Pollution May Contribute to Kidney Disease

Chronic kidney disease rates were higher in counties with higher levels of particulate matter

(RxWiki News) Factors like aging, diabetes and high blood pressure may raise patients' risk of chronic kidney disease. Now, new research suggests that air pollution may also raise that risk.

The authors of a recent study found that areas with higher pollution had higher rates of chronic kidney disease.

The researchers noted that their findings did not confirm that pollution causes kidney disease. They called for further research on the topic.

Matthew T. Smith, MD, of the Baylor Medical Center at Carrollton in Texas, said past research on kidney disease causes has mostly focused on respiratory and cardiovascular factors.

"Research in how air pollution would cause chronic kidney disease is very early," he told dailyRx News. "At this point there is no direct proven link between air pollution and chronic kidney disease. Ambient air pollution has been implicated in increasing mortality from lung cancer and cardiopulmonary disease. Chronic kidney disease can occur as a result of worsened cardiovascular issues such as hypertension."

Jennifer L. Bragg-Gresham, PhD, of the University of Michigan in Ann Arbor, led the current study. The researchers presented their findings at the American Society of Nephrology Kidney Week in Philadelphia Nov. 15.

Chronic kidney disease is the slow loss of kidney function over time. If the kidneys do not work well, waste can build up in the body. Chronic kidney disease can lead to other health problems, such as high blood pressure, nerve damage and heart disease.

Past research found that rates of chronic kidney disease varied widely across the US. The authors of the current study wanted to study why that variation may occur.

Dr. Bragg-Gresham and colleagues looked at 2010 Medicare data on 1.1 million people across the US. They compared data on how many people with chronic kidney disease lived in each county. They then looked at data on levels of pollution in each of those counties from the Environmental Protection Agency.

They found that areas with about 14 micrograms per cubic meter of particulate matter had high numbers of people with chronic kidney disease. This level of pollution is much lower than what is thought unhealthy for sensitive groups like the elderly. Particulate matter up to 40 micrograms per cubic meter is considered healthy for elderly patients.

According to the World Health Organization, the air quality guideline for cities is to have 20 micrograms per cubic meter of particulate matter or less, but many developing areas far exceed this amount, Many major cities around the globe have around 70 micrograms per cubic meter.

Many particles in the air can cause health concerns, such as respiratory health problems. These particles — known as particulate matter — include nitrates, sulfates, organic chemicals and metals. Future work on this topic should focus on individual types of particles — particularly lead and cadmium, as high blood levels of these two heavy metals have previously been tied to chronic kidney disease, Dr. Bragg-Gresham told dailyRx News.

The study authors adjusted for other factors, such as age, sex, race, diabetes and high blood pressure — all thought to have an effect chronic kidney disease risk — and still found that those living in highly polluted areas were more likely to develop kidney disease.

Dr. Smith said patients should take measures to protect themselves from harmful toxins.

"For patients that smoke, stop smoking," he said. "The concentration of harmful chemicals in cigarette smoke is far higher than what is encountered on the worst air pollution days. For everyone, enjoy the outdoors, but use common sense. For people who are sensitive to air quality, limiting outdoor exposure would be reasonable on days where air quality is not good."

Dr. Bragg Gresham and team could not say for sure that air pollution caused chronic kidney disease. They called for more research to look at individual exposure to air pollution, levels of chronic kidney disease and different factors in pollution that may be responsible for the increased risk for chronic kidney disease, such as metals or acids.

“If this association is borne out by future studies, it would have implications for reducing air pollution exposure for those with chronic kidney disease and also for those at risk for the condition," Dr. Bragg-Gresham concluded. "The potential public health significance of this finding is even greater for regions and countries with much higher levels of air pollution than the United States."

The US government funded this study. The authors disclosed no conflicts of interest.

Research presented at conferences may not have been peer-reviewed.

Review Date: 
November 13, 2014