The city is seeking an unspecified financial judgment for lead treatment and cleanup, as well as compensatory damages, punitive damages and reimbursement for legal expenses.

According to news reports, city officials discussed a settlement with the defendant companies for more than a year before deciding to file suit. "It finally became clear the companies were not offering anything that would specifically help Chicago," said Jennifer Hoyle, a spokeswoman for the city's Department of Law.

Named as defendants in the suit are American Cyanimid Co., Atlantic Richfield Co., BP Corp. North America Inc., BP America Inc., DuPont Co., The Glidden Co., Millennium Chemicals Inc., Millennium Inorganic Chemicals Inc., NL Industries Inc., The O'Brien Corp., The Sherwin-Williams Co., and the Chicago Paint and Coatings Association.

Bonnie Campbell, a former attorney general for the state of Iowa who now advises paint companies, issued a statement saying that the public-nuisance legal theory has been discredited in many previous court cases. And she said such litigation has failed to help lead-poisoned children.

"Litigation will not solve the problems that come from poorly maintained housing, and it will not help the children of Chicago," she said. "Lengthy litigation will drain resources and attention from programs that work to reduce the hazard to children. This is a targeted problem with a proven solution. Education, maintenance by property owners and enforcement by government is the way to protect children."