A July Fourth weekend hardly seems complete without the glorious sizzle and boom of fireworks. But are these pyrotechnics bad for the environment?

“Fireworks can unleash a shower of toxins into soil and water, and scientists are only beginning to figure out what that means for human health,” writes Russell McLendon on Mother Nature Network, an environmental website. He cites studies showing perchlorate levels in nearby wells and waterways rose dramatically after a fireworks show. He adds:

Fireworks displays have been eliminated in an increasing number of U.S. cities, largely because of budget cutbacks as well as fire and injury concerns. An effort to ban them in Hawaii cites their impact on human health and has the backing of the state’s American Lung Association, according to the Honolulu Advertiser.

McLendon says the eco-friendliest alternative to fireworks is to avoid them completely and instead go fishing or camping. He says other alternatives include laser light shows, which emit no dangerous chemicals, and Disneyland’s use of compressed air to launch fireworks, which reduce particulates in the air and perchlorates in the water.

Why’s he so concerned? Here are excerpts of his article:

In addition to gunpowder, fireworks are packed with heavy metals and other toxins that produce their sparkling shower of colors. Like perchlorates, the exact effect of fireworks’ heavy-metal fallout is still mainly a mystery, but scientists do know that the metals themselves can wreak havoc in the human body.

• Strontium (red): This soft, silvery-yellow metal turns red when it burns, is extremely reactive with both air and water, and can be radioactive. Some strontium compounds dissolve in water, and others move deep into soil and groundwater; radioactive strontium has a half-life of 29 years. While low levels of stable and radioactive strontium haven’t been shown to affect human health, they both can be dangerous at high doses.

• Aluminum (white): Since aluminum is the most abundant metal in Earth’s crust — and one of humanity’s most widely used — avoiding exposure is almost impossible. Virtually all food, water, air and soil contain some amount of aluminum — the average adult eats about 7 to 9 milligrams of the silvery-white metal every day in food. It’s generally safe at these levels, but it can affect the brain and lungs at higher concentrations.

• Copper (blue): Fireworks’ blue hues are produced by copper compounds. These aren’t very toxic on their own, but the copper jump-starts the formation of dioxins when perchlorates in the fireworks burn…. The most noted health effect of dioxin exposure is chloracne, a severe skin disease with acne-like lesions mostly on the face and upper body. Dioxin doesn’t stop there, though — the World Health Organization has identified it as a human carcinogen, and it’s also been shown to disrupt hormone production and glucose metabolism.

• Barium (green): Fish and other aquatic organisms can accumulate barium, which means it can move up the food chain. The silvery-white metal naturally bonds with other elements to form a variety of compounds that all have different effects — none are known to be carcinogenic, but they can cause gastrointestinal problems and muscular weakness when exposure exceeds EPA drinking water standards.

• Rubidium (purple): This soft, silvery metal is one of the most abundant elements on Earth. It burns purple, melts to a liquid at 104 degrees Fahrenheit and is highly reactive with water, capable of igniting fires even far below the freezing point. It hasn’t been reported to cause any major environmental damage, but it can cause skin irritation since it’s so reactive with moisture, and it’s moderately toxic when ingested, reportedly able to replace calcium in bones (PDF).

• Cadmium (various): Used to produce a wide range of fireworks colors, this mineral is also a known human carcinogen. Breathing high levels of cadmium can seriously damage the lungs, and consuming it can fluster the stomach, often resulting in vomiting and diarrhea.