A pair of medical and engineering studies commissioned by Six Flags, the nation's largest amusement park company and operators of Magic Mountain in Valencia, concluded that roller coasters and other thrill rides do not pose a public health risk.
The announcement comes in the wake of a series of high-profile aneurysm-related deaths on rides at California amusement parks -- including one on Magic Mountain's Goliath roller coaster in 2001 -- and an effort in Washington to enact federal safety regulations for theme parks.
The studies were conducted by the American Assn. of Neurological Surgeons and Exponent Failure Analysis Associates, an engineering firm that investigated the Oklahoma City bombing and the Challenger space shuttle explosion. They conclude the gravitational forces on roller coasters are well within safe levels and that there is no medical evidence linking rides and brain injuries.
"Our panel concluded that there is no proof that roller coasters cause neurological injury, and there is no significant public health risk associated with amusement park attendance," said Dr. Robert Harbaugh, one of the researchers on the medical study.
Over the last few years, amusement park safety has sparked a highly charged debate, with industry officials and critics interpreting data to support their positions on whether the rides are safe.
Two recent medical studies reached opposite conclusions about the risk of brain injury posed by thrill rides. One, published in the Annals of Emergency Medicine, determined roller coaster riders face a small but real risk of brain injury.
A University of Pennsylvania study discounted that conclusion, finding that even the most rough-and-tumble rides do not pose a risk to a healthy person.
Next month the Brain Injury Assn. of America, an advocacy and research group, plans to release its study on dozens of brain injury cases allegedly caused by roller coasters.
Critics could not comment on the studies sponsored by Six Flags because they will not be made public until today, but they immediately questioned the reports' credibility.
"Any study that Six Flags funded, I'd have to look upon with suspicion," said Beverly Hills attorney Barry Novack, who has sued Disneyland and Six Flags for clients who allegedly suffered brain injuries on rides.
"The public has to be warned that these rides can cause serious injury, including brain bleeds. They cannot sweep away the bodies and say they didn't occur. They did occur."
Studies Cost $200,000
Six Flags President Gary Story said Monday that when he commissioned the two studies for about $200,000, he knew he was staking his company's reputation on the outcome. But, he said, he decided to "let the chips fall where they may."
Before accepting, both the medical researchers and Exponent demanded their studies be independent.
"We felt that it was our responsibility to reassure the patrons of theme parks that all this sensational hype was not accurate," Story said. "We would hope that introducing science would shut down a lot of the reckless and irresponsible statements that have been made."
Today, Story is expected to announce Six Flags will continue to research and monitor ride-related injuries, including head injuries.
There is no federal oversight or regulation of amusement parks, or federal requirement for the parks to report injuries suffered on the rides. The Consumer Product Safety Commission collects annual data on ride-related injuries from hospital emergency rooms, but both consumer advocates and industry representatives agree those figures are flawed.
U.S. Rep. Edward J. Markey (D-Mass.) plans to reintroduce the Roller Coaster Safety Act in this congressional session, which would authorize the federal government to investigate serious accidents.
Markey's office has compiled a list of alleged brain-injury cases associated with roller coaster rides, ranging from hemorrhages to headaches.
The Six Flags study conducted by the American Assn. of Neurological Surgeons reviewed published medical studies on 20 cases of brain injuries allegedly caused by roller coasters. The study also reviewed a list of about 60 alleged brain-injury cases that were reported in lawsuits, in news reports and by safety advocates.
Of those cases, they determined that only nine of the head injuries plausibly could have been caused by the violent motion of a roller coaster. The researchers said even in those cases there was no conclusive evidence that the ride caused the injury.
The medical research team also surveyed members of the American Assn. of Neurological Surgeons about the type and frequency of injuries they may have treated that could be associated with thrill rides.
More than 280 neurosurgeons responded and reported 50 cases of patients who might have been injured on a ride. Of those, half were neck and back injuries. Of the remainder, 44% of the patients had preexisting conditions that may have been factor in the injury. That left fewer than 20 patients nationwide who may have suffered any degree of head injury on a ride.
An estimated 320 million people visit amusement parks annually, the industry reports. "The safest place we could put somebody is on a roller coaster," said Dr. Gregory L. Henry, former president of the American College of Emergency Physicians and the author of a textbook on neurological emergencies, who reviewed the studies for Six Flags.
"The numbers are so infinitesimally small. What you're talking about is a nonexistent problem."
The study found that while the risk of ride-related injury is not increasing, more data are needed to determine whether some riders are at higher risk of injury. The report recommends more research, and an in-depth epidemiological study to determine whether there is any causal link between brain injury and roller coasters.
Along with the neurological report, Six Flags also commissioned an engineering study by Exponent -- which conducted an in-depth scientific analysis on roller coaster G-forces.
Although there is a wealth of research on the effects of gravitational forces on fighter pilots and astronauts, there had been little published about roller coasters and thrill rides.
While the roller coaster speeds and heights have increased, G-forces and acceleration levels have not, according to the report.
"Our study showed on the basis of all known scientific evidence that roller coasters are safe. We found that the G-force levels on rides do not cause injury," said Lee Dickinson, a principal engineer at Exponent.
The report "debunked conclusively" the popular myth that G-forces on roller coasters have risen over the years as amusement parks have faced fierce competition to build bigger, faster and more thrilling attractions, Story said.
Six Flags, which operates 40% of U.S. roller coasters and half of the coasters more than 50 feet tall, provided Exponent researchers with the G-force data from 124 of its rides.
3 Directions Measured
The G-forces were measured using an accelerometer -- a box containing instruments that take readings 200 times per second on the gravitational force felt from three directions: head-to-toe, toe-to-head and side-to-side. The box was placed at varying levels on the seat and at varying locations on the roller coaster. In addition, they strapped an accelerometer to a person's head to measure G-force on 70 of the rides.
Exponent also designed computer-generated models of the human cardiovascular system to determine whether roller coaster G-forces were great enough to cause "gray out," or unconsciousness. Gray out is one side effect of sustaining G-forces over a long period of time. It occurs when the blood in the brain is forced into the lower limbs. In no scenario did the computer-simulated rider lose consciousness, the study showed.
The study also compared the G-force generated by a roller coaster to other everyday activities, such as swinging, falling down, sneezing and jumping on a pogo stick. In some cases, G-forces generated during those activities were greater than riding a roller coaster.
(BEGIN TEXT OF INFOBOX)
Comparison of maximum G-force (head-to-toe) accelerations experienced during selected activities.
Duration (seconds): 2.74
Max. Gs: 2.4
Activity: Obstacle course
Duration (seconds): 0.04
Max. Gs: 3.3
Duration (seconds): 0.95
Max. Gs: 3.5
Activity: Pogo stick
Duration (seconds): 0.48
Max. Gs: 4.0
Activity: Falling down
Duration (seconds): 0.03
Max. Gs: 9.4
Activity: Pillow strike
Duration (seconds): 0.02
Max. Gs: 15.6
Varying G-forces during an average roller coaster ride: Portion of ride
Duration (seconds): 0.2
Max. Gs: 5.0
Portion of ride
Duration (seconds): 0.5
Max. Gs: 4.0
Portion of ride
Duration (seconds): 2.0
Max. Gs: 3.0Source: Exponent Failure Analysis Associates in a study funded by Six Flags.