GARFIELD, N.J. — The neighborhood looks exceedingly normal: single-family homes and apartment buildings packed together, dogs barking from postage-stamp-size lawns, parents hustling down narrow sidewalks to fetch children from school. But something with dangerous potential lies below the surface, officials say.
The residents’ toenails will provide confirmation.
A plume of hexavalent chromium, a metal used in industrial production that the Centers for Disease Control and Prevention calls a ‘‘well-established carcinogen,’’ has spread under Garfield, putting about one-tenth of the city’s homes — about 600 structures and 3,600 residents — at risk.
The Environmental Protection Agency is about to start drilling on the spill site to determine how much chromium is pooled beneath and remove tainted soil. It is also testing the broader area to determine how it will be cleaned up, and scientists from New York University are working to assess how much chromium residents may have been exposed to.
Because toenails grow slowly, it is possible to see how much chromium has accumulated in the body over 18 months or so, said Judith Zelikoff, a professor of environmental medicine at New York University.
The contamination started 30 years ago, when thousands of pounds of hexavalent chromium leaked from a tank at EC Electroplating Co. The state started cleaning up the spill but stopped two years later. In 1993, chromium was found at a now-shuttered firehouse and later in homes.
The EPA designated the area as a Superfund site — marking it as one of the nation’s most toxic uncontrolled hazardous waste sites — in 2011, and officials cautioned residents to stay out of their basements to prevent potential chromium exposure. EPA officials removed chromium from the factory building and demolished it last year, and found that some tanks had holes in them, potentially releasing even more chromium into the groundwater.
Officials say the contamination has not affected the city’s drinking water, which is drawn from an outside source. Instead, they worry that people could inhale chromium dust that has been found in basements where groundwater has leached in.
The chromium plume is about three-quarters of a mile wide and slightly more than an eighth-mile long, EPA officials said. The substance has traveled from the site underneath the Passaic River and into the city of Passaic. The agency has installed about 40 monitoring wells.
‘‘We’re trying to find out the extent of the plume,’’ said Rich Puvogel, a project manager with the EPA.
High quantities of the metal have been found in 14 homes that have since been cleaned up. Trace amounts were found in 30 to 40 homes. A nearby school did not show elevated chromium levels.
Zelikoff and her team hope to test as many as 250 residents; some must live close to the plume and others about 3 miles away as a control group. When residents sign up, they will be given a kit that contains stainless steel toenail clippers (cheap ones contain chrome), instructions on how to clip the nails (samples from all 10 are needed) and an envelope for the clippings. It will take weeks to know the results.