Although the smoke may have cleared, the noxious chemicals released by the hundreds of fireworks shows that took place over the July 4th weekend still linger over America’s cities and waterways. Toxins like cadmium, barium, arsenic and perchlorates that are released into the atmosphere when the fireworks are set off can remain in the soil and water supply for years, causing irreparable damage to local ecosystems and human health.

The main ingredient in fireworks is gunpowder, composed of sulfur, charcoal and potassium. When that potassium is released into the atmosphere, it breaks down into perchlorate which is known to cause thyroid conditions including goiter and cancer. Although the majority of toxins are believed to be incinerated in the air, a study published earlier this year in the Environmental Science & Technology journal reported that following fireworks shows perchlorate levels in nearby bodies of water can be up to 1,000 times acceptable levels and take up to 80 days to subside. Heavy metals like strontium and copper used to give fireworks color can also have lasting effects on childhood development and cause health problems ranging from skin lesions to lung damage.

Short of eliminating fireworks entirely, researchers are currently working to develop fireworks that look the same, but have drastically safer chemical make-ups. Hoping to eliminate atmospheric perchlorates, nitrogen-rich formulas may be the best alternative to the traditional heavy-metal-laced fireworks. The prohibitive cost of nitrogen-based fireworks, however, may prevent the wider use of their environmentally-friendly alternatives.

photo credit: Barry Yanowitz’s Flickr photostream (creative commons)