Brightly colored powders, shot into the air at running events and some concerts, are designed to breathe excitement into those events.
But have you ever wondered how safe those powders are to breathe?
Promoters use words like "safe" and "non-toxic" to describe those powders.
But a NewsChannel 5 investigation discovered serious questions about those claims.
The brightly colored powders that are designed to make those runs fun. When you do one of these color runs it seems, the thinking goes, the more powder you can get all over yourself, the better.
"I got blasted with blue!" one participant in a recent Nashville race exclaimed.
We asked another pair of runners who were covered in this brightly colored powder, "Is this was you signed up for?"
Without missing a beat, they answered, "It is what we signed up for -- absolutely!"
At these races, runners are pelted with color along the course. Both before and after these races, runners all throw powder into the air at the same time to create giant clouds of powder.
One race director described it by saying, "It makes people look like human rainbows."
NewsChannel 5 Investigates asked Dr. Brian Christman, a lung specialist at Vanderbilt who serves on the American Lung Association's Scientific Advisory Board, about the health risks associated with these runs and breathing in all of the powder you find at these events.
"You'd be hard pressed to find a lung doctor who would advocate that," Christman said.
Doctors say even a small amount of this powder can cause breathing problems for anyone with asthma or other lung issues, as well as young children whose lungs aren't fully developed.
But it's the thick clouds of this fine powder that really concern Christman.
"That's a lot of particulate to be exposed to," the doctor said after watching video from one of these runs.
Christman said breathing in that much powder can be hazardous for just about everyone.
"Those particles can be in there for quite a while in your lungs," he explained, adding, "Some of these tinier particles can get absorbed, they get taken up into the lymphatics and the blood stream."
Testing Shows Color Runs Could Pose Fire Risks
Race promoters do warn that the powder can cause things like skin irritation and vision problems -- and many suggest runners "use a bandana or dust mask."
But scientists say many of the particles in these powders are so tiny, they'd go right through a bandana.
Dr. Ngee Sing Chong, an analytic chemist at Middle Tennessee State University, and Joyce Miller, manager of the university's imaging center, agreed to analyze nearly a dozen samples of colored powder for us.
By magnifying the powders some 2,000 times, you can see the tiny particles in most of the powders look like small smooth pebbles.
But this intense magnification revealed that one of pink powders tested was filled with sharp, jagged edges.
"They consist of very thin flakes and very elongated needle-like structures," described Dr. Chong, who said they could easily get lodged in the lungs and cause damage.
According to the various color run websites, the colored powder they use is simply dyed cornstarch.
MTSU's analysis found many of our samples did have the same chemical makeup as cornstarch or pancake mix.
But one of the pink powders we tested, Chong reported, "certainly it is not pancake mix. It's something else."
In fact, it most closely matched the chemical composition of Decon rat killer, which also was one of the top matches for one of the green powders we had analyzed.
"That closely resembles, at least, rat killer? Rat poison?" NewsChannel 5 Investigates asked Chong.
"Correct," he replied.
But Chong cautioned further testing is needed.
And even the powders that did appear to be cornstarch were concerning to Chong. He said he found solvents in all of the samples.
"Solvents typically are highly volatile -- are very volatile -- and they have a low flash point," Chong stated, which might explain, he said, why our fire testing found these powders ignite rather easily.
And all of the powders tested also had compounds known to cause cancer as well as various metals not usually found in cornstarch, like cobalt.
"Cobalt?" we asked MTSU's Joyce Miller.
"Cobalt, yes," she confirmed.
"And, what was that doing in there?" we probed.
"That's a good question," Miller replied.
All of these questions now lead some to wonder whether we really know enough about these powders.
Vanderbilt's Dr. Brian Christman said, "Until we have more analysis, I'm a little more concerned."
And some wonder if we should stop throwing caution to the wind.
Right now, these powders are not regulated in the U.S., nor has there been any sort of formal testing.
But the experts we talked to say, based on these findings, there should be.
The MTSU scientists say these were preliminary results.
Chong tells NewsChannel 5 Investigates he plans to continue to test and analyze these powders.
When we get those findings, we'll be sure to share them.