Pesticides and Neurological Disorders
Pesticide exposures are associated with numerous disorders. Some of those associations have been studied extensively but many are only suspected or somewhat likely. Research on the effects of different pesticides has obstacles such as metabolites being quickly eliminated or the long period of time between exposure to a chemical and the changes in tissues. Still, there is enough information to be able to guide decisions, such as whether to buy organic produce or what to use if you have insects in your house.
There are also a couple groups of people that are at high risk for some of the effects of pesticides. Infants, small children, and the elderly are particularly vulnerable. And considering the fact that pesticides are most often used on produce, people that try to eat the recommended number of fruit and vegetable servings each day are also susceptible to illnesses linked to pesticides. This will be the first of several articles on pesticide-associated diseases. It is a sad annotation that there are so many neurological disorders pesticides may cause that they warrant an entire article.
Infants and small children are so vulnerable because of their neurological development. Exposure to pesticides has been postulated to increase the chances of a child having an attention deficit disorder or developmental delay.
In “Dietary Intake and its contribution to longitudinal Organophosphorus Pesticide Exposure in Urban/Suburban Children,” by C. Lu, et al (Environmental Health Perspectives, vol. 116, #4, April, 2008) it is noted that levels of organophosphorus urine metabolites were higher in children during winter and spring. This is the time of year children are most likely to be fed fruits and vegetables imported from other countries. Since the Food Quality Protection Act of 1996, produce from the U.S. has had lower levels of such pesticides. Many countries don’t have these restrictions so their produce typically has more pesticide residues on them. The article also notes that children fed only organic produce usually don’t have pesticide metabolites in their urine, further underscoring that produce is the main source of pesticides.
There is also a suspected link between prenatal pesticide exposure and a group of neurological abnormalities called autism spectrum disorders. These disorders are more likely to develop if the mother was exposed to pesticides and had a folate deficiency while pregnant. This is from “Combined Prenatal Pesticide exposure and folic acid intake in relation to Autism Spectrum Disorders,” in Environmental Health Perspectives, 097007-1. Since 1 in 68 children is affected by one of these disorders, avoiding home and agriculture pesticides is certainly worth the extra effort.
The link between Parkinson’s disease is strong enough to also make changes. In “Association of Parkinson’s Disease and Its Subtypes with Agricultural Pesticide Exposures in Men: A Case Control Study in France,” (by F. Maisan, et al, in Environmental Health Perspectives, vol. 123, #11, November, 2015) there is a 60% increase in Parkinson’s Disease risk associated with insecticide exposure. The subtype of the disease it may cause is tremor-dominant Parkinson’s, the most common type. Because there is a 3 to 7-year lag between the destruction of nerve cells and motor (movement) symptoms, it took a while to uncover this likely cause.
An individual’s risk of developing Alzheimer’s disease also increases with pesticide exposure. In “Alzheimer’s disease linked to DDT pesticide,” (in Nursing and Residential Care, April 2014, p. 189), those with an elevated level of DDE, a metabolite of DDT, had a quadruple risk of getting this disorder. This risk is even higher in individuals with one or more genes associated with Alzheimer’s disease. Of note, having a gene for a disease doesn’t automatically mean the person will get it, and the field of epigenetics covers the multitude of ways genetic effects can be modified. Conversely, not having a gene associated with a disease doesn’t mean you won’t get it.
In Dennis Relojo’s article “On the Road to Therapeutics: Biological Mechanisms of Parkinson’s Disease and Alzheimer’s Disease,” (I-manager’s Journal on Nursing, vol. 5, #3, October, 2015) Alzheimer’s disease accounts for two-thirds of the cases of dementia and is the most common neurodegenerative disease. The second most common is Parkinson’s disease. Kind of makes organic produce, at least for produce from the “dirty dozen,” worth the extra money or effort, doesn’t it?