City parks can be a haven for homebound residents looking to escape the quarantine blues this year, but an invisible threat might be lurking just below the surface. A new study describes dangerously high levels of lead in the soil of several parks in New York City. Researchers found that lead levels are highest in areas undergoing rapid growth and redevelopment.
“We have over 36,000 people moving into these areas—and lead contamination in the soil,” said study coauthor Brian Pavilonis, a professor at the Graduate School of Public Health and Health Policy at the City University of New York (CUNY). “That’s a lot of people who could all be exposed.”
Pavilonis and his colleagues at CUNY and Brooklyn College analyzed hundreds of samples from 34 parks in six different geographical areas throughout the city. Many of the results far exceeded the Environmental Protection Agency’s soil cleanup value of 400 milligrams of lead per kilogram of soil.
In Long Island City, for example, abandoned factories and parking lots have given way to glittering apartment towers with waterfront views and short commutes to Manhattan. The population has grown by more than 20% in the past 10 years. Soil samples from parks in the area ranged from 26 to 6,300 milligrams of lead per kilogram of soil. “We confirmed our initial hypothesis, that [lead] levels in these areas would be very, very high,” Pavilonis said, “but I was surprised to see samples in the thousands of milligrams, especially in a park.”
The study was published in the August issue of the International Journal of Hygiene and Environmental Health.
“Condemned to Being Lead Poisoned”
Lead in soil comes mostly from legacy uses in paint, industry, or transportation. Between 1926 and 1985, motorists burned 7 million tons of tetraethyl lead in gasoline. Although leaded gasoline has been nearly phased out, the lead persists today, having stuck to vertical surfaces such as buildings and trees and then been washed into the soil. During dry summer months, wind and construction activity resuspend lead-containing soil into the air as dust. Lead levels in the blood of children living nearby rise during these months and fall again each winter.
“People think if there is lead in the soil, the kid has to go to the park and ingest it somehow, but you don’t even have to use that park or outdoor space—that lead gets into the air and then it’s inhaled,” Pavilonis said.
“Lead paint has certainly been a horrendous problem,” said Howard Mielke of Tulane University who was not involved in the new study. “But the immediate lead in the atmosphere has been the source that has really just condemned us to being lead poisoned.”
The median lead concentration in soil, according to a 2013 U.S. Geological Survey report describing 4,841 soil samples from nonurban locations in the United States, was only 18 milligrams of lead per kilogram of soil. This figure led some experts to suggest that the EPA cleanup value (400) is far too high. Among them is Mielke, who said that in areas where children have low levels of lead in their blood, lead levels in the soil are below 40 milligrams of lead per kilogram of soil.
According to the Centers for Disease Control and Prevention (CDC), there is no safe level of lead in the bloodstream. The disastrous effects of lead on brain development in children are the most alarming and well known, but the CDC’s toxicological profile for lead describes health effects on every organ system.
Research by Mielke and others suggests that combating these effects may be as simple as covering contaminated soil with clean soil and grass. Toward this aim, New York City’s Office of Environmental Remediation established the PUREsoil NYC program in 2018. Using soil excavated from deep underground at construction sites, the program distributes free, clean soil to community organizations for use in gardens and other open spaces.
Meanwhile, Pavilonis plans to continue exploring how soils differ from neighborhood to neighborhood. Researchers are now collecting samples from all of the parks in Brooklyn for use in an ecological study of the relationship between lead in the soil and blood lead levels of children living in the area. “We’re much more concerned with the effects on children,” Pavilonis said. “The problem with lead is, once it impacts the developing brain, that’s permanent.”
—Matthew Stonecash (@mattstonecash), Science Writer
This piece was produced with support from the National Association of Science Writers’ David Perlman Virtual Mentoring Program.
5 October 2020: This article has been updated to correct the concentrations of lead represented in the infographic.