As you gaze into the night sky this holiday weekend and marvel at the colorful fireworks display exploding before your eyes, give thanks that the founding fathers didn’t sign the Declaration of Independence on February 4, 1776.
Fireworks and snowfall, it seems, are a problematic combination.
That’s the conclusion of a 2008 study, one of several published in recent years that suggest these awe-inspiring fireworks displays may have unforeseen health and environmental consequences. This very old technology, which has been traced back to China’s Song Dynasty (960-1280 A.D.), has been delighting spectators for a millennium or more, but it may not be as benign as we tend to assume.
As Katharina Breitenecker of the International Atomic Energy Agency noted in 2009, the basic component of fireworks is black powder — a mix of 75 percent potassium nitrate, 15 percent charcoal and 10 percent sulfur.
“Without the addition of a coloring agent, the fuel would provide an almost white light,” she wrote in the journal Environmental Research Letters. “Therefore, several metal salts can be added to cause colorful luminescence upon combustion. In general, barium is used to obtain a green colored flame, strontium for red, copper for blue and sodium for yellow.”
If you’re wondering why someone from the IAEA was writing about fireworks, the answer is … the one you feared. She was introducing an article by Georg Steinhauser and Andreas Musilek of the Vienna University of Technology, which asked “Do pyrotechnics contain radium?”
Their answer: Yes, albeit at low levels. In Breitenecker’s words, fireworks “contain a certain amount of radioactive material.”
“Due to their chemical similarities to radium, barium and strontium ores can accumulate radium, causing a remarkable activity in these minerals,” Steinhauser and Musilek explained. Especially when they are used indoors — say, in a large sports arena — “the health aspects of pyrotechnic devices should be taken seriously with respect to air pollution by toxic and radioactive substances,” the researchers added.
Radiation fears aside, barium can pose significant health hazards, according to Steinhauser. He was also the lead author of the aforementoned 2008 paper, which analyzed fallen snow before and after a New Year’s fireworks display in the Austrian town of Saalbach.
His team found that in some locations, on the day after the display, concentrations of barium were 500 times higher than they were the day before. That’s troublesome, since barium poisoning has been found to constrict airways, thereby aggravating asthma symptoms.
OK — can’t they just shoot off the fireworks over a body of water? Sadly, it appears that, too, could be problematic.
“Perchlorate salts of potassium and ammonium are the primary oxidants in pyrotechnic mixtures,” a research team led by Richard Wilkin of the U.S. Environmental Protection Agency wrote in the journal Environmental Science and Technology in 2007. They noted that these salts “are highly soluble in water,” which is a potential problem since “perchlorate ingestion may pose an adverse health risk.”
“Perchlorate interferes with the production of thyroid hormones required for normal metabolism and the development of mental functions,” they wrote. Human health concerns aside, “Elevated perchlorate concentrations may also pose a risk to aquatic ecosystems,” they added.
The researchers collected surface water samples along the shoreline of a small lake in Ada, Okla., following Fourth of July fireworks displays in 2004, 2005 and 2006, as well as a late-fall fireworks fiesta in 2005. After each display, they found “spikes in perchlorate concentrations significantly above background levels.” In one case, the concentration exceeded the allowable level in drinking water in several states.
Fortunately, they found that in the Oklahoma lake, the perchlorate degraded rapidly, thanks to “the availability of organic carbon to provide energy for perchlorate-reducing bacteria.” But they added that this welcome process occurs “in the absence of nitrate.”
While nitrate occurs naturally in some groundwater, concern has been raised in recent years about increased concentrations, due to runoff contaminated with (among other things) fertilizers. This study suggests yet another reason this trend could be worrisome.
No one is arguing that the risk of fireworks is so great they should be banned. But together, these studies suggest the importance of ongoing research to create more environmentally friendly pyrotechnics, based on nitrogen-rich compounds that are free of heavy metals and perchlorates.
Fireworks can produce a rainbow of colors, but there are very good reasons to try to make them greener.