The state is the first in the nation to set rules regulating the gravitational pull, or G-force, of rides. But there is disagreement in the medical community and the industry over whether a link exists between fast-moving thrill rides and brain injuries.

The Batman and Robin Ride at Six Flags Great Adventure in Jackson, which has the highest rate, peaks at a G-force of 5. (Six Flags Great Adventure)

"Right now it's too soon to say whether there should be a panic," said Gregory O'Shanick, medical director of the Arlington, Va.-based Brain Injury Association of America, which is studying rides and injuries. "The jury is still out."

G-force is the pressure put on the body when it is suddenly accelerated from a motionless position, resulting in a person's body being pushed back into their seat. The sudden up-and-down movements and twists of amusement rides cause the pressure to sharply increase.

New Jersey lawmakers agreed to let the state regulate the design of new rides after a mother and daughter were thrown from an Ocean City roller coaster and killed in 1999. Machinery malfunction, not G-force, was responsible for the accident, officials said.

Kimberly and Jessica Bailey of Pomona, N.Y., died after their roller coaster car slipped on a 35-foot incline that started the ride. The car plummeted backward and rounded a 90-degree turn, ejecting both. They were thrown against a steel support structure.

The new state regulations take effect Oct. 1. They prohibit rides from exceeding G-forces of 5.6 for more than one second, which is similar to national industry practice, said William Connolly, director of the state's Division of Codes and Standards. The new rules also regulate structural design and seat restraints.

There is little data tracking brain injuries and rides, which makes it difficult to know if injuries may have been caused by something other than the rides or if a person may have unknowingly had a pre-existing medical condition, some experts say.

Douglas Smith, a traumatic brain injury scientist at the University of Pennsylvania said G-force alone may have little, if any, link to brain injuries. Smith said brain injuries are more likely to occur when the head is whipped around quickly than just simply pushed back in the seat.

"I think New Jersey was a little misguided to regulate G-force," Smith said. "Studies show if you plop down in chair it can be 10 G's."

David Hovda, a neuroscientist at the University of California, Los Angeles, encourages states like New Jersey to do their own studies because the data he has seen so far doesn't make a compelling case.

"When you look at the incident rate of these alleged brain injuries it is pretty doggone small," said Hovda, a members of a team studying brain injuries and rides.

Despite the dispute over a possible link between the two, New Jersey officials believe restrictions will protect riders.

"There is clearly some correlation, the issue is how much," Connolly said.

One of the strongest advocates for G-force limits is U.S. Rep. Edward Markey, D-Mass., who has proposed federal legislation for restrictions. He cites 58 cases of people sustaining brain injuries from roller coaster or other amusement park rides in the past decade.

Markey has called the competition between amusement parks a "roller coaster arms race." Technology and commercial pressures are combining in ways that are testing the limits of the safety in high-speed, high G-force rides, he said.

Some of Markey's data has been disputed by industry officials and experts, who say it's difficult to show a clear link and that 320 million people a year ride amusements safely.

But Bill Powers, a spokesman for the International Association for Amusement Parks and Attractions, said supporters of regulations are needlessly scaring people.

"In the end, you have to acknowledge the base fact that there is simply no medical or scientific evidence anywhere that points to the kind of rhetoric we see from Congressman Markey," Powers said.

In New Jersey, no existing rides will be affected by the change because none exceed the current limits, Connolly said. The Batman and Robin Ride at Six Flags Great Adventure in Jackson, which has the highest rate, peaks at a G-force of 5.

Jim Hanson, 33, a roller coaster enthusiast from Eastampton, said he isn't too worried about New Jersey's regulations because they won't slow down the rides he loves.

"No manufacturer or park is going to put out a ride that isn't safe," said Hanson, who has been on more than 200 coasters.

Chris Campbell, 16, of South Orange, doesn't mind the limits either _ as long as nothing chances at his favorite park, Six Flags.

"As long as they don't do anything to affect the rides there I am OK with it," Campbell said. "I ride roller coasters every chance I get."

(Copyright 2002 by The Associated Press. All Rights Reserved.)