But now it is also coming to residential neighborhoods like South Prescott in Oakland, which this month became the first in the country where fishbone meal is being mixed into the soil for lead control under a project organized by the Environmental Protection Agency.

“It’s fair to say, looking forward, that just about every urban residential area probably has a lead problem and we just can’t afford economically and socially to move that amount of dirt any more,” said Steve Calanog, the E.P.A. official in the San Francisco office that is overseeing the project. “Topsoil is a precious resource, and we don’t have enough topsoil to replace it.”

Although the agency does not record its spending by individual contaminants, it is safe to say it has spent millions of dollars on lead cleanup. If the new techniques of neutralizing toxic metals catch on the money would go further by replacing the method of digging up and disposing of hundreds of thousands of tons of soil that has been used for more than two decades.

The effects of lead poisoning, particularly on young children’s ability to learn, have long been recognized by scientists. Yet lead remains one of the most prevalent contaminants in the country, particularly in urban areas.

The project in South Prescott, expected to cover a six-block area and cost $4 million over two years, will train up to 75 workers, many previously unemployed, in toxic cleanup methods. In this 100-year-old neighborhood of west Oakland, the average contamination levels in the soil are twice the federal limit of 400 parts per million, and some hot spots have lead levels five or six times greater, Mr. Calanog said. South Prescott was built on landfills holding the detritus of the 1906 San Francisco earthquake. When the houses were built for workers at the nearby railyards, pipes and paint contained large quantities of lead. Later, trucks rumbled by on the way to the port of Oakland, and highways were built nearby.