While it's been found that living near highways may make residents more susceptible to cardiovascular-related deaths, researchers recently examined what this could mean for your kidneys.

Researchers found that those living in close proximity to major roadways had lower kidney function than residents farther away.

"These results imply that exposures associated with living near a major roadway reduces renal function, an important risk factor for cardiovascular events," the authors wrote.

The study, which was published in the journal British Medical Journal on May 13, analyzed information from hospital records of 1,103 patients, ages 21 and older, who suffered acute ischemic stroke in the Boston area.

While being treated at the time of their strokes, the patients received tests that estimated glomerular filtration rate (eGFR), which measures how much blood passes through the tiny filters, called glomeruli, of the kidney every minute. This tests for how well the kidneys function.

Researchers found that even after accounting for patient age, gender, socioeconomic backgrounds, and past medical ailments, the lowest levels of eGFR were found in patients who lived closer to major roadways. That means their kidneys were functioning more poorly than those living farther away.

In addition, they observed that those living closer to the major roads were more likely to be men, older, and of minority background when compared to participants residing outside the major roadways.

The National Insitutes of Health previously found that end-stage renal disease (ESRD), a condition in which permanent kidney failure gives way to fluid and waste accumulation, is three times more likely to occur in Afican-Americans compared to whites.

Distance-wise, these individuals who lived at least 50 meters away from traffic had an eGFR reading of 3.9 ml per minute less than those who were living at least 1000 meters away. The difference was especially stark for those living near A2 roadways, where the primary road had very few limitations.

Low eGFR was previously tied to increased risk for cardiovascular-related deaths.

In a 2012 study, researchers found that living near ambient air pollution and traffic-ridden roads increased the risk for heart attack by 12 percent. They speculated that the constant noise from traffic disrupts sleep and escalates stress, a risk factor for cardiovascular disease.

Biologically, the connection between kidney health and cardiovascular health is strong. The kidney is vulnerable to large vessel artherosclerotic disease and small vessel dysfunction because it's constantly filtering bodily fluids. So greater noise and air pollution from traffic directly affects cardiovascular health, which in turn impacts kidney function.

Researchers added that certain factors were not included in this study. Among them being data on how often the residents spend time at home and whether they had unhealthy behaviors. In addition, Boston's major roads carrying both trucks and cars that could carry emissions that could impact renal function, but would need to be studied further.

According to the National Kidney and Urologic Diseases Information Clearinghouse, chronic kidney disease (CKD), is prevalent in one in 10 adult Americans, mostly in people ages 60 and above, while more than 20 million have some form of CKD.

CKD could be measured as a condition that gradually diminishes the function of a kidney over time. An eGFR below 60ml per minute for more than three months is a major indicator of CKD.

A patient suffering from ESRD has a more severe, permanent case of kidney failure. Treatment options for those with ESRD include dialysis or a kidney transplant.

Source:

Lue S-H, Wellenius GA, Wilker EH, et al. Residential proximity to major roadways and renal function. [published online first 13 May 2013]. J Epidemiol Community Health. 2013; doi:10.1136/jech-2012-202307. Accessed May 13, 2013.