(Beyond Pesticides, February 1, 2024) A study published in Science of The Total Environment finds an insecticide ban would be economically beneficial in preventing Parkinson’s disease (PD). Despite differing pesticide exposure scenarios, PD risk lowers without pesticide exposure, especially insecticides that elicit neurotoxicity. In fact, a study published in 2023 notes high exposure to household pesticides, which are primarily insecticides, increases the risk of developing Parkinson’s disease (PD) two-fold.
There is a multitude of epidemiologic research on Parkinson’s disease demonstrating several risk factors, including specific genetic mutations and external/environmental triggers (e.g., pesticide use, pollutant exposure, etc.). However, several studies find exposure to chemical toxicants, like pesticides, has neurotoxic effects or exacerbates preexisting chemical damage to the nervous system. Studies suggest neurological damage from oxidative stress, cell dysfunction, and synapse impairment, among others, can increase the incidence of PD following pesticide exposure. Despite the widespread commercialized use of household pesticides among the general population, few epidemiologic studies examine the influence household pesticides, mainly insecticides or disinfectants, have on the risk of PD. Additionally, many studies demonstrate the association between PD onset and occupational (work-related) pesticide exposure patterns.
Parkinson’s disease is the second most common neurodegenerative disease, with at least one million Americans living with PD and about 50,000 new diagnoses annually. Alzheimer’s ranks first. The disease affects 50 percent more men than women, and individuals with PD have a variety of symptoms, including loss of muscle control and trembling, anxiety and depression, constipation and urinary difficulties, dementia, and sleep disturbances. Over time, symptoms intensify, but there is no current cure for this fatal disease. While only 10 to 15 percent of PD incidents are genetic, PD is quickly becoming the world’s fastest-growing brain disease. Therefore, research like this highlights the need to examine alternate risk factors for disease development, especially if disease triggers are overwhelmingly nonhereditary.
The study evaluated whether the of banning specific insecticides to reduce the PD burden in three counties in Central California (CA) is cost-effective. Researchers applied a cost-effectiveness analysis to estimate the impact and costs of banning seven insecticides (methomyl, dimethoate, carbaryl, acephate, malathion, naled, or oxydemeton-methyl) linked to PD in these counties. The analysis also investigated mixed exposures of these pesticides. The cohort included 65- and 66-year-olds living in these CA counties and estimated their incidence, costs, and reduction in quality-adjusted life-years (QALY) from developing PD over 20 years. After applying various scenarios, the analysis finds banning insecticides to reduce the occurrence of PD in three Central CA counties would be cost-effective compared to not prohibiting the insecticides. For the worst-case scenario depicting exposure to one insecticide, exposure to methomyl would result in a 12 percent increase in PD cases, increasing health-related costs by $72 million, with each additional PD patient incurring $109,327 in costs per QALY loss from PD. Overall, the highest PD burden and the cost associated with PD occurs from exposure to multiple pesticides simultaneously, particularly for oxydemeton-methyl, dimethoate, and carbaryl.
Parkinson’s disease occurs when there is damage to dopaminergic nerve cells (i.e., those activated by or sensitive to dopamine) in the brain responsible for dopamine production, one of the primary neurotransmitters mediating motor function. Although the cause of dopaminergic cell damage remains unknown, evidence suggests that pesticide exposure, especially chronic exposure, may be the culprit. Data is increasingly showing that cumulative exposures over one’s life increase the risk of developing Parkinson’s disease, and other factors such as genetics and exposure to other chemicals further elevate the threat. Strong links to this chronic condition are incredibly concerning, given emerging evidence of a Parkinson’s pandemic, predicting that rates of the disease will double between now and 2040. Occupational exposure poses a unique risk, as pesticide exposure is direct via handling and application. A 2017 study finds that occupational use of pesticides (i.e., fungicides, herbicides, or insecticides) increases PD risk by 110 to 211 percent. Even more concerning, some personal protection equipment (PPE) may not protect workers from chemical exposure during application. However, indirect nonoccupational (residential) exposure to pesticides, such as proximity to pesticide-treated areas, can also increase the risk of PD. A Louisiana State University study finds that residents living adjacent to pesticide-treated pasture and forest land by the agriculture and timber industry have a higher incidence of PD. Furthermore, pesticide residues in waterways and on produce present an alternate route for residential pesticide exposure to increase the risk for PD via ingestion. In addition to PD, pesticide exposure can cause severe health problems even at low residue levels, including endocrine disruption, cancers, reproductive dysfunction, respiratory problems (e.g., asthma, bronchitis), and other neurological impacts. Nevertheless, direct occupational and indirect nonoccupational pesticide exposure can increase the risk of PD.
This study is one of the first to assess the cost-effectiveness of banning insecticides to reduce PD burden. However, a 2021 cost-effective analysis has already shown that a ban on highly hazardous pesticides can reduce pesticide-related suicides by 28,000 deaths each year, at $0.007 per capita globally. Therefore, model-based cost-effectiveness analyses can help to estimate long-term cost benefits from reducing health effects from environmental hazards.
The analysis’s focus on insecticides is important as insecticides are the most commonly used household pesticides, and a history of high exposure to household pesticides increases the risk of PD regardless of the age at PD onset. However, herbicides like glyphosate, 2,4-D, and paraquat and fungicides like maneb can also increase the risk of PD, demonstrating that PD risk can occur regardless of pesticide category.
The cost-effectiveness analysis in this study is essential in comparing the impacts of banning pesticides according to different exposure scenarios, as it helps inform policymakers and stakeholders on regulatory decisions based on economic and long-term health consequences. Banning the seven insecticides in this analysis is a cost-effective solution when considering PD-associated costs, suggesting that reducing PD burden costs offsets the ban’s cost. However, the study may underestimate the impact of multiple insecticide exposures. Thus, the cost-effectiveness of withdrawing insecticides would be even more significant since it would reduce PD risk from single pesticide exposure while eliminating the interaction with other pesticides.
The study highlights that farmers and the agricultural industry may experience immediate financial loss when eliminating insecticide use to switch to another product, which needs to be evaluated against the long-term health benefits and the costs or burden of disease. Thus, the researchers note that “a real-world-based cost-effectiveness analysis is crucial for guiding policies that balance public health priorities and less apparent long-term benefits against economic aspects related to agricultural practices.”
The study concludes, “[T]he population-level long-term health benefits and health savings would outweigh the financial losses due to the pesticide ban. [This] study adds a financial dimension to the understanding of environmental health impacts, particularly on vulnerable populations like the elderly in rural communities. Policymakers and agricultural industries should consider healthcare costs when deciding to continue using certain pesticides and consider immediate action to reduce harm. [… The researchers would] like to highlight the necessity for further research to expand these findings to other geographic areas and pollutants to enrich and support a broader discourse concerning pesticide regulation and public health.”
Parkinson’s disease has no cure, but preventive practices, like organic agriculture or Parks for a Sustainable Future, eliminate exposure to toxic PD-inducing pesticides, especially as a 2023 study points to PD as a predominantly environmentally induced disease. Considering health officials expect Parkinson’s disease diagnosis to double over the next 20 years, mitigating preventable exposure from disease-inducing pesticides becomes increasingly essential. For more information on the effects of pesticide exposure on neurological health, see the Pesticide-Induced Diseases Database (PIDD) pages on Parkinson’s disease, dementia-like diseases, such as Alzheimer’s, and other impacts on cognitive function.
Organic agriculture represents a safer, healthier approach to crop production that does not necessitate toxic pesticide use. Beyond Pesticides encourages farmers to embrace regenerative, organic practices and consumers to purchase organically grown food. A complement to buying organic is contacting various organic farming organizations to learn more about what you can do. Those affected by pesticide drift can refer to Beyond Pesticides’ webpage on What to Do in a Pesticide Emergency and contact the organization for additional information. Furthermore, see Beyond Pesticides’ Parkinson’s Disease article from the Spring 2008 issue of Pesticides and You.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Science of The Total Environment
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