OCEANO DUNES, CALIF. – The little girl perches her all-terrain vehicle at the top of a towering dune and prepares to plunge into one of the wildest places to go off-roading in America.She is 4 years old.

Two dozen ATVs zoom past her. The girl, named Nina, has never driven an ATV until today. The model she's riding was designed for drivers 12 and older. Her only training took place an hour earlier, when a rental company worker spent about five minutes explaining how the brakes and throttle work.

"We were amazed," said Stacey Situ, Nina's mother. "We thought she was too small."

In California, one of the nation's most popular four-wheeling markets, no one is too young to drive.

Despite federal and industry warnings that children can be injured on ATVs designed for older drivers, California doesn't impose restrictions on vehicle size or speed. No matter their age, operators simply must show they can "reach and operate all controls."

Most states, including Minnesota, won't allow children under a certain age to drive adult-sized ATVs on public lands, typically requiring they be 12 or older. California is one of 19 states that don't have a minimum.

"The requirements are so low they're ridiculous," said Rachel Weintraub, senior counsel for the Consumer Federation of America, a nonprofit that focuses on product safety. "Just because a 12-year-old can reach the gas and brakes doesn't mean a 12-year-old should operate a car."

Nationally, hundreds of thousands of children have been hospitalized in ATV-related incidents since 2003. Most involved children on ATVs made for drivers over the age of 16, federal records show.

In California, 93 people died in ATV accidents from 2009 to 2012, the sixth-highest total in the United States, according to the Consumer Product Safety Commission, which regulates the industry. The federal agency and California regulators declined requests for year-by-year data on child ATV fatalities.

California parks officials, however, say the state's regulations are effective because they allow riders of all ages to enjoy off-roading without putting children in jeopardy, noting provisions that require parental supervision. "Right now, every indicator is our approach is working," said Phil Jenkins, the chief off-road regulator at California State Parks.

Just 5 miles from the Oceano Dunes, Dr. Larry Foreman works in the emergency room at Arroyo Grande Community Hospital. He says he sees way too many children from the dunes getting injured on ATVs. Over the past 10 years, Foreman has campaigned to get the state to impose tougher restrictions on ATV drivers younger than 16.

"I'm not against ATVs at all. They're fun," said Foreman, 62. "But we have an obligation to protect our children. That's why you have to have a minimum age."

Parents are given the choice

On Labor Day, one of the Oceano Dunes' busiest weekends, visitors brought in more than 3,000 off-road vehicles. The dunes, 75 miles north of Santa Barbara along California's central coast, is the state's only beach that allows four-wheeling.

Tourists swamped the five companies that rent four-wheelers.

"It's a cool business," said Wayne Foster, owner of BJ's ATV Rentals. "You get to make a lot of people happy."

Foster will let anyone ride as long as they can reach the controls and show they can "understand and listen."

"If the parent wants them to go riding and have them experience that thrill, that is their call," Foster said. "I'm not a policing power."

Along the dunes, action is intense. Children race four-wheelers in packs across the sand, barreling down slopes at 60 miles an hour. They leap over the tops of dunes, competing to see who can catch the most air. Riders slam on the brakes to avoid tumbling over drop-offs that can be as high as 80 feet.

Since 2009, at least five adults have died in the park driving off-road vehicles, including a search-and-rescue worker who was killed while trying to reach someone with a broken leg. Two teenagers were paralyzed in ATV crashes.

"It is dangerous — I'm not going to lie," said Amy Dinnendahl, a Los Angeles resident who has been coming to the dunes for 20 years. "Everybody that rides has a crash at some point or another."

No one knows exactly how many children have been injured while trying to navigate the cliffs and ever-shifting sands. Over the past five years, state records show that at least 45 children younger than 14 received emergency room treatment for off-road accidents at the dunes.

Park rangers believe that tally is low, saying many parents avoid them after an accident to make sure they aren't cited for a violation.

"If an injury is non-life-threatening, parents may just decide to take the child to the hospital themselves," said Kevin Pearce, chief ranger.

Doctor makes it his cause

Foreman's frustration boiled over in 2004. A 4-year-old boy arrived at the ER after breaking both wrists while driving an ATV. He was barely potty-trained, Foreman said — what was he doing driving a high-powered machine?

"I was ready to call child protective services," Foreman said. "I know a lot of people will say: 'Why didn't you? This is child abuse.' But when these parents come in, they're pretty devastated. What am I going to do? Pour gasoline on the fire?"

Instead, he gathered data at his hospital and an affiliated facility. In a 22-month period, he counted 230 ATV-related injuries involving children under 14. The most common injury was a fracture, often in the collar bone or hands. One boy broke his neck.

At Foreman's urging, California legislators drafted a bill in 2008 that would have prohibited children under 16 from riding adult machines.

ATV enthusiasts and riding clubs challenged the proposal. The Off-Road Business Association, which represents Minnesota-based Polaris Industries and other major ATV makers, said it went too far in limiting children's access to ATVs.

Fred Wiley, president of the business group, said age limits aren't fair because some younger children are more capable of operating an ATV than others. He said parents should decide who rides the vehicles, though he acknowledged that some parents need to make better choices.

"When I see someone turn their 7-year-old loose on a big [ATV], I shudder," Wiley said. "But what am I supposed to do? In order for us to be good stewards of human beings, we need to put things in place, but they should be at the minimum level."

At many public hearings, Foreman's primary challenger was Jim Suty, an aerospace engineer who has been visiting the dunes for 50 years.

"It is ludicrous," said Suty, whose two sons started riding small ATVs when they were toddlers. "If we start going down this path, you and I are going to be wearing helmets in our cars, wrapped in bubble wrap."

The proposed age restrictions were heavily debated, but the California Assembly rejected the legislation. Since then, nothing similar has gained political momentum.

Close to crashing

Nina's ATV is stuck in the sand.

A stranger hauling a trailer full of off-road machines spots her. He lifts her rear wheels and helps her scoot the vehicle up the slope. When Nina reaches the top of the dune, she hits the throttle without looking and roars into heavy traffic. Another fast-moving ATV is on a collision course.

Nina's mother and several bystanders scream. At the last second, the other ATV veers just enough to avoid a crash.

"Oh my God, that scared me," said Jaime Cardenas, the driver who helped Nina out.

The moment was shocking, but Situ said she was going to let her daughter continue to ride. "It's really fun," she said. "I'm an adrenaline junkie."

When told of the incident, Suty said that is not the kind of personal choice he is fighting for. He said he would talk to park officials about preventing similar incidents.

"That parent should have been cited for negligence," Suty said. "They should have been thrown out of the park."

Pearce, the chief ranger, said it was legal for Nina to ride the ATV, even though she could barely reach the foot rests and was a threat to herself and other riders. The most a ranger could do: take her off the beach if she was caught driving recklessly, he said.

"Is it a perfect system? No," Pearce said. "Could it be improved upon for rider safety? Absolutely. But those are the guidelines we have."

Since California enacted a law in 2007 allowing police to cite parents for their children's driving violations, rangers at Oceano Dunes have issued 109 citations when they found children driving an ATV without adult supervision and other offenses. Rangers said most violations end with a warning.

"Our goal is to be a partner with our visitors," Pearce said. "The main goal here is for safety. And to make sure they come back again."

Continue reading Part 3: Massachusetts has nation's toughest ATV law

Go to Part 1: ATV thrills drive child injuries, deaths

Go to Part 2: States ignore federal ATV age limits

Go to Part 4: New push for changes to ATV design

Go to Part 5: Dangerous terrain: ATVs and open roads