(Beyond Pesticides, August 8, 2023) A study published in PLOS ONE finds a pointed, positive association between chronic kidney disease (CKD) of unknown origins (CKDu) and the use of indoor pesticides. Longer exposure times have an especially detrimental impact on kidney function, even among individuals without underlying diseases like diabetes mellitus and hypertension. The innovation of this study’s purpose highlights the lack of exposure-related studies on kidney health outcomes associated with indoor pesticide use.
Although CKD risk increases with age and is associated with other health factors like smoking, heart disease, and diabetes, cases without clear causes are increasingly common, indicating that environmental factors are likely playing a role. Over six million people in the U.S. have kidney disease (i.e., nephritis [kidney inflammation], nephrotic syndrome [improper protein filtration], and nephrosis). Although many studies find an association between exposure to outdoor environmental contaminants like pesticides and CKD, the association between CKDu and indoor pesticides—whose uses are more commonly concentrated in homes— remains unclear. Therefore, studies like this highlight the need for comprehensive information regarding co-occurring exposure patterns and disease prevalence that can have global implications.
The study notes, “Previous research has highlighted the potential harm of pesticides on kidney function, particularly in outdoor uses. Our findings raise concerns about the impact of indoor pesticide use on kidney function in individuals without common risk factors for CKD. Further, longitudinal studies are needed to evaluate the effects of indoor pesticide use on kidney health outcomes and to determine safe dosage levels for these substances.”
The growing epidemic of CKDu globally, especially among residents of agricultural communities, has scientists questioning the cause of CKDu and if pesticide use plays a role in disease prognosis. Using a population-based study, the Prospective Epidemiological Research Studies in Iran, the researchers tested individuals to estimate a glomerular filtration rate (eGFR) of less than 60 ml/min/1.73 m2 to indicate CKDu. Researchers obtained data on indoor pesticide use and duration of exposure through a questionnaire. After excluding subjects with diabetes mellitus and/or hypertension, estimated glomerular filtration rate (eGFR) between 60-89 ml/min/1.73 m2, and unavailable creatinine measurement, 1079 subjects remained in the study.
The results find that the prevalence of CKD in females was 2.6 times higher than in male subjects. The duration of exposure to indoor use of pesticides is significantly higher in subjects in the CKDu group than those in the non-CKDu group (50.3% and 40.8%, respectively). Additionally, single women participating in low physical activity, with triglyceride (TG) levels of more than 150 mg/dl, a body mass index (BMI) of more than 25 kg/m2, a non-smoker, and high pesticide exposure time for indoor pesticide use have a greater association with CKDu. The most significant factors in the multivariable analysis are age, sex, TG levels of more than 150 mg/dl, pesticide use, and high pesticide exposure time.
Many studies document pesticides’ impacts on kidney function, finding a range of chemicals linked to kidney damage. Even among the 40 most commonly used lawn care pesticides, 80 percent have associations with kidney or liver damage. These chemicals include widely used herbicides like glyphosate and organophosphate insecticides like malathion. Glyphosate was initially created as a chelating agent (bonding ions and molecules to metal ions) to form strong chemical bonds with metals.
In 2013, the Center for Public Integrity highlighted that glyphosate bonds with toxic heavy metals in the environment, such as cadmium and arsenic, forming stable compounds. These compounds are present in food and water for consumption and do not break down until they reach the kidneys. Thus, farmworkers exposed to glyphosate are likely to have these toxic metals in their kidneys. In 2019, researchers Sararath Guanatilake, MD, and Channa Jayasumana, Ph.D., were awarded the Freedom and Responsibility Award from the American Association of the Advancement of Science for their work uncovering the link between glyphosate and chronic kidney disease.
Another pesticide, malathion, has recently been cited for its close link to kidney damage. Individuals may encounter malathion through consuming food produced in chemical-dependent agriculture or drinking water or as a result of drift from pesticide application and public use. A study published in October 2021 found significant associations with malathion exposure, low kidney function, and increased risk of CKD. A 2022 study found that 68 percent of well water sampled in Sri Lanka (south-east Asian) contains at least one pesticide above the global drinking water guidelines, including the organophosphate insecticide diazinon. Individuals reporting drinking well water during their lifetime have significantly (6.7 times) lower kidney health on average than those who never drank well water. With researchers now finding evidence that pesticide-contaminated well water may be a source of kidney dysfunction, it is evident that pesticide mitigation measures must protect those in intensive agricultural areas from pesticide exposure. While there is a desire to neatly separate bad from good actors in environmental ‘mysteries,’ including chronic kidney disease and the ongoing decline of pollinators, it is evident that in a world awash in chemicals, it is a combination of these factors that is likely at play. Therefore, protection from pesticide exposure is critical for those working and living in chemical-intensive agricultural areas.
The study finds longer exposure to indoor pesticides is more frequent among patients with CKDu, with a history of indoor pesticide use having 1.36 times higher odds of CKDu. Although previous studies report the prevalence of CKDu is 1.7 times higher among women than men, this study highlights a greater prevalence of CKDu (2.6 times higher) among female patients, demonstrating a possible uptick in CKDu odds. In fact, the study used multivariable models, including indoor use of pesticides (model 1) and duration of exposure to indoor pesticides (model 2), to determine the odds of having CKDu, with the disease odds increasing 7.5 and 8.6 times among the respective models. The study suggests the disproportionate risk of CKDu to women may be because women spend more time at home in pesticide-treated areas, increasing the risk of pesticide exposure. Moreover, patients who experience the highest quartile of pesticide exposure duration in the study have a 1.64 times higher risk of developing CKDu compared to individuals who never used indoor pesticides.
Thus, the study concludes, “This finding emphasizes the role of cumulative exposure dose at a specific time on kidney function. Although we cannot comment on safe threshold dose of house use of pesticides, as this was not in our study scope, but finding the safe use threshold of these materials could be of great interest that could be evaluated in longitudinal studies.”
The kidneys are one of the most important organs for filtering waste out of the human body. However, kidneys are often the main target of pesticide toxicity mediated through oxidative stress. Therefore, we must protect human and ecological health by shifting to organic/regenerative systems to limit exposure to these toxic chemicals. Additionally, buying, growing, and supporting organic can help eliminate the extensive use of pesticides in the environment. Organic agriculture has many health and environmental benefits, eliminating the need for chemical-intensive agricultural practices. Considering pesticide levels in the human body can decrease by 70% through a one-week switch to an organic diet, purchasing organic food whenever possible—which eliminates toxic pesticide use—limits overall exposure (toxic body burden) and resulting adverse health effects. Learn about pesticides’ impacts on human health by visiting Beyond Pesticides’ pages on kidney/renal cancer and disease, oxidative stress, and other diseases in the Pesticide-Induced Diseases Database. This database supports the need for strategic action to shift away from pesticide dependency. For more information on how organic is the right choice for consumers and farmers, see the Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
