A judge has ordered three paint companies to pay 10 California cities and counties $US1.1 billion ($A1.23 billion) to remove lead from millions of older homes.
Judge James Kleinberg found the companies, Conagra Grocery Products, NL Industries and Sherwin-Williams marketed paint they knew was harmful to children.
Atlantic Richfield and DuPont were found not liable.
The companies have 15 days to object to the ruling, which the judge labelled as "tentative."
"There is a clear and present danger that needs to be addressed," Kleinberg wrote in his 110-page decision.
"The defendants sold lead paint with actual and constructive knowledge that it was harmful."
Lead-based paints were barred from the US market in 1978, but millions of homes painted before then still pose a health risk.
The paint industry argued that it never deliberately sold a harmful product and the old paint is no longer a significant public health risk.
Exposure to lead is linked to learning disabilities and other health problems, especially in children.
The case has taken 13 years to reach trial because of objections from the industry.
It alleges the manufacturers knew of lead-paint dangers starting in the 1890s but still sold it to consumers without health warnings.
The industry has faced similar lawsuits across the US, winning most them.