over time, especially in chemical-intensive occupations like farming. However, many studies find a stark association between pesticide exposure and neurotoxic impacts that manifest as physical ailments like Alzheimer’s Disease, Dementia, Parkinson’s Disease, brain tumors, and more. Additionally, the notes state that anticholinesterase compounds like OPs are found in farmers and individuals close to agricultural areas, suggesting that direct and indirect chronic low-level exposure influences cognitive functioning. Overstimulation and continued activation of muscarinic and nicotinic receptors from acetylcholine accumulation are potential mechanisms involved in cognitive impairment from OP exposure. The review suggests “that future studies engage in similar projects, addressing the aspects mentioned above and assessing the specific categories of pesticides most harmful to cognition and the toxicological mechanisms by which they act. Finally, [they review] consider[s] the monitoring of the mode of pesticide application to be important, favoring lower occupational exposure of farmers to pesticides and, consequently, lower cognitive impairment.”
There is a lack of complete understanding of the etiology of pesticide-induced diseases, including predictable lag time between chemical exposure, health impacts, and epidemiological data. Pesticides themselves can possess the ability to disrupt neurological function. Pesticides’ impact on the brain is mainly of concern for chronically exposed individuals or during critical windows of vulnerability and development. Therefore, studies related to pesticides and neurological disorders can help scientists understand the underlying mechanisms that cause neurodegenerative diseases. Although occupational and environmental factors, like pesticide exposure, adversely affect human health, regulatory reviews are plagued by numerous limitations in defining real-world poisoning, as captured by epidemiologic studies in Beyond Pesticides’ Pesticide-Induced Diseases Database (PIDD) and Daily News Blog. The adverse health effects of pesticides, exposure, and the aggregate risk of pesticides showcase a need for a precautionary approach to regulating pesticides as more precise research is conducted on occupational and residential pesticide exposure—allowing more complete determinations. Existing information, including this study, supports the clear need for a strategic shift away from pesticide dependency. For more information on the effects of pesticide exposure on neurological health, see Beyond Pesticides’ PIDD pages on brain and nervous system disorders and other impacts on cognitive function.
Organic agriculture represents a safer, healthier approach to crop production that does not necessitate pesticide use. Beyond Pesticides encourages farmers to embrace regenerative, organic practices, consumers to purchase organic, and gardeners and municipalities to adopt organic land management practices. A complement to buying organic is contacting various organic farming organizations to learn more about what you can do.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
