Children poisoned by lead paint cannot allege that manufacturers defectively designed the product since the dangerous lead was a key ingredient, the Wisconsin Supreme Court ruled Tuesday.

The 6-0 decision limits the potential liability of companies that made components of lead paint for decades and are now facing dozens of lawsuits by Milwaukee children who ingested paint chips.

The lawsuits, including about 30 that are pending, will still move forward claiming the companies failed to warn consumers of the risks and created a market for a dangerous product, said Milwaukee attorney Peter Earle, who represents the children. But the plaintiffs now cannot add claims of defective product design, which could have been easier to prove.

The case at issue involved a boy who sustained lead poisoning after ingesting paint chips while living in a Milwaukee apartment in 1998, when he was 1. The boy, now 12, suffered learning disabilities as a result, Earle said.

Writing for the majority, Justice Ann Walsh Bradley said the boy and other plaintiffs cannot claim manufacturers of white lead carbonate products used as a pigment in residential paints were responsible for a design defect.