David Rozga loved the Packers. He had a No. 4 tattoo for Brett Favre on his right shoulder, and he planned to add a No. 12 for Aaron Rodgers. He played football until he broke his leg as a sophomore in high school, and he often made the trip with his dad to Lambeau Field from his home in Indianola, Iowa. David Rozga dreamed of seeing the Pack win a Super Bowl.

He didn’t get the chance. Last June, he left a high school graduation party, returned home and took his own life.

David Rozga was 18.

His parents, Mike and Jan, blamed themselves. “It really made us look deeply at ourselves,” Mike says. “How terrible parents we were to not have seen this in our son.”

Two days later, David’s girlfriend, Carrie, came by with a confession: On the day he died, she said, David had been smoking a synthetic marijuana called K2, also known as Spice.

David’s parents had never heard of it. Carrie hadn’t, either. But when Mike Rozga called the police, he began to learn about an herbal blend sprayed with chemicals that mimic the high from marijuana. It’s marketed as incense but it is nothing like the stuff that makes your kitchen smell like potpourri.

Reporting by ThePostGame.com shows K2 use may be on the rise in the athlete population –- not only at various levels of amateur sport, but in professional sports as well. “I go straight weed in the off-season,” one NFL veteran told ThePostGame.com on condition of anonymity. “Then, in-season, when they test, I go to [K2].”

“It’s a danger to anybody who thinks this is a legal way to get high without being caught,” says Jay Schauben, director of the Florida Poison Control Center. “The possible side effects include significant hallucination, cardiac effects, seizures, rapid heart rate, hypertension, severe agitation, passing out, and panic attacks.”

Rozga believes a K2 high led to his son’s suicide. The Indianola police chief, Steve Bonnett, wrote a letter saying David “had a severe panic attack after smoking K2, which resulted in his death.”

“David suffered greatly,” Mike Rozga says. “He was tormented by this drug.”

Leading health experts believe more tragedy is to come -- and that athletes may be at particular risk.

“We’re receiving more reports of its use in the athlete population,” says Frank Uryasz, director of the National Center of Drug-Free Sport. “It appears to be marketed heavily to young people -- high school age and below, and college. We’re getting reports from colleges, where athletes are asking about it.”

One such report to the Drug-Free Sport hotline, from an NCAA athletic trainer, reads:

“Three student-athletes were breaking apart cigarettes, mixing it with K2, rolling it back up into papers and then smoking. One young man, who had NO past medical history, had a seizure and lost consciousness. He was found outside the dorm by campus security convulsing. His heart rate was elevated above 200 for enough time that he was admitted for 24 hours of observation … When asked why he did it: "I didn't think it would be that much of a rush, I had no control over my body in that I could see but could not talk or speak.”

Here’s another report, from another athletic trainer:

“We have a student-athlete who was in the emergency room over the weekend! Says he was smoking ‘Spice.’ His heart was racing, his blood pressure was off the charts, and he was hallucinating. This went on for hours!!”

K2, which was first identified in December 2008, has an active ingredient called JWH-018, which is very similar to the compound that produces the high of marijuana. But K2 does not produce a positive drug test, and that is part of why its use has skyrocketed in the U.S. over the last two years. According to the American Association of Poison Control Centers, there were 14 cases of K2 exposure in the 48 states plus the District of

Columbia in 2009. In 2010, that number exploded to 2,888. Already this year, there have been nearly 1,000. In the last four months alone, 151 Navy sailors have been accused of using or possessing the drug.

The U.S. Naval Academy expelled eight midshipmen last month for using K2.

Several forms of synthetic marijuana were added to the DEA’s controlled substance list last week, including JWH-018, but it’s virtually impossible to identify and ban all of them.

K2 is relatively inexpensive and widely available; it’s even sold at some gas stations, according to several experts. David Rozga got his at a mall near Des Moines, according to his father.

ThePostGame.com recently bought a three-gram package of “K2 Peach” at a smoke shop in Orlando for $59.95. The package said “Not for consumption,” and it came with a small leaflet that said “Not … for human consumption” three times.

But it is being consumed, and athletes who use it are at particular risk, some experts say. “For athletes, you run the danger of having cardiovascular effects,” says David Kroll, professor of pharmaceutical sciences at North Carolina Central University. “I would hypothesize that with enough people using this stuff, you’re bound to see a heart attack.”

Performance-enhancing drugs may add yet another layer of risk. “If you combine these products and steroids, I can’t begin to predict the negative consequences,” says Anthony Scalzo, director of toxicology at St. Louis University. “If you add these stresses to the heart, someone’s probably going to have a heart attack from it.”

But those who use it often fail to see the danger behind the high.

“I used it freshman year,” one Division I NCAA athlete told ThePostGame.com, on condition of anonymity. “We tried it and realized that it has similar effects to weed. It was the first time where you could do something that you shouldn’t be doing but you couldn’t get in trouble for it.”

There are no confirmed deaths from K2, however the Drug Abuse Warning Network reports there were 374 emergency room admits last year because of K2 and similar substances.

“Sometimes you feel like your heart is going to come out of your chest, going to explode,” says the D-I athlete. “Your pulse just goes up like crazy. You literally feel like sometimes you’re going to die. But you wake up the next morning and you’re like, ‘Whatever, it’s fine.’

“If you smoke weed, you’re just chill. When you smoke K2, you are (messed) up. Sometimes I felt almost like drops of water were landing on my body somewhere. You’ll feel like a cool drop somewhere and I’ll check but there’s nothing. It’s weird. It’ll trigger different kind of senses around your body.”

The DEA plans to keep K2 illegal for at least a year. The NCAA has also decided to ban it, effective August 1 of this year, but according to NCAA associate director of health and safety Mary Wilfert, “We don’t have a punishment until a student tests positive.” And tests for K2 are not widely accessible.

“This market is always going to be available,” says the D-I athlete. “No matter what laws they pass, there will be a way to get around it. I don’t think there’s a way to test for (K2), so athletes are going to use it. Athletes are going to keep doing stuff they can get away with.”

That’s Mike Rozga’s biggest fear. He started the site K2DrugFacts.com as a way to warn the public, but it’s too late to save his son. He watched the Packers win the Super Bowl in his home, weeks after spreading some of David’s ashes in an end zone at Lambeau Field.

“We would have watched the Super Bowl together, without a doubt,” Rozga says. “As a lifelong fan, I was really happy. But it was one of the many things I’ll never get to share with David. I’ll never go to another Packers game with him.”