A Healthier July Fourth To Light Up The Sky ! Chemists seek environmentally friendlier fireworks

It started with a migraine, not even five minutes after the fireworks show began. Damon Thorne tried to look away but the entire sky was lit up. "Even closing my eyes -- I could still see the fireworks through my eyelids," he says.

Then, his right hand began to quiver. Little points of light, much like the "stars" that compose a firework's bloom, panned across his field of view. This was Thorne's "aura," visible only to him, and a warning sign that a seizure was about to happen.

 

In what's called reflex epilepsy, the seizures can be sparked by things patients see or hear, even sense in the environment around them. A small percentage of people with epilepsy -- somewhere between 3 and 5 percent -- are considered photosensitive, because light can trigger their seizures. The source could be a computer monitor, a television or even sunlight reflecting off water in a certain way.

 

"There are literally thousands of different triggers for seizures," says Dr. John Gibbs, a neurologist who now treats Damon Thorne in Greeneville, N.C. "[Fireworks] certainly can mimic photostimulation."

From the rockets' red glare to bombs bursting in air, researchers are developing more environmentally friendly fireworks and flares to light up the night sky while minimizing potential health risks.

The big challenge in developing these "eco-friendly" pyrotechnics is making them as cost-effective as conventional fireworks while maintaining their dazzle and glow, the article states.

WHETHER THEY'RE lighting up Roman candles or basking in the glow of a fireworks extravaganza this Fourth of July, chemists are entitled to feel a certain amount of professional pride along with their patriotism. After all, it's chemistry that gives a humble bottle rocket its pop and makes a chrysanthemum shell bloom into a crowd-pleasing explosion of colored sparks.That v of the Arctic shows an ultraet e of electromagnetic radiation from the auroral oal during the Janary 1997 magnetic storm. Im provided ctesof Marshall Space Flight Center.

Even so, when it comes to pyrotechnics, students of chemistry would be wise to bear in mind this old adage from physics: What goes up must come down. The complex brew of oxidizers, propellants, fuels, binders, and coloring agents is what makes each firework's burst brilliant. But it leaves behind a smoky ghost of combustion products and particulate matter, which waft their way into the nearby soil and water.

The same thing happens when real rockets give off their red glare. Military pyrotechnics, which encompass everything from missile propellants to handheld flares, release a plume of smoke and potentially toxic products that pose a health hazard to the men and women of the armed forces who may breathe them in.

Consequently, chemists have been working to make new pyrotechnic compounds and formulations so that bombs bursting in air do so more benignly.

Typical pyrotechnics function by burning, so their basic chemical components consist of an oxidant and a fuel. Black powder, the original pyrotechnic, blends potassium nitrate oxidizer with charcoal and sulfur fuel. Set this witch's brew alight, and in a flash the nitrate oxidizes the charcoal and sulfur, producing glowing solids and a vast volume of hot gases. Other components, such as colorants, binders, and propellants, can be added to the mix, depending on the task the pyrotechnic has to perform.

Over the years, perchlorate has become the oxidizer of choice for most pyrotechnic applications, supplanting less stable chlorate oxidants that were the cause of numerous deadly explosions. "Potassium perchlorate is the ideal oxygen donor to use in pyrotechnics in terms of safety, cost, and reproducibility," says John A. Conkling, a pyrotechnics expert and adjunct professor of chemistry at Washington College, in Chestertown, Md.

Unfortunately, perchlorate has also been identified as a potential human health hazard. Studies suggest that it inhibits the thyroid's ability to take up iodine from the bloodstream and can reduce the production of thyroid hormone. And because the anion is highly water soluble, it readily slips into groundwater. "The major effort in most areas of environmentally friendly pyrotechnics research is to find perchlorate replacement materials," Conkling says.