02
Mar
Pesticide Exposure and the Link to Irritable Bowel Syndrome (IBS)
(Beyond Pesticides, March 2, 2023) Populations experiencing higher levels of environmental pollutant exposure, specifically pesticides, also experience a higher rate of irritable bowel syndrome (IBS), according to a study published in Environmental Toxicology and Pharmacology. IBS is a gastrointestinal disorder that causes abdominal pain or discomfort and changes in bowel behaviors. IBS affects 25 to 45 million individuals in the U.S., mostly female (two-thirds). Additionally, a quarter to half of all gastrointestinal-related visits are for IBS symptoms. Despite the unknown etiology of IBS, ample evidence demonstrates environmental contaminants, like pesticides, negatively affect the gut microbiota, causing a microorganism imbalance and resulting in inflammation associated with IBS. The gut, also known as the “second brain,” shares similar structural and chemical parallels to the brain. The microbiota in the gut plays a crucial role in lifelong digestion, immune and central nervous system regulation, as well as other bodily functions.
Although studies show how chemical exposures affect overall human health, a growing body of peer-reviewed scientific literature is now questioning how these toxic chemicals influence gut health and the subsequent occurrence of diseases. The study notes, “These findings may help to understand the relationship between pesticide exposure and IBS; however, more epidemiological and experimental research is needed to understand and confirm the role of these exposures in the development of IBS.”
This study assesses whether people experiencing continuous exposure to pesticides from areas near intensive agriculture have an association with the occurrence and risk of IBS. Using a case-control study over 20 years (2000-2021), researchers evaluate IBS diagnosis among over 1.5 million residents from Andalusia, southern Spain, and categorize geographical locations as two areas of high or low pesticide use. In the two areas, insecticides, including organophosphates [chlorpyrifos], N-methyl carbamates, macrocyclic lactones, neonicotinoids, and pyrethroids, are commonly used. Fungicides (i.e., [di] thiocarbamates, conazoles, dicarboximide), anilino-pyrimidines, and copper salts, and herbicides, including bipyridyl (paraquat, diquat), organophosphonates (glyphosate), chlorotriazine, and phenylurea, are commonly used in these areas. Over the 20 years, 18,807 individuals in the two areas of pesticide exposure received an IBS diagnosis. About 10,302 of these individuals live near areas of high pesticide use/exposure, while 8,506 individuals reside in areas of low pesticide use/exposure. However, IBS rates are significantly higher among individuals experiencing higher levels of pesticide exposure.
The intestines host a group of microorganisms that form the gut microbiome. These microorganisms, including bacteria, archaea, viruses, and fungi, play a crucial role in digestion, bodily function, detoxification, and immune and central nervous system regulation. Through the gut biome, pesticide exposure can enhance or exacerbate the adverse effects of additional environmental toxicants on the body. Since the gut microbiome shapes metabolism, it can mediate some toxic effects of environmental chemicals. However, with prolonged exposure to various environmental contaminants, critical chemical-induced changes may occur in the gut microbes, influencing adverse health outcomes. The impacts of pesticides on the human gut microbiome represent another pesticide assault on human health. Because the biome harbors between 10 and 100 trillion symbiotic microbes, pesticide exposure can affect some bacteria. The human gastrointestinal tract and its digestive processes (a.k.a., the “gut”) mediate the function of several systems. Dysfunction of the gut microbiome is associated with a host of diseases, including cardiovascular disease, some cancers, multiple sclerosis, diabetes, asthma, Crohn’s disease, Parkinson’s disease, and inflammatory bowel disease, as well as allergies, autism, depression, obesity, and other disorders or syndromes. Studies even find low levels of pesticide exposure during pregnancy or childhood cause adverse health effects, including metabolic disorders tied to gut microbiome disruption (dysbiosis).
The study highlights the increased risk of IBS in pesticide-heavy areas, particularly among women. In addition, the research suggests consideration of sex and age can act as predictors of IBS. Scientific studies demonstrate the male and female immune systems may differ as males may be more susceptible to infection, while females are more vulnerable to autoimmune disorders. IBS may be chronic or recurrent diarrhea, constipation, or both. For instance, in males, an infection can induce changes in the gut microbiome resulting in diarrhea-predominant IBS. However, IBS among female patients is more likely to affect immune function, including hormone balances associated with mood disorders and thyroid issues. For instance, in women, hormones, like estrogen, may play a role in gut sensitivity as there are gender differences in hormone activity involving the enteric nervous system that regulates intestinal activity. The study concludes, “The widespread use of pesticides has raised concerns about environmental pollutants, and policies to address these concerns should be implemented. However, more research supported to confirm our findings since epidemiological evidence is scarce even though data obtained in experimental animals supports the deleterious effects of pesticides on intestinal health.”
Pesticides themselves can possess the ability to disrupt gut function, especially for chronically exposed individuals (e.g., farmworkers) or during critical windows of vulnerability and development (e.g., childhood, pregnancy). As IBS incidence increases, it is essential to mitigate further exposure to disease-inducing pesticides that may exacerbate the onset of symptoms. For more information on the link between pesticides and autoimmune disorders, see the page on Immune System Disorders in Beyond Pesticides’ Pesticide Induced Diseases Database.
One way to reduce human and environmental contamination from pesticides is to buy, grow, and support organic. Numerous studies find that levels of pesticides in urine significantly drop when switching to an all-organic diet. Furthermore, given the wide availability of non-pesticidal alternative strategies, families, from rural to urban, can apply these methods to promote a safe and healthy environment, especially among chemically vulnerable individuals or those with health conditions. In addition to positive impacts on the human microbiome, organically grown food (e.g., milk, meat, strawberries, tomatoes, and a range of other foods) contain a much more diverse bacterial community than their chemical-intensively grown counterparts. For more information on why organic is the right choice for consumers and the farmworkers that grow our food, see the Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
