Long-term air pollution exposure linked to increased risk of acute kidney injury and mortality

By Dr. Chinta SidharthanReviewed by Lily Ramsey, LLMOct 24 2024

New research uncovers the hidden dangers of air pollution on kidney function and survival.

​​​​​​​Study: Prolonged exposure to air pollution and risk of acute kidney injury and related mortality: a prospective cohort study based on hospitalized AKI cases and general population controls from the UK Biobank. Image Credit: New Africa/Shutterstock.com

In a recent study published in BMC Public Health, researchers examined the long-term impact of air pollution on kidney health, specifically focusing on acute kidney injury and related mortality.

They found that prolonged exposure to pollutants such as particulate matter below 2.5 microns (PM_2.5) and nitrogen oxides significantly increased the risk of developing acute kidney injury.

Background

One factor substantially contributing to the development of chronic kidney disease and end-stage renal disease is acute kidney injury, where kidney function undergoes a sudden decline.

Despite the substantial progress made in medical research, acute kidney injury continues to pose long-term health risks, making it crucial to identify and prevent the factors that lead to it.

Air pollution has been strongly linked to kidney diseases. Inhaled pollutants can reach the kidneys through the bloodstream and cause oxidative stress and inflammation.

Although previous studies have examined the association between exposure to air pollutants such as nitrogen oxides and PM_2.5 and chronic kidney disease, there is a paucity of studies investigating the link between air pollution and acute kidney injury.

About the study

In the present study, the researchers investigated the impact of long-term exposure to PM_2.5, particulate matter below 10 microns (PM₁₀), and nitrogen oxides on the risk of acute kidney injury and deaths due to acute kidney injury.

The data was collected from a large cohort in the United Kingdom (U.K.). Biobank, the researchers examined whether air pollution increased the likelihood of acute kidney injury.

The cohort consisted of over 500,000 participants between the ages of 40 and 69 who were recruited into the U.K. Biobank cohort between 2006 and 2010.

The researchers excluded any individuals who had acute kidney injury and those missing data on demographic characteristics or air pollution exposure before the onset of the study, resulting in a final dataset of close to 415,000 individuals.

Hospital admission records were used to identify cases of acute kidney injury during the study period, and the researchers used International Statistical Classification of Diseases Tenth Revision (ICD-10) codes to determine whether the acute kidney injury was of the tubular necrosis or cortical necrosis type. Mortalities due to acute kidney injury were also identified.

Additionally, the study evaluated the exposure to different air pollutants, including nitrogen dioxide, nitrogen oxides, PM_2.5, and PM₁₀. The researchers used the Land Use Regression model to estimate the pollution levels in each participant’s area of residence.

This model considers environmental factors such as traffic, population density, and land use to predict the annual mean concentration of pollutants in an area. The accuracy of the model’s estimations was also cross-validated.

Furthermore, the study accounted for a wide range of variables that could potentially impact the results, including demographic factors such as sex, age, and ethnicity; medical history including hypertension, diabetes, and body mass index; and lifestyle choices such as alcohol consumption and smoking.

The analysis also factored in the use of medications such as non-steroidal anti-inflammatory drugs (NSAIDs) and angiotensin-converting enzyme (ACE) inhibitors and included lab results for C-reactive protein and creatinine levels in the analysis.

Results

The findings confirmed that prolonged exposure to air pollutants was linked to a higher risk of acute kidney injury and related mortality.

The study found a linear, as well as non-linear, relationship between exposure to nitrogen oxides and fine particulate matter and kidney-related health outcomes, with some pollutants showing complex dose-response patterns.

More specifically, exposure to PM_2.5, nitrogen oxides, and nitrogen dioxide was linked to an elevated risk of death from acute kidney injury. However, the risk of developing acute kidney injury showed a non-linear relationship with various pollutants, indicating that the impact of air pollution on kidney health could vary depending on the exposure levels.

The researchers also explored the possible biological mechanisms underlying the association between exposure to air pollutants and elevated risk of acute kidney injury. The study suggested that inhaled pollutants that reach the kidney through the bloodstream could induce oxidative stress and inflammation, which could impair kidney function.

Furthermore, pre-existing health conditions such as hypertension and diabetes could increase vulnerability to the harmful impact of air pollution on kidney health.

Conclusions

Overall, the study underscored the critical impact of long-term exposure to air pollutants such as nitrogen oxides and fine particulate matter on kidney health and highlighted the need for strict regulations and policies on air quality monitoring.

These findings also support the value of integrating kidney health into public health and environmental policies to improve overall health and reduce the burden of acute kidney injury.