Parkinson’s disease is the fastest growing neurodegenerative disorder, surpassing dementia. Neurologists in Canada diagnose more than 25 patients per day, with expectation that that will rise to more than 50 per day by 2031. Over the last 25 years, the prevalence rates adjusted for age, increased by 22 per cent around the world, 30 per cent in India and 116 per cent in China. It is more prevalent in men who typically work more in industrialized occupations. There is definitely a genetic link through the LRRK2 gene, although this is only present in about 10 per cent of those with Parkinson’s. However, 90 per cent of people who develop Parkinson’s disease have no family history.

What then, is happening? More and more evidence is accumulating linking Parkinson’s disease to environmental toxins.

 1. Pesticides/herbicides/ insecticides: rotenone and permethrin, organochlorines, herbicides like paraquat and 2,4 dichlorophenoxyacetic acid. Paraquat, used since the 1960s for weed and grass control, has been banned in 58 countries. In the U.S., its use has doubled in the last three years, but its use is restricted to “licensed applicators.” Farmers who use rotenone and paraquat (sold as Gramaxone) have twice the risk of developing Parkinson’s than farmers who do not use these products. When inhaled, it is readily accessible to our brains. Despite all the evidence of its toxicity, it has been in use in Canada until February 2023. There was a class-action lawsuit last summer against the makers of Gramaxone. I believe it is still used in the U.S.

2. MPTP: a synthetic neurotoxin

3. Agent Orange: a chemical herbicide and defoliant

4. Manganese and other metals: manganese from welding, and exposure to lead

5. Solvents: Trichloroethylene is a solvent used for metal degreasing, dry cleaning, paint thinners and detergents.TCE, which has been used for over 100 years, is more widespread than you imagine with up to 30 per cent of American water supply being contaminated by it. It can evaporate into the air, spreading into peoples’ homes, schools and workplaces. Studies in Michigan alone have shown 7,300 contamination sites. Two years of exposure to TCE may increase the risk of PD by 70 per cent. When used for degreasing, it is heated in a tank to create a vapour that dissolves the grease, but it is also released into the atmosphere. If it enters soil or groundwater, it persists for years. TCE was used in a military camp, Camp Lejuene in Carolina. For the military personnel who spent at least three months there in the 1970s, their incidence of Parkinson’s 20 years later was 70 per cent higher than military veterans who spent their time in California. TCE is a nasty compound and has been recognized as a known carcinogen, especially causing kidney cancer, causing liver damage, headaches, nausea, skin irritation and confusion, etc. The U.S. has recently banned it. Canada does not manufacture this and has some regulations about its use, such as recommending personal protective equipment and reducing the duration of exposure, engineering controls to reduce exposure. Hopefully, they will follow the lead of the U.S. in banning this harmful chemical. In the Netherlands, where this and other toxic prod ducts are banned, they are seeing a decline in the incidence of Parkinson’s disease.

6. Organic pollutants: PCBs polychlorinated biphenyls were banned in the 1970s. Researchers have found high levels of this in the brains of those who have died from Parkinson’s. There seems to be some connection between the genetic potential that is realized on exposure to these chemicals. New and exciting research is being done. For example, researchers from UCLA Health and Harvard studied 10 pesticides that significantly damage neurons.

 In California, there are over 14,000 pesticide products with over 1,000 active ingredients registered for use. California exports its products widely. It found that certain combinations of products were more toxic. They were able to go back decades and calculate exposure in Parkinson’s patients who had participated in studies, discovering 53 possible toxins that had previously not been identified as harmful and are still in use. They then studied these in neurological tissue and came up with 10 leading chemicals. Harvard University and Brigham Young University are also looking into trifluralin, a herbicide used on cotton fields. Combinations with this chemical are more toxic. Ending Parkinson’s Disease: A Prescription for Action by Ray Dorsey, Todd Sherer, Michael Okun and Bastian Bloem is a book written by four neurologists who feel strongly about this subject. You may find it interesting!

Dr. Vicki Holmes is a Saskatoon retired family physician who has a special interest in Palliative Care and Women’s Health. She is passionate about sharing medical information with the public! (Vicki’s Photo: Memories by Mandy)

-Dr Vicki Holmes