Alzheimer's, Dementia, Parkinson's from Pesticides

Pesticide Exposure Diseases: Alzheimer’s, Parkinson’s, and Dementia

Pesticides, or specifically insecticides, work as a neurotoxin that causes enough neurological damage to the insects or “pests”, to kill them. Often, the amount applied to fresh fruits and vegetables is toxic enough to damage the nervous system of insects, but not enough to acutely harm a human. Studies are required by the U.S. Environmental Protection Agency, demonstrating the maximum amount of the pesticide that will not immediately harm most adults. This amount is called the “maximum residue limit”, and is based on recommendations from the World Health Organization.

Increased Risk For Alzheimer’s Disease

What is not taken into consideration is the chronic, long-term effects of pesticides on the human neurological system. Many neurodegenerative diseases are associated with pesticide exposure. In fact, the Canadian Study of Health and Aging found that pesticide occupational exposure increases the risk of dementia by double. One environmental factors study including nearly 18,000 people revealed found that those living in areas with high pesticide exposure (near farms) had a significant increase in the prevalence of Alzheimer’s Disease by 110%.

Increased Risk For Parkinson’s Disease

A new study done in California found that carbamate exposure increased the risk of developing Parkinson’s Disease by 455%! Specific pesticides like organophosphates and organochlorine pesticides increase the risk of Parkinson’s Disease by double. Fungicides, herbicides, and insecticides cause a higher risk for developing Parkinson’s Disease by 110% to 211%. In this California study, the individuals exposed to the pesticides either lived on a farm (environmental exposure) or worked on a farm (occupational pesticide exposure). Some farmers even wore personal protective equipment, however further studies are needed to determine the effectiveness of the PPE. Agricultural workers and others that live in rural areas often retreat indoors while nearby fields are being sprayed. Evidence is showing that being inside is not enough protection from pesticide exposure.

Pesticide Exposure Causes Oxidative Stress and Damage to Nerve Cells

Animal studies have demonstrated the neuropathological mechanisms of the pesticides, allowing them to cause Alzheimer’s Disease. One mechanism includes the pesticides causing oxidative stress on the body. Chronic oxidative stress causes neuron damage and death. The damaged neurons trigger an inflammatory response in the body. Alzheimers Disease is known as a disease of chronic system inflammation. Other previous studies demonstrate pesticide effects on AB peptides and tau, and their relationship to pathways in the aging brain. Lastly, there is some evidence that suggests that pesticides induce DNA damage. DNA damage more commonly causes cancer mutations, however chronic exposure in low dosage to pesticides also result in mutations that impair neuron (nerve) health and function. These mutations include somatic mutations, and variants in low allele frequencies.

Pesticides Play Important Roles in Genetic Memory Loss

There are some genetic risk factors that cause an early-onset Alzheimer’s Disease, when compared to the general population. Pesticide exposure to one generation can also cause health issues for the next generation. A previous study found that pregnant mothers with DDT exposure had daughters 4x more likely to develop breast cancer, and they had no family history of breast cancer. The study included 9,300 daughters born to mothers that had measurable serum levels of DDE in their blood samples during pregnancy. (DDT breaks down in the body to DDE.) This study shows that the pesticide DDT has transgenerational effects, harming generations never directly exposed to it. Eventually, after 30 years of use on our food supply, the US banned DDT in 1972 for public health concerns. Unfortunately, the damage has been done to a large number of people, and future research will be done to decrease the risk of cognitive decline of exposed children aging into older adults. DDT is not the only pesticide that has been linked to birth defects in prenatal and postnatal development. Early-life exposure to chlorpyrifos has been shown to affect children’s neurons, impair their learning, and reduce memory. Evidence has shown a decrease in IQ levels of children exposed to chlorpyrifos. This evidence is part of the reason that chlorpyrifos was banned in the United States in August of 2021, after 56 years of use.

Gut Health Has a Significant Association With the Risk of Alzheimer

The gut microbiome also affects brain health. The gut microbial can influence neuroinflammation, and gut microbiota dysbiosis (the reduction of microbial diversity) is known to occur in Alzheimer’s patients. Oddly enough, there is a fecal study done on Alzheimers patients that found this link. A number of reports have proven that pesticides like propamocarb (fungicide), glyphosate a.k.a. RoundUp (herbicide), aldicarb (carbamate insecticide), and chlorpyrifos, alter gut microbial and cause gut microbial dysbiosis. This study demonstrates that agricultural pesticide use plays another indirect role in Alzheimer’s Disease pathogenesis.

Heavy Metal Toxins Associated with Cognitive Impairment

There are also extensive studies that have shown a relationship between environmental toxins and many neurodegenerative disorders. Some of these toxins include heavy metals. There are some environmental risk factors to heavy metal exposure, including water contamination (Flint, Michigan), food contamination (like elevated mercury levels in fish), aluminum food storage and cooking utensils, and occupational risk factors like welding or soldering. Many researchers have gone through great lengths to exclude heavy metal exposures from their pesticide epidemiological studies. Data from the Hellenic Longitudinal Investigation of Aging and Diet Study in Greece, made sure to exclude heavy metal toxins with their reported association between a decrease in cognitive function and pesticide exposure.

Pesticides Affect Low Income Areas and Agricultural Areas

Low-income areas are also affected by pesticide exposure. A study done in Oakland, California found that more than half of the households reported using pesticides indoors for pest control and insect infestations in 2006. Dust samples were taken from homes and analyzed. Pesticide residues indoors have a prolonged presence, because there is no sunlight, rain, and temperature changing factors that promote the pesticide to degrade. The pesticide residues absorb into surfaces like furniture, carpet, and bedding, increasing pesticide exposure for household members and children. Young children are at the highest risk, as they have frequent hand-to-mouth contact with pesticide-covered surfaces.

What You Can Do to Avoid Pesticide Exposure

  • Use organic lawn sprays, or wear PPE when applying pesticides. Most people will use pesticides like RoundUp, Ready-to-Spray lawn insect killers (the ones that connect to your garden hose), or yard fog, without wearing gloves or a mask. While these pesticides work well for ants and mosquitos, they can harm pets and children. Use an organic pesticide (Amazon Link) instead of brands like Cutter, Off, Ortho, Spectricide, etc.
  • Eat a healthy ORGANIC diet. One study has shown that eating a strictly organic diet has reduced the amount of specific pesticides in their urine within 1 week. Organic foods have less chemicals applied, however to go completely pesticide-free you need your own garden!
  • Grow your own fruits and vegetables. Studies have shown that those who garden live on average 4.2 years longer than those who don’t. The lifestyle changes with starting a garden are 100% beneficial! Other recent studies have shown that young children that grow up gardening have better overall health, more diversified gut microbiome (better overall gut health), improved nutrient intake, and increased physical activity. They are also more likely to try nutritious foods when helping in the garden, when compared to store-bought foods.


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