TOURISTS' TELLTALE HEARTS

GAMMA EMISSION SAID TO ALARM WHITE HOUSE

The list of dos and don'ts for tourists who wish to visit security-conscious Washington grows ever longer. A new warning from three Ohio cardiologists urges patients who have just undergone a common heart test to steer clear of the White House visitors' tour on pain of being detained by the Secret Service.

Last spring, they said, two unsuspecting women from Cincinnati set off the elaborate White House security system while attempting to take the public tour. The false alarms were triggered by tiny amounts of radioactivity in their bodies left from a radioisotope scan for possible heart disease that each had undergone several days earlier.

Drs. Robert J. Toltzis, David J. Morton and Myron C. Gerson at the University of Cincinnati Medical Center describe the two separate incidents in a letter entitled "Problems on Pennsylvania Avenue" in this week's New England Journal of Medicine.

It provides new clues to the highly sensitive security efforts that have been undertaken to protect the White House from terrorist acts involving radioactive materials.

The authors of the letter suggested that doctors who administer a heart exercise test involving the radionuclide thallium 201 should advise their patients to avoid the White House "soon after the test" to prevent the "acute embarrassment" suffered by his patients.

The two women, who on separate dates went to Washington with their husbands, had undergone exercise-treadmill testing with radioactive thallium within four days of their attempted White House tours.

While neither patient triggered the conventional airport security devices, which detect concealed metal, they were surprised to be stopped by the Secret Service when they entered the White House grounds.

Toltzis said that his patients reported being told that they had been found to emit gamma radiation. Gamma radiation consists of high-energy, short-wavelength rays, which are very penetrating and similar to X-rays.

They are emitted continuously by nuclear materials such as Uranium 235 and Plutonium 239, which can be made into a bomb, according to one expert. Even if no bomb was present, such materials could pose a serious threat to health if they were distributed on the White House grounds.

The expert added that an extremely sensitive detector is needed because various measures can be taken to diminish the emission of gamma radiation from nuclear materials in order to avoid detection.

"Each was detained," wrote Toltzis and his colleagues, "until the cause of the breach of security could be established." The women were each asked, he said, whether they had undergone medical tests recently, and then the Cincinnati doctors' offices were called to confirm this.

"I was very surprised. It must be a phenomenal security system," said Toltzis, who declined to identify his patients. He said that the amount of radiation involved used in the exercise test was a "very low level" -- 2.5 millicuries -- to start with. Thallium 201 has a half-life of 72 hours, which means that it loses half its radioactivity every 72 hours.

The tests, which are commonly used to detect signs of coronary artery disease in individuals with chest discomfort, involve the injection of radioactive thallium into the blood stream to visualize heart activity during exercise and at rest. "We do three or four a day," said Toltzis.

Jack Taylor, a spokesman for the Secret Service, said yesterday that "it's our policy not to discuss any of our security systems . . . . We do have systems in place that would detect problems from the people entering the White House."

Taylor said that at the East Wing visitors' entrance there is a visible magnetometer to detect metal, and that "there are other systems we employ for the protection of the White House." He would not "confirm or deny" that special radiation detectors are now in place.

He said that each year more than 1 million people take the public tours and that the Secret Service "could not recall any ladies from Cincinnati being held as stated in that article. Quite a few people are detained for various reasons."

Fortunately, for the women from Cincinnati there was a happy ending. After their brief detention, "they got to see the White House eventually," said Toltzis.

Articles appear as they were originally printed in The Washington Post and may not include subsequent corrections.