LONDON, Dec. 29 (UPI) -- A British radiologist says his research reveals sword-swallowers are prone to sore throats, perforated intestines, internal bleeding and hemorrhages.

Brian Witcombe said he began researching injuries suffered by practitioners of the unconventional performance art after seeing a throat X-ray from an injured swallower, The Times of London reported Friday.

"I see patients with swallowing disorders and was sent an X-ray of a sword-swallower, which got me interested in what medical side-effects they have," he said.

Witcombe collected questionnaires and medical data from about 60 sword-swallowers for his research, which appears in the British Medical Journal.

The researcher said most injuries occurred when a performer became distracted from the task.

"A lot of sword swallowers are involved in sideshows and the like, and they are at the greatest risk because they are swallowing up to 200 swords every two or three months," he said.

"Six had perforations of the gullet, quite a few had suffered serious internal bleeding and three had a major hemorrhage involving a transfusion."