30
Sep
Commonly Used Neurotoxic Pesticide Exposure Increases ALS Risk to Workers and Residents
(Beyond Pesticides, September 30, 2021) Individuals working or living in areas with frequent neurotoxic pesticide use experience more amyotrophic lateral sclerosis (ALS) incidences than the general population. The study, published in NeuroToxicology, finds a positive association between sporadic (non-genetic, spontaneous) ALS incidences among individuals exposed to neurotoxic pesticides.
Amyotrophic lateral sclerosis (or Lou Gehrig’s disease) is a neurodegenerative disease that affects the nerves in the brain and spinal cord. As many as 16,000 – 20,000 Americans live with this condition, which weakens muscle/motor function leading to loss of muscle control for walking, talking, eating/swallowing, and breathing. Severe ALS progression is fatal and has no current cure. Although research supports genetic factors play a role in disease etiology (cause), most ALS cases do not result from genetic inheritance. Several research studies demonstrate exposure to environmental or work-related toxicants (i.e., pesticides) predispose humans to the disease. With researchers predicting a global ALS incidence increase of 69% by 2040, identifying ALS’s causal factors are important to future research. Therefore, research like this showcases the importance of assessing aggregate health risks associated with toxic chemical exposure, especially for illnesses, which are not curable. In this study, the researchers note, “[W]e identified pesticides applied to crops in the area of residences associated with risk of ALS in a large healthcare claims network. Our analysis identified several herbicides, insecticides, and fungicides that have been implicated in the literature as being neurotoxic as potential ALS risk factors. Other less-studied pesticides that we identified also may warrant further investigation in the laboratory to assess mechanisms, their potential as etiologic contributors to sporadic ALS risk, and as targets for exposure mitigation.”
Using U.S. Geological Survey (USGS) data, researchers estimated potential exposure to pesticides, including insecticides, herbicides, and fungicides, at residential locations. The USGS data includes applications of 423 pesticides on crops and compared results to the geospatial diagnosis of approximately 26,000 ALS patients identified through the medical claims database, SYMPHONY Integrated Dataverse®. The study split patients from the SYMPHONY dataset into two groups, with researchers confirming results via residential information on ALS mortality from various state studies (e.g., New Hampshire, Vermont, Ohio). Both the study results and the confirmation studies validate pesticides have the highest positive association with neurotoxicity. Scientists find and 2,4-D (herbicide), glyphosate (herbicide), carbaryl (insecticide), and chlorpyrifos (insecticide) significantly increase ALS risk among residentially exposed populations.
ALS is a nervous system disorder that is progressive and fatal, affecting the brain, spinal cord, a vast network of nerves and neurons. The nervous system is responsible for many bodily functions, from the five senses to motor function. However, exposure to chemical toxicants, like pesticides, can cause neurotoxic effects or exacerbate preexisting chemical damage to the nervous system. The impacts of pesticides on the nervous system, including the brain, are hazardous. Mounting evidence over the past years shows that chronic exposure to sublethal (low) levels of pesticides adversely affects the central nervous system (CNS). Specifically, researchers identify agricultural chemical exposure as a cause of many adverse CNS impacts. In addition to CNS effects, pesticide exposure can impact a plethora of neurological diseases. These diseases include amyotrophic lateral sclerosis (ALS) and Parkinson’s disease, dementia-like diseases such as Alzheimer’s, and other effects on cognitive function.
The agricultural industry has a long-standing history of synthetic chemical use, which disproportionally affects farmworkers’ health. Farmworkers’ children are at greater risk as their immune system response is immature and especially vulnerable to stressors from pesticide exposure. Synthetic chemicals present in pesticides can accumulate in bodies, causing an amalgamation of health effects. Pesticides expose farmers, farmworkers, landscapers, and their families to heightened risks of various cancers (i.e., prostate, hepatic, liver, etc.), mental health problems (i.e., depression), respiratory illnesses (asthma), endocrine disruption, and many other pesticide-induced diseases. However, pesticide exposure is ubiquitous and not only confined to a field. The general population encounters pesticides from chemical applications and, most likely, residues in food and water resources.
Various studies indicate agricultural occupations as frontrunners for major pesticide exposure scenarios significantly associated with ALS development. However, this study is one of the few to evaluate ALS incidents among residential populations living near chemical-intensive agricultural fields. Like this study, past studies indicate that specific pesticide groups (e.g., herbicides) have higher associations with ALS risk and demonstrate neurotoxicity. For instance, herbicides glyphosate and 2,4-D increase the risk for neurological anomalies, including Parkinson’s disease. Particularly, glyphosate induces toxicity similar to paraquat, another herbicide associated with increased ALS risk. These compounds increase ALS risk through oxidization and reduction in ATP (adenosine triphosphate) levels that provide energy to cells in all organisms. The insecticide carbaryl is a notoriously dangerous carbamate insecticide with the ability to inhibit acetylcholinesterase (AChE), an enzyme important for the transmission of nerve impulses. Acetylcholine inhibition leads to overstimulation of neurotransmitters, resulting in muscle weakness, confusion, and paralysis, among other symptoms. Exposure to chlorpyrifos causes neurotoxicity among children, who may develop learning/developmental disabilities, as well as increasing Parkinson’s disease risk for all individuals living close to agricultural areas. These chemicals represent some of the most used compounds throughout the U.S. Even with residential uses of glyphosate and uses of chlorpyrifos on food crops (already banned for residential use) ending in February 2022, these compounds will remain in the environment for years, further contaminating the ecosystem. Moreover, the pesticide marketplace still contains many chemicals that cause neurotoxic health effects.
Although the study demonstrates ALS incidents are highest in the Midwest, where pesticide use is most chemically intensive, proximity to agricultural fields does not generally result in higher rates of ALS. In fact, geospatial analysis suggests certain chemical compounds used in agricultural areas, especially the Midwest, have neurotoxic effects that increase disease risk. However, scientists suggest future studies should focus on the relationship between exposure patterns and how that influences ALS incidents in specific regions. The researchers conclude, “Detailed residential history studies centered in high exposure areas would help elucidate the etiologic period. in situ sampling at varying distances from fields during various pesticide application events and weather conditions would aid exposure estimation efforts. Additional approaches such as behavioral questionnaires and biosample pesticide measurements in prospective longitudinal studies could provide a more complete picture of pre-diagnostic exposures.”
There is a lack of understanding on the etiology of pesticide-induced diseases, including predictable lag time between chemical exposure, health impacts, and epidemiological data. Exposure to pesticides can increase the risk of developing chronic illnesses that may be rare and disproportionately impact various populations. 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 pesticides, adversely affect human health, there are several 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 more precise research surrounding occupational and residential pesticide exposure in order to make complete determinations. However, current evidence suggests the need for a precautionary approach. Existing information, including this study, supports the clear need for a strategic shift away from pesticide dependency. For more information on pesticides’ harm to human health, see PIDD pages on brain and nervous system disorders (including ALS) and other diseases.
Beyond Pesticides advocates a precautionary approach to pest management in land management and agriculture by transitioning to organic. Buying, growing, and supporting organic can help eliminate the extensive use of pesticides in the environment and from your diet. A complement to buying organic is contacting various organic farming organizations to learn more about what you can do. For more information on why organic is the right choice for consumers and the farmworkers who grow our food, see Beyond Pesticides webpage, Health Benefits of Organic Agriculture. Those impacted by pesticide drift can refer to Beyond Pesticides’ webpage on What to Do in a Pesticide Emergency and contact the organization for additional information.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: NeuroToxicology
My husband used round up for years. I always told him not to but he did anyway. He just passed away this February 4th of ALS. He was diagnosed and passed within a years time. So sad that round and other toxins is still on the market for people to buy and possibly end there life unknowingly. Please stop toxins. Thanks
August 24th, 2022 at 7:58 pm