Central. Slauson. Florence. Alameda. Vernon.
Those are a few of the busy streets running through parts of South Los Angeles – and according to a new study, living near those thoroughfares could be bad for your kidneys.
Dr. Murray Mittleman, the director of cardiovascular epidemiology at Beth Israel Deaconess Medical Center, was the senior author of the study, published in the Journal of Epidemiology and Community Health.
"What we found was that among individuals who had a history of having had a stroke, people who lived closer to major roadways had a [decrease] in their kidney function," he said. "The closer an individual lived to a major roadway, the bigger the [decrease] in their kidney function we observed."
While Mittleman and his team didn't establish a cause-and-effect relationship – only an association – he did suggest that association could have substantial health implications.
"It was comparable to what's seen with about a four-year increase in age," he said. "So living closer [to major roadways] seems to be associated with aging your kidneys by about four years."
South L.A. is no stranger to busy thoroughfares – the freeway corridors highlighted on the map below were among the top 100 most congested according to INRIX, which compiles traffic data:
The South L.A. neighborhoods around those freeways are also among the most densely populated in L.A. County, according to data compiled by the L.A. Times' Mapping L.A. project. Here's a sampling – click on the blue borders to see that neighborhood's population density:
Those areas are among the densest rates in L.A. County, according to the Times. To put it in perspective, Playa Vista on the westside only has about 1,900 residents per square mile.
More on the study
The researchers found that among 1,100 stroke patients, those who lived very close to (within three-fifths of a mile of) a busy road had a 4 percent higher chance of dying from heart problems and a 1 percent greater chance of dying from any cause. Kidney failure could play a role in all of that; its role is to filter the blood.
Dr. Mittleman said this particular study was done "on top of another study," which is why it focused on stroke survivors. While he said it's possible that affected the outcome, he said there was another reason to pay attention to the findings.
"The reason to look at the question of whether kidney function is associated with living close to a road, and the increased level of traffic pollution that comes along with that, is that we've seen in other studies that living close to a roadway … is associated with other vascular outcomes," he said.
Which means it affects the blood vessels, which has major implications for the kidney, said Mittleman. The kidney itself is fed via blood vessels, and it carries out the actual filtration through a "very dense network of blood vessels."
The researchers tested how much creatine was produced in the bodies of the study's participants and how well their bodies filtered it. Creatine is a chemical involved in the creation of energy that the muscles need to function properly, and a low filtration rate indicates reduced kidney function.