Air pollution poses a significant threat to human health, extending beyond the well-known risks to respiratory and cardiovascular systems. Recent scientific findings underscore the connection between polluted air and chronic kidney disease (CKD), shedding light on the lesser-known impact on renal health.

A study conducted at the University of Michigan, published in PLOS One, emphasizes the direct link between air pollution and CKD. Lead author Jennifer Bragg-Gresham, M.S., Ph.D., highlights the presence of harmful toxins in air pollution, comparable to the dangers of smoking. Kidneys, with their extensive blood flow, act as an early indicator of harm to the circulatory system, making individuals with pre-existing conditions like diabetes, obesity, high blood pressure, or heart disease particularly susceptible.

The study focused on fine particulate matter, PM2.5, found in air pollution. These microscopic particles, virtually weightless, linger in the air, exposing individuals to health risks through regular inhalation. Analyzing Medicare claims data and air quality data from the Centers for Disease Control and Prevention, the study found a positive association between CKD rates and PM2.5 concentration. Rajiv Saran, M.D., a Michigan Medicine nephrologist, emphasized the correlation, stating that areas with higher pollution levels exhibit increased rates of chronic kidney disease.

Pollution from highway traffic can impact kidney health and lower the estimated glomerular filtration rate (eGFR) through various mechanisms:

1. Inhaled Particles: Traffic emissions contain harmful particles that, when breathed in, directly affect kidneys.
2. Inflammation: Inhaled pollutants trigger systemic inflammation, impacting renal blood flow and eGFR.
3. Vasoconstriction: Traffic pollutants narrow blood vessels, reducing kidney blood flow and potentially damaging glomeruli.
4. Endothelial Dysfunction: Pollutants compromise blood vessel function, affecting eGFR.
5. Oxidative Stress: Traffic pollution causes oxidative stress, damaging renal tissues and contributing to kidney disease.
6. Inflammatory Activation: Pollutants activate kidney inflammation, potentially causing chronic damage.
7. High Blood Pressure: Traffic pollution is linked to elevated blood pressure, straining renal vessels.
8. Autoregulation Impact: Pollutants may disrupt renal autoregulation, affecting blood flow and eGFR.

While the study’s focus was on the United States, the implications for countries with higher PM2.5 levels, such as China and India, suggest significantly elevated odds of CKD. Despite lower PM2.5 levels in the U.S., the association remains significant, emphasizing the importance of precautions, especially for high-risk individuals and those in densely populated or polluted areas.

Air pollution contains heavy metals like lead, mercury, and cadmium, known to harm kidneys. Prior research, including studies in coal-mining areas of Appalachia, further supports the association between environmental pollutants and increased CKD risk. Jessie Fidler, reporting on the study, encourages preventive measures for individuals exposed to air pollution, suggesting strategies like wearing masks in heavily polluted areas, limiting outdoor hours, and minimizing extended commutes in high-traffic areas.

Building upon the concern of air pollution’s impact on kidneys, a separate study explored the relationship between smoking and renal function. Published in Frontiers in Medicine, the research aimed to determine the connection between smoking and decreased renal function in individuals over 20 years old. The study, conducted in China, recruited 10,267 participants from the National Health and Nutrition Program Testing Survey (NHANES) between 2013 and 2018.

The findings revealed an inverse relationship between serum cotinine (a marker of tobacco exposure) and estimated glomerular filtration rate (eGFR), indicating that increased smoking correlates with decreased renal function. Subgroup analyses highlighted variations in this relationship based on age, sex, and ethnicity. Notably, young individuals showed a clearer negative correlation between serum cotinine and eGFR, suggesting that early smoking cessation could effectively prevent kidney disease in this population.

The study reinforces smoking as an independent risk factor for chronic kidney disease. The complex mechanisms by which smoking contributes to various diseases, including cardiovascular and respiratory conditions, involve the diverse chemicals present in cigarette smoke. While smoking-related vascular lesions and endothelial dysfunction are well-established, the specific mechanisms leading to kidney injury are still under investigation.

Cotinine, a primary metabolite of nicotine, serves as a useful marker for tobacco exposure. The study’s comprehensive approach, incorporating large-scale data and subgroup analyses, emphasizes the importance of recognizing smoking as a risk factor for renal decline. The identification of specific populations at higher risk, such as young individuals, enables targeted interventions for smoking cessation to prevent kidney-related complications.

Shifting the focus to environmental risk factors during critical stages of kidney development, Dr. Alison P. Sanders from Mount Sinai delves into the intricate relationship between environmental exposures and kidney health. In a conversation, Dr. Sanders emphasizes the commonality of environmental risk factors, including air pollution, metals, cigarette smoke exposure, and phthalates. Studies suggest that up to 26% of kidney diseases in high-risk populations may be attributable to environmental factors.

A recent study reveals that secondhand smoke exposure, known for causing cancer and heart disease, significantly increases the risk of chronic kidney disease (CKD) and kidney failure. Published in the Clinical Journal of American Society of Nephrology, the study indicates that this risk is comparable to active smoking. Findings from a Korean study of 131,196 nonsmokers show a 66% higher likelihood of CKD in those exposed three or more days per week. Even with fewer exposures, a 59% increased risk persists. The study suggests direct vascular and kidney injuries from secondhand smoke and nicotine, impacting podocyte cells and the circulatory system. Nephrologists stress the importance of quitting smoking for CKD patients, with legislative measures playing a role in reducing exposure.

The rise of public marijuana smoking poses health risks akin to the dangers of secondhand tobacco smoke, according to experts. As marijuana use increases, concerns grow about the impact on nonsmokers exposed to secondhand smoke containing cancer-causing substances. Studies indicate similarities between secondhand marijuana and tobacco smoke, with shared toxic chemicals and associated health risks, including asthma and cardiovascular issues. With the marijuana industry pushing for more lenient regulations, experts call for stronger smoke-free protections, likening marijuana regulation to that of tobacco, with excise taxes, limited advertising, and safeguards against secondhand exposure.

Marijuana/Cannabis and Air Pollution and Risks

1. A recent poll shows that half of Americans find the smell of pot offensive. 
2. Secondhand marijuana smoke contains many of the same cancer-causing substances and toxic chemicals as secondhand tobacco smoke, including ammonia, mercury, lead, formaldehyde, benzene, hydrogen cyanide and toluene, and is associated with asthma and cardiovascular risks in nonsmokers.
3. Secondhand marijuana smoke is not just a growing nuisance, it’s dangerous

Dr. Sanders’ research explores critical windows of susceptibility during fetal, infant, and childhood development, where environmental exposures can influence kidney function and potentially lead to chronic diseases later in life. Air pollution emerges as a significant risk factor, contributing to hypertension and high blood pressure. Studies indicate that 12% of adult hypertension is attributable to ambient PM2.5 exposure, emphasizing the pervasive impact of environmental factors on kidney health.

Critical windows of susceptibility during the second and third trimesters, as well as postnatal exposures, may influence kidney function or blood pressure, setting individuals on trajectories toward kidney disease or hypertension in adulthood. Dr. Sanders emphasizes the complexity of chronic kidney disease, highlighting the need to understand the interplay between environmental factors and traditional risk factors like obesity and preterm birth.

Dr. Sanders’ laboratory collaborates with experts in renal cell physiology and developmental biology to assess the timing of environmental exposures on kidney cell and organ development. By exploring specific mechanisms and environmentally relevant mixtures of toxicants, the research aims to uncover how exposures during critical periods can lead to altered cell functions, kidney injury, and impaired growth and development.

The implications for preventing kidney disease starting early in life are profound. Biomonitoring pregnant women and children for toxic exposures, coupled with reducing exposure levels, becomes crucial. While some toxic exposures, like lead, have monitored guideline values, the lack of a safe level for lead underscores the importance of continuous monitoring. Biomonitoring for various toxic exposures, including particulate matter air pollution, mercury, arsenic, cadmium, and organic chemicals, provides insights into daily exposure to mixtures, informing risk assessments and preventive measures.

As the scientific community unravels the intricate connections between environmental exposures and kidney health, physicians play a pivotal role in raising public awareness. Dr. Sanders emphasizes the role of institutions like Mount Sinai’s Transdisciplinary Center on Early Environmental Exposures in fostering communication and collaboration between health professionals and the community. The center provides guidance and support to heighten awareness of environmental exposures, contributing to strategies for building a healthier environment.

Building upon the impact of air pollution on renal function, the final study investigates the association between air pollution and renal function. The research, conducted by scientists Łukasz Kuźma, Jolanta Małyszko, Hanna Bachórzewska-Gajewska, Paweł Kralisz, and Sławomir Dobrzycki, delves into both short-term and long-term impacts of air pollution on kidney function.

The study, focusing on PM2.5, NO2, and SO2, employed linear, log-linear, and logistic regression models to assess the relationship between renal function and air pollutants. The findings reveal a concerning association between air pollution and chronic kidney disease. An increase in annual concentrations of PM2.5 and NO2 is linked to a higher prevalence of chronic kidney disease. Additionally, short-term exposure to elevated air pollution levels is associated with a decrease in estimated glomerular filtration rate (eGFR), indicating adverse effects on kidney function.

The study underscores the serious consequences of air pollution on human health, extending beyond the respiratory and circulatory systems to renal function. The adverse effects observed in both short-term and long-term exposures emphasize the urgent need for measures to reduce air pollution levels.

Summary

Air pollution and smoking are identified as significant threats to kidney health, revealing a complex web of connections in recent studies. A study from the University of Michigan sheds light on the direct association between air pollution, particularly PM2.5, and chronic kidney disease (CKD). The research underscores the similarities between the harmful toxins in air pollution and the risks associated with smoking, posing a notable danger to individuals with existing health conditions. In China, a separate study establishes smoking as an independent risk factor for reduced renal function, particularly in young individuals, revealing a clear negative correlation.

Dr. Alison P. Sanders from Mount Sinai enriches our understanding of environmental risk factors impacting maternal and child kidney health. Her research delves into the effects of air pollution, metals, and cigarette smoke exposure during critical developmental stages—fetal, infant, and childhood. The findings emphasize the vulnerable windows of susceptibility, where environmental exposures can shape kidney function, potentially contributing to chronic diseases later in life.

Adding to this narrative, scientists investigating the impact of air pollution on renal function emphasize both short-term and long-term adverse effects. Collectively, these studies emphasize the pressing need for preventive measures and increased public awareness to navigate the intricate interplay between environmental factors and kidney health.

Environmental Sources Linked to CKD

The main airborne and environmental causes linked to Chronic Kidney Disease (CKD) in healthy people include:

1. Air Pollution (PM2.5): Fine particulate matter (PM2.5) found in air pollution is a major contributor to CKD. Studies, such as the one from the University of Michigan, highlight the direct association between increased PM2.5 concentration and elevated CKD rates.
2. Smoking: Cigarette smoke contains various harmful chemicals, including cadmium, which poses a significant risk to kidney health. Independent research, particularly in China, establishes smoking as an independent risk factor for decreased renal function, indicating a clear negative correlation.
3. Heavy Metals: Air pollution contains heavy metals like lead, mercury, and cadmium, all known to negatively affect the kidneys. Exposure to these metals, either through airborne particles or environmental contamination, contributes to the development and progression of CKD.
4. Maternal and Childhood Exposures: Research by experts like Dr. Alison P. Sanders from Mount Sinai emphasizes the impact of environmental factors during critical windows of susceptibility—fetal, infant, and childhood stages. Exposures to air pollution, metals, and cigarette smoke during these stages can influence kidney function, potentially leading to CKD in adulthood.
5. Traffic-Related Pollution: The presence of vehicle traffic pollution, including emissions from vehicles, contributes to air pollution. Traffic-related air pollutants, such as nitrogen dioxide (NO2) and particulate matter, have been linked to adverse effects on renal function, adding to the overall environmental burden on kidney health.
6. Phthalates and Other Environmental Chemicals: Environmental chemicals like phthalates are known to be present in air and various consumer products. These chemicals, when present in the environment, can contribute to the overall burden on kidney health.

Understanding these links is crucial for public health initiatives and policies aimed at reducing environmental exposures and preventing the development and progression of CKD in healthy individuals.

Medical Disclaimer: The information provided in this article is for informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read in this article.

Sources:
https://www.michiganmedicine.org/health-lab/why-polluted-air-may-be-threat-your-kidneys
https://www.frontiersin.org/articles/10.3389/fmed.2022.870278/full https://reports.mountsinai.org/article/peds2021-03-environmental-risk-factors-kidney-health
https://www.nature.com/articles/s41598-021-91000-0
https://www.nbcnews.com/think/opinion/secondhand-marijuana-smoke-not-just-growing-nuisance-it-s-dangerous-ncna1007161
https://fmcna.com/insights/articles/secondhand-smoke-exposure-increases-kidney-disease-risk–study-f/
https://www.nytimes.com/2019/03/07/well/live/secondhand-smoke-exposure-tied-to-kidney-disease.html