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A review published in Pesticide Biochemistry and Physiology finds organophosphate, organochlorine and pyrethroid pesticides have links to insulin resistance (IR) associated with metabolic disorders like diabetes, obesity, chronic kidney disease and hypertension.

Metabolic disorders are among the leading causes of morbidity and mortality, with over 11% (more than 37 million) of individuals in the U.S. having diabetes, and cases are growing by the millions annually.

Additionally, there is a rise in metabolic disorders among young people.

Studies find that low levels of pesticide exposure during pregnancy or childhood cause adverse health effects, including metabolic disorders tied to gut microbiome disruption (dysbiosis).

With increasing rates of diabetes and obesity, the two most prominent metabolic diseases in the review, studies like these highlight the importance of evaluating how chemical contaminants deregulate normal bodily function through metabolic changes.

To investigate the association between pesticide exposure and insulin-related metabolic disorders in humans, researchers searched the PubMed database for articles, performing a systematic review.

The review notes:

“IR is defined as a pathological state in which a higher-than-normal level of insulin is required to produce the optimal response in cells.”

The search generated 4,051 articles related to the topic. However, after excluding duplicates and irrelevant studies, 75 epidemiologic studies linked human exposure to pesticides and IR-related metabolic diseases remained.

In total, 30 articles find an association with diabetes, 20 with obesity, seven with hypertension (associated with cardiac issues), seven with chronic kidney disease, six with metabolic syndrome (i.e., high blood pressure, sugar and serum triglycerides) and three with polycystic ovarian syndrome.

The review highlights specific mechanisms of pesticide exposure associated with IR-related metabolic disorders, including liver enzymes and lipid profile alterations, weakening of intracellular insulin signaling from xenobiotic (a foreign chemical in the body) effects, oxidative stress and inflammation response to chemical exposure.

There are many pesticides linked with the growing global metabolic disorder incidence rates over the past few decades.

The World Health Organization, European Union and endocrine disruptor expert (deceased) Theo Colborn, Ph.D., classify over 55 to 177 chemical compounds (e.g., detergents, disinfectants, plastics and pesticides, etc.) as endocrine disruptors associated with notorious metabolic disorders like diabetes/obesity that can span generations.

The obesity rate is increasing and has been over the last five decades. Although general overeating and underexercising are attributed to obesity, researchers find the current obesity epidemic has alternative factors contributing to development.

Besides genetics, exposure to obesogenic compounds, like pesticides, can promote obesity development. These compounds routinely cause reproductive, cardiovascular and endocrine (hormone) issues among exposed individuals, especially farmers.

Obesogenic (obesity-causing) compounds affect the general population and future generational health. For instance, studies demonstrate that ancestral DDT exposure increases the risk of breast cancer and cardiometabolic disorder — promoting an epigenetic inheritance of obesity — up to three successive generations.

Although the U.S. banned DDT five decades ago, the insecticide (technically, its hazardous metabolite DDE) is still environmentally persistent in all ecosystems and is still used in some countries.

Like DDT, exposure to other persistent organic pollutants, like per- and polyfluoroalkyl substances, or PFAS, during pregnancy can increase cardiometabolic disorders, like obesity, diabetes and cardiovascular diseases, among offspring.

Since DDT/DDE residues, current-use pesticides, and other chemical pollutants contaminate the environment, exposure to these chemical mixtures can synergize to increase toxicity and disease effects

The study is a comparative analysis. This systematic review adds to the growing research indicating pesticides’ role in metabolic disorders.

Pesticides have long been linked to higher rates of diabetes, as a 2008 study on pesticide applicators in two U.S. states found that every pesticide investigated increased diabetes risk by over 50%.

A 2017 study zeroed in on one particular class of insecticides, carbamates, finding a propensity to adversely affect human melatonin receptors that regulate sleep, insulin secretion and glucose homeostasis, increasing the risk of diabetes.

A 2017 report commissioned by Gallup-Sharecare found that farmers recorded the second-highest rate of diabetes among all professions.

Additionally, a 2019 study from the University of California, Davis, found that South Asian immigrants exposed to higher rates of DDT also displayed higher rates of type 2 diabetes.

Regarding obesity, many pesticides are obesogenic compounds that directly impact hormone and receptor function and include pesticides like organochlorines, organophosphates, carbamates and pyrethroids, as mentioned in this study.

These chemicals can negatively affect reproductive function, nervous system function, metabolic/immune function, hormone-related cancers and fetal/body development.

The review concludes:

“Taken together, the link of pesticides with IR-related metabolic diseases can be a wide area of research from different aspects, including epidemiological evidences [of] cellular mechanisms weakening insulin signaling and preventing approaches.

“However, there is a need for studies to evaluate specific mechanisms by which different chemical groups of pesticides can develop IR-related metabolic diseases, especially those with increasing prevalence in the future.”

Pesticides themselves can possess the ability to disrupt metabolic function, especially for chronically exposed individuals (e.g., farmworkers) or during critical windows of vulnerability and development (e.g., childhood, pregnancy). Health officials identify diabetes as one of the most common chronic diseases.

Therefore, it is essential to mitigate preventable exposure to disease-inducing pesticides. For more information on the effects of pesticide exposure on autoimmune and metabolic health, see Beyond Pesticides’ Pesticide-Induced Diseases Database pages on diabetes, obesity, endocrine disruption and more.

Replacing dietary exposure to food grown in chemical-intensive agriculture with organic consistently reduces pesticide levels in one’s body. Preventive practices like organic can eliminate exposure to toxic metabolic disrupting pesticides.

There is an indication that maintaining lower levels of conventional, synthetic pesticides is likely to reduce the risk of developing chronic diseases like type 2 diabetes.

In addition to positive impacts on the human microbiome, organically grown food (i.e., milk, meat, strawberries, tomatoes and a range of other foods) contain a much more diverse bacterial community than their chemically grown counterparts.

Organic agriculture represents a safer, healthier approach to crop production that does not necessitate toxic pesticide use. Beyond Pesticides encourages farmers to embrace and consumers to support regenerative organic practices.

A complement to buying organic is contacting various organic farming organizations to learn more about what you can do.

Originally published by Beyond Pesticides