WASHINGTON -- Tests on the water supply at the vice president's residence have found no traces of chemicals that might have triggered thyroid problems in President Bush and his wife, Barbara, chief White House physician Burton Lee said yesterday.
Dr. Lee said in an interview that he believes the test results should put to rest suspicions that the aging plumbing at the Victorian mansion on the Naval Observatory grounds -- where the Bushes spent eight years -- might have contributed to the rare development of the same non-contagious ailment in husband and wife.
The water supply at the White House can also be exonerated, Dr. Lee said, because "it has been tested to a fare-thee-well" as part of ongoing security measures to protect the chief executive and his family.
But the head of Mr. Bush's medical team said the search would continue for a possible link between the first couple's matching cases of Graves' disease as well as for a connection with a related affliction developed by their dog, Millie.
"It could take a year or two," Dr. Lee said of the epidemiological study, in which he has asked the National Institutes of Health to assist.
Researchers have not given up their hunt for clues at the vice president's residence, according to David C. Beckwith, press secretary for the current resident, Dan Quayle.
"It's my understanding that they're looking into the heating and air conditioning and other possible environmental factors," Mr. Beckwith said.
The medical detective work began shortly after President Bush was discovered earlier this month to be suffering from an overactive thyroid that upset the hormonal balance of his body and caused his heart to beat irregularly.
The condition, diagnosed as Graves' disease, had been discovered in Mrs. Bush 16 months earlier.
Millie was determined last summer to be suffering from another rare ailment of the immune system, known as lupus.
President Bush said this week that he had been told the chance of such a coincidence's occurring naturally was "1 in 3 million," and when the family pet is factored in, "1 in 20 million."
Although the search for clues will delve deep into the Bushes' past as well as their family histories, Dr. Lee said yesterday that he was certain the president did not develop any symptoms of the disease until about three weeks before he first noticed a shortness of breath while jogging May 4.
Mr. Bush, more and more his old self as he takes radioactive iodine treatments to cut down the hormone production of his thyroid gland, said yesterday that he had heard a new theory for the source of his ailment.
The president told graduates of the FBI Academy at ceremonies in Quantico, Va., that he had just received a note from a farmers' organization contending, "This wouldn't have happened if you'd eaten your broccoli."