“Much of the Lower Ninth Ward is also toxic, so it’s really not a surprise,” said a source with intimate knowledge of the project, which Mr. Pitt is helping to fund along with Global Green USA, the American branch of an international environmental organization founded by former Soviet leader Mikhail Gorbachev.

The source elaborated that the three-acre “test” area where Mr. Pitt’s energy-efficient housing units are being built (out of primarily recycled materials!) is a former industrial site and contains several unexpected biohazardous “hot spots.”

Our spy blamed the eager do-gooders’ well-intentioned haste for the snafu, continuing: “You can’t knock Brad or Global Green for their enthusiasm. But what was and is a very ambitious program will have to proceed with caution. There will have to be some cleanup work done before any more buildings go up. It goes to show that no good deed goes unpunished.”

A spokeswoman for Global Green, Jeanne Nathan, acknowledged that “we do have some contamination. Now we’re in the process of remediation.” She said that buying land without testing for toxins first is “common practice” in the region, and insisted the project would be completed on schedule, in spring 2008.

Mr. Pitt’s publicist, Cindy Guagenti, did not return calls for comment. But the bad news has apparently only further motivated her client, a noted design buff who spent years building a Beverly Hills residence with ex-wife Jennifer Aniston. “Brad has interviewed about a dozen more architects to expand his project,” the source reported, information confirmed by Ms. Nathan. “They are looking to develop 10 to 15 times that amount of ground with sustainable housing.”