WEDNESDAY, July 7 (HealthDay News) -- While they're effective at specific locations, suicide barriers on bridges may fail to reduce overall rates of people jumping to their death because jumpers may go elsewhere to commit suicide, Canadian researchers have found.

The investigators examined the effect of a suicide barrier installed on Toronto's Bloor Street Viaduct bridge, which was second only to San Francisco's Golden Gate Bridge for the world's highest yearly rate of suicide by jumping.

The number of suicide deaths at the Bloor Street Viaduct fell from 9.3 per year before the suicide barrier was installed to zero after the barrier was completed in June 2003, the study found.

But, Toronto's overall annual rate of suicide by jumping was almost unchanged (56.4 per year compared to 56.6 per year). In addition, there was a statistically significant rise in suicides by jumping from bridges other than the Bloor Street Viaduct (8.7 suicides per year rising to 14.2 per year).

However, both the overall rate of suicides in Toronto and the rate of suicides by means other than jumping decreased after installation of the barrier on the Bloor Street Viaduct, according to the report released online July 7 in the BMJ.

"This research shows that constructing a barrier on a bridge with a high rate of suicide by jumping is likely to reduce or eliminate suicides at that bridge but it may not alter absolute suicide rates by jumping when there are comparable bridges nearby," Dr. Mark Sinyor, resident physician in the psychiatry department at the University of Toronto and Sunnybrook Health Sciences Centre, and colleagues, concluded in a BMJ news release.

Suicide barriers are used on bridges worldwide and on famous structures such as the Empire State Building and the Eiffel Tower, but no studies have shown that these barriers result in a statistically significant decline in overall suicide rates in an area.

"This study reminds us that means restriction may not work everywhere, and that we have much to learn about the determinants of the choice of method in suicidal acts," David Gunnell of the University of Bristol in England, and Matthew Miller of the Harvard School of Public Health in Boston, wrote in an editorial accompanying the study in the journal.

"Yet, where and when means restriction works, it may save more lives than other suicide prevention strategies, especially in children and young adults, who tend to act impulsively in fleeting suicidal crisis," Gunnell and Miller noted.

More information

The U.S. Centers for Disease Control and Prevention has more about suicide prevention.