Monica Martino had filmed tornadoes in the Midwest, ship collisions in the Antarctic and crab fishermen in Alaska's Bering Sea. But those experiences didn't prepare her for a terrifying nighttime boat ride in the Amazon jungle.

In February, the 41-year-old co-executive producer was thrown into a murky river after getting footage for "Bamazon," a series for the History cable channel about out-of-work Alabama construction workers mining for gold in the rain forest of Guyana.

Martino says the captain was blind in one eye and sailing too fast without a proper light. He lost control of the boat while making a hard turn, sending the crew into the river, where Martino was knocked out by the impact of hitting the water at high speed.

Pulled back into the boat, Martino regained consciousness. But on the journey back to base camp, the vessel struck a tree, slamming Martino into the deck. Although she sustained a concussion, bruised ribs and a badly torn shoulder, Martino said, she had to wait 19 hours to receive medical care at a clinic in Venezuela because the production company had no medical evacuation plan for the crew.

History and the production company, Red Line Films, declined to comment.

"It was a whole cascade of negligence," said Martino, who lives in Santa Monica, Calif. "We were put in a situation far beyond what any production crew should be expected to handle."

As reality TV has boomed in the past decade, action-adventure shows have become a lucrative niche in a medium hungry for high ratings. But the growth has also stirred concerns that some reality TV programs are cutting corners on safety.

A combination of tight budgets, lack of trained safety personnel and pressure to capture dramatic footage has caused serious and, in some cases, fatal incidents, according to interviews with television producers, safety consultants and labor advocates.

Even the companies that provide insurance to Hollywood films and TV shows are reluctant to write policies for some of the edgier programs.

"These reality shows are getting riskier to get more ratings," said Wendy Diaz, senior underwriting director for the entertainment division of Fireman's Fund Insurance, one of the leading insurance carriers that serve the entertainment industry.

Records from the U.S. Occupational Safety and Health Administration and the California Division of Occupational Safety and Health show fewer than a dozen citations and accidents involving reality TV sets in the past five years, including a fatality that occurred this summer in Colorado during production of a planned Discovery Channel series. But union officials, safety consultants and producers say those numbers don't begin to reveal the extent of the problem.

Many incidents go unreported because crew members sign non-disclosure agreements and fear being blacklisted if they file lawsuits. Record-keeping is further muddled by the fact that many of the shows are nonunion, and workers are often classified as independent contractors. OSHA typically tracks only serious accidents involving employees and has no jurisdiction if the incident occurs in a foreign country.

"Reality has a lot of near-misses and things that happen that you never hear about," said Vanessa Holtgrewe, an industry veteran and former camera operator on "The Biggest Loser" and "The X Factor" who now works as an organizer for the International Alliance of Theatrical Stage Employees. "On a lot of these shows, you're completely on your own. There is no one you can call if you feel you're in a dangerous situation."

State and federal OSHA officials declined to comment specifically on incidents involving the reality TV sector.

Fireman's Fund estimated that it would underwrite 160 action-adventure reality shows in 2012, a 25 percent increase over the previous year. But it passed on about 50 other reality TV programs because they were deemed too risky, Diaz said.

"We had people who wanted to go to Mexico to follow the drug cartels around," Diaz said. "We had one show where they were going to blow up a mine. We told them we wouldn't insure the show."

Reality series have provided a huge revenue stream for cable and broadcast networks. The shows have lower production costs than scripted entertainment and tend to attract the younger viewers favored by advertisers.

Among the most popular are action-adventure shows such as the dramatic fishing series "The Deadliest Catch" and the Arctic driving drama "Ice Road Truckers," which give viewers an inside glimpse into gritty, hazardous real-life occupations. The number of shows on the air in this category rose from fewer than a dozen five years ago to nearly 60 in the current season, according to Bob Boden, a veteran executive producer and industry analyst.

The element of danger is vital to the marketing campaigns. History's "Outback Hunters," for example, touts the "dangerous work conditions" of hunters who risk "life and limb to hunt crocodiles in the Australian outback." A news release for "Ax Men" promises "mishaps involving falling trees, bone-crushing equipment, razor-sharp cables and human error."