P claims that he sustained lead poisoning by ingesting lead paint from accessible painted surfaces, paint chips, and paint flakes and dust at two different houses he lived in during the early 1990s. P exhibited an early onset of childhood lead poisoning on two occasions. P was admitted to Children’s Hospital of Wisconsin for five days of chelation treatment. An expert testified that P's cognitive deficits are a “signature or constellation of cognitive effects” that are typical of lead poisoning. These deficits are permanent, and P will require lifetime medical monitoring-surveillance for physical disorders, as he is now at a high risk for developing future medical complications, including kidney disease, peripheral neuropathy, hypertension, and cardiovascular disease. P’s high lead levels are exclusively derived from ingesting lead-based pigments in paint. A toxicologist conclusively ruled out lead sulfate or lead chromate pigments. White lead carbonate was the principal pigment used. P settled with the insurer of one landlord. P sued the remaining two landlords and their insurers and Ds for the injuries he received from lead poisoning. P conceded that he cannot identify the specific pigment manufacturer that produced the white lead carbonate he ingested. Ds moved for summary judgment; P could not prove causation in fact or proximate cause. The motion was granted. The court reasoned that P had a remedy against the negligent landlords. The lead paint could have been applied anytime during what was approaching a one-hundred-year-time span. The court concluded the Ds had no real defense. Further, lead poisoning could be caused by any number of lead products and different forms of lead pigments that were used in varying amounts by paint manufacturers. Ds were not in exclusive control of the risks involved as they did not make the finished paint product or ensure that the product was properly maintained in homes. P appealed, and the court of appeals affirmed. P is unable to identify the precise producer of the white lead carbonate pigment he ingested at his prior residences due to the generic nature of the pigment, the number of producers, the lack of pertinent records, and the passage of time.